03-29-2009 05:01 AM - edited 03-06-2019 04:53 AM
Good Morning,
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.
Any thoughts!!
Thank You,
Joe
03-29-2009 06:04 AM
Hi,
Have you done a packet capture to see if your are seeing igmp join/leave messages?
Also have you tried using static igmp join ie
ip igmp static-group 239.0.0.1
This may help you narrow down if it's a client issue or further upstream.
Regards
03-29-2009 06:20 AM
Thanks for thre quick reply James.
The static IGMP join gives the same results.. video only plays for 255 seconds. I just tried it again.
Regarding the packet capture... I don't remember for certain but I don't *think* we were getting leave requests once the 255 seconds hit.
Thanks,
Joe
03-29-2009 06:22 AM
Hello Joe,
the TTL is expressed in router hops only in the early days it was thought to be a time measure.
However, as already suggested you need to understand where the process fails:
if there is a missing of IGMP reports from receivers.
if it is the PIM join to the upstream router to be missing.
Hope to help
Giuseppe
03-29-2009 06:28 AM
Giuseppe,
Yes I know TTL is expressed in router hops but I am just trying to figure out what else I can relate to the 255 seconds of it working. Maybe somehow the the TTL is increasing once a second... I don't know. My mutlicast threshold is set to 0 on my router so this should be ok.
Interestingly enough Cisco TAC seemed to think our our first call that Layer 2 on on metro ethernet saw the appropriate traffic but that it wasn't being communicated to layer 3 properly unless we cleared the IGMP tables.
Thanks again... will keep everyone informed.
Joe
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