Max-.Aging Time

[giaaaj]

Hallo

We are experiencing a strange behavior in our LAN, the MAC- Addresses of the Workstations that are connected to LAn but not generating traffic are being deleted from the Mac- Address-Table after 10s although the aging - Time is set to 300 s.

Does anybody have an Idea Why.

Thanks

Ali

[Prashanth Krishnappa]

Check for Spanning tree TCN's

http://www.cisco.com/warp/public/473/17.html

[konigl]

Ali,

Is this the 3-switch STP triangle you described in another post? Are you running PortFast on the 10/100 Ethernet ports that connect to computers, printers, etc?

After reading through the link that Prashanth provided, it sounds like topology change notifications are causing this. The recommended solution is enabling PortFast on the ports which go through frequent link state changes.

[giaaaj]

Hello,

No it is not, the Network where this problem noticed is more complex and it is a topology where the three layers exists ( Core,distribution and access), the problem where noticed on access switches have redundant links. portfast is being used on ports connected to workstation. It so the the the switch loses the mac-addresses of the stations that are directly connected to it after approx.

15 sec.

Thanks

[Juan Urti]

Hi man, the TCNs are reducing the Aging Time in your switches.

The TCNs are send by the switch that see the topology change to the root bridge. Later, the RB will send the Config BPDU + TC Flag to L2 topology.