The use of protocol authentication is recommended to protect against malicious attack on the communications between routing protocol neighbors. These attacks could aim to either disrupt communications or to inject incorrect routing information into the systems routing table. The use of authentication keys can help to protect the routing protocols from these types of attacks.
Authentication must be explicitly configured and can be done so through two separate mechanisms. First is configuration of an explicit authentication key and algorithm through the use of the authentication and authentication-type commands. The second method is through the use of the authentication keychain mechanism. Both mechanisms are described in the following sections.