[Xorp-users] Problem with network reachability

Miroslav Todorovic miro_todorovic at yahoo.com
Mon Jun 14 12:06:21 PDT 2010


I use xorp-1.6.

ip_forward was set to 0. I changed that to 1, but nothing happened with my reachability.



Something very strange happening for me. I find that one router could
not forward packets to its subnet when I ping from one VM, but when I
ping from another VM, which is attached on the same router as the first
one and need to take the same path to destination, the router  forwards
the packets correctly to the same destination.



I changed the network topology, and now I have network reachability.



But I noticed the problem with multicast streaming. 

I stream a file on one router's interface, and notice that router start
to send traffic on another interface although nobody ask for stream on
that interface. So, to manage that router stop sending stream on that
interface I need to set one VM to ask for the stream on that interface,
and then to stop streaming on that VM.

It is happening always on the same router's interface. Another works fine - there is traffic only if somebody ask for.

It seems like adjacent router is looking for the stream. When I shut
down that VM, router stops sending stream on that interface. But I just
have xorp running on adjacent Ubuntu VM.  



Any idea what is happening?



Thank you!

From: Ben Greear <greearb at candelatech.com>
Subject: Re: [Xorp-users] Problem with network reachability
To: "Miroslav Todorovic" <miro_todorovic at yahoo.com>
Cc: "xorp comunity" <xorp-users at xorp.org>
Date: Sunday, June 13, 2010, 9:38 PM

On 06/13/2010 01:00 PM, Miroslav Todorovic wrote:
>
> Thank you!
>
> I didn't check routing tables in windows, but I did use traceroute for
> forwarding paths monitoring.
> If the packets could not be delivered to destination address, problem is
> router's forwarding. There is always one router, (first, the second or
> third on the path), in the network where the packets getting stuck. It
> could not realise how to forward packets to some other router, or its
> subnet.
> All router's routing tables are formed correctly.

If the routes are correct, then I have a hard time understanding
why it would not be forwarding packets.  Is ip_forward enabled?

Can you set up routes manually (w/out xorp running) to get it
working?

For multicast, make sure you have the time-to-live set to a large number
so that it will route through your network.

What version of xorp are you using?

Thanks,
Ben

-- 
Ben Greear <greearb at candelatech.com>
Candela Technologies Inc  http://www.candelatech.com



      
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