All things related to multicast

[John Kristoff <>]

I have a situation where I have a pair of Cisco routers attached to the
same edge LAN segment in a redundant configuration.  I'd like to try to
minimize packet loss when one of the routers is intentionally brought
down for maintenance activity.  In my case there will more likely be
high-rate multicast receivers on the edge segment rather than sources,
but reducing sender loss/latency is probably most important.

I see that my recent IOS code there is a 'ip pim dr-priority <#>' option
in interface mode only.  In a cursory search it appears that IOS XR has
a global option so hopefully that is on the horizon for existing trains
of code.  In either case I was planning on testing this option to see
what I can expect during planned maintenance activities, but thought I
would check with folks here to see if this is the right and worthwhile
path to go down.

Is there a better way to minimize or eliminate multicast forwarding loss
in a scenario such as this?  It's not clear to me exactly what will
happen in real-time situations when the DR priority is changed from one
interface to another.  Any pointers to PIM join/prune state examples
when a new DR priority is announced by a peer interface.  I presume the
new DR priority will be announced during the next random interval.

John