Network protocol for distributing routing information to network equipment
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. 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 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 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.
Types.
Although there are many types of routing protocols, three major classes are in widespread use on IP networks:
OSI layer designation.
Routing protocols, according to the OSI routing framework, are layer management protocols for the network layer, regardless of their transport mechanism:
Interior gateway protocols.
Interior gateway protocols (IGPs) exchange routing information within a single routing domain. Examples of IGPs include:
Exterior gateway protocols.
Exterior gateway protocols exchange routing information between autonomous systems. Examples include:
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 to allow a packet to be forwarded from one network to another. Examples of routed protocols are the Internet Protocol (IP) and Internetwork Packet Exchange (IPX).
References.
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