[LARTC] building a multicast router

[Bob Yeaw <byeaw@widevine.com>]

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Hi,

I have been reading: http://lartc.org/howto/lartc.multicast.html in effort
to understand how to route multicast traffic and just joined the group.

History: I am trying to multicast mpeg (using the videolan server) on a
private network.   The server side of the network is copper gigabit, which
connects to one of those cheap fast Ethernet switches with a single gigabit
uplink.   The problem I'm having is the ports are getting flooded on the
client side switch (i.e., all multicast traffic sent to all ports on the
switch).

After doing some research it sounds like installing a multicast router
between the client and server side is the best solution.  So that's what I'm
trying to do now.

I have Red hat Linux 7.3 installed. I've gone through the steps described on
the how-to (link above):

$ demsg | grep IGMP 
IP Protocols: ICMP, UDP, TCP, IGMP
$ cat /proc/sys/net/ipv4/ip_forward
1
$ netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt
Iface
192.168.3.0     0.0.0.0         255.255.255.0   U        40 0          0
eth1
10.100.100.0    0.0.0.0         255.255.255.0   U        40 0          0
eth0
127.0.0.0       0.0.0.0         255.0.0.0       U        40 0          0 lo
224.0.0.0       0.0.0.0         240.0.0.0       U        40 0          0
eth1
0.0.0.0         10.100.100.254  0.0.0.0         UG       40 0          0
eth0

# NOTE: eth1 is the client side, eth0 is the server side.

Problem:
The problem is that no multicast is getting through the router (unicast
traffic works fine).  When I run:

$ tcpdump -n -i eth0

I see all of the multicast traffic being sent. Unfortunately:

$ tcpdump -n -i eth1

shows none of that multicast traffic (whether the client has requested it or
not). Interestingly, when I run iptraf and select eth0 it reports little to
no activity, which indicates to me that the traffic is getting dropped at a
low level.

Question:
My question at this point is problem identification.  Is the router
configured correctly and acting as expected but the client just isn't
sending the IGMP join requests?  Do I need to install additional software
packages like Zebra or mrouted to make this work?  Am I completely missing
something?  

Any help or suggestions are greatly appreciated!

regards,

-bob



-bob



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