Cisco 3560G 48TS Software Configuration Guide - Page 754

Configuring MSDP Chapter 33 Configuring MSDP Step 3 Step 4 Step 5 Step 6 Step 7 Command ip prefix-list name [description string] | seq number {permit | deny} network length ip msdp description {peer-name | peer-address} text end show running-config copy running-config startup-config Purpose (Optional) Create a prefix list using the name specified in Step 2. • (Optional) For description string, enter a description of up to 80 characters to describe this prefix list. • For seq number, enter the sequence number of the entry. The range is 1 to 4294967294. • The deny keyword denies access to matching conditions. • The permit keyword permits access to matching conditions. • For network length, specify the network number and length (in bits) of the network mask that is permitted or denied. (Optional) Configure a description for the specified peer to make it easier to identify in a configuration or in show command output. By default, no description is associated with an MSDP peer. Return to privileged EXEC mode. Verify your entries. (Optional) Save your entries in the configuration file. To remove the default peer, use the no ip msdp default-peer ip-address | name global configuration command. This example shows a partial configuration of Router A and Router C in Figure 33-2. Each of these ISPs have more than one customer (like the customer in Figure 33-2) who use default peering (no BGP or MBGP). In that case, they might have similar configurations. That is, they accept SAs only from a default peer if the SA is permitted by the corresponding prefix list. Router A Router(config)# ip msdp default-peer 10.1.1.1 Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a Router(config)# ip prefix-list site-b permit 10.0.0.0/1 Router C Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a Router(config)# ip prefix-list site-b permit 10.0.0.0/1 Caching Source-Active State By default, the switch does not cache source/group pairs from received SA messages. When the switch forwards the MSDP SA information, it does not store it in memory. Therefore, if a member joins a group soon after a SA message is received by the local RP, that member needs to wait until the next SA message to hear about the source. This delay is known as join latency. If you want to sacrifice some memory in exchange for reducing the latency of the source information, you can configure the switch to cache SA messages. 33-6 Catalyst 3560 Switch Software Configuration Guide 78-16156-01