[c-nsp] Bridge devices - ARP takeover

[Jeff Fitzwater]

It's interesting to note that this occurs at about the default ARP  
timeout of 1800 seconds  (Is that what the router is configured  
for?).   That implies that when the arp times out and the router arps  
for the other end, it get an ARP REPLY from the wireless device.   Is  
that what you are saying?   This would seem to say that the wireless  
device may have some local proxy arp enabled so it responds to arp  
requests on the local net.



Jeff Fitzwater
OIT Network Systems
Princeton University
On Aug 13, 2009, at 3:08 PM, Rodney Dunn 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
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