Routing
protocols, according to the OSI routing framework, are layer management
protocols for the network layer, regardless of their transport mechanism:
IS-IS
runs on the data link layer (Layer 2)
Open
Shortest Path First (OSPF) is encapsulated in IP, but runs only on the IPv4
subnet, while the IPv6 version runs on the link using only link-local
addressing.
IGRP,
and EIGRP are directly encapsulated in IP. EIGRP uses its own reliable
transmission mechanism, while IGRP assumed an unreliable transport.
RIP
runs over UDP
BGP runs over TCP
