Subject: PIM - DVMRP interop

From: "Sundeep Singatwaria" <[email-masked]>
Date: Fri, 3 Nov 2000 16:00:21 -0800

I have a couple of questions regarding PIM-DVMRP interop

Dvmrp(R1) ---- DVMRP(R2)----MBR(R3)----PIM(R4)----RP(R5)---PIM(R6) ---
(Source)

Let's us say that the receiver is connected to the DVMRP router (R2). Data
from the source falls all the way to the receiver on DVMRP router (R2).
Now the receiver on DVMRP router (R2) goes away. We send a prune all the
way upstream towards the source. Now we keep the prune entry on DVMRP
router (R2) for DVMRP prune lifetime and all routers in the PIM domain have
a (S,G) prune entry which will expire in a while (say 210 seconds). Now we
don't
have an (S,G) prune entry at the MBR. If the receiver in the DVMRP domain
(say
DVMRP router R1) comes back then how do we receive packets from the source -
if for during this duration the packets are going from source to RP during
all this while.

- Should (S,G) prune entry on RP be refreshed with a (*,*,RP) join from the
MBR. If that happens data will be flowing all the way between RP and MBR 
every time a (*,*,RP) join is received by RP.

- Or should (S,G) prune entries be maintained all the way between MBR and RP
so that the (S,G) join can be initiated. In this case when do we delete
the (S,G) prune entry on all routers between MBR and RP. In this case if the
receiver comes on DVMRP router R1 when we are in the pruned state then how
we
do receive traffic on DVMRP router R1 since DVMRP router r1 does not have
any
state information about (S,G) entry.

- Also what is the significance of (*,*,RP) prune message and when do we
send
(*,*,RP) prune.

Thanks.
Sundeep