My network has VLANs span across the access layer. We have seen the return path traffic of unicast flooding to all access layer switches
and end points under each. According the Cisco document this problem can be fixed by tune the ARP aging timer less than the CAM aging timer. Currently, on the Catalyst 6500 the ARP aging timer is 4 hours and CAM aging timer is 300 seconds. It looks like 300 seconds is too short for ARP aging timer. What is the best practice aging timer for ARP & CAM for fixing unicast flooding issue.
Thereare logical and good reasons why the ARP timer (reflecting layer 3 forwarding device operation) is relatively long ( 4 hours) while the CAM (or mac-address table) aging timer is pretty short (300 seconds). The difference in the timers can sometimes lead to issues including unicast flooding of frames. A frequent solution is to make the timer match, or perhaps to make the ARP timer shorter than the CAM timer.
Why would you say that 300 seconds is too short for the ARP timer?
If you are experiencing unicast flooding then I would say that best practice would be to set your ARP timer down to match the CAM timer (at 300 seconds) or perhaps set ARP timer slightly less than 300 seconds.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.