225When the SA cache mechanism is enabled and the router receives a new (*, G) join message, the routersearches its SA cache first.• If the corresponding (S, G) entry does not exist in the cache, the router waits for the SA message thatits MSDP peer will send in the next cycle.• If the corresponding (S, G) entry exists in the cache, the router joins the corresponding SPT rootedat S.To protect the router effectively against denial of service (DoS) attacks, you can set a limit on the numberof (S, G) entries the router can cache.To configure the SA message cache:Step Command Remarks1. Enter system view. system-view N/A2. Enter public network MSDP view orVPN instance MSDP view.msdp [ vpn-instancevpn-instance-name ] N/A3. Enable the SA cache mechanism. cache-sa-enable Optional.Enabled by default.4. Configure the maximum number of (S,G) entries learned from the specifiedMSDP peer that the router can cache.peer peer-addresssa-cache-maximum sa-limitOptional.8192 by default.Displaying and maintaining MSDPStep Command Remarks1. Display brief informationabout MSDP peers.display msdp [ all-instance |vpn-instance vpn-instance-name ]brief [ state { connect | down |listen | shutdown | up } ] [ |{ begin | exclude | include }regular-expression ]Available in any view2. Display detailed informationabout the status of MSDPpeers.display msdp [ all-instance |vpn-instance vpn-instance-name ]peer-status [ peer-address ] [ |{ begin | exclude | include }regular-expression ]Available in any view3. Display the (S, G) entryinformation in the SA cache.display msdp [ all-instance |vpn-instance vpn-instance-name ]sa-cache [ group-address |source-address | as-number ] * [ |{ begin | exclude | include }regular-expression ]Available in any view4. Display the number of (S, G)entries in the SA cache.display msdp [ all-instance |vpn-instance vpn-instance-name ]sa-count [ as-number ] [ | { begin |exclude | include }regular-expression ]Available in any view
