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Cisco 3550 switch ARP/Mac-Address-Table

Posted on 2013-01-14
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I have four Cisco 3550 switches.  I'm trying to figure out what port on what switch a SQL Cluster with teamed NIC's is plugged into.  I am able to find any other server that isn't clustered or has teamed NIC's in the ARP Table and Mac-Address-Table just fine.   I can see the mac-address for the SQL server, but only on the uplink ports, it doesn't tell me what actual port the server is plugged into.  I've initiated a ping to all switches from the server and I still can't see where its plugged in.  Any assistance would be greatly appreciated.  Thanks.
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Question by:denver218
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by:giltjr
ID: 38774865
If you only see the MAC address on a uplink port, that means the server is not on that switch.

You need to go to what ever switch the uplink is connected to and look at that switch.

Did you really mean that the only ports it shows on are trunked ports?  If so, then it is possible that the server that SQL is running on supports tagged VLAN's and has IP addresses in multiple VLAN's.  In that case, you have to know which physical port the server is connected to, as a trunked port is a trunked port no matter what is connected to it, another switch or a server.
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by:denver218
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No, I can see all ports that servers plug into except those servers that have clustered or teamed nics.  

For the server with clustered/teamed NIC's that I'm looking for,  I see only a dynamic entry for the mac-address on one switch, and then I see the mac-address on the uplink ports of the other swithes.   I'm guessing its the switch I see the dynamic entry for as I don't see the mac on its uplink port.  Now I just need to figure out what ports on this switch its on.  I don't see the mac-address on a physical port.
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giltjr earned 500 total points
ID: 38775323
As part of preventing loops in the network a MAC address can only be associated with one port on a switch.

If you using Etherchanne/LACP, the MAC will show up on the Port Channel for that group.

So if you have a server with two NIC's connected to the same switch and you have those port configured as an Etherchannel, the MAC will show up on the port group definition for those ports.
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by:rochey2009
ID: 38776095
Hi,

Giltjr may be onto something.

Please post the output of show mac address-table address xxxx.xxxx.xxxx for each switch using the mac address you're looking for.

What type of clustering are you using?
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by:mat1458
ID: 38776671
On what port do you see the MAC address of the cluster if not on a physical one? Please post sh mac address-table.
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by:denver218
ID: 38890381
Thanks
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