Routing Protocols

A routing protocol is a set of standards that defines how routers communicate with each other. It enables routers to choose the path to utilize among a series of network within the Internet through a routing algorithm. In order to do that, it utilizes the following metrics in analyzing the path:

  • Count of the network layer devices along its path
  • Delay
  • Bandwidth
  • Cost
  • MTU
  • Load

Routing protocol is different from routed protocol. The former is responsible for determining the path on which to send traffic, the latter facilitates the actual sending of traffic or forwarding of packet from one host to another.

There are basically two types of routing protocols. They are:

  1. The Interior
  2. This type of routing protocols enables free dissemination of information within a given routing domain. The basic idea of the autonomous system (AS) lies in the fact that it allows the administrator independent control over the details within an AS. Hence, all the details of activity within one AS are made exclusive to that particular AS.

    Current interior routing protocols include the following:

    • Interior Gateway Routing Protocol
    • Enhanced Interior Gateway Routing Protocol
    • Routing Information Protocol (RIP)
    • The RIP automatically finds the routing tables on its own instead of the system administrator figuring them out. Hence, it utilizes the automatic routes and also redirects to a secondary path if the first one fails.

    • Open Shortest Path First
    • This is one of the most commonly used IGP’s. This, however, uses a different method in building route tables. It leans towards other OSPF enabled routers that have the same information used by other OSPF enabled routers in building its own route tables.

    • Intermediate System to Intermediate System
    • This type of routing protocol is similar to the OSPF. Under this are two types of addresses: the Network Service Access Point (NSAP) and the Network Entity Title (NET) .

  3. The Exterior
  4. This type of routing protocol facilitates routing information support autonomous system or outside a given domain. The following are common examples of exterior routing protocols:

    • Exterior Gateway Protocol
    • Constrained Shortest Path First
    • This particular algorithm is an advanced version of the SPF algorithm utilized for the OSPF and IS-IS route. When directing paths, the CSPF considers the following: topology of the network, attributes of the LSP, and the links.

    • Border Gateway Protocol (BGP)
    • The BGP is considered a distance vector protocol. Meanwhile, this type of protocol is also commonly used for the large internetworks and the Internet.