collision issue

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Jun 28th, 2009
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Hi guys, would like to check out what's really the logging telling and what's the problem it will be.

I have 2 unit of 6500 boxes with CSM. The topology is doing in single subnet mode.

The server NIC is doing in SLB, where 1 primary 1 standby, and the NIC physically doing in Switched tolerance fault way. The 2 switches are interconnect and trunking allow vlan 11, 12 to carry thru.

I facing intermittent performance issue once trying to access the services. So this is what i get from sh logging :

%CSM_SLB-4-TOPOLOGY: Module 1 warning: IP address conflict: ARP frame from 202.160.xx.xx with MAC 00:01:64:f9:1a:01 received on VLAN 11

%CSM_SLB-4-TOPOLOGY: Module 1 warning: IP address conflict: ARP frame from 10.0.xx.xx with MAC 00:01:64:f9:1a:01 received on VLAN 12

Any idea what i should deal with it?



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Gilles Dufour Sun, 06/28/2009 - 23:31
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as I said, MAC 00:01:64:f9:1a:01 is the CSM mac-address of the active.

So, you could have active-active issues or a loop somewhere.

You will need to capture sniffer traces on both Cat6k vlan 11 and vlan 12 and see what is happening with the arp packets.


ubdnet_kkipc Mon, 06/29/2009 - 03:49
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Hi Gilles,

I am not so sure on what you mean of the active-active issues. Is it done over the ft group x vlan y?

But i did configure both CSM , only variant in between is the value of priority.

Both of my box showing "active"...

anyway i can manually config this pair in active-standby ?



Gilles Dufour Mon, 06/29/2009 - 07:05
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only 1 device can be active !!!!

The csm does not support active-active.

If you do a 'show mod csmx ft' you should see one device saying active and the other one standby.

You need to do some troubleshooting to figure out which device send the arp response.

This needs to be done with sniffer trace on both CSM simulatneously.

(no other solution since the mac is shared).

See if there is any loop.

This is typical layer 2 issues and they do not get solve with simple config commands.

You need to figure out which device send the arp response and if this is normal behaivior or not.

Once we know which device sends the arp respones we can decide which device to fix.


cisco_jiang Fri, 07/03/2009 - 19:31
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Hi Gilles,

after a full inspection on the L2 config, found out there's no trunking allowed vlan on the FT and the VLAN server pass thru between the interconnecting switch...

now 2 boxes in active-standby mode, and everything running smooth.

Anyhow, i want to thanks for the support along these days, the words are inspired me to go further and inspect..




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