Interior gateway protocol
Encyclopedia
An interior gateway protocol (IGP) is a routing protocol
that is used to exchange routing information within an autonomous system
(AS).
In contrast, an Exterior Gateway Protocol
(EGP) is for determining network reachability between autonomous systems and makes use of IGPs to resolve routes within an AS.
The interior gateway protocols can be divided into two categories: 1) Distance-vector routing protocol
and 2) Link-state routing protocol
.
. In these protocols, each router does not possess information about the full network topology. It advertises its distance value (DV) calculated to other routers and receives similar advertisements from other routers unless changes are done in local network or by neighbours (Routers). Using these routing advertisements each router populates its routing table. In the next advertisement cycle, a router advertises updated information from its routing table. This process continues until the routing tables of each router converge to stable values.
Some of these protocols have the disadvantage of slow convergence.
Some examples of Distance Vector routing protocol are:
This contrasts with distance-vector routing protocols, which work by having each node share its routing table with its neighbors. In a link-state protocol, the only information passed between the nodes is information used to construct the connectivity maps.
Some examples of Link-State routing protocol are:
Routing protocol
A routing protocol is a protocol that specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network, the choice of the route being done by routing algorithms. Each router has a priori knowledge only of...
that is used to exchange routing information within an autonomous system
Autonomous system (Internet)
Within the Internet, an Autonomous System is a collection of connected Internet Protocol routing prefixes under the control of one or more network operators that presents a common, clearly defined routing policy to the Internet....
(AS).
In contrast, an Exterior Gateway Protocol
Exterior Gateway Protocol
The Exterior Gateway Protocol is a now obsolete routing protocol for the Internet originally specified in 1982 by Eric C. Rosen of Bolt, Beranek and Newman, and David L. Mills. It was first described in RFC 827 and formally specified in RFC 904...
(EGP) is for determining network reachability between autonomous systems and makes use of IGPs to resolve routes within an AS.
The interior gateway protocols can be divided into two categories: 1) Distance-vector routing protocol
Distance-vector routing protocol
In computer communication theory relating to packet-switched networks, a distance-vector routing protocol is one of the two major classes of routing protocols, the other major class being the link-state protocol...
and 2) Link-state routing protocol
Link-state routing protocol
A link-state routing protocol is one of the two main classes of routing protocols used in packet switching networks for computer communications . Examples of link-state routing protocols include OSPF and IS-IS....
.
Distance-vector routing protocol
Distance-vector routing protocols use the Bellman-Ford algorithmBellman-Ford algorithm
The Bellman–Ford algorithm computes single-source shortest paths in a weighted digraph.For graphs with only non-negative edge weights, the faster Dijkstra's algorithm also solves the problem....
. In these protocols, each router does not possess information about the full network topology. It advertises its distance value (DV) calculated to other routers and receives similar advertisements from other routers unless changes are done in local network or by neighbours (Routers). Using these routing advertisements each router populates its routing table. In the next advertisement cycle, a router advertises updated information from its routing table. This process continues until the routing tables of each router converge to stable values.
Some of these protocols have the disadvantage of slow convergence.
Some examples of Distance Vector routing protocol are:
- Routing Information ProtocolRouting Information ProtocolThe Routing Information Protocol is a distance-vector routing protocol, which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops allowed for RIP is 15....
(RIP) - Interior Gateway Routing ProtocolInterior Gateway Routing ProtocolInterior Gateway Routing Protocol is a distance vector interior routing protocol invented by Cisco. It is used by routers to exchange routing data within an autonomous system....
(IGRP) - Enhanced Interior Gateway Routing ProtocolEnhanced Interior Gateway Routing ProtocolEnhanced Interior Gateway Routing Protocol - is a Cisco proprietary routing protocol loosely based on their original IGRP. EIGRP is an advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of...
(EIGRP)
Link-state routing protocol
In the case of Link-state routing protocols, each router possesses information about the complete network topology. Each router then independently calculates the best next hop from it for every possible destination in the network using local information of the topology. The collection of best next hops forms the routing table.This contrasts with distance-vector routing protocols, which work by having each node share its routing table with its neighbors. In a link-state protocol, the only information passed between the nodes is information used to construct the connectivity maps.
Some examples of Link-State routing protocol are:
- Open Shortest Path FirstOpen Shortest Path FirstOpen Shortest Path First is an adaptive routing protocol for Internet Protocol networks. It uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system . It is defined as OSPF Version 2 in RFC 2328 for IPv4...
(OSPF) - Intermediate system to intermediate system (IS-IS)
Hybrid routing protocol
Hybrid routing protocols have both the features of distance vector routing protocols & linked state routing protocols. An example of this protocol is EIGRP.See also
- Exterior Gateway ProtocolExterior Gateway ProtocolThe Exterior Gateway Protocol is a now obsolete routing protocol for the Internet originally specified in 1982 by Eric C. Rosen of Bolt, Beranek and Newman, and David L. Mills. It was first described in RFC 827 and formally specified in RFC 904...
- Route analyticsRoute analyticsRoute analytics is an emerging network monitoring technology specifically developed to analyze the routing protocols and structures in meshed IP Networks...