How to determine which interface is used for site to site connection

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Jul 24th, 2009
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site A (CATALYST4006)and Site B(CISCO3750) are connected via 100Megs Lan EXTENSION.How do we determine which interfaces/ports on these switches are actually used for this site to site connection?I did "sh cdp neigh'did not help and I do not have physical access to switches.


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Giuseppe Larosa Fri, 07/24/2009 - 12:04
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look for the MAC address associated in the ARP table with the ip address of an host in site B from a site A host/gateway and then look for that MAC address in the site A switch cam table with

sh mac-address-table address

the outgoing interface that appears in the rightmost column is the interface from site A to site B

Hope to help


jbrenesj Fri, 07/24/2009 - 14:08
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Another idea in case the ARP entry for the other switch is not present is checking the system's MAC of the switch. Look in the show spanning-tree

Core3560#sh spanning-tree


Spanning tree enabled protocol ieee

Root ID Priority 32768

Address 000e.8389.8d00

Cost 19

Port 12 (FastEthernet0/10)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

>>>>>>>> Address 0014.f246.e080

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300


Check the Bridge ID MAC address of Switch A and then look in the MAC table of Switch B for this MAC and you will find the port used to connect between each other


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