From: Labcciee (labccie@uol.com.br)
Date: Fri Feb 04 2005 - 13:35:11 GMT-3
Hi,
The "ip pim nbma-mode" must be configured on subinterfaces running frame
relay multipoint mode.
It's required because without it, with the reouter receives a prune message
on the phisical interface it could cut off the multicast traffic for all
others subinterfaces. This explanation is on the CCIE Practical Studies
volume II
----- Original Message -----
From: "null void" <nullv0idmain@yahoo.com>
To: <ccielab@groupstudy.com>
Sent: Friday, February 04, 2005 2:18 PM
Subject: Requirement details of "IP PIM NBMA"
> Say we have the following topology:
>
> R1 - is the hub of frame relay hub-spoke toplogy. Serial 0/0.1 multipoint
goes to 2 spoke routers R2 , R3. Serial 0/1.1 point-to-point goes to R6's
S0/1 this is frame-relay circuit also
>
> R6 - is a standalone stub router with a point to point serial sub
interface off of Ser0/1 to R1's S0/1
>
> R3 - Ser0/0 physical interface connects into R1 the frame relay hub
router's s0/0.1 multipoint so R3 , R2 and R1 are all layer 3 reachable on
same ip subnet in hub spoke topology.
>
> If we configure say R3 as RP on its loopback 0 interface for all groups.
Then configure ip pim sparse-mode on all interfaces of R3 , R6 , R1 . So now
R3 , R6 and R1 see each other as pim neighbors and the RP is found being
hardcoded to R3 loopback . Is IP PIM NBMA mode required on R1's S0/0.1
multipoint and s0/1.1 point to point interfaces ?? Without it I can still
from all multicast enabled routers , in this case being R3 , R6 and R1 ping
the groups that we configured onto R6's Loopback 0 interace via the ip igmp
join-group x.x.x.x command so it is working ... But my question is when is
ip pim nbma requried and why ??? Any resources / docs on this would be
greatly appreciated... TIA Null
>
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