user manual

Configuring Data-Link Switching Plus
DLSw+ Configuration Task List
BC-303
Cisco IOS Bridging and IBM Networking Configuration Guide
78-11737-02
To configure promiscuous peer defaults, use the following command in global configuration mode:
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, page 303
• Ethernet Redundancy, page 305
• Backup Peers, page 305
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.
Command Purpose
Router(config)# dlsw prom-peer-defaults
[bytes-netbios-out bytes-list-name] [cost cost]
[dest-mac destination-mac-address]
[dmac-output-list access-list-number]
[host-netbios-out host-list-name] [keepalive
seconds] [lf size] [lsap-output-list list]
[tcp-queue-max size]
Configures promiscuous peer defaults.