Prerequisites for BFD

CE.

Bidirectional Forwarding Detection (BFD) is a protocol used to detect failures in communication paths between two systems, particularly for use with IP networks. BFD is used to determine network failures quickly and is particularly useful for detecting issues that can cause longer failover times with traditional protocols such as Open Shortest Path First (OSPF).

Let's go through each of the options given and determine which two are the correct prerequisites for BFD.

A. For Layer 2 port channels used by BFD, you must disable LACP on the port channel.

This statement is true. When using BFD on Layer 2 port channels, you must disable Link Aggregation Control Protocol (LACP) on the port channel. BFD requires individual links in a port channel to be independent and not aggregated, which means that the LACP protocol should be disabled.

B. Install NETWORK_SERVICES_PKG license.

This statement is not a prerequisite for BFD. The installation of the NETWORK_SERVICES_PKG license is not required to use BFD.

C. For Layer 3 port channels used by BFD, you must enable LACP on the port channel.

This statement is not true. For Layer 3 port channels, the use of LACP is optional and not a requirement. BFD can be used on Layer 3 port channels with or without LACP.

D. Enable ICMP redirect messages on BFD-enabled interfaces.

This statement is not a prerequisite for BFD. ICMP redirect messages are not required for BFD to function.

E. Disable the IP packet verification check for identical IP source and destination addresses.

This statement is not a prerequisite for BFD. The IP packet verification check is not related to BFD and does not need to be disabled.

Therefore, the two prerequisites for BFD that are true are:

• For Layer 2 port channels used by BFD, you must disable LACP on the port channel.
• There are no prerequisites for Layer 3 port channels used by BFD.