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8/14/2019 3600 DLSw Peer Group Clusters
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DLSw+ Peer Group Clusters 1
DLSw+ Peer Group Clusters
Feature SummaryIn a large DLSw+ network with heavily populated branches sessions are sometimes dropped and
performance is impacted because a DLSw+ router does not have enough memory and processing
resources to relay all circuits between the branches and the data center. This problem is typicallyfixed by placing routers in the data center and peering a set of branch routers to each of them,
creating a border peer design (Figure 1).
Figure 1 Typical Large DLSw+ Network
If, however, more than one router is connected to the same LAN within the same peer group to
circumvent overloading one router (for example, member peer A MPA and member peer B
MPB), then theexplorersareduplicated when theborder peer forwards an explorer within its Peer
Group. In Figure 1, BP2 forwards the explorer to all the routers in Peer Group 2 (including MPA and
BP2
MPA
MPB
BP1
Peer group 1 Peer group 2
17267
TokenRing
TokenRing
TokenRing
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Feature Summary
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MPB even though they are serving the same LAN.) The DLSw+ Peer Clusters feature avoids these
explorer replications and resolves some circuit connectivity issues that are the result of the explorer
replication.
BenefitsThe DLSw+ Peer Clusters feature reduces explorer replication that typically occurs in a large
DLSw+ peer group design where there are multiple routers connected to the same LAN (Figure 2).
Figure 2 DLSw+ with the DLSw+ Peer Clusters Feature Configured
In Figure 2, MPA and MPB are serving the same Token Ring LAN to share the circuit load between
the branches (for example, workstations X through Y) and the data center (BP2). The problem arises
when workstation X wants to communicate with workstation Y because the explorer is sent three
times on the LAN. The explorer, which originated from MPA, follows these paths:
X>MPA>BP2>MPB, all other MPs in Peer Group 2, BP1>Y,
X>MPB>BP2>MPA>Y
X>Y
The border peer will not forward an explorer back to the peer from which it originated. For example,
the X packet will not travel X> MPA>BP>MPA>Y. Although Peer Group Caching (a
feature implemented in Cisco IOS 11.3) lessens the impact beyond the first explorer, there is stilladditional load on the internetwork that affects performance, bandwidth and CPU memory.
The DLSw+ Peer Clusters feature clusters DLSw+ peers (that are connected to the same LAN)
into logical groups. Once the multiple peers are defined in the same peer group cluster, the DLSw+
border peer recognizes that it does not have to forward explorers to more than one member within
the same peer group cluster.
BP2
Peer cluster
ID 5
MPA
X
Y
MPB
BP1
Peer group 1 Peer group 2 17268
TokenRing
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Configuration Tasks
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Configuration TasksThe 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-idof a particular peer is
defined in either the border peer or on the member peer, but not both because of potential
configuration confusion.
Enable DLSw+ Peer Clusters on Local RouterWhen 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.
To enable the DLSw+ Peer Clusters feature on the member peer, use the following command in
global configuration mode:
Enable DLSw+ Peer Clusters on the Border PeerWhen the user configures the cluster option in the dlsw remote-peer command on a border peer,
they 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
dlsw local-peer [cluster cluster-id] Defines the Member Peer as partof a
particular cluster and enables the
DLSw+ Peer Clusters feature
locally.
Command Purpose
dlsw remote-peer tcp [cluster cluster-id] Defines the border peer router as
part of a particular cluster and
enables the DLSw+ Peer Clusters
feature.This feature is used only for
the configuration of a border peer.
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Enable DLSw+ Peer Clusters on the Border Peer
DLSw+ Peer Group Clusters 5
Configuration ExamplesFigure 3shows a DLSw+ network configured with the DLSw+ Peer Clusters feature.
Figure 3 DLSw+ with the DLSw+ Peer Clusters Feature
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.
BP2source-bridge ring-group 310
dlsw local-peer 10.1.1.3 border group 2 promiscuous
MPAsource-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
MPBsource-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
MPCdlsw local-peer 10.1.1.4 group 2 promiscuous
dlsw remote-peer tcp 0 10.1.1.3
To verify that the DLSw+ Peer Clusters feature is enabled, issue the show dlsw capabilities
command or the show dlsw capabilities local command on the border peer or member peer.
BP2
MPC
Peer cluster
ID 5
MPB
MPA
BP1
Peer group 1 Peer group 2 17269
TokenRing
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Configuration Examples
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The following is output from the show dlsw capabilities command on BP1:
ibm-45k#show dlsw cap local
DLSw:Capabilities for local peer 10.1.1.3
vendor id (OUI) :'00C' (cisco)
version number :2
release number :0init pacing window :20
unsupported saps :none
num of tcp sessions :1
loop prevent support :no
icanreach mac-exclusive :no
icanreach netbios-excl. :no
reachable mac addresses :none
reachable netbios names :none
V2 multicast capable :yes
DLSw multicast address :none
cisco version number :1
peer group number :2
peer cluster support :yes------>indicates peer cluster feature enabled
border peer capable :yes
peer cost :3
biu-segment configured :no
UDP Unicast support :yes
cisco RSVP support :no
current border peer :local-peer
version string :
Cisco Internetwork Operating System Software
IOS (tm) 4500 Software (C4500-AJS-M), Experimental Version 12.0(19981113:101717)
[vtubati-120t_3_pi 110]
Copyright (c) 1986-1998 by cisco Systems, Inc.
Compiled Fri 13-Nov-98 10:33 by vtubati
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Enable DLSw+ Peer Clusters on the Border Peer
DLSw+ Peer Group Clusters 7
The following is output from the show dlsw capabilities local command on MPB:
ibm-25kb#show dlsw cap local
DLSw:Capabilities for local peer 10.1.1.2
vendor id (OUI) :'00C' (cisco)
version number :2
release number :0init pacing window :20
unsupported saps :none
num of tcp sessions :1
loop prevent support :no
icanreach mac-exclusive :no
icanreach netbios-excl. :no
reachable mac addresses :none
reachable netbios names :none
V2 multicast capable :yes
DLSw multicast address :none
cisco version number :1
peer group number :2
peer cluster support :yes
peer cluster id :5------->Indicates the value configured for peer cluster id.
border peer capable :no
peer cost :3
biu-segment configured :no
UDP Unicast support :yes
cisco RSVP support :no
current border peer :peer 10.8.218.61(2065) cost 3
version string :
Cisco Internetwork Operating System Software
IOS (tm) 2500 Software (C2500-AJS-L), Experimental Version 12.0(19981113:101717)
[vtubati-120t_3_pi 114]
Copyright (c) 1986-1998 by cisco Systems, Inc.
Compiled Fri 13-Nov-98 15:49 by vtubati
Command ReferenceThis section documents new or modified commands. All other commands used with this feature aredocumented in the Cisco IOS Release 12.0 command references.
dlsw local-peer
dlsw remote-peer tcp
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Command Reference
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dlsw local-peerUse the dlsw local-peerglobal configurationcommand to define theparameters of theDLSw+ local
peer. Use the no form of this command to cancel the definitions.
dlsw local-peer [cluster cluster-id] [peer-id ip-address] [group group] [border] [cost cost]
[lfsize] [keepalive seconds] [passive] [promiscuous] [biu-segment][init-pacing-window size] [max-pacing-window size]
no dlsw local-peer [cluster cluster-id] [peer-id ip-address] [group group] [border] [cost cost]
[lfsize] [keepalive seconds] [passive] [promiscuous] [biu-segment]
[init-pacing-window size] [max-pacing-window size]
Syntax Description
cluster cluster-id (Optional) Implements the DLSw+ Peer Clusters feature and
defines the router as part of a particular cluster. The valid range
is 1 to 255.
peer-id ip-address (Optional) Local peer IP address. This address is required whenFast-Sequenced Transport (FST) or TCP is used.
group group (Optional) Peer group number for this router. The valid range is
1 to 255.
border (Optional) Enables the router as a border peer. The group option
must be specified to use the border peer option.
cost cost (Optional) Peer cost advertised to remote peers in the
capabilities exchange. The valid range is 1 to 5.
lfsize (Optional) Largest frame size for this local peer. Valid
maximum frame sizes are as follows:
516-516 byte
1470-1470 byte
1500-1500 byte
2052-2052 byte
4472-4472 byte
8144-8144 byte
11407-11407
11454-11454
17800-17800
keepalive seconds (Optional) Default remote peer keepalive interval in seconds.
The valid range is 0 to 1200 seconds. The default is 30 seconds.The value 0 means no keepalives.
passive (Optional) Specifies that this router does not initiate remote
peer connections to configured peers.
promiscuous (Optional) Accept connections from nonconfigured remote
peers.
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dlsw local-peer
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Default
No parameters are defined.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3.
When there are multiple peers to a specific destination, use the cost keyword to determine which
router is preferred and which is capable. The cost keyword only applies in fault tolerance mode.
The biu-segment option is a performance and utilization improvement. If a frame that arrives from
a remote peer is too large for the destination station to handle, DLSw+ segments the frame. If you
choose to implement this option, you must add the option to both DLSw peer partners.
Example
The following command defines the local peer IP address and specifies the peer group number forthis router:
dlsw local-peer peer-id 10.2.17.1 group 2
Related Commands
dlsw duplicate-path-bias
show dlsw capabilities
biu-segment (Optional) DLSw+ spoofs the maximum receivable I-frame size
in XID so that each end station sends its largest frame.
init-pacing-window size (Optional) Size of the initial pacing window as defined in RFC
1795. The valid range is 1 to 2000.
max-pacing-window size (Optional) Maximum size of the pacing window as defined in
RFC 1795. The valid range is 1 to 2000.
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Command Reference
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dlsw remote-peer tcpUse the dlsw remote-peer tcp global configuration command to identify the IP address of a peer
with which to exchange traffic using TCP. Use theno form of this command to remove a remote peer.
dlswremote-peer list-numbertcp ip-address [backup-peer [ip-address | frame-relay interface
serial number dlci-number| interface name]] [bytes-netbios-out bytes-list-name][cluster cluster-id] [cost cost] [dest-mac mac-address]
[dmac-output-list access-list-number] [dynamic] [host-netbios-out host-list-name]
[inactivity minutes] [dynamic] [keepalive seconds] [lfsize] [linger minutes]
[lsap-output-list list] [no-llc minutes] [passive] [priority]
[rif-passthru virtual-ring-number] [tcp-queue-max size] [timeout seconds]
no dlsw remote-peer list-numbertcp ip-address [backup-peer [ip-address | frame-relay
interface serial number dlci-number| interface name]] [bytes-netbios-out bytes-list-name]
[cluster cluster-id] [cost cost] [dest-mac mac-address]
[dmac-output-list access-list-number] [dynamic] [host-netbios-out host-list-name]
[inactivity minutes] [dynamic] [keepalive seconds] [lfsize] [linger minutes]
[lsap-output-list list] [no-llc minutes] [passive] [priority]
[rif-passthru virtual-ring-number] [tcp-queue-max size] [timeout seconds]
Syntax Description
list-number Remote peer ring group list number. This ring group list
number default is 0. Otherwise, this value must match the
number you specify with the dlsw ring-list, dlsw port-list
or dlsw bgroup-list command.
tcp ip-address IP address of the remote peer with which the router is to
communicate.
backup-peer ip-address (Optional) IP address of the existing TCP/FST peer for
which this peer is the backup peer.
backup-peerframe-relay interface
serial number dlci-number
(Optional) Serial interface and DLCI number of the
existing Direct/LLC2 Frame-Relay peer for which this peer
is the backup peer.
backup-peer interface name (Optional) Interface name of the existing direct peer for
which this peer is the backup peer.
bytes-netbios-out bytes-list-name (Optional) Configures NetBIOS bytes output filtering for
this peer. The bytes-list-name argument is the name of the
previously defined NetBIOS bytes access list filter.
cluster cluster-id (Optional) Used to indicate to a border peer that aparticular remote-peer should be treated as part of a
specific peer cluster. The valid Range is 1 to 255.
cost cost (Optional) Cost to reach this remote peer. The valid range
is 1 to 5.
dest-mac mac-address (Optional) Establishes the TCP connection only when there
is an explorer frame destined for the specified 48-bit MAC
address written in dotted triplet form.
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dlsw remote-peer tcp
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dmac-output-list
access-list-number
(Optional) Establishes the TCP connection only when the
explorer frame passes the specified access list. The
access-list-numberis the list number specified in the
access-list command.
dynamic (Optional) Establishes the TCP connection only when there
is DLSw+ data to send.
host-netbios-out host-list-name (Optional) Configures NetBIOS host output filtering for
this peer. The host-list-name is the name of the previously
defined NetBIOS host access list filter.
inactivity minutes (Optional) Length of time a connection is idle before
closing the dynamic remote peer connection. The valid
range is 1 to 300 minutes. The default is 5 minutes.
keepalive seconds Keepalive interval for this remote peer. The range is 0 to
1200 seconds.
lfsize (Optional) Largest frame size, in bytes, this local peer uses
on a circuit to avoid segmented frames. Valid sizes are 516,
1470, 1500, 2052, 4472, 8144, 11407, 11454, and 17800
bytes.
linger minutes (Optional) Length of time the backup peer remains
connected after the primary peer connection is
reestablished. The valid range is 1 to 300 minutes. The
default is 5 minutes.
lsap-output-list list (Optional) Filters output IEEE 802.5 encapsulated packets.
Valid access list numbers are 200 to 299.
no-llc minutes (Optional) Length of time a remote peer remains connected
after all LLC2 connections are gone. The valid range is 1 to
300 minutes. The default is 5 minutes.
passive (Optional) Designates this remote peer as passive.
priority (Optional) Enables prioritization features for this remote
peer. Valid TCP port numbers are the following:
High: 2065
Medium: 1981
Normal: 1982
Low: 1983
rif-passthru virtual-ring-number (Optional) Configures the remote peer as RIF-Passthru.
The virtual-ring-numbervalue is the same number as the
ring numbervalue assigned in the source-bridge
ring-group commands of the DLSw+ Passthru peers.
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Command Reference
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Defaults
No peer IP address is identified.
The linger option is inactive. If the linger option is added with no minutes specified, the default is
5 minutes.
The dynamic option is not on by default. If the dynamic option is added without either the inactivity
or no-llc argument specified, the default is to terminate the TCP connection to the remote peer after
5 minutes of no active LLC2 connection.
Command Mode
Global configuration
Usage Guidelines
This command first appeared in Cisco IOS Release 10.3. The following keywords and arguments
first appeared in Cisco IOS Release 11.1: dynamic, inactivity minutes, linger minutes,
no-llc minutes and timeout seconds. The following keywords and arguments first appeared in
Cisco IOS Release 11.2: dest-mac mac-address, dmac-output-list access-list-number, linger
minutes.
SNA Dial-on-Demand Routing allows switched links to be closedduring idle periods. To enable this
feature, set the keepalive option to 0 and configure the timeout option. When the dynamic option
is configured, the keepalive option is automatically set to 0.
To enhance DDR cost savings, configure the TCP connection to a remote peer so it is dynamically
established (that is, established only when there is DLSw data to send). You can also configure the
TCP connection to terminate after a specified period of idle time on the peer or after a specified
period of no active LLC sessions on the peer.
You cannot use both no-llc and inactivity in a command specifying a dynamic peer.
When you need to permit access to a single MAC address, the dest-mac option takes less time to
configure than the dmac-output-list option.
Use the linger option to specify that a backup peer will remain connected for a specified period of
time after the primary connection is gone.
When the priority option on the dlsw remote-peer command is configured, DLSw+ automatically
activates four TCP ports to that remote peer (ports 2065, 1981, 1982 and 1983) and assigns traffic to
specific ports. Furthermore, if APPN is running with DLSw+ and you specify the priority option on
the dlsw remote-peer command, then the SNA TOS maps APPN COS to TCP TOS and preserves
the APPN COS characteristics throughout the network.
The rif passthru option works only on Token Ring LANs via SRB. Other LANtypes, such as SDLC
and QLLC, are not supported. The RIF Passthru feature is supported with TCP encapsulation and it
disables local acknowledgment.
tcp-queue-max size (Optional) Maximum output TCP queue size for this
remote peer. The valid maximum TCP queue size is
10 to 2000.
timeout seconds (Optional) Retransmit time limit for TCP. The valid range
is 5 to 1200 seconds. The default is 90 seconds.
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dlsw remote-peer tcp
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The following features are not supported with the DLSw+ RIF Passthru feature:
Border peers
Peer-on-demand peers
Dynamic peers
Backup peers
The cluster keyword is available only on border peers.This optionenables the DLSw+ Peer Clusters
feature without forcing every DLSw+ router in the network to upgrade their software.
Examples
The following example specifies a TCP encapsulation connection for remote peer transport:
dlsw remote-peer 0 tcp 10.2.17.8
The following example specifies a TCP peer as backup to a primary FST peer:
dlsw remote-peer 0 fst 10.2.18.9dlsw remote-peer 0 tcp 10.2.17.8 backup-peer 10.2.18.9
Related Commands
show dlsw peers
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Command Reference
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