[c-nsp] Bridge devices - ARP takeover

[Ross Halliday]

I see this happening all the time with cheaper wireless gear. A lot of
802.11-based stuff (Tranzeo comes to mind...) will take over ARP and
sometimes even do MAC NAT, which as you can imagine really breaks PPPoE
and makes troubleshooting a pain.

As a poor man's wireless backhaul the Tranzeo junk has a "PxP" mode of
operation which disables this behaviour and turns it from an AP & CPE
pair into a PTP link that just passes frames all day. Perhaps this is
applicable to your equipment as well?

Cheers

---
Ross Halliday
Network Operations
WTC Communications
 
Office: 613-547-6939 x203
Helpdesk: 866-547-6939 option 2
http://www.wtccommunications.ca



-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Graham Wooden
Sent: Thursday, August 13, 2009 2:42 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] Bridge devices - ARP takeover

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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