Manual

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221
number | access-list-name>]
rules for SA request packets.
28.4.6 Configuration of Parameters of SA-cache
Commands
Explanation
MSDP Configuration Mode
cache-sa-state
no cache-sa-state
To enable the SA packet cache.
To disable the SA packets cache.
MSDP Configuration Mode
cache-sa-holdtime <150-3600>
no cache-sa-holdtime
The aging time for entries in the SA cache.
To restore the default aging time
configuration.
MSDP Configuration Mode or MSDP Peer Configuration Mode
cache-sa-maximum <sa-limit>
no cache-sa-maximum
To configure the maximum size for the SA
cache.
To restore the size of the SA cache to the
default value.
28.4.7 MSDP Configuration Examples
Example 1: MSDP basic function.
Multicast Configuration:
Suppose the multicast server is sending multicast datagram at 224.1.1.1;
The designated router – DR, which is connected to the multicast server, encapsulate the
multicast datagram in the Register packets and send them to the RP(RP1) in the local domain;
The RP unwraps the packets and sends them to all the domain members through the shared
tree. The members in the domain can be configured to be or not to be in the shared tree;
At the same time, the source RP in the domain, generates a SA – Source Active message, and
send it to the MSDP entity – RP2.
If there’s another member in the same domain with the MSDP entity which is named as RP3,
RP3 will distribute the multicast datagram encapsulated in the SA messages to the members
of the shared tree, and send join messages to the multicast source. That means RP creates an
entry (S, G), and send join messages for (S, G) hop by hop, so that (S, G) can reach the SPT
which takes the multicast source as the root across the PIM-SM domain.
If there no members in the same domain with MSDP entity – RP2, RP2 will not create the (S,
G) entry nor it will join the SPT which takes the multicast source as the root.
When the reverse route has been set up, the multicast datagram from the source will be
directly delivered to RP3, and RP will forward the datagram to the shared tree. At this time, the
router which is closest to the domain members can determine itself whether or not to switch to
SPT.