3com 5500-ei pwr Instruccion De Instalación

 

12 

With the SA message caching mechanism enabled on the router, the group that a new member 

subsequently joins can obtain all active sources directly from the SA cache and join the corresponding 

SPT source tree, instead of waiting for the next SA message.  

You can configure the number of SA entries cached in each MSDP peer on the router by executing the 

following command, but the number must be within the system limit. To protect a router against Denial 

of Service (DoS) attacks, you can manually configure the maximum number of SA messages cached on 

the router. Generally, the configured number of SA messages cached should be less than the system 

limit.  

Follow these steps to configure SA message cache: 

Enter system view 

— 

Enter MSDP view 

— 

Enable SA message caching 
mechanism 

Optional 

Enabled by default  

Configure the maximum 
number of SA messages that 
can be cached 

peer peer-address 
sa-cache-maximum sa-limit 

Optional 

The default is 2,048.  

 

After you enable the sending of SA request messages, when a router receives a Join message, it sends 

an SA request message to the specified remote MSDP peer, which responds with an SA message that 

it has cached. After sending an SA request message, the router will get immediately a response from all 

active multicast sources. The SA message that the remote MSDP peer sends in response is cached in 

advance; therefore, you must enable the SA message caching mechanism in advance. Typically, only 

the routers caching SA messages can respond to SA request messages.  

After you have configured a rule for filtering received SA messages, if no ACL is specified, all SA 

request messages sent by the corresponding MSDP peer will be ignored; if an ACL is specified, the SA 

request messages that satisfy the ACL rule are received while others are ignored.  

Follow these steps to configure the transmission and filtering of SA request messages:  

Enter system view 

— 

Enter MSDP view 

— 

Enable SA message caching 
mechanism 

Optional 

By default, the router caches the 
SA state upon receipt of an SA 
message.  

Enable MSDP peers to send 
SA request messages 

peer peer-address 
request-sa-enable 

Optional 

By default, upon receipt of a Join 
message, the router sends no SA 
request message to its MSDP peer 
but waits for the next SA message.