Network Routing Protocols

This post summarizes gateway protocols or routing protocols on computer networks.

All of them are within OSI layer 3.

List of Network Routing Protocols

Overall list of network routing protocols:

  • Interior routing protocols
    • Distance-vector routing protocols
      • IGRP
      • EIGRP
      • RIP
    • Link-state routing protocols
      • OSPF
      • IS-IS
  • Exterior routing protocols
    • Path vector protocols
      • BGP

The two main categories of network routing protocols are:

  • Interior protocols
  • Exterior protocols

Interior Protocols

Interior protocols makes the best decision only taking into account the next hop.

They are typically used within an autonomous system.

Categories of interior protocols

  • Distance-vector protocols
  • Link-state routing protocol

Distance-vector Protocols

Distance-vector protocols use metrics including the direction traffic and distance in hops to the destination to make decision about the next hop routing.

Distance-vector protocols featured on this post:

  • IGRP
  • RIP

Interior Gateway Routing Protocol (IGRP).


Enhanced IGRP (EIGRP) replaces IGRP.


Routing Information Protocol (RIP)

Link-state Routing Protocol

Link-state routing protocol gathers routing characteristics (such a speed latency error rates and actual monetary cost) and uses this information to decide the next hop routing.

Link-state routing protocols:

  • OSPF
  • IS-IS

Open Shortest Path First (OSPF) is a routing protocol that keeps a map of all connected remote networks and uses that map to select the shortest path to a remote destination.


Intermediate System to Intermediate System (IS-IS).

Exterior Routing Protocols

Exterior protocols makes a decision based on the entire remaining path to the destination, instead of the next hop only.

External routing protocols:

  • Path-vector Protocol

Path-vector Protocol

Path-vector protocols:

  • BGP

Border Gateway Protocol (BGP) is a path vector protocol that is primarily used for exchanging routing and reachability information between autonomous systems (AS) on the internet.

It is considered an application layer protocol in the OSI model.

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External References

  • Chapman; “CISSP Study Guide 9th Edition”, chapter 11 “Secure Network Architecture”, section “OSI Model”, p. 503; Wiley, 2021

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