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arp no response


Have a problem that I'm trying to understand and find the solution for. Maybe someone here can help?

As shown in the .pcap files, the problem is, that my switch isn't getting a arp reply when connected to my catalyst 6500.

When I connect the switch to a freeBSD firewall, I get a reply.

The switch isn't configured with an ip adress in either of the subnets used.

Any suggestions are welcome.

Kind regards Anders

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Cisco Employee

Re: arp no response

Hi Anders -

In looking at the two captures I see the ARP sender IP is  There is a bug where we drop these packets if DAI is enabled.  The bug ID is CSCsg18176.

You can view the bug details here:

While the bug was filed for the 3750 the DAI code was ported across multiple platforms including the 6500 so it is impacted and as far as I can tell a fix was never ported to the Cat6500 code train.  If you're hitting this bug and would like to find the status of getting this fixed on the 6500 please open a TAC case and request to have the fix ported over.


Re: arp no response

Hi James

Thanks for responding. I'm not able to view the status of DAI. I haven't enabled it myself, and according to this document (link below), it's disabled per default. I don't have the ability to turn it on. When trying to enter the command "(config)# ip arp inspection vlan xxx" I'm getting nowhere.

When entering "(config)# ip arp ?", the only option I have is "proxy"?!

I'm running 12.2(18)SXF16.

Kind regards Anders

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