PIM SM (S,G) states

[jschweng]

We have a requirement to send data via multicast from source to destination

it only has to go through one MRouter which is a 3750G configured with PIMSM

All the router does is pick up packets from the source which is directly off one interface and statically route them down the appropriate interface to the receiver.

The data is a dump of files which is done periodically and we cannot lose any of the packets.

What happens is if they don't do a dump for a while the (S,G) times out.  Then it has to be created again at the beginning of every dump.

During that time we lose some of the first packets.

Is there any way to get around this by statically creating (S,G) states or any other options?

I know we can increase the sg-expiry-timeout but eventually it will expire.

Can the expiry-timeout be set to never ?

[jschweng]

any idea if usnig PIM SSM instead of PIM SM will resolve the issue on a 3750?

[Peter Paluch]

Hello Martin,

If the multicast traffic is supposed to be only locally routed, do you think you could run PIM-DM instead of PIM-SM? In PIM-DM, there is always an implicit join (multicast is flooded to all multicast-enabled interfaces), and prunes are generated only in the case a router has no directly connected receivers and no grafted PIM-DM neighbors. In your case, I believe, this is just what you need - as long as your receivers keep joined to the group via IGMP, your router has no other PIM-DM neighbor to receive a prune message, and thus should never stop forwarding the multicast.

Best regards,

Peter