[Xorp-users] Multicast Forwarding

[De Hoyos, Samuel]

Hello,
It was actually the RHEL 5 firewall that was preventing the forwarding
of multicast. Once we disabled it the multicast traffic was successful
using our original configuration. 

Thanks for your help.

BTW, if anyone is aware of the proper rules that would allow multicast
to work using XORP with a default iptables configuration, please
respond.

Thanks,
Sam De Hoyos 

-----Original Message-----
From: Pavlin Radoslavov [mailto:pavlin at ICSI.Berkeley.EDU] 
Sent: Thursday, March 06, 2008 12:10 AM
To: De Hoyos, Samuel
Cc: xorp-users at xorp.org
Subject: Re: [Xorp-users] Multicast Forwarding 

De Hoyos, Samuel <Samuel.DeHoyos at NGC.com> wrote:

> Need some help enabling Multicast forwarding with XORP on a server 
> running RHEL 5.
> 
> We followed all the configuration items on the web and the users
manual.
> 
> We enabled each interface, fea, mfea, igmp and even pim in the XORP 
> configuration with our specific information with no luck.
> 
> This should be simple but for some reason MC Forwarding is not
working. 
> 
> Its a simple network with two hosts on either side of a server running

> XORP.
> 
> Here is our simple configuration:
> 
> mcast source---------------LinuxXORP-------mcast receiver
>            ^              ^        ^       ^
>            |              |        |       |
>        10.100.1.2 	 eth0	 eth1     192.168.10.33
>                      10.100.1.3  192.168.10.34
> 
> We checked the output of the show igmp group command and can verify 
> that
> eth1 is part of the group 225.1.1.2 that we are using. When we check 
> the show route table ipv4 multicast final table we cannot see the 
> multicast route being added.

The purpose of the "show route table ipv4 multicast final" is to show
the MRIB (Multicast Routing Information Base); i.e., the unicast routes
that are used by PIM for RPF (Reverse Path
Forwarding) check, hence it won't show the multicast routes.

You should use the "show pim join" to see the multicast routes in
PIM-SM.

Some of the most common problems are:

* The TTL of the multicast sender must be larger than 1. By default,
  all multicast packets are transmitted with TTL of 1, therefore
  they won't be forwarded.

* The Cand-RP set in PIM-SM is missing or is incorrect. The simplest
  thing to do is to use a static RP set to one of the IP addresses
  of the XORP box.

* fib2mrib should be part of the configuration.

* There could be some firewall rules in the Linux box that might be
  stopping some of the multicast packets.

Please send your XORP configuration so I can check whether something is
missing/wrong.
Also, please send the output of "show pim join"

Regards,
Pavlin


> Is there any configuration needed to static routing in the config.boot

> file?
> 
> We also verify that the source is sending on eth0 to 225.1.1.2 but its

> not being forwarded from eth0 to eth1.
> 
> Any help would be appreciated.
> 
> Sam
> 
> 
> 
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