Forced routing

[Monty J. Harder]

On Nov 13, 2007 2:14 PM, Kelly McLaughlin <kelmac at mokancomm.net> wrote:

>  Greetings all, ( Hi Monty and Jim )
>
> I need to specify communication from a multicast IP to communicate on a
> specific Network Card.
>
>
My routing table appears as follows:
>
> Destination                        Gateway
> Genmask                Flags               MSS Window
> irtt                I Face
>
> 216.198.99.0                      0.0.0.0                255.255.255.192
> U                        0 0                             0
> eth1
> 10.0.0.0                             0.0.0.0                255.255.255.0
> U                        0 0
> 0                 eth0
> 169.254.0.0                        0.0.0.0                255.255.0.0
> U                        0
> 0                             0                 eth1
> 0.0.0.0                              216.198.99.254     0.0.0.0
> UG                     0
> 0                             0                 eth1
>
> I have 2 network cards.  One with the adress of 216.198.99.247  and a
> second NIC with an adress of 10.0.0.2.  The NIC with the 10. address is
> what I want to use for a failover communication with a second server.  The
> failover communication software uses a  multicast address of 229.255.0.1.
>
If that software can be reconfigured to use the actual unicast address of
the other server, it would be better. Unicast IP is much cleaner.  Your
Cisco is clearly not in on the multicast games you're trying to play, and by
your description you don't have a router between the servers on the 10.
network, just a crossover cable.

That means you have to teach each of the two machines about the multicast
addresses you want them to use.

If you want packets addressed to 229.255.0.1 to be sent via eth0, then try
using this command:
*/sbin/route add -host 229.255.0.1 dev eth0*
Put it in /etc/rc.local so it will always be run at boot.  This should allow
other multicast packets to stay on eth1.  What this doesn't say is whether
the other server will be listening on that IP.  For that you may need to use
an alias IP.  I've never set up multicast, so I don't know for sure what all
that entails.


> The default gateway is attached to the 216. network.  And ping tests
> result in the following:  Pinging from 10. NIC I can only receive replies
> from the other 10. address.  From the 216. NIC I receive replies from
> everything but I cannot establish the failover on this NIC.
>
> What I want to do is tell my computer ( Red Hat Enterprise Linux V.3 ) to
> force communication from 229.255.0.1 across the 10.0.0.2 network card.  If
> I can accomplish this I believe my failover will work.
>
>
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