[Xorp-users] Unable to forward multicast packets

[James Courtier-Dutton]

On 7/27/05, batkinson <batkinson@virtc.com> wrote:
> Pavlin,
> 
> >>One possible problem that comes to mind is that the original
> >>multicast packets are probably transmitted with the default TTL of
> >>1.
> >>TTL of 1 is sufficient for link-local multicast, but such multicast
> >>packets won't be forwarded across subnets.
> >>
> >>Try to increase the TTL of the transmitted data packets and see if
> >>the problem goes away.
> 
> My test app has a command line switch to change the default of TTL=1, but I
> was not using it.  I increased the TTL, and now everything is working as
> expected.
> 
> Thank you very much for your valuable and prompt assistance with my problem.
> 
> Best Regards,
> 
> Brian D. Atkinson
> Technical Lead Engineer
> Virtual Technology Corporation
> Orlando, FL  USA
> 

The two most common problems for multicast traffic failing to be forwarded are:
1) TTL=1
2) RPF checks fail (Reverse Path Forwarding)