Real multicast loop scenario

Hi guys, I have a "problem" that isn't directly related to CCIE, but my
friend is doing a paper about multicast loop issues and she wants to
simulate a multicast loop in lab that could possibly occur in real network
(so without using things like filtering specific pim or igmp messages,
modifying AD etc.). We had a presentation on cisco expo show a year ago that
presented a kind of this problem, it's mentioned in this PDF ,on page 37 I
think.

http://www.4shared.com/file/167239443/4d5a2b69/PIM-DM__multicast_loop_.html
(I hope sharing this pdf isn't violating anything, it used to be freely
accessible on cisco website)

She simulated this scenario, but she did not manage (at least with commands
that are typical for normal network) to make the router in the middle to be
multicast forwarder for the bottom segment (router on the right will win in
"assert battle" thanks to AD of directly connected route over the 120AD of
rip on other routers, it's possible to add another router and make AD of his
rip routers >120, but it seems to me there would be another problems,
because that would make this router forward multicast also on the upper
segment). Do you think it's possible to simulate this specific loop, or did
you come across another type of multicast loop that could occur on cisco
devices in a real network?
After all, multicast is a part of CCIE, so maybe it refreshes a part of your
knowledge :)
Thanks!

Vladimir

Blogs and organic groups at http://www.ccie.net
Received on Mon Dec 07 2009 - 16:13:28 ART