The MAC address does not show the port

[rajmk_siva]

I tried to locate a device and got this output

switch#sh ip arp | i 10.228.8.218
Internet  10.228.8.218           99   5c26.0a6f.4cf5  ARPA   Vlan8
switch#sh mac add add 5c26.0a6f.4cf5
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----

 I get the MAC Address but I am not getting the port details. May I request the forum - what could be the the reson fro such an output? How to rectify this?

[Richard Burts]

There are a couple of possibilities of things that might cause this result.

- the arp output indicates that the address is associated with vlan 8. Is vlan 8 on this switch? Is it possible that the device with this IP address is connected on another switch?

- there is a possibility of a mismatch between the aging timer for the arp table and the aging timer for mac address table entries. While the arp table typically has a 4 hour timeout the mac address table timeout is usually pretty short (a few minutes). It is possible that the device responded to an arp and its entry has not yet timed out but that the mac address entry has aged out.

HTH

Rick

[rajmk_siva]

Thank you Richard and Jamband. It was informative.

[jamband764]

If the device is still connected and you connect to the Spanning tree Root for VLAN8, you should be able to track down the access port for the above mac address