SA Cache

As an MSDP router learns of new sources either through a PIM-SM Source-Register (SR) message or SA message from its RPF peer, it creates an entry in SA cache (or refreshes the entry if it is already there) and forwards this information to its peers. These entries are refreshed by periodic SA messages received from the MSDP peers. If these entries are not refreshed within six minutes, they will time out. When a PIM-SM RP detects that the source is no longer available it informs MSDP, which in turn removes the SA information from the local database.

Caching makes it easy for local receivers to know immediately about inter-domain multicast sources and to initiate building a source tree towards the source. However, maintaining a cache is heavy both in CPU processing and memory requirements.

Note

Note

Our implementation of MSDP does not support operating with local cache disabled.