ISP-2: This is an AS and it uses OSPF as the IGP.

It interconnects with other autonomous systems and service providers using BGP to explicitly control how traffic is routed.

ISP-1: This is an AS and it uses IS-IS as the IGP.

There are five individual autonomous systems in the scenario: Link-state routing protocols are classless by nature.įigure 3-9 displays a hierarchical view of dynamic routing protocol classification.įigure 3-10 IGP versus EGP Routing Protocols

These routing protocols have evolved into the classless routing protocols, RIPv2 and EIGRP, respectively. The classful routing protocols, RIPv1 and IGRP, are legacy protocols and are only used in older networks.

BGP: EGP, path-vector, classless protocol.

IS-IS: IGP, link-state, classless protocol.

OSPF: IGP, link-state, classless protocol.

EIGRP: IGP, distance vector, classless protocol developed by Cisco.

RIPv2: IGP, distance vector, classless protocol.

IGRP (legacy): IGP, distance vector, classful protocol developed by Cisco (deprecated from 12.2 IOS and later).

RIPv1 (legacy): IGP, distance vector, classful protocol.

Behavior: Classful (legacy) or classless protocolįor example, IPv4 routing protocols are classified as follows:.

Operation: Distance vector protocol, link-state protocol, or path-vector protocol.

Purpose: Interior Gateway Protocol (IGP) or Exterior Gateway Protocol (EGP).

Specifically, routing protocols can be classified by their: Routing protocols can be classified into different groups according to their characteristics.

For now, this section gives a very brief overview of each protocol. Most of these routing protocols will be examined in detail in other chapters. This section gives an overview of the most common IP routing protocols.

Table 3-1 showed how routing protocols can be classified according to various characteristics.

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