Below are some important characteristics of various Dynamic Routing Protocols that are used in Cisco IOS routers.
RIPv2
* Distance Vector Protocol.
* Suitable for small to medium networks.
* Average convergence speed.
* Supports VLSM.
* Supports CIDR.
* Standardized protocols (supports multi-vendor networks.)
* Multicast address for updates: 224.0.0.9
* Administrative distance: 120.
* Difficulty to Administer: Low
EIGRP
* Advanced distance vector protocol.
* Suitable for routing in large networks.
* Very high speed of convergence.
* Supports VLSM.
* Supports CIDR.
* Cisco proprietary.
* Multicast address for updates: 224.0.0.10
* Administrative Distance: internal 90, external 170.
* Difficulty to Administer: Medium
OSPFv2
* Link state protocol.
* Suitable for routing in large networks.
* High convergence speed.
* Supports VLSM.
* Supports CIDR.
* Standardized (supports multi-vendor networks.)
* Multicast address for updates: 224.0.0.5 / 224.0.0.6
* Administrative distance: 110.
* Difficulty to Administer: Medium
IS-IS
* Link state protocol.
* Suitable for routing in large networks.
* High convergence speed.
* Supports VLSM.
* Supports CIDR.
* OSI standard (it supports multi-vendor networks.)
* Administrative distance: 115.
* Difficulty to Administer: High.
BGPv4
* Path vector protocol.
* Suitable for the Internet (between Autonomous Systems or within ISP networks).
* Speed of convergence: low.
* Supports VLSM.
* Supports CIDR.
* Standard (supports multi-vendor networks.)
* Updates unicast.
* Administrative Distance: 20 eBGP, iBGP 200.
* Difficulty to Administer: High.
Some Notes about MPLS
Service Providers use MPLS networks (MultiProtocol Label Switching) to offer IP network connectivity to their clients. The usual connectivity services offered from MPLS networks are Layer3 VPNs and Layer2 VPNs (usually point-to-point Layer 2). An MPLS network makes use of two different Routing Protocols. An Interior Gateway Protocol (usually OSPF or IS-IS) and also BGPv4 which is a modified version of the regular BGP protocol and is used to carry MPLS label information within the MPLS network.
