Routing - CEF adjacency fixup error

When employing CEF an error that may appear when attempting to route packets is the following:

*Sep 30 15:34:55.381: CEF-Drop: Packet from 192.168.1.100 (Et0/1) to 192.168.2.254, adjacency fixup

This error is one that may appear when using CEF. The “adjacency fixup” message typically indicates that CEF couldn’t properly find an entry for the next-hop address in its adjacency table, leading to packet drops.

Disabling CEF by issuing the no ip cef command may resolve the issue, as it forces the device to revert to process switching, which may handle the packets differently. This is not always preferrable, and further troubleshooting may be necessary to resolve the problem.

Links:

https://forum.networklessons.com/t/ipsec-static-virtual-tunnel-interface/2374/49?u=lagapidis

https://networklessons.com/switching/cef-cisco-express-forwarding