Other Internet Layer Protocols

A number of other protocols also inhabit the Internet layer. Some of these other protocols, such as Border Gateway Protocol (BGP) and Routing Information Protocol (RIP), facilitate the routing process. See Hour 8, “Routing,” for more on routing in TCP/IP.

The IPsec protocols, which are optional in IPv4 but will become mandatory in IPv6, operate at the Internet layer to provide secure encrypted communication (see Hour 23, “TCP/IP Security”). Other Internet layer protocols assist with tasks such as multicasting. As mentioned earlier, the Internet protocol layer is known in OSI shorthand as Layer 3. Any protocol referred to as a Layer 3 protocol is operating at the Internet layer.