[Xorp-users] IGMP/PIM question ?

Pavlin Radoslavov pavlin at icir.org
Tue May 23 12:10:15 PDT 2006


> Unfortunately, those mods won't eliminate the suppression problem,
> because as I mentioned above it happens inside the kernel, and you
> cannot disable it by userland programs.

On second thought, you might be able to use the following hack to
get around the IGMP suppression problem:
Install firewall filters to each router so the IGMP messages from
everybody else will be dropped. Thus, the kernel IGMP stack won't
see any IGMP messages from other hosts/routers. With this hack then
probably you don't need to modify the XORP IGMP code because the
filtering will be done by the firewall rules.

> Also, they won't eliminate the PIM Register encapsulation issue.
> Though, if you always switch to the shortest path (to the sender)
> after the first data packet, then the PIM Register duplicated packet
> will happen only when a new sender becomes active (until the SPT
> switch to that sender is completed).

If you can live with the initial data duplicates as described above,
then you need to hack only the PIM-SM DR election (and configure
your PIM-SM routers to perform the SPT switch after the first data
packet).

I believe you understand well that such modifications can be very
dangerous and you should use them only on your testbed for
experimental purpose.

Please let me know if you run into any issues.

Pavlin



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