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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter25 Configuring MSDP
Configuring MSDP
To remove the default peer, use the no ip msdp default-peer global configuration command.
This example shows a partial configuration of Router A and Router C i n Figure 25-2. Each of these ISPs
have more than one customer (like the customer in Figure 25-2) who use default pe ering (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 10.0.0.0/8
Router C
Router(config)# ip msdp default-peer 10.1.1.1 prefix-list site-a
Router(config)# ip prefix-list site-b permit 10.0.0.0/8
Caching Source-Active State
By default, the multilayer 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 l atenc y.
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.
Step3 ip prefix-list name [description string] |
seq number {permit | deny} network
length
(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.
Step4 ip msdp description {peer-name |
peer-address} text (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.
Step5 end Return to privileged EXEC mode.
Step6 show running-config Verify your entries.
Step7 copy running-config startup-config (Optional) Save your entries in the configuration file.
Command Purpose