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Configuring SA message content
Some multicast sources send multicast data at an interval longer than the aging time of (S, G) entries. In
this case, the source-side DR must encapsulate multicast data packet by packet in register messages and
send them to the source-side RP. The source-side RP transmits the (S, G) information to the remote RP
through SA messages. Then the remote RP joins the source-side DR and builds an SPT. Because the (S, G)
entries have timed out, remote receivers can never receive the multicast data from the multicast source.
After the source-side RP is enabled to encapsulate multicast data in SA messages, if the RP wants to sends
a multicast packet, it encapsulates the multicast packet in an SA message and sends it. After receiving the
SA message, the remote RP de-encapsulates the SA message and delivers the multicast packet to the
receivers in the local domain along the RPT.
The MSDP peers deliver SA messages to one another. After receiving an SA message, a router performs
RPF check on the message. If the router finds that the remote RP address is the same as the local RP
address, it discards the SA message. In the Anycast RP application, however, you must configure RPs with
the same IP address on two or more routers in the same PIM-SM domain and configure these routers as
MSDP peers to one another. Therefore, a logic RP address (namely, the RP address on the logic interface)
that is different from the actual RP address must be designated for SA messages so that the messages can
pass the RPF check.
To configure the SA message content:
Ste
Remarks
1. Enter system view.
system-view N/A
2. Enter MSDP view.
msdp N/A
3. Enable encapsulation of multicast
data in SA messages.
encap-data-enable
Optional.
Disabled by default.
4. Configure the interface address as
the RP address in SA messages.
originating-rp interface-type
interface-number
Optional.
PIM RP address by default.
Configuring SA request messages
By default, after receiving a new join message, a router does not send an SA request message to any
MSDP peer. Instead, it waits for the next SA message from its MSDP peer. This will cause the receiver to
delay obtaining multicast source information. To enable a new receiver to get the active multicast source
information as early as possible, you can configure routers to send SA request messages to the
designated MSDP peers after receiving a join message of a new receiver.
IMPORTANT:
Before you can enable the device to send SA requests, be sure to disable the SA message cache
mechanism.
To configure SA message transmission and filtering:
Ste
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