CAM Table Duplicate

[Antonio Knox]

Guys,

I'm having a problem with some servers losing connectivity randomly. Whenever I clear the arp cache, the problem goes away, but eventually resurfaces. I figure this is a layer 2 issue. So I pull the MAC addresses of the servers of interest and take a look at the CAM table. As I look at the MAC addresses one by one, I notice this for one of the particular MAC addresses of interest:

switch1#sh mac-add add 0011.855c.0959

Legend: * - primary entry

age - seconds since last seen

n/a - not available

vlan mac address type learn age ports

------+----------------+--------+-----+----------+--------------------------

Module 12[FE 1]:

* 9 0011.855c.0959 dynamic Yes 5 Gi12/12

Module 12[FE 2]:

* 9 0011.855c.0959 dynamic Yes 60 Gi12/12

Why am I getting two entries for this port, and could this create a problem of any sort? And could anyone explain what 'FE 1' and 'FE 2' is?

[chrismarget · Accepted solution]

It looks like you've got a DFC installed on the card in slot 12.

I think this means that the DFC is keeping its own (extra) copy of the L2 forwarding table.

This is normal.

/chris

[Ryan Carretta]

Chris is correct. Moreover, there are two forwarding engines that maintain their own CAM entries. That's what you're seeing in the [FE1] and [FE2].