Configuring Data-Link Switching Plus
This chapter describes how to configure data-link switching plus (DLSw+), Cisco’s implementation of
the DLSw standard for Systems Network Architecture (SNA) and NetBIOS devices. Refer to the DLSw+
Design and Implementation Guide for more complex configuration instructions. For a complete
description of the DLSw+ commands mentioned in this chapter, refer to the “DLSw+ Commands”
chapter of the Cisco IOS Bridging and IBM Networking Command Reference (Volume 1 of 2). To locate
documentation of other commands that appear in this chapter, use the command reference master index
or search online.
This chapter contains the following sections:
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To identify the hardware platform or software image information associated with a feature, use the
Feature Navigator on Cisco.com to search for information about the feature or refer to the software
release notes for a specific release. For more information, see the “Identifying Platform Support for
Cisco IOS Software Features” section on page lv in the “Using Cisco IOS Software” chapter.
Technology Overview
DLSw+ is a method of transporting SNA and NetBIOS. It complies with the DLSw standard documented
in RFC 1795 and the DLSw Version 2 standard. DLSw+ is an alternative to RSRB that addresses several
inherent problems that exist in RSRB, such as:
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SRB hop-count limits (SRB’s limit is seven)
Broadcast traffic (including SRB explorer frames or NetBIOS name queries)
Unnecessary traffic (acknowledgments and keepalives)
Data-link control timeouts
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UDP Unicast
DLSw Version 2 uses UDP unicast in response to an IP multicast. When address resolution packets
(CANUREACH_EX, NETBIOS_NQ_ex, NETBIOS_ANQ, and DATAFRAME) are sent to multiple
destinations (IP multicast service), DLSw Version 2 sends the response frames (ICANREACH_ex and
NAME_RECOGNIZED_ex) via UDP unicast.
UDP unicast uses UDP source port 0. However, some firewall products treat packets that use UDP source
port 0 as security violations, discarding the packets and preventing DLSw connections. To avoid this
situation, use one of the following procedures:
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Configure the firewall to allow UDP packets to use UDP source port 0.
Use the dlsw udp-disable command to disable UDP unicast and send address resolution packets in
the existing TCP session.
Enhanced Peer-on-Demand Routing Feature
DLSw Version 2 establishes TCP connections only when necessary and the TCP connections are brought
down when there are no circuits to a DLSw peer for a specified amount of time. This method, known as
peer-on-demand routing, was recently introduced in DLSw Version 2, but has been implemented in Cisco
DLSw+ border peer technology since Cisco IOS Release 10.3.
Expedited TCP Connection
DLSw Version 2 efficiently establishes TCP connections. Previously, DLSw created two unidirectional
TCP connections and then disconnected one after the capabilities exchange took place. With DLSw
Version 2, a single bidirectional TCP connection establishes if the peer is brought up as a result of an IP
multicast/UDP unicast information exchange.
DLSw+ Features
DLSw+ is Cisco’s version of DLSw and it supports several additional features and enhancements.
DLSw+ is a means of transporting SNA and NetBIOS traffic over a campus or WAN. The end systems
can attach to the network over Token Ring, Ethernet, Synchronous Data Link Control (SDLC) Protocol,
Qualified Logical Link Control (QLLC), or Fiber Distributed Data Interface (FDDI). See the DLSw+
Design and Implementation Guide Appendix B, “DLSw+ Support Matrix,” for details. DLSw+ switches
between diverse media and locally terminates the data links, keeping acknowledgments, keepalives, and
polling off the WAN. Local termination of data links also eliminates data-link control timeouts that can
occur during transient network congestion or when rerouting around failed links. Finally, DLSw+
provides a mechanism for dynamically searching a network for SNA or NetBIOS resources and includes
caching algorithms that minimize broadcast traffic.
DLSw+ is fully compatible with any vendor’s RFC 1795 implementation and the following features are
available when both peers are using DLSw+:
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Peer groups and border peers
Backup peers
Promiscuous and on-demand peers
Explorer firewalls and location learning
NetBIOS dial-on-demand routing feature support
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Technology Overview
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UDP unicast support
Load balancing
Support for LLC1 circuits
Support for multiple bridge groups
Support for RIF Passthrough
SNA type of service feature support
Local acknowledgment for Ethernet-attached devices and media conversion for SNA PU 2.1 and
PU 2.0 devices
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Conversion between LLC2 to SDLC between PU 4 devices
Local or remote media conversion between LANs and either SDLC Protocol or QLLC
SNA View, Blue Maps, and Internetwork Status Monitor (ISM) support
MIB enhancements that allow DLSw+ features to be managed by the CiscoWorks Blue products, SNA
Maps, and SNA View. Also, new traps alert network management stations of peer or circuit failures. For
more information, refer to the current Cisco IOS release note for the location of the Cisco MIB website.
Local Acknowledgment
When you have LANs separated by wide geographic distances, and you want to avoid sending data
multiple times, and the loss of user sessions that can occur with time delays, encapsulate the source-route
bridged traffic inside IP datagrams passed over a TCP connection between two routers with local
acknowledgment enabled.
Logical Link Control, type 2 (LLC2) is an ISO standard data-link level protocol used in Token Ring
networks. LLC2 was designed to provide reliable sending of data across LAN media and to cause
minimal or at least predictable time delays. However, DLSw+ and WAN backbones created LANs that
are separated by wide, geographic distances-spanning countries and continents. As a result, LANs have
time delays that are longer than LLC2 allows for bidirectional communication between hosts. Local
acknowledgment addresses the problem of unpredictable time delays, multiple sendings, and loss of user
sessions.
In a typical LLC2 session, when one host sends a frame to another host, the sending host expects the
receiving host to respond positively or negatively in a predefined period of time commonly called the T1
time. If the sending host does not receive an acknowledgment of the frame it sent within the T1 time, it
retries a few times (normally 8 to 10). If there is still no response, the sending host drops the session.
Figure 127 illustrates an LLC2 session in which a 37x5 on a LAN segment communicates with a 3x74
on a different LAN segment separated via a wide-area backbone network. Frames are transported
between Router A and Router B by means of DLSw+. However, the LLC2 session between the 37x5 and
the 3x74 is still end-to-end; that is, every frame generated by the 37x5 traverses the backbone network
to the 3x74, and the 3x74, on receipt of the frame, acknowledges it.
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Figure 127 LLC2 Session w ithout Local Acknow ledgm ent
Router B
Router A
Token
Ring
Token
Ring
WAN
37x5
3x74
LLC2 session
SNA session
On backbone networks consisting of slow serial links, the T1 timer on end hosts could expire before the
frames reach the remote hosts, causing the end host to resend. Resending results in duplicate frames
reaching the remote host at the same time as the first frame reaches the remote host. Such frame
duplication breaks the LLC2 protocol, resulting in the loss of sessions between the two IBM machines.
One way to solve this time delay is to increase the timeout value on the end nodes to account for the
maximum transit time between the two end machines. However, in networks consisting of hundreds or
even thousands of nodes, every machine would need to be reconfigured with new values. With local
acknowledgment for LLC2 enabled, the LLC2 session between the two end nodes would not be not
end-to-end, but instead, would terminate at two local routers. Figure 128 shows the LLC2 session with
the 37x5 ending at Router A and the LLC2 session with the 3x74 ending at Router B. Both Router A and
Router B execute the full LLC2 protocol as part of local acknowledgment for LLC2.
Figure 128 LLC2 Session w ith Local Acknow ledgm ent
TCP session
Token
Ring
Token
Ring
WAN
37x5
Router A
Router B
3x74
LLC2 session
LLC2 session
SNA session
With local acknowledgment for LLC2 enabled in both routers, Router A acknowledges frames received
from the 37x5. The 37x5 still operates as if the acknowledgments it receives are from the 3x74. Router
A looks like the 3x74 to the 37x5. Similarly, Router B acknowledges frames received from the 3x74. The
3x74 operates as if the acknowledgments it receives are from the 37x5. Router B looks like the 3x74 to
37x5. Because the frames do not have to travel the WAN backbone networks to be acknowledged, but
are locally acknowledged by routers, the end machines do not time out, resulting in no loss of sessions.
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Enabling local acknowledgment for LLC2 has the following advantages:
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Local acknowledgment for LLC2 solves the T1 timer problem without having to change any
configuration on the end nodes. The end nodes are unaware that the sessions are locally
acknowledged. In networks consisting of hundreds or even thousands of machines, this is a definite
advantage. All the frames acknowledged by the Cisco IOS software appear to the end hosts to be
coming from the remote IBM machine. In fact, by looking at a trace from a protocol analyzer, one
cannot say whether a frame was acknowledged by the local router or by a remote IBM machine. The
MAC addresses and the RIFs generated by the Cisco IOS software are identical to those generated
by the remote IBM machine. The only way to find out whether a session is locally acknowledged is
to use either a show local-ack command or a show source-bridge command on the router.
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All the supervisory (RR, RNR, REJ) frames that are locally acknowledged go no farther than the
router. Without local acknowledgment for LLC2, every frame traverses the backbone.
With local acknowledgment, only data (I-frames) traverse the backbone, resulting in less traffic on
the backbone network. For installations in which customers pay for the amount of traffic passing
through the backbone, this could be a definite cost-saving measure. A simple protocol exists
between the two peers to bring up or down a TCP session.
Notes on Using LLC2 Local Acknowledgment
LLC2 local acknowledgment is enabled with TCP and DLSw+ Lite remote peers.
If the LLC2 session between the local host and the router terminates in either router, the other will be
informed to terminate its connection to its local host.
If the TCP queue length of the connection between the two routers reaches the high-water mark, the
routers sends Receiver-Not-Ready (RNR) messages to the local hosts until the queue limit is reduced to
below this limit. It is possible, however, to prevent the RNR messages from being sent by using the dlsw
llc2 nornr command.
The configuration of the LLC2 parameters for the local Token Ring interfaces can affect overall
performance. Refer to the chapter “Configuring LLC2 and SDLC Parameters” in this manual for more
details about fine-tuning your network through the LLC2 parameters.
The routers at each end of the LLC2 session execute the full LLC2 protocol, which could result in
significant router overhead. The decision to use local acknowledgment for LLC2 should be based on the
speed of the backbone network in relation to the Token Ring speed. For LAN segments separated by
slow-speed serial links (for example, 56 kbps), the T1 timer problem could occur more frequently. In
such cases, it might be wise to turn on local acknowledgment for LLC2. For LAN segments separated
by a T1, backbone delays will be minimal; in such cases, DLSw+, FST or direct encapsulation should
be considered in order to disable local acknowledgement. Speed mismatch between the LAN segments
and the backbone network is one criterion to help you decide to use local acknowledgment for LLC2.
There are some situations (such as the receiving host failing between the time the sending host sends
data and the time the receiving host receives it), in which the sending host would determine, at the LLC2
layer, that data was received when it actually was not. This error occurs because the router acknowledges
that it received data from the sending host before it determines that the receiving host can actually
receive the data. But because both NetBIOS and SNA have error recovery in situations where an end
device goes down, these higher-level protocols will resend any missing or lost data. Because these
transaction request/confirmation protocols exist above LLC2, they are not affected by tight timers, as is
LLC2. They also are transparent to local acknowledgment.
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If you are using NetBIOS applications, note that there are two NetBIOS timers—one at the link level
and one at the next higher level. Local acknowledgment for LLC2 is designed to solve link timeouts only.
If you are experiencing NetBIOS session timeouts, you have two options:
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Experiment with increasing your NetBIOS timers and decreasing your maximum NetBIOS frame
size.
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Avoid using NetBIOS applications on slow serial lines.
Note
By default, the Cisco IOS software translates Token Ring LLC2 to Ethernet 802.3 LLC2. To
configure the router to translate Token Ring LLC2 frames into Ethernet 0x80d5 format frames, refer
to the section “Enable Token Ring LLC2-to-Ethernet Conversion” in the “Configuring Source-Route
Bridging” chapter of the Cisco IOS Bridging and IBM Networking Command Reference (Volume 1
of 2).
DLSw+ Support for Other SNA Features
DLSw+ can be used as a transport for SNA features such as LNM, DSPU, SNA service point, and SNA
Switching Services (SNASw) through a Cisco IOS feature called virtual data-link control (VDLC).
LNM over DLSw+ allows DLSw+ to be used in Token Ring networks that are managed by IBM’s LNM
software. Using this feature, LNM can be used to manage Token Ring LANs, control access units, and
Token Ring attached devices over a DLSw+ network. All management functions continue to operate as
they would in a source-route bridged network or an RSRB network.
DSPU over DLSw+ allows Cisco’s DSPU feature to operate in conjunction with DLSw+ in the same
router. DLSw+ can be used either upstream (toward the mainframe) or downstream (away from the
mainframe) of DSPU. DSPU concentration consolidates the appearance of multiple PUs into a single PU
appearance to VTAM, minimizing memory and cycles in central site resources (VTAM, NCP, and
routers) and speeding network startup.
SNA service point over DLSw+ allows Cisco’s SNA service point feature to be used in conjunction with
DLSw+ in the same router. Using this feature, SNA service point can be configured in remote routers,
and DLSw+ can provide the path for the remote service point PU to communicate with NetView. This
allows full management visibility of resources from a NetView 390 console, while concurrently offering
the value-added features of DLSw+ in an SNA network.
SNASw over DLSw+ allows Cisco’s APPN Branch Extender functionality to be used in conjunction with
DLSw+ in the same router. With this feature, DLSw+ can be used to access SNASw in the data center.
DLSw+ can also be used as a transport for SNASw upstream connectivity, providing nondisruptive
recovery from failures.
Using DLSw+ as a transport for other Cisco IOS SNA features requires a feature called VDLC.
Cisco IOS data-link users (such as LNM, DSPU, SNA service point, and SNASw) write to a virtual
data-link control interface. DLSw+ then reads from this interface and sends out the traffic. Similarly,
DLSw+ can receive traffic destined for one of these data-link users and write it to the virtual data-link
control interface, from which the appropriate data-link user will read it.
controls, and use virtual data-link control to communicate between themselves. When one of the
high-layer protocols passes data to the virtual data-link control, the virtual data-link control must pass
it to a higher-layer protocol; nothing leaves the virtual data-link control without going through a
data-link user.
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Figure 129 VDLC Interaction w ith Higher-Layer Protocols
DLSw+
Data-link users
SNASw
CLSI
Token
Ring
Data-link controls
Ethernet
VDLC
The higher-layer protocols make no distinction between the VDLC and any other data-link control, but
they do identify the VDLC as a destination. In the example shown in Figure 129, SNASw has two ports:
a physical port for Token Ring and a virtual port for the VDLC. When you define the SNASw VDLC
port, you can specify the MAC address assigned to it. Data transport from SNASw to DLSw+ by way of
the VDLC is directed to the VDLC MAC address. The type of higher-layer protocol you use determines
how the VDLC MAC address is assigned.
DLSw+ Configuration Task List
DLSw+ supports local or remote media conversion between LANs and SDLC or QLLC.
To configure DLSw+, complete the tasks in the following sections:
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Defining a DLSw+ Local Peer for the Router
Defining a DLSw+ local peer for a router enables DLSw+. Specify all local DLSw+ parameters as part
of the local peer definition. To define a local peer, use the following command in global configuration
mode:
Command
Purpose
Router(config)# dlsw local peer [peer-id
ip-address] [group group] [border] [cluster
cluster-id] [cost cost] [lf size] [keepalive
seconds] [passive] [promiscuous]
Defines the DLSw+ local peer.
[init-pacing-window size] [max-pacing-window
size] [biu-segment]
The following is a sample dlsw local peer statement:
dlsw local peer peer-id 10.2.34.3
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Defining a DLSw+ Remote Peer
Defining a remote peer in DLSw+ is optional, however, usually at least one side of a peer connection has
a dlsw remote-peer statement. If you omit the dlsw remote-peer command from a DLSw+ peer
configuration, then you must configure the promiscuous keyword on the dlsw local-peer statement.
Promiscuous routers will accept any peer connection requests from other routers that are not
preconfigured. To define a remote peer, use the dlsw remote-peer command in global configuration
mode.
One of the options in the remote peer statement is to specify an encapsulation type. Configure one of the
following types of encapsulations with the dlsw remote-peer statement:
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Which encapsulation type you choose depends on several factors, including whether you want to
terminate the LLC flows. TCP and DLSw+ Lite terminate the LLC, but the other encapsulation types do
not. For details on each encapsulation type, see the DLSw+ Design and Implementation Guide. See the
“Local Acknowledgement” section in the overview chapter of this publication for a discussion on local
acknowledgement.
TCP Encapsulation
To configure TCP encapsulation on a remote peer, use the following command in global configuration
mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number tcp
ip-address [
Defines a remote peer with TCP encapsulation.
[ip-address | frame-relay interface serial
number dlci-number | interface name]]
[bytes-netbios-out bytes-list-name]
[circuit-weight weight] [cluster cluster-id]
[cost cost] [dest-mac mac-address]
[dmac-output-list access-list-number]
[host-netbios-out host-list-name] [inactivity]
[dynamic] [keepalive seconds] [lf size] [linger
minutes] [lsap-output-list list] [no-llc
minutes] [passive] [priority] [rif-passthru
virtual-ring-number] [tcp-queue-max size]
[timeout seconds]
The following command specifies a dlsw remote peer with TCP encapsulation:
dlsw remote-peer 0 tcp 10.23.4.5
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TCP/IP with RIF Passthrough Encapsulation
To configure TCP/IP with RIF Passthrough encapsulation, use the following command in global
configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number tcp
ip-address [backup-peer [ip-address |
frame-relay interface serial number dlci-number
|interface name]] [bytes-netbios-out
bytes-list-name] [circuit-weight weight] [cost
cost] [dest-mac mac-address] [dmac-output-list
access-list-number] [host-netbios-out
host-list-name] [inactivity] [dynamic]
[keepalive seconds] [lf size] [linger minutes]
[lsap-output-list list] [no-llc minutes]
[passive] [priority] [rif-passthru
Defines a remote peer with TCP/IP with RIF Passthrough
encapsulation.
virtual-ring-number] [tcp-queue-max size]
[timeout seconds]
The following command specifies a remote peer with TCP/IP with RIF Passthrough encapsulation:
dlsw remote-peer 0 tcp 10.2.23.5 rif-passthru 100
FST Encapsulation
To configure FST encapsulation on a remote peer, use the following command in global configuration
mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number fst
ip-address [backup-peer [ip-address |
frame-relay interface serial number dlci-number
| interface name]]
Defines a remote peer with FST encapsulation.
[bytes-netbios-out bytes-list-name]
[circuit-weight weight] [cost cost] [dest-mac
mac-address] [dmac-output-list
access-list-number] [host-netbios-out
host-list-name] [keepalive seconds] [lf size]
[linger minutes] [lsap-output-list list]
The following command specifies a DLSw remote peer with FST encapsulation:
dlsw remote-peer 0 fst 10.2.23.5
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Direct Encapsulation
To configure direct encapsulation, use the following command in global configuration mode:
Command
Purpose
Defines a remote peer with direct encapsulation.
Router(config)# dlsw remote-peer list-number
frame-relay interface serial number dlci-number
[backup-peer [ip-address | frame-relay interface
serial number dlci-number | interface name]]
[bytes-netbios-out bytes-list-name]
[circuit-weight weight] [cost cost] [dest-mac
mac-address] [dmac-output-list
access-list-number] [host-netbios-out
host-list-name] [keepalive seconds] [lf size]
[linger minutes] [lsap-output-list list]
pass-thru
Direct encapsulation is supported over High-Level Data Link Control (HDLC) and Frame Relay.
The following command specifies a DLSw remote peer with direct encapsulation over HDLC:
dlsw remote-peer 0 interface serial 01
Direct encapsulation over Frame Relay comes in two forms: DLSw Lite (LLC2 encapsulation) and
Passthrough. Specifying the pass-thru option configures the router so that the traffic will not be locally
acknowledged. (DLSw+ normally locally acknowledges traffic to keep traffic on the WAN to a
minimum.)
The following command specifies a DLSw remote peer with Direct encapsulation with pass-thru over
Frame Relay:
dlsw remote-peer 0 frame-relay interface serial 01 pass-thru
DLSw Lite Encapsulation
To configure DLSw Lite encapsulation, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number
frame-relay interface serial number dlci-number
[backup-peer [ip-address | frame-relay interface
serial number dlci-number | interface name]]
[bytes-netbios-out bytes-list-name]
Defines a remote peer with DLSw Lite encapsulation.
[circuit-weight weight] [cost cost] [dest-mac
mac-address] [dmac-output-list
access-list-number] [host-netbios-out
host-list-name] [keepalive seconds] [lf size]
[linger minutes] [lsap-output-list list]
pass-thru
The following command specifies a DLSw remote peer with DLSw Lite encapsulation over Frame
Relay:
dlsw remote-peer 0 frame-relay interface serial 01
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Mapping DLSw+ to a Local Data-Link Control
In addition to configuring local and remote peers, you must map one of the following local data-link
controls to DLSw+:
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Token Ring
Traffic that originates from Token Ring is source-route bridged from the local ring onto a source-bridge
ring group and then picked up by DLSw+. You must include a source-bridge ring-group command that
specifies a virtual ring number when configuring Token Ring with DLSw+. In addition, you must
configure the source-bridge command that tells the DLSw+ router to bridge from the physical Token
Ring to the virtual ring.
To specify a virtual ring number, use the following command in global configuration mode:
Command
Purpose
Router(config)# source-bridge ring-group
ring-group [virtual-mac-address]
Defines a virtual ring.
To enable DLSw+ to bridge from the physical Token Ring ring to the virtual ring, use the following
command in interface mode:
Command
Purpose
Router(config-if)# source-bridge
source-ring-number bridge-number
target-ring-number
Defines SRB on interface.
To enable single-route explorers, use the following command in interface mode:
Command
Purpose
Router(config-if)# source-bridge spanning
Enables single-route explorers.
Configuring the source-bridge spanning command is required because DLSw+ uses single-route
explorers by default.
The following command configures a source-bridge ring-group and a virtual ring with a value of
100 to DLSw+:
source-bridge ring-group 100
int T0
source-bridge 1 1 100
source-bridge spanning
The ring-group number specified in the source-bridge command must be the number of a defined
source-bridge ring-group or DLSw+ will not see this interface.
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Ethernet
Traffic that originates from Ethernet is picked up from the local Ethernet interface bridge group and
transported across the DLSw+ network. Therefore, you must map a specific Ethernet bridge group to
DLSw+.
To map an Ethernet bridge group to DLSw+, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw bridge-group group-number
[llc2 [N2 number] [ack-delay-time milliseconds]
[ack-max number] [idle-time milliseconds]
[local-window number] [t1-time milliseconds]
[tbusy-time milliseconds] [tpf-time
Links DLSw+ to the bridge group of the Ethernet LAN.
milliseconds] [trej-time milliseconds]
[txq-max number] [xid-neg-val-time milliseconds]
[xid-retry-time milliseconds]] [locaddr-priority
lu address priority list number] [sap-priority
priority list number]
To assign the Ethernet interface to a bridge group, use the following command in interface configuration
mode:
Command
Purpose
Router(config-if)# bridge-group bridge-group
Assigns the Ethernet interface to a bridge group.
The following command maps bridge-group 1 to DLSw+:
dlsw bridge-group 1
int E1
bridge-group 1
bridge 1 protocol ieee
SDLC
Configuring SDLC devices is more complicated than configuring Ethernet and Token Ring. There are
several considerations that affect which interface commands are configured. See the DLSw+ Design and
Implementation Guide for more details.
To establish devices as SDLC stations, use the following commands in interface configuration mode:
Command
Purpose
Router(config-if)# encapsulation
sdlc
Step 1
Step 2
Step 3
Step 4
Step 5
Sets the encapsulation type of the serial interface to SDLC.
Router(config-if)# sdlc role {none |
primary | secondary | prim-xid-poll}
Establishes the role of the interface.
Router(config-if)# sdlc vmac
mac-address1
Configures a MAC address for the serial interface.
Assigns a set of secondary stations attached to the serial link.
Router(config-if)# sdlc address
hexbyte [echo]
Router(config-if)# sdlc partner
mac-address sdlc-address {inbound |
outbound}
Specifies the destination address with which an LLC session is
established for the SDLC station.
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Command
Purpose
Router(config-if)# sdlc xid
Step 6
Step 7
Specifies an XID value appropriate for the designated SDLC station
associated with this serial interface.
Router(config-if)# sdlc dlsw
{sdlc-address | default | partner
mac-address [inbound | outbound]}
Enables DLSw+ on an SDLC interface.
1. The last byte of the MAC address must be 00.
Use the default option if you have more than 10 SDLC devices to attach to the DLSw+ network. To
configure an SDLC multidrop line downstream, you configure the SDLC role as either primary or
prim-xid-poll. SDLC role primary specifies that any PU without the xid-poll parameter in the
sdlc address command is a PU 2.0 device. SDLC role prim-xid-poll specifies that every PU is type 2.1.
We recommend that you specify sdlc role primary if all SDLC devices are type PU 2.0 or a mix of
PU 2.0 and PU 2.1. Specify sdlc role prim-xid-poll if all devices are type PU 2.1.
To configure DLSw+ to support LLC2-to-SDLC conversion for PU 4 or PU 5 devices, specify the echo
option in the sdlc address command. A PU 4-to-PU 4 configuration requires that none be specified in
the sdlc role command.
on page 319 for sample configurations.
The following configuration shows a DLSw+ router configured for SDLC:
dlsw local-peer peer-id 10.2.2.2
dlsw remote-peer 0 tcp 10.1.1.1
interface Serial1
mtu 6000
no ip address
encapsulation sdlc
no keepalive
nrzi-encoding
clockrate 9600
sdlc vmac 4000.3745.0000
sdlc N1 48016
sdlc address 04 echo
sdlc partner 4000.1111.0020 04
sdlc dlsw 4
QLLC
SNA devices use QLLC when connecting to X.25 networks. QLLC essentially emulates SDLC over
x.25. Therefore, configuring QLLC devices is also complicated. There are several considerations that
affect which interface commands are configured. See the DLSw+ Design and Implementation Guide for
details.
You can configure DLSw+ for QLLC connectivity, which enables both of the following scenarios:
•
Remote LAN-attached devices (physical units) or SDLC-attached devices can access an FEP or an
AS/400 over an X.25 network.
Our QLLC support allows remote X.25-attached SNA devices to access an FEP without requiring
X.25 NCP Packet Switching Interface (NPSI) in the FEP. This may eliminate the requirement for
NPSI (if GATE and DATE are not required), thereby eliminating the recurring license cost. In
addition, because the QLLC attached devices appear to be Token Ring-attached to the Network
Control Program (NCP), they require no preconfiguration in the FEP. Remote X.25-attached SNA
devices can also connect to an AS/400 over Token Ring using this support.
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•
Remote X.25-attached SNA devices can access an FEP or an AS/400 over a Token Ring or over
SDLC.
For environments just beginning to migrate to LANs, our QLLC support allows deployment of
LANs in remote sites while maintaining access to the FEP over existing NPSI links. Remote
LAN-attached devices (physical units) or SDLC-attached devices can access a FEP over an X.25
network without requiring X.25 hardware or software in the LAN-attached devices. The Cisco IOS
software supports direct attachment to the FEP over X.25 without the need for routers at the data
center for SNA traffic.
To enable QLLC connectivity for DLSw+, use the following commands in interface configuration mode:
Command
Purpose
Router(config-if)# encapsulation x
25
Step 1
Step 2
Step 3
Specifies an interface as an X.25 device.
Router(config-if)# x25 address
subaddress
Activates X.25 subaddresses.
Router(config-if)# x25 map qllc
virtual-mac-addr x121-addr
[cud cud-value] [x25-map-options]
Associates a virtual MAC address with the X.121 address of the remote
X.25 device.
Router(config-if)# qllc dlsw
{subaddress subaddress | pvc pvc-low
[pvc-high]} [vmac vmacaddr
[poolsize]] [partner
Step 4
Enables DLSw+ over QLLC.
partner-macaddr] [sap ssap dsap]
[xid xidstring] [npsi-poll]
The following configuration enables QLLC connectivity for DLSw+:
dlsw local-peer peer-id 10.3.12.7
dlsw remote-peer 0 tcp 10.3.1.4
interface S0
encapsulation x25
x25 address 3110212011
x25 map qllc 1000.0000.0001 3 1104150101
qllc dlsw partner 4000.1151.1234
FDDI
Configure an FDDI interface the same as a Token Ring or Ethernet interface, depending on whether you
are configuring SRB or Transparent Bridging. If you are configuring the router for SRB, configure the
FDDI interface for Token Ring. If you are configuring the router for Transparent Bridging, configure the
FDDI interface for Ethernet.
Configuring Advanced Features
DLSw+ goes beyond the standard to include additional functionality in the following areas:
•
•
traffic, which enhances their scalability.
multiple active peers, ports, and channel gateways.
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•
•
according to those capabilities.
Network Management, page 307—Works with enhanced network management tools such as
CiscoWorks Blue Maps, CiscoWorks SNA View, and CiscoWorks Blue Internetwork Status Monitor
(ISM).
•
•
Traffic Bandwidth and Queueing Management, page 307—Offers several bandwidth management
and queueing features to enhance the overall performance of your DLSw+ network. Controls
different types of explorer traffic using multiple queues, each with a wide range of depth settings.
Access Control, page 307—Provides access control to various resources throughout a network.
Scalability
One significant factor that limits the size of Token Ring internet works is the amount of explorer traffic
that traverses the WAN. DLSw+ includes the following features to reduce the number of explorers:
•
•
•
•
•
•
•
•
Peer Groups and Border Peers
Perhaps the most significant optimization in DLSw+ is a feature known as peer groups. Peer groups are
designed to address the broadcast replication that occurs in a fully meshed network. When any-to-any
communication is required (for example, for NetBIOS or Advanced Peer-to-Peer Networking [APPN]
environments), RSRB or standard DLSw implementations require peer connections between every pair
of routers. This setup is not only difficult to configure, but it results in branch access routers having to
replicate search requests for each peer connection. This setup wastes bandwidth and router cycles. A
better concept is to group routers into clusters and designate a focal router to be responsible for broadcast
replication. This capability is included in DLSw+.
With DLSw+, a cluster of routers in a region or a division of a company can be combined into a peer
group. Within a peer group, one or more of the routers is designated to be the border peer. Instead of all
routers peering to one another, each router within a group peers to the border peer; and border peers
establish peer connections with each other. When a DLSw+ router receives a TEST frame or NetBIOS
NAME-QUERY, it sends a single explorer frame to its border peer. The DLSw+ border peer router
checks its local, remote and group cache for any reachability information before forwarding the explorer.
If no match is found, the border peer forwards the explorer on behalf of the peer group member. If a
match is found, the border peer sends the explorer to the appropriate peer or border peer. This setup
eliminates duplicate explorers on the access links and minimizes the processing required in access
routers.
You can further segment DLSw+ routers within the same border peer group that are serving the same
LANs into a peer cluster. This segmentation reduces explorers because the border peer recognizes that
it only has to forward an explorer to one member within a peer cluster. Only TCP encapsulation can be
used with the DLSw+ Peer Clusters feature.
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The DLSw+ Peer Clusters feature is configured locally on the member peer or on a border peer. Although
both options can be configured, we recommend that the cluster-id of a particular peer is defined in either
the border peer or on the member peer, but not both because of potential configuration confusion.
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To define peer groups, configure border peers and assign the local peer to a peer cluster, use the
following command in global configuration mode:
Command
Purpose
Router(config)# dlsw local-peer [peer-id
ip-address] [group group] [border] [cost cost]
[cluster cluster-id] [lf size] [keepalive
seconds] [passive] [promiscuous] [biu-segment]
[init-pacing-window size] [max-pacing-window
size]
Enables peer groups and border peers.
Use the group keyword to define a peer group, the border keyword to define a border peer and the
cluster keyword to assign the local peer to a peer cluster. When the user defines the cluster option in
the dlsw local-peer command on the member peer router, the cluster information is exchanged with the
border peer during the capabilities exchange as the peers become active. The border peer uses this
information to make explorer replication and forwarding decisions.
The following command configures the router as the Border peer that is a member of group 2:
dlsw local-peer peer-id 10.2.13.4 group 2 border
Configure the cluster option in the dlsw remote-peer command on a border peer to enable the DLSw+
Peer Clusters feature without forcing every DLSw+ router in the network to upgrade their software. To
enable the DLSw+ Peer Clusters feature on a Border Peer, use the following command in global
configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number tcp
ip-address [backup-peer [ip-address |
frame-relay interface serial number dlci-number
|interface name]] [bytes-netbios-out
bytes-list-name] [circuit-weight weight]
[cluster cluster-id] [cost cost] [dest-mac
mac-address] [dmac-output-list
Defines the border peer router as part of a particular cluster and
enables the DLSw+ Peer Clusters feature.
access-list-number] [host-netbios-out
host-list-name] [inactivity] [dynamic]
[keepalive seconds] [lf size] [linger minutes]
[lsap-output-list list] [no-llc minutes]
[passive] [priority] [rif-passthru
virtual-ring-number] [tcp-queue-max size]
[timeout seconds]
The following command configures a border router as a member of cluster 5:
dlsw remote-peer tcp 10.2.13.5 cluster 5
A peer-on-demand peer is a non-configured remote-peer that was connected because of an LLC2 session
established through a border peer DLSw+ network. On-demand peers greatly reduce the number of peers
that must be configured. You can use on-demand peers to establish an end-to-end circuit even though the
DLSw+ routers servicing the end systems have no specific configuration information about the peers.
This configuration permits casual, any-to-any connection without the burden of configuring the
connection in advance. It also allows any-to-any switching in large internetworks where persistent TCP
connections would not be possible.
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To configure peer-on-demand defaults, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw peer-on-demand-defaults
[fst] [bytes-netbios-out bytes-list-name] [cost
cost] [dest-mac destination mac-address]
[dmac-output-list access-list-number]
Configures peer-on-demand defaults.
[host-netbios-out host-list-name] [inactivity
minutes] [keepalive seconds] [lf size]
[lsap-output-list list] [port-list
port-list-number] [priority] [tcp-queue-max]
To define the maximum entries maintained in a border peer’s group cache, use the following command
in global configuration mode:
Command
Purpose
Router(config)# dlsw group-cache max-entries
number
Defines the maximum entries in a group cache.
To remove all entries from the DLSw+ reachability cache, use the following command in privileged
EXEC mode:
Command
Purpose
Router# clear dlsw reachability
Removes all entries from the DLSw+ reachability cache.
To reset to zero the number of frames that have been processed in the local, remote and group caches,
use the following command in privileged EXEC mode:
Command
Purpose
Router# clear dlsw statistics
Resets to zero the number of frames that have been processed in
the local, remote, and group caches.
To disable the border peer caching feature, use the following command in global configuration mode:
Command
Purpose
Router(config-if)# dlsw group-cache disable
Disables the border peer caching feature.
To verify that the peer cluster feature is enabled or that the border peer is configured, issue the show
dlsw capabilities command on the router. To verify the cluster id number of which the peer is a member,
issue the show dlsw capabilities local command on the local router.
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To display the contents of the reachability caches, use the following command in privileged EXEC
command mode:
Command
Purpose
Router# show dlsw reachability [[group [value] |
local | remote] | [mac-address [address]
[netbios-names [name]
Displays content of group, local and remote caches.
Use the group keyword to display the reachability information for the border peer.
Explorer Firewalls
An explorer firewall permits only a single explorer for a particular destination MAC address or NetBIOS
name to be sent across the WAN. While an explorer is outstanding and awaiting a response from the
destination, subsequent explorers for that MAC address or NetBIOS name are merely stored. When the
explorer response is received at the originating DLSw+, all explorers receive an immediate local
response. This eliminates the start-of-day explorer storm that many networks experience. Configure the
page 310 for details of the command.
To enable explorer firewalls, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw timer
Tunes an existing configuration parameter.
{icannotreach-block-time | netbios-cache-timeout
| netbios-explorer-timeout | netbios-group-cache
| netbios-retry-interval |
netbios-verify-interval | sna-cache-timeout |
explorer-delay-time | sna-explorer-timeout |
explorer-wait-time | sna-group-cache |
sna-retry-interval | sna-verify-interval} time
NetBIOS Dial-on-Demand Routing
This feature allows you to transport NetBIOS in a dial-on-demand routing (DDR) environment by
filtering NetBIOS Session Alive packets from the WAN. NetBIOS periodically sends Session Alive
packets as LLC2 I-frames. These packets do not require a response and are superfluous to the function
of proper data flow. Furthermore, these packets keep dial-on-demand interfaces up and this up time
causes unwanted per-packet charges in DDR networks. By filtering these NetBIOS Session Alive
packets, you reduce traffic on the WAN and you reduce some costs that are associated with
dial-on-demand routing.
To enable NetBIOS DDR, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw netbios keepalive-filter
Enables NetBIOS DDR.
The following command enables NetBIOS DDR:
dlsw netbios keepalive-filter
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SNA Dial-on-Demand Routing
This feature allows you to run DLSw+ over a switched line and have the Cisco IOS software take the
switched line down dynamically when it is not in use. Utilizing this feature gives the IP Routing table
more time to converge when a network problem hinders a remote peer connection. In small networks
with good IP convergence time and ISDN lines that start quickly, it is not as necessary to use the
keepalive option. To use this feature, you must set the keepalive value to zero, and you may need to use
a lower value for the timeout option than the default, which is 90 seconds.
To configure SNA DDR, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number tcp
ip-address [backup-peer [ip-address |
frame-relay interface serial number dlci-number
|interface name]] [bytes-netbios-out
bytes-list-name] [circuit-weight weight]
[cluster cluster-id] [cost cost] [dest-mac
mac-address] [dmac-output-list
Configures SNA DDR.
access-list-number] [host-netbios-out
host-list-name] [inactivity] [dynamic]
[keepalive seconds] [lf size] [linger minutes]
[lsap-output-list list] [no-llc minutes]
[passive] [priority] [rif-passthru
virtual-ring-number] [tcp-queue-max size]
[timeout seconds]
The following command configures the SNA DDR feature:
dlsw remote-peer 0 tcp 10.2.13.4 keepalive 0
UDP Unicast Feature
The UDP Unicast feature sends the SSP address resolution packets via UDP unicast service rather than
TCP. (SSP packets include: CANUREACH_EX, NETBIOS_NQ_ex, NETBIOS_ANQ, and
DATAFRAME.) The UDP unicast feature allows DLSw+ to better control address resolution packets and
unnumbered information frames during periods of congestion. Previously, these frames were carried
over TCP. TCP resends frames that get lost or delayed in transit, and hence aggravate congestion.
Because address resolution packets and unnumbered information frames are not sent on a reliable
transport on the LAN, sending them reliably over the WAN is unnecessary. By using UDP for these
frames, DLSw+ minimizes network congestion.
Note
UDP unicast enhancement has no affect on DLSw+ FST or direct peer encapsulation.
This feature is enabled by default. To disable User Datagram Protocol (UDP) Unicast, use the following
command in global configuration mode:
Command
Purpose
Router(config)# dlsw udp-disable
Disables UDP Unicast.
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LLC1 Circuits
Support for LLC1 circuits more efficiently transports LLC1 UI traffic across a DLSw+ cloud. With
LLC1 circuit support, the LLC1 unnumbered information frames (UI) are no longer subject to input
queueing and are guaranteed to traverse the same path for the duration of the flow. This feature improves
transportation of LLC1 UI traffic because there is no longer the chance of having a specifically routed
LLC1 UI frame broadcast to all remote peers. The circuit establishment process has not changed except
that the circuit is established as soon as the specifically routed LLC1 UI frame is received and the
DLSw+ knows of reachability for the destination MAC address. Furthermore, the connection remains in
the CIRCUIT_ESTABLISHED state (rather than proceeding to the CONNECT state) until there is no UI
frame flow for a MAC/SAP pair for 10 minutes.
This feature is enabled by default.
Dynamic Peers
In TCP encapsulation, the dynamic option and its suboptions no-llc and inactivity allow you to specify
and control the activation of dynamic peers, which are configured peers that are activated only when
required. Dynamic peer connections are established only when there is DLSw+ data to send. The
dynamic peer connections are taken down when the last LLC2 connection using them terminates and the
time period specified in the no-llc option expires. You can also use the inactivity option to take down
dynamic peers when the circuits using them are inactive for a specified number of minutes.
Note
Because the inactivity option may cause active LLC2 sessions to be terminated, you should not use
this option unless you want active LLC2 sessions to be terminated.
To configure a dynamic peer, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer list-number tcp
ip-address [backup-peer [ip-address |
frame-relay interface serial number dlci-number
| interface name]] [bytes-netbios-out
bytes-list-name] [circuit-weight weight]
[cluster cluster-id] [cost cost] [dest-mac
mac-address] [dmac-output-list
Configures a dynamic peer.
access-list-number] [host-netbios-out
host-list-name] [inactivity] [dynamic]
[keepalive seconds] [lf size] [linger minutes]
[lsap-output-list list] [no-llc minutes]
[passive] [priority] [rif-passthru
virtual-ring-number] [tcp-queue-max size]
[timeout seconds]
The following command specifies a dynamic peer with TCP encapsulation:
dlsw remote-peer 0 tcp 10.23.4.5 dynamic
Promiscuous Peer Defaults
If you do not configure a dlsw remote-peer statement on the DLSw+ router, then you must specify the
promiscuous keyword on the dlsw local-peer statement. The promiscuous keyword enables the router
to accept peer connection requests from those routers that are not preconfigured. Setting the dlsw
prom-peer-defaults command allows the user to determine various settings for the promiscuous
transport.
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To configure promiscuous peer defaults, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw prom-peer-defaults
[bytes-netbios-out bytes-list-name] [cost cost]
[dest-mac destination-mac-address]
Configures promiscuous peer defaults.
[dmac-output-list access-list-number]
[host-netbios-out host-list-name] [keepalive
seconds] [lf size] [lsap-output-list list]
[tcp-queue-max size]
Availability
DLSw+ supports the following features that allow it to dynamically finds alternate paths quickly and
optionally load balances across multiple active peers, ports, and channel gateways:
•
•
•
Load Balancing
DLSw+ offers enhanced availability by caching multiple paths to a given MAC address or NetBIOS
name (where a path is either a remote peer or a local port). Maintaining multiple paths per destination is
especially attractive in SNA networks. A common technique used in the hierarchical SNA environment
is assigning the same MAC address to different Token Ring interface couplers (TICs) on the IBM FEPs.
DLSw+ ensures that duplicate TIC addresses are found, and, if multiple DLSw+ peers can be used to
reach the FEPs, they are cached.
The way that multiple capable peers are handled with DLSw+ can be configured to meet either of the
following network needs:
•
Fault tolerance—To rapidly reconnect if a data-link connection is lost. If load balancing is not
enabled, the Cisco IOS software, by default, maintains a preferred path and one or more capable
paths to each destination. The preferred path is either the peer or port that responds first to an
explorer frame or the peer with the least cost. If the preferred path to a given destination is
unavailable, the next available capable path is promoted to the new preferred path. No additional
broadcasts are required, and recovery through an alternate peer is immediate. Maintaining multiple
cache entries facilitates a timely reconnection after session outages.
A peer with the least cost can also be the preferred path. You can specify cost in either the dlsw local
peer or dlsw remote peer commands. See the DLSw+ Design and Implementation Guide for details
on how cost can be applied to control which path sessions use.
•
Load balancing—To distribute the network traffic over multiple DLSw+ peers in the network.
Alternately, when there are duplicate paths to the destination end system, you can configure load
balancing. DLSw+ alternates new circuit requests in either a round-robin or enhanced load
balancing fashion through the list of capable peers or ports. If round-robin is configured, the router
distributes the new circuit in a round-robin fashion, basing it’s decision on which peer or port
established the last circuit. If enhanced load balancing is configured, the router distributes new
circuits based on existing loads and the desired ratio. It detects the path that is underloaded in
comparison to the other capable peers and will assign new circuits to that path until the desired ratio
is achieved.
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For multiple peer connections, peer costs must be applied. The DLSw+ Enhanced Load Balancing
feature works only with the lowest (or equal) cost peers. For example, if the user specifies dlswrtr1,
dlswrtr2 and dlswrtr3 with costs of 4, 3, and 3 respectively, DLSw+ establishes new circuits with
only dlswrtr 2 and dlswrtr3.
To enable the DLSw+ Enhanced Load Balancing feature on the local router, use the following command
in global configuration mode:
Command
Purpose
Router(config)# dlsw load-balance [round-robin |
circuit count circuit-weight]
Configures the DLSw+ Enhanced Load Balancing feature on the
local router.
To adjust the circuit weight for a remote peer with TCP encapsulation, use the following command in
global configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer tcp
[circuit-weight value]
Adjusts the circuit weight on the remote peer.
To adjust the circuit weight for a remote peer with DLSw+ Lite encapsulation, use the following
command in global configuration mode:
Command
Purpose
Router(config)# dlsw remote-peer frame-relay
interface serial number dlci number
[circuit-weight value]
Adjusts the circuit weight on the remote peer.
The circuit-weight of a remote peer controls the number of circuits that peer can take. If multiple, equally
low-cost peers can reach a remote source, the circuits to that remote source are distributed among the
remote peers based on the ratio of their configured circuit-weights. The peer with the highest
circuit-weight takes more circuits.
Because a DLSw+ peer selects its new circuit paths from within its reachability cache, the user must
configure the dlsw timer explorer-wait-time command with enough time to allow for all the explorer
responses to be received. If the new DLSw+ Enhanced Load Balancing Feature is enabled, a message is
displayed on the console to alert the user if the timer is not set.
To configure the amount of time needed for all the explorer responses to be received, use the following
command in global configuration mode:
Command
Purpose
Router(config)# dlsw timer {explorer-wait-time}
Sets the time to wait for all stations to respond to explorers.
See the DLSw+ Design and Implementation Guide for details on how to configure load balancing in
DLSw+. Refer to the “DLSw+ with Enhanced Load Balancing Configuration Example” section on
page 327 for a sample configuration.
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Ethernet Redundancy
The DLSw+ Ethernet Redundancy feature, introduced in Cisco IOS Release 12.0(5)T, provides
redundancy and load balancing between multiple DLSw+ peers in an Ethernet environment. It enables
DLSw+ to support parallel paths between two points in an Ethernet environment, ensuring resiliency in
the case of a router failure and providing load balancing for traffic load. The feature also enables DLSw+
to support multiple DLSw+ routers on the same transparent bridged domain that can reach the same
MAC address in a switched environment.
To enable the DLSw+ Ethernet Redundancy feature, issue the following command in interface
configuration mode:
Command
Purpose
Router(config-if)# dlsw transparent
redundancy-enable
Configures transparent redundancy.
To enable the DLSw+ Ethernet Redundancy feature in a switched environment, enter the following
commands in interface configuration mode:
Command
Purpose
Router(config-if)# dlsw transparent
switch-support
Step 1
Step 2
Enables DLSw+ Ethernet Redundancy feature when using a switch
device.
Router(config-if)# dlsw transparent
map local mac mac address remote mac
mac address neighbor mac address
Configures a single destination MAC address to which multiple MAC
addresses on a transparent bridged are mapped.
The Ethernet Redundancy feature is a complex feature. See the DLSw+ Design and Implementation
Configuration Example” section on page 332 for sample configurations.
Backup Peers
The backup-peer option is common to all encapsulation types on a remote peer and specifies that this
remote peer is a backup peer for the router with the specified IP-address, Frame Relay Data-Link Control
Identifier (DLCI) number, or interface name. When the primary peer fails, all circuits over this peer are
disconnected and the user can start a new session via their backup peer. Prior to Cisco IOS
Release 11.2(6)F, you could configure backup peers only for primary FST and TCP.
Also, when you specify the backup-peer option in a dlsw remote-peer tcp command, the backup peer
is activated only when the primary peer becomes unreachable. Once the primary peer is reactivated, all
new sessions use the primary peer and the backup peer remains active only as long as there are LLC2
connections using it. You can use the linger option to specify a period (in minutes) that the backup peer
remains connected after the connection to the primary peer is reestablished. When the linger period
expires, the backup peer connection is taken down.
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Note
If the linger keyword is set to 0, all existing sessions on the backup router immediately drop when
the primary recovers. If the linger keyword is omitted, all existing sessions on the backup router
remain active (as long as the session is active) when the primary recovers, however, all new sessions
establish via the primary peer. If the linger keyword is set to
x minutes, all existing sessions on the backup router remain active for x minutes once the primary
recovers, however, all new sessions establish via the primary peer. Once x minutes expire, all existing
sessions on the backup router drop and the backup peer connection is terminated. The linger keyword
can be used to minimize line costs if the backup peer is accessed over dial lines, but can be set high
enough to allow an operator warning to be sent to all the SNA end users. It will not, however, pass
explorers and will not create any new circuits while the primary is up.
To configure a backup peer, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw remote peer backup-peer
ip-address
Configures a backup peer.
Modes of Operation
It is sometimes necessary for DLSw+ and RSRB to coexist in the same network and in the same router
(for example, during migration from RSRB to DLSw+). Cisco DLSw+ supports this environment. In
addition, DLSw+ must also interoperate with other vendors’ implementations that are based upon other
DLSw RFC standards, such as DLSw Version 1 and Version 2.
Cisco routers, implementing Cisco DLSw+, automatically supports three different modes of operation:
•
Dual mode⎯A Cisco router can communicate with some remote peers using RSRB and with others
using DLSw+, providing a smooth migration path from RSRB to DLSw+; in dual mode, RSRB and
DLSw+ coexist on the same box; the local peer must be configured for both RSRB and DLSw+; and
the remote peers must be configured for either RSRB or DLSw, but not both.
•
•
Standards compliance mode⎯DLSw+ can detect automatically (via the DLSw capabilities
exchange) if the participating router is manufactured by another vendor, therefore operating in
DLSw standard mode (DLSw Version 1 RFC 1795 and DLSw Version 2 RFC 2166).
Enhanced mode⎯DLSw+ can detect automatically that the participating router is another DLSw+
router, therefore operating in enhanced mode, making all of the features of DLSw+ available to the
SNA and NetBIOS end systems.
Note
DLSw+ does not interoperate with the DLSw RFC 1434 standard.
Some enhanced DLSw+ features are also available when a Cisco router is operating in standards
compliance mode with another vendor’s router. In particular, enhancements that are locally controlled
options on a router can be accessed even though the remote router does not have DLSw+. These include
reachability caching, explorer firewalls and media conversion.
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DLSw+ Configuration Task List
Network Management
There are several network management tools available to the user to help them more easily manage and
troubleshoot their DLSw+ network. CiscoWorks Blue Maps provides a logical view of the portion of
your router network relevant to DLSw+ (there is a similar tool for RSRB and APPN). CiscoWorks Blue
SNA View adds to the information provided by Maps by correlating SNA PU and LU names with DLSw+
circuits and DLSw+ peers. CiscoWorks Blue Internetwork Status Monitor (ISM) support allows you to
manage your router network from the mainframe console using IBM’s NetView or Sterling’s
SOLVE:Netmaster. See the DLSw+ Design and Implementation Guide “Using CiscoWorks Blue: Maps,
SNA View, and Internetwork Status Monitor” chapter for more details.
Traffic Bandwidth and Queueing Management
Cisco offers several bandwidth management and queueing features (such as DLSw+ RSVP) to enhance
the overall performance of your DLSw+ network. The queueing and bandwidth management features are
described in detail in the DLSw Design and Implementation Guide “Bandwidth Management Queueing”
chapter.
Access Control
DLSw+ offers the following features that allow it to control access to various resources throughout a
network:
•
•
•
•
•
DLSw+ Ring List or Port List
DLSw+ ring lists map traffic on specific local rings to remote peers. You can create a ring list of local
ring numbers and apply the list to remote peer definitions. Traffic received from a remote peer is only
forwarded to the rings specified in the ring list. Traffic received from a local interface is only forwarded
to peers if the input ring number appears in the ring list applied to the remote peer definition. The
definition of a ring list is optional. If you want all peers and all rings to receive all traffic, you do not
have to define a ring list. Simply specify 0 for the list number in the remote peer statement.
To define a ring list, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw ring-list list-number rings
ring-number
Defines a ring list.
DLSw+ port lists map traffic on a local interface (either Token Ring or serial) to remote peers. Port lists
do not work with Ethernet interfaces, or any other interface types connected to DLSw+ by means of a
bridge group. You can create a port list of local ports and apply the list to remote peer definitions. Traffic
received from a remote peer is only forwarded to peers if the input port number appears in the port list
applied to the remote peer definition. The port list command provides a single command to specify both
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DLSw+ Configuration Task List
Figure 130 Mapping Traffic Using Port Lists
Token
Ring
22
Explorer
Token
Ring
19
Token
Ring
12
Peer A
Peer B
Port list 2
Token
Ring
15
Peer C
Port list 1
Peer B: Port list 1
Peer C: Port list 2
The definition of a port list is optional. If you want all peers and all interfaces to receive all traffic, you
do not have to define a port list. Simply specify 0 for the list number in the remote peer statement.
To define a port list, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw port-list list-number type
number
Defines a port list.
Note
Either the ring list or the port list command can be used to associate rings with a given ring list. The
ring list command is easier to type in if you have a large number of rings to define.
DLSw+ Bridge Group List
DLSw+ bridge group lists map traffic on the local Ethernet bridge group interface to remote peers. You
can create a bridge group list and apply the list to remote peer definitions. Traffic received from a remote
peer is only forwarded to the bridge group specified in the bridge group list. Traffic received from a local
interface is only forwarded to peers if the input bridge group number appears in the bridge group list
applied to the remote peer definition. The definition of a bridge group list is optional. Because each
remote peer has a single list number associated with it, if you want traffic to go to a bridge group and to
either a ring list or port list, you should specify the same list number in each definition
To define a bridge-group list, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw bgroup-list list-number
bgroups number
Defines a ring list.
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DLSw+ Configuration Task List
Static Paths
Static path definitions allow a router to setup circuits without sending explorers. The path specifies the
peer to use to access a MAC address or NetBIOS name.
To configure static paths to minimize explorer traffic originating in this peer, use one of the following
commands in global configuration mode, as needed:
Command
Purpose
Router(config)# dlsw mac-addr mac-addr {ring
ring number | remote-peer {interface serial
number | ip-address ip-address} | rif rif string
| group group}
Configures the location or path of a static MAC address.
or
or
Router(config)# dlsw netbios-name netbios-name
{ring ring number | remote-peer {interface
serial number | ip-address ip-address} | rif rif
string | group group}
Configures a static NetBIOS name.
Static Resources Capabilities Exchange
To reduce explorer traffic destined for this peer, the peer can send other peers a list of resources for which
it has information (icanreach) or does not have information (icannotreach). This information is
exchanged as part of a capabilities exchange.To configure static resources that will be exchanged as part
of a capabilities exchange, use one of the following commands in global configuration mode, as needed:
Command
Purpose
Router(config)# dlsw icannotreach saps sap
[sap...]
Configures a resource not locally reachable by the router.
or
or
Router(config)# dlsw icanreach {mac-exclusive |
netbios-exclusive | mac-address mac-addr [mask
mask] | netbios-name name |saps}
Configures a resource locally reachable by the router.
Filter Lists in the Remote-Peer Command
The dest-mac and dmac-output-list options allow you to specify filter lists as part of the dlsw
remote-peer command to control access to remote peers. For static peers in direct, FST, or TCP
encapsulation, these filters control which explorers are sent to remote peers. For dynamic peers in TCP
encapsulation, these filters also control the activation of the dynamic peer. For example, you can specify
at a branch office that a remote peer is activated only when there is an explorer frame destined for the
Media Access Control (MAC) address of an FEP.
The dest-mac option permits the connection to be established only when there is an explorer frame
destined for the specified MAC address. The dmac-output-list option permits the connection to be
established only when the explorer frame passes the specified access list. To permit access to a single
MAC address, use the dest-mac option, because it is a configuration “shortcut” compared to the
dmac-output-list option.
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Verifying DLSw+
Configuring DLSw+ Timers
To configure DLSw+ timers, use the following command in global configuration mode:
Command
Purpose
Router(config)# dlsw timer
Configures DLSw+ timers.
{icannotreach-block-time | netbios-cache-timeout
| netbios-explorer-timeout | netbios-group-cache
|netbios-retry-interval |
netbios-verify-interval |sna-cache-timeout |
sna-explorer-timeout | sna-group-cache |
sna-retry-interval | sna-verify-interval} time
See the DLSw+ Design and Implementation Guide “Customization” chapter and the Cisco IOS Bridging
and IBM Networking Command Reference (Volume 1 of 2) for command details.
Verifying DLSw+
To verify that DLSw+ is configured on the router, use the following command in privileged EXEC mode:
Command
Purpose
Router# show dlsw capabilities local
Displays the DLSw+ configuration of a specific peer.
The following sample shows that DLSw+ is configured on router milan:
milan#show dlsw capabilities local
DLSw:Capabilities for peer 1.1.1.6(2065)
vendor id (OUI)
:'00C' (cisco)
version number
:1
release number
:0
init pacing window
unsupported saps
num of tcp sessions
loop prevent support
:20
:none
:1
:no
icanreach mac-exclusive :no
icanreach netbios-excl. :no
reachable mac addresses :none
reachable netbios names :none
cisco version number
peer group number
border peer capable
peer cost
:1
:0
:no
:3
biu-segment configured :no
UDP Unicast support
local-ack configured
priority configured
:yes
:yes
:no
Cisco Internetwork Operating System Software IOS GS Software (GS7-K-M),
Experimental Version 11.1(10956) [sbales 139]
Copyright (c) 1986-1996 by cisco Systems, Inc.
Compiled Thu 30-May-96 09:12 by sbales8
If only a command prompt appears, then DLSw+ is not configured for the router.
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Monitoring and Maintaining the DLSw+ Network
Alternately, to verify that DLSw+ is configured, issue the following command in privileged EXEC
mode:
Command
Purpose
Router# show running configuration
Displays the running configuration of a device.
The global DLSw+ configuration statements, including the dlsw local-peer statement, appear in the
output before the interface configuration statements. The following sample shows that DLSw+ is
configured on router milan:
milan# show run
version 12.0
!
hostname Sample
!
source-bridge ring-group 110
dlsw local-peer peer-id 10.1.1.1 promiscuous
!
interface TokenRing0/0
no ip address
ring-speed 16
source-bridge 222 1 110
source-bridge spanning
!
Monitoring and Maintaining the DLSw+ Network
To monitor and maintain activity on the DLSw+ network, use one of the following commands in
privileged EXEC mode, as needed:
Command
Purpose
Router# show dlsw capabilities interface type
number
Displays capabilities of a direct-encapsulated remote peer.
Router# show dlsw capabilities ip-address
ip-address
Displays capabilities of a TCP/FST remote peer.
Router# show dlsw capabilities local
Router# show dlsw circuits
Displays capabilities of the local peer.
Displays DLSw+ circuit information.
Router# show dlsw fastcache
Displays the fast cache for FST and direct-encapsulated peers.
Router# show dlsw local-circuit
Displays DLSw+ circuit information when doing local
conversion.
Router# show dlsw peers
Displays DLSw+ peer information.
Router# show dlsw reachability
Router# dlsw disable
Displays DLSw+ reachability information.
Disables and re-enable DLSw+ without altering the configuration.
Router# show dlsw statistics [border-peers]
Displays the number of frames that have been processed in the
local, remote, and group caches.
Closes all the DLSw+ circuits1. Also used to reset to zero the
number of frames that have been processed in the local, remote,
and group cache.
Router# clear dlsw circuit
1. Issuing the clear dlsw circuits command will cause the loss of any associated LLC2 sessions.
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DLSw+ Configuration Examples
See the DLSw+ Design and Implementation Guide “Using Show and Debug Commands” chapter and the
Cisco IOS Bridging and IBM Networking Command Reference (Volume 1 of 2) for details of the
commands.
DLSw+ Configuration Examples
The following sections provide DLSw+ configuration examples:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
DLSw+ Using TCP Encapsulation and LLC2 Local Acknowledgment—Basic
Configuration Example
This sample configuration requires the following tasks, which are described in earlier sections of this
document:
•
•
•
•
Define a Source-Bridge Ring Group for DLSw+
Define a DLSw+ Local Peer for the Router
Define DLSw+ Remote Peers
Assign DLSw+ to a local data-link control
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Figure 131 illustrates a DLSw+ configuration with local acknowledgment. Because the RIF is
terminated, the ring group numbers do not have to be the same.
Figure 131 DLSw + w ith Local Acknow ledgm ent—Sim ple Configuration
Ring Group
10
Ring Group
12
Router A
10.2.25.1
Router B
10.2.5.2
Token
Ring
5
Token
Ring
25
37x5
3x74
Router A
source-bridge ring-group 10
!
dlsw local-peer peer-id 10.2.25.1
dlsw remote-peer 0 tcp 10.2.5.2
interface loopback 0
ip address 10.2.25.1 255.255.255.0
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 25 1 10
source-bridge spanning
Router B
source-bridge ring-group 12
dlsw local-peer peer-id 10.2.5.2
dlsw remote-peer 0 tcp 10.2.25.1
interface loopback 0
ip address 10.2.5.2 255.255.255.0
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 5 1 12
source-bridge spanning
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DLSw+ Using TCP Encapsulation with Local Acknowledgment—Peer Group
Configuration Example 1
Figure 132 illustrates border peers with TCP encapsulation. Router A is configured to operate in
promiscuous mode, and border peers Routers B and C forward broadcasts. This configuration reduces
processing requirements in Router A (the access router) and still supports any-to-any networks.
Configure Border peer B and C so that they peer to each other.
Figure 132 DLSw + w ith Peer Groups Specified (Exam ple 1)
Token
Ring
3
Router A
Router C
Router B
s0
Token
Ring
200
Token
Ring
33
t0
t3/1
t0
IP cloud
t3/0
s0
128.207.152.5
128.207.150.8
border
128.207.169.3
border
NetBIOS
server
NetBIOS
requester
Group 70
Group 69
Router A
hostname Router A
!
source-bridge ring group 31
dlsw local-peer peer-id 128.207.152.5 group 70 promiscuous
dlsw remote peer 0 tcp 128.207.150.8
interface loopback 0
ip address 128.207.152.5 255.255.255.0
!
interface serial 0
ip unnumbered tokenring
clockrate 56000
!
interface tokenring 0
ip address 128.207.152.5 255.255.255.0
ring-speed 16
source-bridge 200 13 31
source-bridge spanning
!
router igrp 777
network 128.207.0.0
Router B
hostname Router B
!
source-bridge ring-group 31
dlsw local-peer peer-id 128.207.150.8 group 70 border promiscuous
dlsw remote-peer 0 tcp 128.207.169.3
interface loopback 0
ip address 128.207.150.8 255.255.255.0
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!
interface serial 0
ip unnumbered tokenring 0
bandwidth 56
!
interface tokenring 0
ip address 128.207.150.8 255.255.255.0
ring-speed 16
source-bridge 3 14 31
source-bridge spanning
!
router igrp 777
network 128.207.0.0
Router C
hostname Router C
!
source-bridge ring-group 69
dlsw local-peer peer-id 128.207.169.3 group 69 border promiscuous
dlsw remote-peer 0 tcp 128.207.150.8
interface loopback 0
ip address 128.207.169.3 255.255.255.0
!
interface tokenring 3/0
description fixed to flashnet
ip address 128.207.2.152 255.255.255.0
ring-speed 16
multiring all
!
interface tokenring 3/1
ip address 128.207.169.3 255.255.255.0
ring-speed 16
source-bridge 33 2 69
source-bridge spanning
!
router igrp 777
network 128.207.0.0
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DLSw+ Configuration Examples
DLSw+ Using TCP Encapsulation with Local Acknowledgment—Peer Group
Configuration Example 2
Figure 133 illustrates a peer group configuration that allows any-to-any connection except for Router B.
Router B has no connectivity to anything except router C because the promiscuous keyword is omitted.
Figure 133 DLSw + w ith Peer Groups Specified (Exam ple 2)
Token
Token
Ring
Ring
93
92
Token
Ring
96
Token
Ring
500
Router C
T0
Mainframe
S0
FEP
150.150.100.1
S9
Router A
T0/1
T0/2
T0/0
S1/0
150.150.99.1
150.150.96.1
S7
S8
Router D
S1/1
Token
Ring
99
Router B
150.150.98.1
S0
S1
S0
150.150.97.1
SDLC “01”
controller
T0
Router E
T0
Token
Ring
98
Token
Ring
97
Group 2
Group 1
Router A
hostname Router A
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.99.1 group 2 promiscuous
dlsw remote-peer 0 tcp 150.150.100.1
!
interface loopback 0
ip address 150.150.99.1 255.255.255.192
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 99 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
Router B
hostname Router B
!
source-bridge ring-group 2000
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DLSw+ Configuration Examples
dlsw local-peer peer-id 150.150.98.1 group 2
dlsw remote-peer 0 tcp 150.150.100.1
!
interface loopback 0
ip address 150.150.98.1 255.255.255.192
!
interface serial 1
no ip address
encapsulation sdlc
no keepalive
clockrate 9600
sdlc role primary
sdlc vmac 4000.8888.0100
sdlc address 01
sdlc xid 01 05d20006
sdlc partner 4000.1020.1000 01
sdlc dlsw 1
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 98 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
Router C
hostname Router C
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.100.1 group 2 border promiscuous
dlsw remote-peer 0 tcp 150.150.96.1
!
interface loopback 0
ip address 150.150.100.1 255.255.255.192
interface tokenring 0
no ip address
ring-speed 16
source-bridge 500 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
Router D
hostname Router D
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.96.1 group 1 border promiscuous
dlsw remote-peer 0 tcp 150.150.100.1
!
interface loopback 0
ip address 150.150.96.1 255.255.255.192
!
interface tokenring 0/0
no ip address
ring-speed 16
source-bridge 96 1 2000
source-bridge spanning
!
interface tokenring 0/1
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DLSw+ Configuration Examples
no ip address
ring-speed 16
source-bridge 92 1 2000
source-bridge spanning
!
.interface tokenring 0/2
no ip address
ring-speed 16
source-bridge 93 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
Router E
hostname Router E
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.97.1 group 1 promiscuous
dlsw remote-peer 0 tcp 150.150.96.1
!
interface loopback 0
ip address 150.150.97.1 255.255.255.192
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 97 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
DLSw+ with SDLC Multidrop Support Configuration Examples
In the following example, all devices are type PU 2.0:
interface serial 2
mtu 4400
no ip address
encapsulation sdlc
no keepalive
clockrate 19200
sdlc role primary
sdlc vmac 4000.1234.5600
sdlc address C1
sdlc xid C1 05DCCCC1
sdlc partner 4001.3745.1088 C1
sdlc address C2
sdlc xid C2 05DCCCC2
sdlc partner 4001.3745.1088 C2
sdlc dlsw C1 C2
The following example shows mixed PU 2.0 (device using address C1) and PU 2.1 (device using address
C2) devices:
interface serial 2
mtu 4400
no ip address
encapsulation sdlc
no keepalive
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DLSw+ Configuration Examples
clockrate 19200
sdlc role primary
sdlc vmac 4000.1234.5600
sdlc address C1
sdlc xid C1 05DCCCC1
sdlc partner 4001.3745.1088 C1
sdlc address C2 xid-poll
sdlc partner 4001.3745.1088 C2
sdlc dlsw C1 C2
In the following example, all devices are type PU 2.1 (Method 1):
interface serial 2
mtu 4400
no ip address
encapsulation sdlc
no keepalive
clockrate 19200
sdlc role primary
sdlc vmac 4000.1234.5600
sdlc address C1 xid-poll
sdlc partner 4001.3745.1088 C1
sdlc address C2 xid-poll
sdlc partner 4001.3745.1088 C2
sdlc dlsw C1 C2
In the following example, all devices are type PU 2.1 (Method 2):
interface serial 2
mtu 4400
no ip address
encapsulation sdlc
no keepalive
clockrate 19200
sdlc role prim-xid-poll
sdlc vmac 4000.1234.5600
sdlc address C1
sdlc partner 4001.3745.1088 C1
sdlc address C2
sdlc partner 4001.3745.1088 C2
sdlc dlsw C1 C2
DLSw+ with LLC2-to-SDLC Conversion Between PU 4-to-PU 4 Communication
Example
The following example is a sample configuration for LLC2-to-SDLC conversion for PU 4-to-PU 4
Figure 134 LLC2-to-SDLC Conversion for PU 4-to-PU 4 Com m unication
Token
Frame Relay
Ring
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DLSw+ Configuration Examples
Router A
source-bridge ring-group 1111
dlsw local-peer peer-id 10.2.2.2
dlsw remote-peer 0 tcp 10.1.1.1
interface loopback 0
ip address 10.2.2.2 255.255.255.0
interface TokenRing 0
no ip address
ring-speed 16
source-bridge 2 1111
source-bridge spanning
Router B
dlsw local-peer peer-id 10.1.1.1
dlsw remote-peer 0 tcp 10.2.2.2
interface loopback 0
ip address 10.1.1.1 255.255.255.0
interface serial 0
mtu 4096
no ip address
encapsulation sdlc
no keepalive
nzri-encoding
clockrate 9600
sdlc vmac 4000.3745.0000
sdlc N1 48016
sdlc address 04 echo
sdlc partner 4000.1111.0020 04
sdlc dlsw 4
DLSw+ Translation Between Ethernet and Token Ring Configuration Example
DLSw+ also supports Ethernet media. The configuration is similar to other DLSw+ configurations,
except for configuring for a specific media. The following example shows Ethernet media (see
Figure 135 DLSw + Translation Between Ethernet and Token Ring
Router B
Router A
e0
e1/2
128.207.1.145
128.207.111.1
Token
Ring
7
AS/400
Router A
hostname Router A
!
dlsw local-peer peer-id 128.207.111.1
dlsw remote-peer 0 tcp 128.207.1.145
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DLSw+ Configuration Examples
dlsw bridge-group 5
!
interface loopback 0
ip address 128.207.111.1 255.255.255.0
interface Ethernet 0
no ip address
bridge-group 5
!
bridge 5 protocol ieee
Router B
hostname Router B
!
source-bridge transparent 500 1000 1 5
dlsw local-peer peer-id 128.207.1.145
dlsw remote-peer 0 tcp 128.207.111.1
dlsw bridge-group 5
!
interface loopback 0
ip address 128.207.1.145 255.255.255.0
interface ethernet 1/2
no ip address
bridge-group 5
!
interface tokenring 2/0
no ip address
ring-speed 16
source-bridge 7 1 500
source-bridge spanning
!
bridge 5 protocol ieee
Because DLSw+ does not do local translation between different LAN types, Router B must be
configured for SR/TLB by issuing the source-bridge transparent command. Also, note that the bridge
groups are configured on the ethernet interfaces.
DLSw+ Translation Between FDDI and Token Ring Configuration Example
DLSw+ also supports FDDI media. The configuration is similar to other DLSw+ configurations except
Figure 136 DLSw + Translation Between FDDI and Token Ring
Token
Ring
DLSw+
FDDI
Router A
Router B
In the following configuration, an FDDI ring on Router A is connected to a Token Ring on Router B
across a DLSw+ link.
Router A
source-bridge ring-group 10
dlsw local-peer peer-id 132.11.11.2
dlsw remote-peer 0 tcp 132.11.11.3
interface loopback 0
ip address 132.11.11.2 255.255.255.0
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interface fddi 0
no ip address
source-bridge 26 1 10
source-bridge spanning
Router B
source-bridge ring-group 10
dlsw local peer peer-id 132.11.11.3
dlsw remote-peer 0 tcp 132.11.11.2
interface loopback 0
ip address 132.11.11.3 255.255.255.0
interface tokenring 0
no ip address
source-bridge 25 1 10
source-bridge spanning
DLSw+ Translation Between SDLC and Token Ring Media Example
DLSw+ provides media conversion between local or remote LANs and SDLC. For additional
information about configuring SDLC parameters, refer to the chapter “Configuring LLC2 and SDLC
Parameters.”
Figure 137 illustrates DLSw+ with SDLC encapsulation. For this example, 4000.1020.1000 is the MAC
address of the FEP host (PU 4.0). The MAC address of the AS/400 host is 1000.5aed.1f53, which is
defined as Node Type 2.1. Router B serves as the primary station for the remote secondary station 01.
Router B can serve as either primary station or secondary station to remote station D2.
Figure 137 DLSw + Translation Between SDLC and Token Ring Media
1000.5aed.1F53
AS/400
Token
Ring
500
Token
Ring
400
FEP
4000.1020.1000
Router B
S0
S8
Token
Ring
100
S2 S1
Router A
PU type 2.1
sdlc address
D2
PU type 2.0
sdlc address
01
Router A
hostname Router A
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.10.2
dlsw remote-peer 0 tcp 150.150.10.1
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!
interface loopback 0
ip address 150.150.10.2 255.255.255.0
interface serial 8
ip address 150.150.11.2 255.255.255.192
clockrate 56000
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 500 1 2000
source-bridge spanning
!
router eigrp 202
network 150.150.0.0
Router B
hostname Router B
!
source-bridge ring-group 2000
dlsw local-peer peer-id 150.150.10.1
dlsw remote-peer 0 tcp 150.150.10.2
!
interface loopback 0
ip address 150.150.10.1 255.255.255.0
interface serial 0
ip address 150.150.11.1 255.255.255.192
!
interface serial 1
description PU2 with SDLC station role set to secondary
no ip address
encapsulation sdlc
no keepalive
clockrate 9600
sdlc role primary
sdlc vmac 4000.9999.0100
sdlc address 01
sdlc xid 01 05d20006
sdlc partner 4000.1020.1000 01
sdlc dlsw 1
!
interface serial 2
description Node Type 2.1 with SDLC station role set to negotiable or primary
encapsulation sdlc
sdlc role prim-xid-poll
sdlc vmac 1234.3174.0000
sdlc address d2
sdlc partner 1000.5aed.1f53 d2
sdlc dlsw d2
!
interface tokenring 0
no ip address
ring-speed 16
source-bridge 100 1 2000
source-bridge spanning
!
interface tokenring 1
no ip address
ring-speed 16
source-bridge 400 1 2000
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source-bridge spanning
!
router eigrp 202
network 150.150.0.0
DLSw+ over Frame Relay Configuration Example
Frame Relay support extends the DLSw+ capabilities to include Frame Relay in direct mode. Frame
Relay support includes permanent virtual circuit capability. DLSw+ runs over Frame Relay with or
without local acknowledgement. It supports the Token Ring-to-Token Ring connections similar to FST
and other direct data link controls. Figure 138 illustrates a DLSw+ configuration over Frame Relay with
RIF Passthrough.
Figure 138 DLSw + over Fram e Relay
Router A
Router B
End station
End station
Frame Relay
Network
Token
Ring
Token
Ring
Frame Relay
Session
Direct Session
The following configuration examples are based on Figure 139. The Token Rings in the illustration are
in Ring 2.
Router A
source-bridge ring-group 100
dlsw local-peer 10.2.23.1
dlsw remote-peer 0 frame-relay interface serial 0 30 passthru
interface loopback 0
ip address 10.2.23.1 255.255.255.0
interface tokenring 0
ring-speed 16
source-bridge spanning 1 1 100
!
interface serial 0
mtu 3000
no ip address
encapsulation frame-relay
frame-relay lmi-type ansi
frame-relay map dlsw 30
Router B
source-bridge ring-group 100
dlsw local-peer 10.2.23.2
dlsw remote-peer 0 frame-relay interface serial 0 30 passthru
interface loopback 0
ip address 10.2.23.2 255.255.255.0
interface tokenring 0
ring-speed 16
source-bridge spanning 2 1 100
!
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interface serial 0
mtu 3000
no ip address
encapsulation frame-relay
frame-relay lmi-type ansi
frame-relay map dlsw 30
DLSw+ over QLLC Configuration Examples
The following three examples describe QLLC support for DLSw+.
Example 1
In this configuration, DLSw+ is used to allow remote devices to connect to a DLSw+ network over an
X.25 public packet-switched network.
In this example, all QLLC traffic is addressed to destination address 4000.1161.1234, which is the MAC
address of the FEP.
The remote X.25-attached IBM 3174 cluster controller is given a virtual MAC address of
1000.0000.0001. This virtual MAC address is mapped to the X.121 address of the 3174 (31104150101)
in the X.25 attached router.
interface serial 0
encapsulation x25
x25 address 3110212011
x25 map qllc 1000.0000.0001 31104150101
qllc dlsw partner 4000.1611.1234
Example 2
In this configuration, a single IBM 3174 cluster controller needs to communicate with both an AS/400
and a FEP. The FEP is associated with subaddress 150101 and the AS/400 is associated with subaddress
151102.
If an X.25 call comes in for 33204150101, the call is mapped to the FEP and forwarded to MAC address
4000.1161.1234. The IBM 3174 appears to the FEP as a Token Ring-attached resource with MAC
address 1000.0000.0001. The IBM 3174 uses a source SAP of 04 when communicating with the FEP,
and a source SAP of 08 when communicating with the AS/400.
interface serial 0
encapsulation x25
x25 address 31102
x25 map qllc 1000.0000.0001 33204
qllc dlsw subaddress 150101 partner 4000.1161.1234
qllc dlsw subaddress 150102 partner 4000.2034.5678 sap 04 08
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Example 3
In this example, two different X.25 resources want to communicate over X.25 to the same FEP.
In the router attached to the X.25 network, every X.25 connection request for X.121 address
31102150101 is directed to DLSw+. The first SVC to be established will be mapped to virtual MAC
address 1000.0000.0001. The second SVC to be established will be mapped to virtual MAC address
1000.0000.0002.
interface serial 0
encapsulation x25
x25 address 31102
x25 map qllc 33204
x25 map qllc 35765
qllc dlsw subaddress 150101 vmacaddr 1000.0000.0001 2 partner 4000.1611.1234
DLSw+ with RIF Passthrough Configuration Example
Figure 139 is a sample configuration for DLSw+ using the RIF Passthrough feature.
Figure 139 Network Configuration w ith RIF Passthrough
VR
VR
100
100
A 10.1.12.1
B 10.1.14.2
TCP/IP
25
51
3745
3745
Router A
source-bridge ring-group 100
dlsw local-peer peer id 10.1.12.1
dlsw remote-peer 0 tcp 10.1.14.2 rif-passthru 100
interface loopback 0
ip address 10.1.12.1 255.255.255.0
interface tokenring 0
ring-speed 16
source-bridge 25 1 100
source-bridge spanning
Router B
source-bridge ring-group 100
dlsw local-peer peer id 10.1.14.2
dlsw remote-peer 0 tcp 10.1.12.1 rif-passthru 100
interface loopback 0
ip address 10.1.14.2 255.255.255.0
interface tokenring 0
ring-speed 16
source-bridge 51 1 100
source-bridge spanning
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DLSw+ with Enhanced Load Balancing Configuration Example
Figure 140 shows DLSw+ with the Enhanced Load Balancing feature.
Figure 140 DLSw + w ith Enhanced Load Balancing
Token
Ring
RTR B
Token
Ring
Token
Ring
RTR A
RTR C
RTR D
Router A is configured for the DLSw+ Enhanced Load Balancing feature to load balance traffic among
the DLSw+ remote peers B, C, and D.
Router A
dlsw local-peer 10.2.19.1
dlsw remote-peer 0 tcp 10.2 24.2 circuit-weight 10
dlsw remote-peer 0 tcp 10.2.19.5 circuit-weight 6
dlsw remote-peer 0 tcp 10.2.20.1 circuit-weight 20
dlsw load-balance circuit-count
dlsw timer explorer-wait-time 100
Router B
dlsw local-peer 10.2.24.2 cost 1 promiscuous
Router C
dlsw local-peer 10.2.19.5 cost 1 promiscuous
Router D
dlsw local-peer 10.2.20.1 cost 1 promiscuous
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DLSw+ Peer Cluster Feature Configuration Example
Figure 141 shows a DLSw+ network configured with the DLSw+ Peer Clusters feature.
Figure 141 DLSw + Peer Cluster Feature
X
Peer cluster
ID 5
MPA
MPB
Token
Ring
BP1
BP2
Y
Peer group 1
Peer group 2
Because BP2 is configured as the border peer with the DLSw+ Peer Clusters feature, it does not forward
explorers to both MPA and MPB since they are part of the same peer cluster.
BP2
source-bridge ring-group 310
dlsw local-peer 10.1.1.3 border group 2 promiscuous
MPA
source-bridge ring-group 310
dlsw local-peer 10.1.1.1 group 2 promiscuous cluster 5
dlsw remote-peer 0 tcp 10.1.1.3
MPB
source-bridge ring-group 310
dlsw local-peer 10.1.1.2 group 2 promiscuous cluster 5
dlsw remote-peer tcp 0 10.1.1.3
MPC
dlsw local-peer 10.1.1.4 group 2 promiscuous
dlsw remote-peer tcp 0 10.1.1.3
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DLSW+ RSVP Bandwidth Reservation Feature Configuration Example
Figure 142 shows a DLSw+ network with the DLSw+ RSVP Bandwidth Reservation feature configured.
Figure 142 DLSw + RSVP Bandw idth Reservation Feature Configured
DLSW RTR 1
IP RTR 1
IP RTR 2
DLSW RTR 2
10.2.24.3
Token
Ring
10.2.17.1
10.1.15.2
10.1.16.2
Workstation 1
Workstation 2
Workstation 3
Workstation 4
DLSWRTR 1 and DLSWRTR 2 are configured for the DLSw+ RSVP Bandwidth Reservation feature
with an average bit rate of 40 and a maximum-burst rate of 10.
DLSWRTR 1
dlsw local-peer peer id 10.2.17.1
dlsw remote-peer 0 tcp 10.2.24.3
dlsw rsvp 40 10
DLSWRTR2
dlsw local-peer peer id 10.2.24.3
dlsw remote-peer 0 tcp 10.2.17.1
dlsw rsvp 40 10
The following output of the show ip rsvp sender command on the DLSWRTR2 verifies that PATH
messages are being sent from DLSWRTR2:
DLSWRTR2#show ip rsvp sender
To
10.2.17.1 10.2.24.3 TCP 2065 11003
10.2.24.3 10.2.17.1 TCP 11003 2065 10.2.17.1 Et1/1 10K
From
Pro DPort Sport Prev Hop I/F BPS
Bytes
28K
28K
10K
The following output of the show ip rsvp req command on the DLSWRTR2 verifies that RESV
messages are being sent from DLSWRTR2:
DLSWRTR2#show ip rsvp req
To
From
10.2.17.1
Pro DPort Sport Next Hop
TCP 11003 2065 10.2.17.1
I/F
Fi Serv BPS Bytes
28K
10.2.24.3
Et1/1 FF RATE 10K
If the IP cloud is able to guarantee the bandwidth requested and the show ip rsvp sender and show ip
rsvp req commands are successful, issue the show ip rsvp res command to verify that a reservation was
made from DLSWRTR1 to DLSWRTR2:
DLSWRTR2#show ip rsvp rese
To
From
10.2.24.3 TCP 2065 11003 10.2.17.1 Et1/1 FF RATE
10.2.17.1 TCP 11003 2065 FF RATE
Pro DPort Sport Next Hop
I/F
Fi Serv BPS Bytes
10.2.17.1
10.2.24.3
10K
10K
28K
28K
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DLSw+ RSVP Bandwidth Reservation Feature with Border Peers Configuration
Example
Figure 143 DLSw + RSVP Bandw idth Reservation Feature in a Border Peer Network
DLSW RTR 1
IP RTR 1
IP RTR 2
DLSW RTR 2
Token
Ring
Token
Ring
10.2.17.1
10.3.15.2
10.3.16.2
10.14.25.2
Workstation 1
Workstation 2
Group 1
Group 2
The following example configures DLSWRTR1 to send PATH messages at rates of 40 kbps and 10 kbps
and DLSWRTR2 to send PATH messages at rates of 10.
DLSWRTR1
dlsw local-peer peer-id 10.2.17.1 group 1 promiscuous
dlsw rsvp default
dlsw remote-peer 0 tcp 10.3.15.2
dlsw peer-on-demand-defaults rsvp 40 10
IPRTR1
dlsw local-peer peer-id 10.3.15.2 group 1 border promiscuous
dlsw remote-peer 0 tcp 10.3.16.2
IPRTR2
dlsw local-peer peer-id 10.3.16.2 group 2 border promiscuous
dlsw remote-peer 0 tcp 10.3.15.2
DLSWRTR2
dlsw local-peer peer-id 10.14.25.2 group 2 promiscuous
dlsw rsvp default
dlsw remote-peer 0 tcp 10.3.16.2
The following output of the show ip rsvp sender command on DLSWRTR2 verifies that PATH messages
are being sent from DLSWRTR2:
DLSWRT2#show ip rsvp sender
To
From
10.14.25.2
10.2.17.1
Pro DPort Sport Prev Hop
TCP 2065 11003
TCP 11003 2065 10.2.17.1
I/F BPS Bytes
10.2.17.1
10.14.25.2
10K
28K
28K
Et1/1 10K
The following output of the show ip rsvp request command on DLSWRTR2 verifies that RESV
messages are being sent from DLSWRTR 2:
DLSWRT2#show ip rsvp req
To
From
10.2.17.1
Pro DPort Sport Next Hop
TCP 11003 2065 10.2.17.1
I/F
Fi Serv BPS Bytes
28K
10.14.25.2
Et1/1 FF RATE 10K
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The following output of the show ip rsvp res command on the DLSWRTR1 verifies that the RSVP
reservation was successful:
DLSWRTR1#show ip rsvp rese
To
From
10.14.25.2
10.2.17.1
Pro DPort Sport Next Hop
TCP 2065 11003 10.14.25.2
TCP 11003 2065
I/F
Fi Serv BPS Bytes
10.2.17.1
10.14.25.2
Et1/1 FF RATE 10K
FF RATE 10K
28K
28K
DLSw+ with Ethernet Redundancy Configuration Example
Figure 144 shows that Router A, Router B, and Router C advertise their presence on the Ethernet via
their Ethernet interfaces to the multicast MAC address 9999.9999.9999. Because Router B is the master
router, it keeps a database of all circuits handled within the domain and grants or denies permission for
new circuit requests for Router A and Router C. There is no special configuration required for the end
stations or for the remote peer. Only the DLSw+ devices on the LAN need the extra configuration.
Master Router B waits 1.5 seconds after it receives the first IWANTIT primitive before assigning the new
SNA circuit to one of its ethernet redundancy peers because of the dlsw transparent timers sna 1500
command.
Figure 144 DLSw + w ith Ethernet Redundancy
Workstation X
Router A
Router B
Router C
Router D
Router A
dlsw local-peer peer id 10.2.24.2
dlsw remote-peer 0 tcp 10.2.17.1
interface loopback 0
ip address 10.2.24.2 255.255.255.0
int e1
ip address 150.150.2.1 255.255.255.0
dlsw transparent redundancy-enable 9999.9999.9999
Router B
dlsw local-peer peer-id 10.2.24.3
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dlsw remote-peer 0 tcp 10.1.17.1
interface loopback 0
ip address 10.2.24.3 255.255.255.0
int e1
ip address 150.150.2.2 255.255.255.0
dlsw transparent redundancy-enable 9999.9999.9999 master priority 1
dlsw transparent timers sna 1500
Router C
dlsw local-peer peer-id 10.2.24.4
dlsw remote-peer 0 tcp 10.2.17.1
interface loopback 0
ip address 10.2.24.4 255.255.255.0
int e1
ip address 150.150.2.3 255.255.255.0
dlsw transparent redundancy-enable 9999.9999.9999
Router D
dlsw local-peer peer-id 10.2.17.1 promiscuous
DLSw+ with Ethernet Redundancy Enabled for Switch Support Configuration
Example
Figure 145 is a sample configuration of the DLSw+ Ethernet Redundancy feature in a switched
environment. The ethernet switch sees the device with MAC address 4000.0010.0001 one port at a time
because Router A and Router B have mapped different MAC addresses to it. This configuration is known
as MAC-address mapping. Router A is configured so that MAC address 4000.0001.0000 maps to the
actual device with MAC address 4000.0010.0001. Router B is configured so that MAC address
4000.0201.0001 maps to the actual device with MAC address 4000.0010.0001. Router A and B backup
one another. Router A is configured as the master with a default priority of 100. Master Router A waits
1.5 seconds after it receives the first IWANTIT primitive before assigning the new SNA circuit to one of
its ethernet redundancy peers because of the dlsw transparent timers sna 1500 command.
Figure 145 DLSw + w ith Ethernet Redundancy in a Sw itched Environm ent
Workstation Z
Router A
Router B
Workstation X
Workstation Y
4000.0010.0001
Ethernet switch
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Router A
dlsw local peer peer-id 10.2.17.1
dlsw remote-peer 0 tcp 10.3.2.1
dlsw transparent switch-support
interface loopback 0
ip address 10.2.17.1 255.255.255.0
int e 0
mac-address 4000.0000.0001
ip address 150.150.2.1 255.255.255.0
dlsw transparent redundancy-enable 9999.9999.9999 master-priority
dlsw transparent map local-mac 4000.0001.0000 remote-mac 4000.0010.0001
neighbor 4000.0000.0011
dlsw transparent timers sna 1500
Router B
dlsw local peer peer-id 10.2.17.2
dlsw remote-peer 0 tcp 10.3.2.1
dlsw transport switch-support
interface loopback 0
ip address 10.2.17.2 255.255.255.0
int e 1
mac-address 4000.0000.0011
ip address 150.150.3.1 255.255.255.0
dlsw transparent redundancy-enable 9999.9999.9999
dlsw transparent map local-mac 4000.0201.0001 remote-mac 4000.0010.0001
neighbor 4000.0000.0001
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