Interior Gateway Protocol

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As Interior Gateway Protocol ( IGP ) are routing protocols referred to, the inside of autonomous systems can be used.

In contrast to Exterior Gateway Protocols  (EGP), they are characterized by their special capabilities in dealing with complex network topologies . Traffic engineering functions such as OSPF-TE can also be found.

The EGPs used are normally based on the infrastructure secured by the IGPs. Therefore, in the normal case, exactly one EGP runs in parallel with exactly one IGP per network protocol .


Depending on the topology of the network, the following are mostly used today:

Due to their age or their simple structure, they are only rarely used or in special network topologies:

Norms and standards

  • RFC 1074 The NSFNET Backbone SPF based Interior Gateway Protocol
  • RFC 3785 Use of Interior Gateway Protocol (IGP) Metric as a second MPLS Traffic Engineering (TE) Metric
  • RFC 3906 Calculating Interior Gateway Protocol (IGP) Routes Over Traffic Engineering Tunnels