The peer request-sa-enable command enables the function of immediately sending the SA Request message to a specified MSDP peer.
The undo peer request-sa-enable command restores the default configuration.
By default, when receiving a new Join message for a group, the switch does not send an SA Request messages to MSDP peer but waits to receive the next SA message.
| Parameter | Description | Value |
|---|---|---|
| peer-address | Specifies the address of an MSDP peer. | The address is in dotted decimal notation. |
Usage Scenario
When a new user joins multicast group G in a PIM-SM domain, a (*, G) entry is created on the RP. If no corresponding (S, G) information exists on the RP and SA cache is not enabled on the RP, multicast routes cannot be generated for this user. The RP then must wait for the next SA message from the remote MSDP peer to obtain valid (S, G) information.
Generally, the interval for an MSDP peer to send SA messages is set to a large value to reduce traffic load in the PIM-SM domain. This, however, will cause a delay in joining the source's SPT. To minimize the delay, enable the function of immediately sending SA Request messages on the local RP and enable the SA cache function on the remote MSDP peer. If a new Join message is received but the local entries and SA cache do not contain corresponding (S, G) information, the local RP immediately sends an SA Request message to the remote MSDP peer instead of waiting to receive the next SA message.
Prerequisites
MSDP peers have been configured using the peer connect-interface (MSDP) command.
Precautions
Before configuring the peer request-sa-enable command on the local switch, disable SA cache on the local switch and enable SA cache on the peer of the specified peer-address. Therefore, when the local switch has new receiving requests, it can actively send SA Request messages to the peer and receive responses from the peer.