Subject: group joining question...

From: Mark Abene <[email-masked]>
Date: Mon, 12 Feb 1996 06:21:29 -0500 (EST)

Pardon if this is a fool question, but I'm experiencing what I consider odd...

I have a Solaris x86 machine running mrouted 3.8, a leaf of mbone3.uu.net.
I have a SPARC machine also running Solaris on the same LAN.  Both are 2.4,
with version 3.5 of the ip multicasting kernel drivers.

Everything appears to be functioning properly, EXCEPT, I do NOT receive any
mbone traffic on the SPARC machine unless I first join the desired group on
the Intel machine which is running mrouted.  For example, if I run sd on the
SPARC, I receive no session directory info unless I join group 224.2.127.255,
port 9876, on the Intel machine.  If I run vat on the SPARC machine, I won't
hear any audio unless I join the desired group on the Intel machine in 
addition.

Is this normal behavior?  I thought it was mrouted's job to route multicast
traffic onto the local ether and vice versa.  The multicast traffic only 
appears to other machines on the ether if I join the desired group on the
machine running mrouted.

Puzzled.
-Mark

---

From: Bill Fenner <[email-masked]>
Date: Mon, 12 Feb 1996 15:10:10 PST

Sounds like your intel box is not properly handling IGMP.

It's too bad that 'snoop' doesn't know about IGMP, but you can try
running

snoop -p 'ip[9] = 2'

on both the intel and the sparc, and see what you see.  The mrouter should
be sending out occasional queries, which will look something like

   tibia-235 -> ALL-SYSTEMS.MCAST.NET IP  D=224.0.0.1 S=13.2.116.239 LEN=28, ID=26679

and the hosts which are members of groups will send replies, which will look
something like

    crevenia -> 224.2.0.3    IP  D=224.2.0.3 S=13.2.116.11 LEN=28, ID=9041

  Bill