Hi guys, I am struggling with SSM - but not with the theory concepts (at least that was my impression) but with the practical tests. Every doc I was able to find at the end led me to a confusion about what to configure and where.
So, my conclusion about the concepts was: - configure "ip pim ssm" only on the router directly connected to the receivers - enable IGMPv3 on the segment where the receivers are - enable PIM SM or SM-DM on the multicast traffic path The first bullet maybe sounds strange, but that sentence I directly pulled out of Cisco 12.4T doc... Anyway, I tried various configs - using "ip pim ssm" everywhere for instance, using variuos SSM JOINs, pinging with various sources... Let's say R1 will be the source, doing pings, and R2 makes the JOIN. And it all boils down to the following: - it does not matter if I enable IGMP v3 at all on R2 (??) - it does not matter from which R1 interface I am doing the pings (???) - defeats the purpose of SSM... - the only thing that made a difference, meaning either multicast works or not, is how I configure JOIN command on R2. The only way the ping would work is if the source configured in the JOIN command is the IP address of R1's interface CLOSEST TO R2 Example: R1 and R2 are on an ethernet segment 10.10.12.0/24. I am doing JOIN on R2 loopback, and I want the source to be R1 loopback... So, the command on R2 is (besides the "ip pim ssm" of course) ip igmp join 232.0.0.1 source 1.1.1.1 And no matter what I do on R1, how I ping, it won't work. Not until I erase the previous command on R2 and enter: ip igmp join 232.0.0.1 source 10.10.12.1 As soon as I form the JOIN like this, everything works! And what is frustrating for me, even the ping from R1 loopback works - even if I strictly said I want the source from 10.10.12.1 .... Does this make any sense to you? The concept is so easy, few commands, but the practical side is killing me. Of course, there is no multicast filtering whatsoever. I repeat one more time, I was doing all combinations really, making various configs, but this is the only one that works. This is all done in dynamips, but I strongly think this is not some kind of a dyna-bug. Every time, during preparing for the exam, I thought that something does not work because of the dynamips - I was proven wrong later. :) It was my lack of knowledge every single time. ? Best Regards, Bojan Zivancevic Network Engineer _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
