Cisco Cisco IOS Software Release 12.2(55)SE Notas de publicación

You should review this section before you begin working with the switch. These are known limitations 
that will not be fixed, and there is not always a workaround. Some features might not work as 
documented, and some features could be affected by recent changes to the switch hardware or software.

The BFD session with the neighbor flaps when there is close to 100 percent bidirectional line- rate 
traffic sent through the physical links connecting the neighbors. This happens only on the sessions 
with Layer 3 BFD neighboring switches connected through a Layer 2 intermediate switch. 

The workaround is to make sure that there is no 100 percent bidirectional unknown traffic flowing 
through the intermediate Layer 2 switch in the same links that connect Layer 3 switches. An 
alternate workaround is to always directly the Layer 3 switches when BFD is running. 
(CSCsu94835)

If you create a BFD session between two switches and then create an ACL that includes the permit 
ip any any log-input access-list configuration command, when you attach the ACL to one of the 
connecting interfaces, the BFD session goes down. If you remove the ACL from the interface, BFD 
comes back up.

The workaround is to not use the permit ACL entry with the log option on interfaces participating 
in BFD. (CSCtf31731)