Host Learning (MAC) on Cisco 45xx and 65xx

[davidhuynh5]

On the Cisco 4948, I can run the command #show platform cpu packet statistics. The output includes "host learning, L2 Fwd Low, and L3 Rx low."

This command allows me to determine how many times the cam table has changed when troubleshooting port-fapping issues.

What is the equivilent command on a Cisco 45xx or 65xx?

[Shashank Singh · Accepted solution]

Hi David,

show platform cpu packet statistics all command is support on 4500 switches also:

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00804cef15.shtml

There is no direct equivalent for this command on 6500 switches. To troubleshoot port flapping issues on 6500, you can do the following:

enable mac flap notification (disabled by default on 6500) and check for the MAC_FLAP logs in sh log.

switch(conf)#mac-address-table notification mac-move

You can also check out the spanning tree topology changes which will tell you the port sending out TCNs  because of the flap.

switch# sh span detail

Cheers,

Shashank

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[davidhuynh5]

Thanks Shashank.

What exactly am I looking for in the "switch# sh span detail" ?

[Shashank Singh]

Hi David,

This command will tell which interfaces have been sending topology change notifications on this switch. For example:

Router#sh span det | i from|topology

  Number of topology changes 1 last change occurred 00:58:08 ago     

          from TenGigabitEthernet3/1                   <<-------- 

  Times:  hold 1, topology change 35, notification 2

  Timers: hello 0, topology change 0, notification 0, aging 300

  Number of topology changes 1 last change occurred 00:58:08 ago

          from TenGigabitEthernet3/1

  Times:  hold 1, topology change 35, notification 2

  Timers: hello 0, topology change 0, notification 0, aging 300

Cheers,

Shashank