Arp problem in 6500 and ASA trunk

Unanswered Question
Sep 15th, 2010

Hi !

I have a problem that I hope any other have  hade and can help me to resolv.

I would like to connect an ASA 5520 firewall to my 6500 LAN-card.

When I connect my ASA to a port on slot 7 as a trunk, it's not possible

to get arp-answer from the ASA. I can see with a sniffer that arp-request and

arp-answer come on the trunk but i don't get no arp-answer on the PC that is

connected to the same VLAN on slot 3 or 5, but if i use slot 7 to connect

my PC all works fine.

The problem is with the arp because when i put arp-antry in my PC manualy

its works to flow traffic to the ASA.

If I use slot 3 that is fibercard to connect my ASA all works fine.

I have no more ideas and hope anyone can help me.

My setup of 6500 i like this.

Slot          card

3              WS-X6415-GBIC

5              WS-SUP32-GE-3B

7              WS-X6148-GE-TX

I have this problem too.
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nicolas.flossmann Fri, 10/22/2010 - 06:19


we have the same problem here with a Linux Firewall connected via a dot1q Trunk on a c6509. If we connect the Firewall and the PC on the same cu-module(WS-X6148-GE-TX) we have problems to get arp answers from the Firewall. Devices on Fibercards get an arp answer from the firewall.


Version 12.2(33)SXI4



Can anyone help?


Giuseppe Larosa Mon, 10/25/2010 - 11:54

Hello Nicolas,

sorry for misleading information looking at the same release notes for another thread I have found out that the linecard is supported


you are fine 6148-AF are listed as supported under the 10/100 linecards category


if you haven't already done I would open a service request  for this issue

Hope to help


ppcisco Mon, 10/25/2010 - 23:35


Thanks Giuslar for that you are engage in this case.

Are you working at Cisco ?

I have still the problem and don't know how to solf it.

Giuseppe Larosa Tue, 10/26/2010 - 03:17


look at Nicolas' last post you may be facing the same issue he refers to a field notice about some specific linecards


if the serial number of your linecars is within the ranges declared in above range you should ask for an RMA (haraware substitution)

>> Are you working at Cisco ?

no I do not work for  Cisco, people working at Cisco has the Cisco logo near their icon.

Hope to help


ppcisco Tue, 10/26/2010 - 04:52


Yes my card is in that range. Trying to get a new one and hope that it will solve the


I will come back how it works.

Thanks a lot

tqhosting59 Mon, 11/05/2012 - 11:29

Hi, did you get the card replaced?  I think I'm running into the same problem.

ppcisco Tue, 11/06/2012 - 00:27

Hi Mark.

Yes I had got a new card and it works. It's a long time since that so I dont remember all of it.

But it was some problem with small packet, not special witch arp request but to all packet that was

under a specific size, I dont remember the exact size.

Hope you can resolve your problem.

God luck.



nicolas.flossmann Mon, 10/25/2010 - 23:32

Hello Giuseppe,

we believe that we hit the bug described in the field notice:

Field Notice: FN - 26096-WS-X6148-GE-TX,  WS-X6548-GE-TX-May Drop Valid Packets on Egress-Hardware Modification  Has Been Implemented

Two of our modules are affected by this issue. We open a SR and make a RMA for the moduls.

Thx a lot for support,



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