Limiting which packets the router sends
Configure the time-to-live (TTL) threshold to limit which multicast data packets the router encapsulated in SA Messaged forwarded to an MSDP peer. The TTL limits the number of hops a packet can take before the router drops the packet. The router sends out SA Messages with encapsulated data only if TTL equals or exceeds the value you configure. If the TTL is lower than the value you configure, the router drops the data packet and forwards the SA Message without the encapsulated data.
Note
MSDP transmits encapsulated multicast data packets inside forwarded MSDP messages. If the received SA is an encapsulated SA, then the switch parses the TTL value of the encapsulated data and compares it against the configured value. If the configured value is less than or equal to the parsed value, then the switch forwards the encapsulated data along with the SA, otherwise the switch forwards the SA alone by stripping the encapsulate data. By default, MSDP forwards encapsulated data along with the SA message. MSDP does not forward the encapsulated data to the local receivers.
When MSDP generates SA messages for SPB sources, the local cache miss data cannot be encapsulated into the SA messages that are sent to the peers.
The switch supports forwarding SA messages with encapsulated data from sources to MSDP peers but not from MSDP peers to the receivers.
Procedure
Example
Switch:1>enable
Switch:1#configure terminal
Switch:1(config)#ip msdp ttl-threshold 21.0.0.2 10
Variable definitions
The following table defines parameters for the ip msdp ttl-threshold command.
|
Variable |
Value |
|---|---|
|
{A.B.C.D} |
Specifies the MSDP peer IP address. |
|
<1-255> |
Specifies the TTL value. Default value is 1. |