show ip msdp sa-limitIf the total number of active sources is already larger than the limit when limiting is applied, the sources that are already in Dell NetworkingOS are not discarded. To enforce the limit in such a situation, use the clear ip msdp sa-cache command to clear all existing entries.Clearing the Source-Active CacheTo clear the source-active cache, use the following command.• Clear the SA cache of all, local, or rejected entries, or entries for a specific group.CONFIGURATION modeclear ip msdp sa-cache [group-address | local | rejected-sa]Enabling the Rejected Source-Active CacheTo cache rejected sources, use the following command.Active sources can be rejected because the RPF check failed, the SA limit is reached, the peer RP is unreachable, or the SA message has aformat error.• Cache rejected sources.CONFIGURATION modeip msdp cache-rejected-saAccept Source-Active Messages that Fail the RFPCheckA default peer is a peer from which active sources are accepted even though they fail the RFP check.Referring to the following illustrations:• In Scenario 1, all MSPD peers are up.• In Scenario 2, the peership between RP1 and RP2 is down, but the link (and routing protocols) between them is still up. In this case,RP1 learns all active sources from RP3, but the sources from RP2 and RP4 are rejected because the reverse path to these routers isthrough Interface A.• In Scenario 3, RP3 is configured as a default MSDP peer for RP1 and so the RPF check is disregarded for RP3.• In Scenario 4, RP1 has a default peer plus an access list. The list permits RP4 so the RPF check is disregarded for active sources fromit, but RP5 (and all others because of the implicit deny all) are subject to the RPF check and fail, so those active sources are rejected.Multicast Source Discovery Protocol (MSDP) 563
