From: Petr Lapukhov (petrsoft@gmail.com)
Date: Sun Mar 26 2006 - 10:02:44 GMT-3
-- Sorry, repating e-mail to group address
Hello David,
If you run PIM Dense mode over FR H&S topology, you basically
face an OLIST problem when you try to reach group joined on spoke
from another spoke.
Hub won't forward mpacket on the same interface it was received from.
This problem could be solved with single tunnel (either R1-R2, R2-R3, R1-R3)
and proper static mroute on _receiving_ side of the tunnel (to prefer tunnel
over
physical interface for sure).
Now if you run PIM Sparse over H&S, you may face the same problem,
and more.
1) You may miss BSR/AutoRP announces due to OLIST problem.
2) You may be unable to join shared tree if RP is places improperly (spoke)
3) You may face OLIST problem with mpacket delivery (the same as above).
Leaving 1,2 aside, lets look at 3.
For that mpacket OLIST problem, you may basically:
1) use tunnel/mroute, as in PIM-DM
2) use "pim nbma-mode" on hub multipoint interface,
3) enable PIM bidir mode to use bidirectional shared tree and place RP on
hub
HTH
Petr
2006/3/26, david robin <robindavi@gmail.com>:
>
> dear all,
> I want to very something with ip multicast, if we have a frame-relay
> connection, R1 is the hub connected wih a multipoint interface to r2 and
> r3
> the spokes, the qusetion is if we had a multicast group on r2 fast
> ethernet
> ( using ip igmp join), the fact that I cant ping this multicast group from
> r3, does i have to configure tunnels ( 1 tunnel between r1 and r2 and 1
> tunnel between r1 and r3) in order to make the multicast packets flow ??
>
> Also there is another question in case i run pim sparse-dense as r1 is the
> RR the same problem will occur and does i have to configure tunnel too ???
>
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