Subject: mrouted 3.8 Pruning Strangeness

From: "Craig M. Votava" <[email-masked]>
Date: Wed, 21 Jan 1998 11:45:54 -0600

Folks-

I'm seeing an interesting effect while running mrouted 3.8 with
pruning turned on. Please help to explain this if you can.

My machine (SGI O2, IRIX 6.3, mrouted 3.8) accepts a tunnel from
a cisco router in never-never-land on the upstream side, and
sends tunnels to 3 other places on the downstream side.

If I'm not actually running sd on my machine, the downstream
folks never see the session announcements. Further, if I'm
not running any given session, the downstream folks don't see
it either.

Remember, I'm tunneling to a cisco on my upstream side. I believe
this is the cause, I just don't know what. Please help me to
understand this if you can.

Thanks

-Craig
-- 

	()_()	Craig Votava
	 (_)	Lucent Technologies
		[email-masked]

---

From: Bill Fenner <[email-masked]>
Date: Wed, 21 Jan 1998 10:17:56 PST

Your downstream folks should use "mtrace" to find out where the traffic
isn't flowing.  You should join a session and find out who is transmitting
to it, then quit it and wait for the downstream folks to stop seeing it.
Then the downstream folks should run "mtrace <source> <group>" and look
at the traffic statistics section to see what hop is dropping the traffic.

  Bill

---

From: "Craig M. Votava" <[email-masked]>
Date: Thu, 22 Jan 1998 10:26:15 -0600

Folks-

Thanks for the help, I think we're making progress.
Here's a quick recap, and the latest:

RECAP:

1.) My machine, nimrod (SGI O2, IRIX 6.3) runs mrouted3.8, pruning on.
2.) Nimrod has an upstream DVMRP tunnel to CISCO router.
3.) Nimrod has 3 downstream tunnels.

PROBLEM:
A vat and vic session are coming in from an upstream machine.
The vic (video) session works fine all of the time. The vat
(audio) session will only work for the downstream people when
nimrod is also running vat. If nimrod stops running vat, the audio
to the downstream people stops after a few minutes.

Here's the mtrace output between the source and a downstream
machine, after audio has stopped:

Mtrace from 135.9.216.2 to 135.185.15.246 via group 224.2.165.179
Querying full reverse path... 
  0  nwsgpb.ih.lucent.com (135.185.15.246)
 -1  nimrod.ih.lucent.com (135.185.11.1)  DVMRP  thresh^ 1  Not
forwarding [default]
 -2  demimonde-ospf-gtwy1-backup.dnrc.bell-labs.com (135.180.254.18) 
PIM/Special  thresh^ 24  
 -3  curie.dr.lucent.com (135.9.216.2)  DVMRP  thresh^ 24  
 -4  curie.dr.lucent.com (135.9.216.2)
Round trip time 108 ms; total ttl of 26 required.

Waiting to accumulate statistics... Results after 10 seconds:

  Source        Response Dest    Overall     Packet Statistics For
Traffic From
135.9.216.2     224.0.1.32       Packet      135.9.216.2 To
224.2.165.179
     v       __/  rtt   90 ms     Rate       Lost/Sent = Pct  Rate
135.9.216.2     curie.dr.lucent.com 
     v     ^      ttl   25        68 pps        1/510  =  0%  51 pps
135.180.254.10 
135.180.254.18  demimonde-ospf-gtwy1-backup.dnrc.bell-l 
     v     ^      ttl   26        68 pps       -2/509  =  0%  50 pps
135.185.11.1    nimrod.ih.lucent.com Not forwarding
     v      \__   ttl   26        17 pps        ?/511         51 pps
135.185.15.246  135.185.11.1
  Receiver      Query Source

QUESTIONS:

1.) Why does this happen at all?
2.) Why does this seem to happen only for audio, and not for video?
3.) What can I do to fix it and still have pruning work?

Thanks

-Craig

---

From: "Craig M. Votava" <[email-masked]>
Date: Thu, 29 Jan 1998 11:12:46 -0600

Folks-

Wow, nobody was able to help me at all! I must
have hit a very strange bug inside mrouted 3.8!

By the way, is there a reason why there is no
mrouted 3.8.2 available for SGI's IRIX?

This problem is getting even stranger. Here are
some facts:

1.) Everybody gets any session that I'm participating
	in (my machine is also running mrouted).

2.) Some upstream sessions are sent downstream
	without my participating in them, others
	aren't.

3.) Sessions on my segment won't be sent downstream
	unless I'm participating.

Any guesses? Suggestions? All help is appreciated.

Thanks

-Craig

Subject: Re: mrouted 3.8 Pruning Strangeness
From: "Craig M. Votava" <[email-masked]>
To: [email-masked]
Date: Thu, 22 Jan 1998 10:26:15 -0600

Folks-

RECAP:

PROBLEM:

QUESTIONS:

Thanks

-Craig