MAC aging does not work

rgups · ‎12-09-2002

I have Catalyst1900, Catalyst2900 and Catalyst3500 switches in my LAN. I want to know where is each user. I use command "show mac-address-table" for mac address search. But if the user is inactive during 5 minutes I can't locate it, because mac address absence. This caused by defult mac address aging-time 300 seconds. I set this parameter to maximal value 1000000 seconds for each switch. But mac addresses are aged more rapidly than 11 days. Sometimes 10-15 min. Why? And second question, can spanning tree affect this process somehow?

wong34539 · ‎12-16-2002

The command used is :

mac-address-table aging-time age

age can be a Number from 10 to 1000000 (seconds). Your configuration should work.

Try reducing the age value slightly day 800000 or something.

All the 3 switches mentioned by you support this command.

Use the related commands given here to verify:

http://www.cisco.com/univercd/cc/td/doc/product/lan/c2900xl/29_35wc5/cli/clicmds.htm#xtocid39

I don't think the spanning tree process has anyhting to do with this. Please however record any error message or log, so that it would be useful to troubleshoot.

ji.xie · ‎12-18-2002

Spanning tree protocol do affect the aging time of the mac table.When the netowrk topoloy changes,Spanning tree protocol will shorten the aging time of the mac address

efrahim · ‎12-22-2002

If there is some problem due to spanning tree convergence,, this start the fast aging time, which flushes all the mac addresss in 15 sec. as part of network convergence. you probably need to check if you are getting the spanning tree tcns.. is portfast is enabled on all server/workstations ports etcc.

This link talks about the fast aging..

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a0080094956.shtml#causes

Hope this helps..

Report Inappropriate Content · ‎12-22-2002

Since you know or can tell which vlan the port is located and you can correspond the vlan to the subnet, Try pinging the entire subnet first (direct broadcast). Then try to show the cam table/ mac addres table. It should be there if the device is connected.