Cisco IE 4000, Software Configuration Manual

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Configuring MSDP
Configuring MSDP
Configuring a Default MSDP Peer
In this software release, because BGP and MBGP are not supported, you cannot configure an MSDP peer on the local
switch by using the
ip msdp peer global configuration command. Instead, you define a default MSDP peer (by using the
ip msdp default-peer global configuration command) from which to accept all SA messages for the switch. The default
MSDP peer must be a previously configured MSDP peer. Configure a default MSDP peer when the switch is not BGP- or
MBGP-peering with an MSDP peer. If a single MSDP peer is configured, the switch always accepts all SA messages from
that peer.
Figure 93 on page 734 shows a network in which default MSDP peers might be used. In Figure 93 on page 734 , a
customer who owns Switch B is connected to the Internet through two Internet service providers (ISPs), one owning
Router A and the other owning Router C. They are not running BGP or MBGP between them. To learn about sources in
the ISP’s domain or in other domains, Switch B at the customer site identifies Router A as its default MSDP peer. Switch
B advertises SA messages to both Router A and Router C but accepts SA messages only from Router A or only from
Router C. If Router A is first in the configuration file, it is used if it is running. If Router A is not running, only then does
Switch B accept SA messages from Router C. This is the default behavior without a prefix list.
If you specify a prefix list, the peer is a default peer only for the prefixes in the list. You can have multiple active default
peers when you have a prefix list associated with each. When you do not have any prefix lists, you can configure multiple
default peers, but only the first one is the active default peer as long as the router has connectivity to this peer and the
peer is alive. If the first configured peer fails or the connectivity to this peer fails, the second configured peer becomes
the active default, and so on.
The ISP probably uses a prefix list to define which prefixes it accepts from the customer’s router.
Figure 93 Default MSDP Peer Network
Follow this procedure to specify a default MSDP peer. This procedure is required.
BEFORE YOU BEGIN
An MSDP default peer must be a previously configured MSDP peer. Before configuring a default MSDP peer, you must
first configure an MSDP peer.
ISP A PIM domain
ISP C PIM domain
SA
Router A
Switch B
10.1.1.1
Default MSDP peer
Default MSDP peer
Default MSDP peer
Customer PIM domain
Router C
SA
SA
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