1-13z TTL threshold for multicast packet encapsulation in SA messagesz Maximum number of (S, G) entries learned from the specified MSDP peer that the router can cacheConfiguring SA Message ContentSome multicast sources send multicast data at an interval longer than the aging time of (S, G) entries. Inthis case, the source-side DR has to encapsulate multicast data packet by packet in register messagesand send them to the source-side RP. The source-side RP transmits the (S, G) information to theremote RP through SA messages. Then the remote RP joins the source-side DR and builds an SPT.Since the (S, G) entries have timed out, remote receivers can never receive the multicast data from themulticast source.If the source-side RP is enabled to encapsulate register messages in SA messages, when there is amulticast packet to deliver, the source-side RP encapsulates a register message containing themulticast packet in an SA message and sends it out. After receiving the SA message, the remote RPdecapsulates the SA message and delivers the multicast data contained in the register message to thereceivers along the RPT.The MSDP peers deliver SA messages to one another. Upon receiving an SA message, a routerperforms RPF check on the message. If the router finds that the remote RP address is the same as thelocal RP address, it will discard the SA message. In the Anycast RP application, however, you need toconfigure RPs with the same IP address on two or more routers in the same PIM-SM domain, andconfigure these routers as MSDP peers to one another. Therefore, a logic RP address (namely the RPaddress on the logic interface) that is different from the actual RP address must be designated for SAmessages so that the messages can pass the RPF check.Follow these steps to configure the SA message content:To do... Use the command... RemarksEnter system view system-view —Enter public instance MSDP view orVPN instance MSDP viewmsdp [ vpn-instancevpn-instance-name ] —Enable encapsulation of a registermessage encap-data-enable OptionalDisabled by defaultConfigure the interface address asthe RP address in SA messagesoriginating-rp interface-typeinterface-numberOptionalPIM RP address by defaultConfiguring SA Request MessagesBy default, upon receiving a new Join message, a router does not send an SA request message to anyMSDP peer; instead, it waits for the next SA message from its MSDP peer. This will cause the receiverto delay obtaining multicast source information. To enable a new receiver to get the currently activemulticast source information as early as possible, you can configure routers to send SA requestmessages to the designated MSDP peers upon receiving a Join message of a new receiver.Follow these steps to configure SA message transmission and filtering:
