I have an older 6509 (WS-SUP720-BASE running Cisco Internetwork Operating System Software IOS (tm) s72033_rp Software (s72033_rp-PSV-M), Version 12.2(18)SXD7b,) as part of our core network that was configured by a previous admin. I noticed a lot of input drops on the VLAN interfaces so I did some digging... it seems they turned CEF off or it was off by default on the VLAN interfaces. I believe that may explain the input drops. It seems to be enabled globally because if I do show ip cef, I see some stuff. Will enabling it on the VLAN interfaces cause any kind of network interruption? Can there be some detrimental effects I am not aware of? Any input is appreciated. Thanks!
In some old versions of software there were some issues related to CEF. Here is a link to release notes for the version of code you are running. As you look through them you will find some possible issues involving CEF. You will need to evaluate whether you believe these issues would impact your particular environment.
