From: Koen Zeilstra (koen@koenzeilstra.com)
Date: Tue Dec 19 2006 - 04:41:41 ART
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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