All things related to multicast

["Garry Peirce" <>]

An intriguing problem ;  fwiw, the Okenaos feed looks fine here.

 

Not knowing the topology/mcast environment of your internal network will make it hard to assist.

First I might suggest contacting your gigapop to see if they are experiencing the issue.

Perhaps another PNW connector might chime in to help quickly rule out an upstream forwarding issue as well.

As you cannot view traffic coming into your border, are you able to put a client directly off your border, minimizing the path, to see if it sees the problem?

 

If the gigapop and other related sites see no issue, but your directly connected client still does, it would seem a forwarding issue on your border.

Else, keep working your way down to the client subnet.

 

Good luck and feel free to send more details, I’m sure others are interested in what you find.

 

 

From: [mailto:] On Behalf Of Michael Knezevich
Sent: Thursday, June 07, 2012 2:03 PM
To:
Subject: {Disarmed} multicast streams stop once a minute

 

Hi,

We're having a strange problem that I'm unable to explain.  Perhaps somebody out there can point me in the right direction.  The problem seems to have started in the last month, but we're not sure exactly when since we only make use of multicast for the NOAA Okeanos Explorer's live feed (rtp://MailScanner warning: numerical links are often malicious: MailScanner warning: numerical links are often malicious: 233.25.229.1:5501), and we last started viewing it again less than a week ago.  What we're seeing on any multicast stream we call up is that the data stops flowing at either 8 seconds or 53 seconds after the top of the minute.  It's been totally consistent and reproducible since I discovered what the pattern was a couple of days ago.  The data doesn't stop once a minute; rather it stops at those 2 times.  A couple of streams stop at 53 seconds after the minute, and several others stop at 8 seconds after the minute.  Like I said, it happens every time we start a stream. So, if I start viewing at the top of the minute, the data stops flowing 8 seconds later; if I start at 10 seconds after the minute, the data stops 58 seconds later.  I checked from different systems on our network, in different locations on our network, using different programs to view the stream (VLC and the Northwestern and Wisconsin video furnace sites), and the behavior is the same.

 

I've looked at the traffic with wireshark as far out on our network as I can get, and as far as I can tell, the data just stops without any prodding (igmp or pim) from anybody.  What I can't see is the data on the link between our edge router and our provider, so I can't say if we're sending something or not.  The client still thinks it is receiving the stream, as do the routers, but the data just isn't arriving from our provider (PNW Gigapop).  Everything works as it should if I stop and start the stream manually within that minute.

 

What do you think could be causing this?  It's clearly something on a timer, but I don't know what, or what to do about it.  Is it at our end?  Any advice on how to troubleshoot would be appreciated.

 

thanks

Mike Knezevich

NOAA/PMEL

Seattle