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Table Of Contents
Define a Source-Bridge Ring Group for DLSw+
Define a DLSw+ Local Peer for the Router
Enable DLSw+ on a Token Ring Interface
Configure Remote Peer with TCP Encapsulation
RIF Passthru in DLSw+
Feature Summary
By default, DLSw+ terminates the RIF for Token Ring, terminates the LLC for all media types and forwards data only across a WAN with DLSw+ and TCP/IP headers. The RIF is a field in source-route bridged frames that indicates the SRB path the frame should take when traversing a Token Ring network. In the case of an explorer packet, the RIF is a field of the source-route bridged frame that indicates the SRB path that the SRB explorer has traversed so far. The RIF is limited to seven hop counts by the IBM standards. Because DLSw+ terminates the RIF at the virtual ring, the network's scalability increases because the hop count of the packet starts over, and the packet can traverse seven additional hops. Also, RIF termination simplifies network design because ring numbers no longer have to be unique throughout an entire enterprise.
However, some environments do not function properly if the RIF is terminated. For that reason, DLSw+ now supports the RIF Passthru feature, in which the entire source-route bridged path appears in the RIF.
shows a DLSw+ network without the RIF Passthru feature configured.
Figure 1
DLSw+ Network Without RIF Passthru
shows a DLSw+ network with the RIF Passthru feature configured.
Figure 2
DLSw+ Network with RIF Passthru
Benefits
When DLSw+ is used between FEPs (PU 4s), the RIF Passthru feature enables two key functions. First, RIF Passthru is required to allow multiple active paths between FEPs. Second, RIF Passthru is required to remotely load an NCP (in other words, set initialization mode/request initialization mode support).
List of Terms
Set initialization mode—DLC command that initiates system-specified procedures to initialize link-level functions.
Request initialization mode—DLC command that requests system-specified procedures to initialize link-level functions
Remote NCP load—Operation that occurs when an IBM 3745 does not contain a network control program (NCP). The IBM 3745 replies with request initialization mode when it is contacted by the host. The host (partner NCP) sends a set initialization mode, and then remotely transmits an NCP to the IBM 3745.
Restrictions
The DLSw+ RIF Passthru feature works only on Token Ring LANs via SRB. Other LAN types, such as SDLC and QLLC, are not supported. The RIF Passthru feature is supported with TCP encapsulation and it disables local acknowledgment.
The following features are not supported with the DLSw+ RIF Passthru feature:
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Border peers
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Platforms
This feature is supported on the following platforms:
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Prerequisites
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Define a Source-Bridge Ring Group for DLSw+
The source-bridge ring can be shared between DLSw+ and SRB/RSRB. In DLSw+, the source-bridge ring group specifies the virtual ring that will appear to be the last ring in the RIF. Because RIFs are terminated at the router, there is no correlation between the ring-group number specified in DLSw+ peers. The numbers can be the same for management simplicity, but they do not have to be the same.
In DLSw+ with RIF Passthru, however, the ring numbers must be unique throughout the network and DLSw peers must have the same virtual ring number because RIFs are passed through.
To define a source-bridge ring group for DLSw+, perform the following task in global configuration mode:
Define a DLSw+ Local Peer for the Router
Defining a DLSw+ local peer for a router enables DLSw+. You specify all local DLSw+ parameters as part of the local peer definition. To define a local peer, perform the following task in global configuration mode:
Enable DLSw+ on a Token Ring Interface
To enable DLSw+ on a Token Ring interface, perform the following task in interface configuration mode:
Enable DLSw+ on a Token Ring interface.
source-bridge local-ring bridge-number ring-group
Supported MIBs and RFCs
None.
Configuration Task
To configure DLSw+ RIF Passthru, define the DLSw+ remote peer with TCP encapsulation.
Configure Remote Peer with TCP Encapsulation
To configure TCP encapsulation on a remote peer, perform the following task in global configuration mode:
Note
Configuration Examples
is a sample configuration for DLSw+ using the RIF Passthru feature.
Figure 3
Network Configuration with RIF Passthru
Router A
source-bridge ring-group 100dlsw local-peer peer id 10.1.12.1dlsw remote-peer 0 tcp 10.1.14.2 rif-passthru 100interface tokenring 0ring-speed 16source-bridge 25 1 100source-bridge spanningRouter B
source-bridge ring-group 100dlsw local-peer peer id 10.1.14.2dlsw remote-peer 0 tcp 10.1.12.1 rif-passthru 100interface tokenring 0ring-speed 16source-bridge 51 1 100source-bridge spanningCommand Reference
This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 11.3 command references.
dlsw remote-peer tcp
Use the dlsw remote-peer tcp global configuration command to identify the IP address of a peer with which to exchange traffic using TCP. Use the no form of this command to remove a remote peer.
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]
[cost cost] [dest-mac mac-address] [dmac-output-list access-list-number] [dynamic]
[host-netbios-out host-list-name] [inactivity minutes] [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]
no 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]
[cost cost] [dest-mac mac-address] [dmac-output-list access-list-number] [dynamic]
[host-netbios-out host-list-name] [inactivity minutes] [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]Syntax Description
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. The following keyword first appeared in Cisco IOS Release 11.3 T: rif-passthru virtual ring number.
SNA DDR technology allows switched links to be closed during 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, you can configure the TCP connection to a remote peer to be dynamically established (that is, established only when there is DLSw data to send). You can further 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 is a shortcut over 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 will map APPN class of service (COS) to TCP TOS and will preserve the APPN COS characteristics throughout the network.
Examples
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 1 tcp 10.2.17.8 backup-peer 10.2.18.9The following example specifies a TCP encapsulation connection for remote peer transport:
dlsw remote-peer 1 tcp 10.2.17.8The following is an example policy routing configuration that shows how to modify the default setting of TCP port 2065. The configuration changes the default setting on IP packets from network control precedence to routine precedence.
ip local policy route-map testaccess-list 101 permit tcp any eq 2065 anyaccess-list 101 permit tcp any any eq 2065route-map test permit 20match ip address 101set ip precedence routineRelated Commands
