Subject: Multicast routing on Linux ?

From: Christopher Samuel <[email-masked]>
Date: Wed, 02 Jul 1997 09:58:20 +0100

Has anyone got multicast tunnelling to work on Linux 2.0.30 ?

Current setup:

Linux box:  2.0.30 with necessary experimental kernel options turned on
            mrouted 3.9beta2 (or the pre-built for linux mrouted 3.8)
            sdr 2.4a6
            wb 1.59

tunnels with ttl 1 threshold 1 rate_limit 0 to/from

Alpha box:  DU4.0B (+patches) or DU4.0A
            mrouted 3.9beta2
            sdr 2.4a6
            wb 1.59

tunnels with ttl 1 threshold 1 rate_limit 0 to/from

Alpha box:  DU4.0A
            mrouted 3.9beta2
            sdr 2.4a6
            wb 1.59

A session created on the same network as either of the two alphas appears
on the network of the other alpha with no problem. Very occasionally it
appears on the network of the Linux machine as well.

If a user on the linux network joins such a session they see things as
they should, but the alpha users never see them.

A linux user can join a session that doesn't appear in his sdr window by
giving the correct options to wb, but you get the same behaviour as above.

A session created on the linux network never seems to appear on the networks
the alphas are routing for.

I've followed the FAQs, dug around in mailing list archives, and I still
can't see if it's something I'm doing wrong, a linux bug, an alpha bug or
an interoperability bug.  At the moment I guess I'm tending to think of it
more as a linux bug.

Help?!

cheers!
Chris
-- 
 Christopher Samuel,   IT Vulnerabilities Group,   [email-masked]
 N-115, Defence Research Agency, St Andrews Road, Great Malvern, England, UK
 DISCLAIMER: I write only for myself, not for DRA.    Phone: +44 1684 894644
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From: Christopher Samuel <[email-masked]>
Date: Wed, 02 Jul 1997 15:09:55 +0100

In message <[email-masked]>, 

> Has anyone got multicast tunnelling to work on Linux 2.0.30 ?

I've worked around this now by dropping an ATM ELAN interface from the
middle alpha onto the same network that the Linux box sits on and using

phyint elan0 ttl 1 threshold 1

rather than the tunnel.

The only reason I'd not done this previously was because I was seeing
crashes caused by ATM problems, but that I was before I applied the
latest set of jumbo patches.

Chris

---

From: Bill Fenner <[email-masked]>
Date: Wed, 2 Jul 1997 08:47:53 PDT

Chris,

  Try doing a "kill -USR1 `cat /etc/mrouted.pid`" on both
the alpha with the tunnel to the Linux machine, and the Linux
machine.  Check two things in the resulting /usr/tmp/mrouted.dump:

1. The "packets out" on the Alpha's tunnel is the same as the
"packets in" on the Linux box's tunnel
2. The two machines have approximately the same set of routes.

  If those work out, then do a kill -USR2 and look at
/usr/tmp/mrouted.cache, and check that the Linux machine has
forwarding cache entries pointing to the tunnel (IVif) for the same
traffic for which the Alpha has forwarding cache entries pointing
out the tunnel (Forwvifs).

  Bill