Configuring Sa Message; Content; Configuring Sa Request Messages - 3Com MSR 50 Series Configuration Manual

1142 C 70: MSDP C
HAPTER

Configuring SA Message

Content

Configuring SA Request
Messages
ONFIGURATION
ACL as a filtering rule for SA request messages
■
ACL as an SA message creation rule
■
ACL as a filtering rule for receiving or forwarding SA messages
■
Minimum TTL value of multicast packets encapsulated in SA messages
■
Maximum SA message cache size
■
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 has to 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. Since
the (S, G) entries have timed out, remote receivers can never receive the multicast
data from the multicast source.
If the source-side RP is enabled to encapsulate register messages in SA messages,
when there is a multicast packet to deliver, the source-side RP encapsulates a
register message containing the multicast packet in an SA message and sends it
out. After receiving the SA message, the remote RP decapsulates the SA message
and delivers the multicast data contained in the register message to the receivers
along the RPT.
The MSDP peers deliver SA messages to one another. Upon 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 will discard the SA
message. In the Anycast RP application, however, you need to 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.
Follow these steps to configure the SA message content:
To do...
Enter system view
Enter public instance MSDP
view or VPN instance MSDP
view
Enable encapsulation of a
register message
Configure the interface
address as the RP address in
SA messages
By default, upon receiving a new Join message, a router does not send an SA
request message to its designated 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 currently active
multicast source information as early as possible, you can configure routers to
Use the command...
system-view
msdp [ vpn-instance
vpn-instance-name ]
encap-data-enable
originating-rp interface-type
interface-number
Remarks
-
-
Optional
Disabled by default
Optional
PIM RP address by default