We suddenly started having problems multicasting from our Internet2 connection last month, In the past two weeks we have had two conference calls with Cisco TAC totaling 9 hours. We have them stumped so far.
The problem we have is we can only stream videos for a short period and then they just stop working. On our first call with TAC they determined if I do a "clear ip igmp group" I can stream again for a short period. Just clearing igmp for the source stream doesn't help we have to do all the igmp groups.
This morning it occured to me (and I don't know why we didn't think of this sooner) is to clock exactly how long I can play a multicast stream. What I found suprised me.
Multicast streaming stops working 255 seconds after I last clear the IGMP tables. This is significant because as I understand it 255 is the default time to live for multicast traffic. I did the test multiple times running a stopwatch and the results are the same every single time.
If I clear the IGMP tables and wait 195 second before streaming I only get 60 second of streaming. So it is not that clearing the tables lets me stream for 255 seconds whenever I choose but rather my window for streaming anything is 255 seconds from the time I clear the table, period.