From: Bob Sinclair (bsinclair@netmasterclass.net)
Date: Wed Mar 17 2004 - 11:37:33 GMT-3
William,
In a recent lab, I was able to get multicast to go in and back out of a
multipoint frame interface hub. The config used sparse and nbma modes. If
you have time to lab this up and try it, it might show up on your list of
possible solutions.
HTH,
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: "William Chen" <kwchen@netvigator.com>
To: <ccielab@groupstudy.com>
Sent: Wednesday, March 17, 2004 7:20 AM
Subject: Multicast Scenario
> Dear all,
>
> I have a scenario of multicast and want your guys' comment:
>
> It is a hub-and-spoke frame-relay NBMA Network:
>
> R2 ------- R1 ------ R3
>
> And, it is full connectivity, that mean the spoke router no only have
the map to the hub, but also a map to the other spoke router. That is:
>
> ! R2
> int s0/0
> encap frame
> ip addr 172.16.123.2 255.255.255.0
> no frame inverse-arp
> frame map ip 172.16.123.1 201 broadcast
> frame map ip 172.16.123.2 201
> frame map ip 172.16.123.3 201 broadcast
> !
>
> Then, I have to configure multicast (PIM-DM) between R1 and R3, and
there are clients connected to R3. Moverover, I have to source traffic from
R2. I know that will cause a problem, because in R1 multicast traffic come
from the interface S0/0, cannot be forwarded out of the same interface to
R3. The solution can be create a tunnel between R2 and R3, and let the
multicast traffic flows along the tunnel to R3.
>
> My question is: since R2 have two frame-relay maps with broadcast, when
it generates multicast traffic, it will send two copies of packets and
forward it to R1 (pesudo-broadcast). Then R1 will get two copies of packets
of every multicast packet and forward it to R3. I think it will not cause a
big problem, but surely waste bandwidth.
>
> If you have this question in real lab? What will you do? create another
tunnel between R1 and R2?
>
> Best Regards,
> William Chen
>
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