From: Donny MATEO (donny.mateo@sg.ca-indosuez.com)
Date: Sun Dec 28 2003 - 23:04:09 GMT-3
I'll try to answer,
For scenario 1. Your question is whether R4 creates an (S,G) state or not
? It depens. By default configuration in cisco router, the join SPT
treshold is set so that the router immediately send a join to the source
after the first multicast packet received from the shared tree. Otherwise
it will wait until certain treshold is reached before creating an (S,G)
state and send a join to the source's first hop router (which in your case
is R1).
For scenario 2
I'm confused. The member of the LAN should only send 1 join to a router
(if the LAN has 2 router), sort of multicast default gateway. This router
is called the Designated Router if memory served me right. So in this
case, your situation will never exist because no member of the LAN will
send igmp join to R5, it will always send the join to R4. However, don't
take my word blindly, go and test it out on the rack and see for your
self.
Donny Mateo
Amit Khopkar <akhopkar@yahoo.com>
Sent by: nobody@groupstudy.com
12/27/2003 03:16 PM
Please respond to Amit Khopkar
To: ccielab@groupstudy.com
cc: (bcc: Donny MATEO/ADPC/ASIA/BANQUE_INDOSUEZ/FR)
Subject: deisgnated forwarder PIM SM
Hi group,
I am confused about the designated fowarder in PIM SM.
Scenario 1
==========
__________________________
| |
| ____________[R3]-----|
| / |--- receiver
Source--------[R1]-----[R2] |
\____________[R4]-----|
R1 is the RP
R4 is the DR
R3 is the querier
when receiver sends a IGMP report for group G. R4 creates a (*,G) state
and sends a join towrads RP.
assuming RP is already receiving the streanm from R1 it forwards the
stream towards R4.
R4 sends the multicast stream on the receiver LAN.
R4 creates a (s,g) state ...???
now does it send a join towards R3 if it is the next hop (best route) to
reach R1....??? need help here
scenario 2
==========
__________________________
| |
| ____________[R3]-----|
| / |--- receiver 1
Source--------[R1]-----[R2] |
\____________[R4]-----|----[R5]-----[R6]---receiver 2
when receiver sends a IGMP report for group G. R4 creates a (*,G) state
and sends a join towrads RP.
assuming RP is already receiving the streanm from R1 it forwards the
stream towards R4.
R4 sends the multicast stream on the receiver LAN.
R5 is also interested in the stream and creates a (s,G) state and sends a
join towards R3.
R3 sends a join towards R1. R1 adds R3 to its (s,g) OIL and forwards
multicast stream.
now both R4 and R3 forward multicast steam on LAN of receiver 1.
R3 wins and continues forwarding. R4 stops forwarding and sends prune to
RP.
is this assumption right ???
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