IP Routing Protocols
This section covers essential routing protocols used in IPv4 networks. These protocols determine how routers exchange information and calculate the best path for forwarding packets through an internetwork.
Protocol |
Description |
Use Case |
|---|---|---|
EGP (Exterior Gateway Protocol) |
One of the earliest routing protocols used to exchange routing info between autonomous systems. Largely obsolete and replaced by BGP. |
Inter-AS routing in early networks. |
EIGRP (Enhanced Interior Gateway Routing Protocol) |
Cisco proprietary protocol combining features of distance-vector and link-state protocols. Supports VLSM, fast convergence, and uses DUAL algorithm. |
Efficient routing within Cisco-based enterprise networks. |
IGRP (Interior Gateway Routing Protocol) |
Older Cisco proprietary protocol, now deprecated in favor of EIGRP. Limited scalability and slow convergence. |
Legacy enterprise routing. |
IS-IS (Intermediate System to Intermediate System) |
Link-state protocol designed for large ISP networks. Scales well and supports both IPv4 and IPv6. |
Core ISP and enterprise backbone routing. |
Multiprotocol BGP (MP-BGP) |
Extension of BGP that supports routing for multiple protocols, including IPv6 and MPLS VPNs. |
Multi-protocol environments and MPLS networks. |
OSPF (Open Shortest Path First) |
Open standard link-state protocol using Dijkstra’s algorithm. Supports areas, fast convergence, and VLSM. |
Hierarchical and scalable enterprise routing. |
RIPv1 (Routing Information Protocol v1) |
Early distance-vector protocol using hop count metric. No support for CIDR or VLSM. |
Small networks or legacy equipment. |
RIPv2 (Routing Information Protocol v2) |
An enhanced version of RIPv1, supporting authentication, CIDR, and multicast updates. |
Small-to-medium networks with basic routing needs. |
RFC: RFC 904, RFC 1772 (Historic)
Main Features:
One of the earliest routing protocols used to exchange routing info between autonomous systems.
Largely obsolete and replaced by BGP.
Use Cases:
Inter-AS routing in early networks.
Alternative Protocols:
BGP – Modern exterior gateway protocol used globally.
Let us learn more about EGP:
RFC: RFC 1142, RFC 1195, RFC 5308 (IPv6 support)
Main Features:
Link-state protocol designed for large ISP networks.
Scales well and supports both IPv4 and IPv6.
Use Cases:
Core ISP and enterprise backbone routing.
Alternative Protocols:
OSPF – Another scalable link-state protocol.
BGP – For inter-domain routing.
Let us learn more about IS-IS:
RFC: RFC 4271 (BGP-4), RFC 4760 (Multiprotocol Extensions)
Main Features:
Extension of BGP that supports routing for multiple protocols, including IPv6 and MPLS VPNs.
Use Cases:
Multi-protocol environments and MPLS networks.
Alternative Protocols:
EIGRP – For internal routing within organizations.
IS-IS – Alternative backbone routing protocol.
Let us learn more about MP-BGP:
RFC: RFC 2328 (OSPFv2)
Main Features:
Open standard link-state protocol using Dijkstra’s algorithm.
Supports areas, fast convergence, and VLSM.
Use Cases:
Hierarchical and scalable enterprise routing.
Alternative Protocols:
IS-IS – Another open standard link-state protocol.
EIGRP – Cisco proprietary alternative.
Let us learn more about OSPF:
RFC: RFC 1058
Main Features:
Early distance-vector protocol using hop count metric.
No support for CIDR or VLSM.
Use Cases:
Small networks or legacy equipment.
Alternative Protocols:
RIPv2 – Improved version with modern features.
OSPF – For larger or more complex networks.
Let us learn more about RIPv1:
RFC: RFC 2453
Main Features:
An enhanced version of RIPv1, supporting authentication, CIDR, and multicast updates.
Use Cases:
Small-to-medium networks with basic routing needs.
Alternative Protocols:
OSPF – More scalable and feature-rich.
EIGRP – Cisco proprietary alternative.
Let us learn more about RIPv2: