From: Jian Gu (guxiaojian@gmail.com)
Date: Tue Dec 19 2006 - 22:26:50 ART
I totally don't understand the problem you are trying to solve, 1)multicast
from hostB will have hostB's source IP address, routers won't change IP
multicast packet's source IP address, 2) RPF check only check outgoing
interface no specific IP next hop address involved.
Multicast and HSRP are two different entities, they don't work together
(except that HSRP uses multicast for neighbor discover etc). In this
topology, multicast will elect a DR in a LAN segement(either R1 or R2), DR
will be responsible for registering and/or multicast forwarding, (because
only DR will send PIM joins upstream or register message to RP), the other
one will take over once it does not hear PIM hellos from its neighbor.
So to answer your question, you don't need a solution, it just works.
On 12/18/06, Koen Zeilstra <koen@koenzeilstra.com> wrote:
>
> Hey group,
>
> Imagine the following scenario:
>
> |--R1--|
> HOSTA---R4------| |----R3---HOSTB
> |--R2--|
>
>
> On the hostA subnet HSRP runs with virt. ip 192.168.1.3.
>
> R1 f0/0: 192.168.1.1 HSRP prio 120
> R2 f0/0: 192.168.1.2 HSRP prio 110
>
> Host B sends multicast to group 239.1.1.1.
>
> R4 does a RPF check on the mcast packets which are sourced from R1 f0/0
> (192.168.1.1). The RPF check fails because the unicast route to R3 is via
> the HSRP virt. ip address 192.168.1.3.
>
> How is this solved?
>
> 1. We can use static mroutes on R4 pointing to R1, this will work however
> there is no failover for multicast as there is for unicast traffic. The
> mroute will not dissapear because if R1 fails the ethernet interface on R4
> will still be up and running. If R4 f0/0 fails there is no connectivity
> towards R2 anyways...
>
> 2. I can imagine a PBR routing scenario where all traffic from R1 and R2
> towards R4 is sourced from the HSRP virt. ip address? Not nice, since this
> will cause all traffic to be process switched.
>
> Any nice solutions anybody?
>
> all help appreciated!
>
> thanks,
>
> Koen
>
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