Computer Network Routing Protocol Classification-en

A routing protocol specifies how routers communicate with each other to distribute information that enables them to select paths between nodes on a

computer network A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

. Routers perform the traffic directing functions on the Internet; data packets are forwarded through the networks of the internet from router to router until they reach their destination computer.

Routing Routing is the process of selecting a path for traffic in a Network theory, network or between or across multiple networks. Broadly, routing is performed in many types of networks, including circuit-switched networks, such as the public switched ...

algorithms determine the specific choice of route. Each router has a prior knowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network. The ability of routing protocols to dynamically adjust to changing conditions such as disabled connections and components and route data around obstructions is what gives the Internet its

fault tolerance Fault tolerance is the ability of a system to maintain proper operation despite failures or faults in one or more of its components. This capability is essential for high-availability, mission-critical, or even life-critical systems. Fault t ...

and high availability. The specific characteristics of routing protocols include the manner in which they avoid routing loops, the manner in which they select preferred routes, using information about hop costs, the time they require to reach routing convergence, their scalability, and other factors such as relay multiplexing and cloud access framework parameters. Certain additional characteristics such as multilayer interfacing may also be employed as a means of distributing uncompromised networking gateways to authorized ports. This has the added benefit of preventing issues with routing protocol loops. Many routing protocols are defined in technical standards documents called RFCs.Requirements for IP Version 4 Routers
RFC 1812, F. Baker,June 1995

Types

Although there are many types of routing protocols, three major classes are in widespread use on IP networks: * Interior gateway protocols type 1, link-state routing protocols, such as OSPF and IS-IS * Interior gateway protocols type 2, distance-vector routing protocols, such as Routing Information Protocol, RIPv2, IGRP. * Exterior gateway protocols are routing protocols used on the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

for exchanging routing information between Autonomous Systems, such as Border Gateway Protocol (BGP), a path-vector routing protocol. Exterior gateway protocols should not be confused with Exterior Gateway Protocol (EGP), an obsolete routing protocol.

OSI layer designation

Routing protocols, according to the OSI routing framework, are layer management protocols for the network layer, regardless of their transport mechanism: * IS-IS runs on the data link layer (Layer 2) *

Open Shortest Path First Open Shortest Path First (OSPF) is a routing protocol for Internet Protocol (IP) networks. It uses a link state routing (LSR) algorithm and falls into the group of interior gateway protocols (IGPs), operating within a single Autonomous syste ...

(OSPF) is encapsulated in IP, but runs only on the

IPv4 Internet Protocol version 4 (IPv4) is the first version of the Internet Protocol (IP) as a standalone specification. It is one of the core protocols of standards-based internetworking methods in the Internet and other packet-switched networks. ...

subnet, while the

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

version runs on the link using only link-local addressing. * IGRP, and EIGRP are directly encapsulated in IP. EIGRP uses its own reliable transmission mechanism, while IGRP assumed an unreliable transport. * Routing Information Protocol (RIP) runs over the

User Datagram Protocol In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in Network packet, packets) to other hosts on an Internet Protoco ...

(UDP). Version 1 operates in broadcast mode, while version 2 uses multicast addressing. * BGP runs over the Transmission Control Protocol (TCP).

Interior gateway protocols

Interior gateway protocols (IGPs) exchange routing information within a single routing domain. Examples of IGPs include: *

(OSPF) * Routing Information Protocol (RIP) * Intermediate System to Intermediate System (IS-IS) * Enhanced Interior Gateway Routing Protocol (EIGRP)

Exterior gateway protocols

Exterior gateway protocols exchange routing information between autonomous systems. Examples include: * Exterior Gateway Protocol (EGP) * Border Gateway Protocol (BGP)

Routing software

Many software implementations exist for most of the common routing protocols. Examples of open-source applications are Bird Internet routing daemon, Quagga, GNU Zebra, OpenBGPD, OpenOSPFD, and XORP.

Routed protocols

Some network certification courses distinguish between routing protocols and ''routed'' protocols. A routed protocol is used to deliver application traffic. It provides appropriate addressing information in its internet layer or

network layer In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate Router (computing), routers. Functions The network layer provides t ...

to allow a packet to be forwarded from one network to another. Examples of routed protocols are the

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...

(IP) and Internetwork Packet Exchange (IPX).

Types

OSI layer designation

Interior gateway protocols

Exterior gateway protocols

Routing software

Routed protocols

See also

Notes

References

Further reading