vlan mac-address table and timeouts

[jimfixit]

I am trying to overcome a unicast flooding problem caused by asymetrical routing, a by product of the server-farm being on one vlan and users on another. Everything I've read on Cisco's site on this matter says to up the cam table time out(mac address aging) to 14400, which matches the arp timeout.

I set the value on all my 3750's and did a show..each vlan shows 14440 as the timeout. But on my core switches, (6500 series), after I issue the command and then show the setting, I get the following:

SWITCH#show mac-address-table ag
Vlan Aging Time
---- ----------
Global 14400
no vlan age other than global age configured
Routed MAC aging time: 300 seconds

What does the statement "Routed MAC aging time: 300 seconds" imply? I did a search on cisco's site and found one reference, indicating that there was a bug in the IOS that was fixed in 12.1.22. This bug would allow the global setting to be changed but not impact the individual vlans. However we are well beyond that version of IOS, 12.2.18.

Does anyone know what this "routed mac aging time" is, as opposed to the global time out?

 

[BuckWeet]

I wouldn't do this.. I would leave the CAM timers the same and adjust your arp timeout values on your routers to be in tune with your CAM setting..


BuckWeet

 

[Microbyte]

Routed MAC aging time is exactly what it says. Once these learned mac-address has reached the configured age time (300 seconds by default), the switch flushes out of its memory. Switch re-learns these by pings performed by each node.

As far as global time out, I am not quite sure about it. But it seems if they are the same.

Microbyte