Configuring the SA Cache
Context
To shorten the delay of obtaining multicast information, enable the Source-Active (SA) caching function on the device. The device can locally cache (S, G) entities contained in SA messages. When the device receives a new Join message, it searches the local cache for the (*, G) entry carried in the message:
- If the matching (S, G) entry is found, the device adds the sender of the Join message to the shortest path tree (SPT) with S as the root.
- If no matching (S, G) entry is found, the device must wait for the SA message sent by the MSDP peer during the next period.
When there are more (S, G) entries in the cache, they occupy a larger memory space. You can set the maximum number of (S, G) entries to be cached to efficiently protect the device against Denial of Service (DoS) attacks.
Procedure
- Run system-view
The system view is displayed.
- Run msdp [ vpn-instance vpn-instance-name ]
The MSDP view is displayed.
- Run cache-sa-enable
The SA caching function is enabled.
By default, the SA caching function is enabled on the router that has a remote MSDP peer specified.
- (Optional) Run peer peer-address sa-cache-maximum sa-limit
The maximum number of (S, G) entries is set.
By default, a maximum of 1638 (S, G) entries can be saved to the SA cache.
The value takes effect only when it is smaller than the specification of the cache. If the value is larger than the specification of the cache, the specification of the cache takes effect.
At present, for an entire router, the maximum number of (S, G) entries in SA-Cache is 1638.
For the (S, G) entries of a single peer, the following situations occur:
If the number of (S, G) entries is not set or exceeds 1638, the maximum number of (S, G) entries in the SA cache can be set to 1638.
If the number of (S, G) entries is smaller than 1638, the maximum number of (S, G) entries in the SA cache is the configured value. The redundant (S, G) entries are not cached or advertised to PIM-SM but can be forwarded through SA messages.
When there are more (S, G) entries in the cache, they occupy a larger memory space. You can set the maximum number of (S, G) entries to be cached to efficiently protect the device against Denial of Service (DoS) attacks