Open Shortest Path First

Open Shortest Path First (OSPF) is a link-state routing protocol for Internet Protocol (IP) networks. It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system (AS). It is defined as OSPF Version 2 in RFC 2328 (1998) for IPv4. The updates for IPv6 are specified as OSPF Version 3 in RFC 5340 (2008).

OSPF is perhaps the most widely used interior gateway protocol (IGP) in large enterprise networks. IS-IS, another link-state dynamic routing protocol, is more common in large service provider networks. The most widely used exterior gateway protocol is the Border Gateway Protocol (BGP), the principal routing protocol between autonomous systems on the Internet.

Internet protocols
Application layer
  • DHCP
  • DHCPv6
  • DNS
  • FTP
  • HTTP
  • IMAP
  • IRC
  • LDAP
  • MGCP
  • NNTP
  • NTP
  • POP
  • RPC
  • RTP
  • RTSP
  • SIP
  • SMTP
  • SNMP
  • SOCKS
  • SSH
  • Telnet
  • TLS/SSL
  • XMPP
  • (more)
Transport layer
  • TCP
  • UDP
  • DCCP
  • SCTP
  • RSVP
  • (more)
Routing protocols *
  • BGP
  • OSPF
  • RIP
  • (more)
Internet layer
  • IP
    • IPv4
    • IPv6
  • ICMP
  • ICMPv6
  • ECN
  • IGMP
  • IPsec
  • (more)
Link layer
  • ARP/InARP
  • NDP
  • Tunnels
    • L2TP
  • PPP
  • Media access control
    • Ethernet
    • DSL
    • ISDN
    • FDDI
  • (more)
* Not a layer. A routing protocol belongs either to application or network layer.

Read more about Open Shortest Path First:  Overview, Neighbor Relationships, Area Types, Path Preference, OSPF Router Types, Designated Router, OSPF V3 Packet Formats, OSPF in Broadcast and Non-broadcast Networks, Implementations, Applications

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