3Com S7906E - Switch, Руководство по настройке

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z
TTL threshold for multicast packet encapsulation in SA messages
z
Maximum number of (S, G) entries learned from the specified MSDP peer that the router can cache
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 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... Use the command... Remarks
Enter system view system-view —
Enter public instance MSDP view or
VPN instance MSDP view msdp [ vpn-instance
vpn-instance-name ]
—
Enable encapsulation of a register
message
encap-data-enable
Optional
Disabled by default
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, upon 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 currently active
multicast source information as early as possible, you can configure routers to send SA request
messages to the designated MSDP peers upon receiving a Join message of a new receiver.
Follow these steps to configure SA message transmission and filtering: