[c-nsp] Bridge devices - ARP takeover

[Graham Wooden]

Yeah, kinda messy - sorry about that.

It's taking over as when I do a "sh arp ip", instead of seeing the far end
router's MAC for the other end of the /30, I see the radio's.

c6509/sup32 -> radio <------------------------> radio -> c2621

Between the c6509 and c2621 is a routable /30.

I should note that I didn't have this problem when had this setup on a Sup2,
and ran fine for several months.  Is there a different ARP timeout between
the two?

On 8/13/09 2:08 PM, "Rodney Dunn" <rodunn at cisco.com> wrote:

> I can't follow the problem.
> 
> The router should try to defend the mac address it owns but if another
> device simply takes over for it the only way to resolve that is fix that
> device.
> 
> How exactly is it taking over?
> What is the topo (ascii diagram would work).
> 
> Rodney
> 
> 
> 
> Graham Wooden wrote:
>> Hi there,
>> 
>> I have a customer hanging off of my edge router (6509/Sup32/12.2.33SXI),
>> doing a Point-to-Point wireless shot from the DC to another site.
>> On myside, it's a L3 VLAN doing a /30 to a smaller Cisco router on the
>> other end. I am then statically routing some additional subnets to the
>> far end router.
>> 
>> After about 30 minutes of the link being powered up, the MAC address of
>> local Radio appears to take over the /30, and hence all routing breaks.
>> To fix this, seems to that if I hardcode the MAC that belongs to the
>> Cisco router on the far, all seems good and traffic keeps on trucking.
>> The other fix that was being done until the hardcode went into affect,
>> was power cycling the local radio.
>> 
>> My question is this:  While the hardcoding seems to be the trick to
>> solve this, is there another command, maybe on the interface to achieve
>> this fix too?
>> I have yet to find out from the customer if there are any MAC/ARP
>> settings in his radios and that could be doing take over on purpose.
>> 
>> I am hoping that I can curb this type of behaviour without getting him
>> involved.
>> Thoughts to this?  Thanks,
>> 
>> -graham
>> 
>> 
>> _______________________________________________
>> cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/cisco-nsp
>> archive at http://puck.nether.net/pipermail/cisco-nsp/