Classification of dynamic routing protocols
Dynamic routing protocols can be classified in various ways. These can be classified into three groups:
1. IGP and BGP protocols
2. Distance vector and link state protocols
3. Classful and Classless protocols
The first classification is based upon protocol to be used within our network or between our network and another network. In the second classification Distance vector means that routes are advertise as vector of distance and direction, the link state routing protocol create a complete view or topology of the network by gathering information from all the other router.Classful routing protocol do not send the subnet mask information in the routing updates whereas classless protocol send the subnet mask information in their updates.
Interior gateway protocol (IGP) and Exterior gateway protocol (EGP)
IGP is used for intra – autonomous system routing means routing inside the autonomous system and EGP used for inter-autonomous system routing means routing between the autonomous systems.
An autonomous system is a collection of routers under a common administration. Example of autonomous system is company’s internal network and ISP’s network.
IGP are used for routing within a routing domain, network within the control of single organization. An IGP is used to route within the autonomous system and also to route within network themselves.IGPs for IP includes RIP(Routing information protocol),IGRP(Interior gateway routing protocol),EIGRP(Enhance interior gateway routing protocol)-it is a Cisco proprietary protocol designed by the Cisco system for use on their router,OSPF(Open shortest path first) and IS-IS(Intermediate system-Intermediate system).IGP tend to a simpler and require less overhead in a router.EGP are designed to scale to the largest network but is more complex than IGP and require more overhead.
Routing protocol uses the metric to determine the best path to a network. The metric used by the routing protocol RIP is hop count, which is the number of the routers over the packet passes to reach the destination network.OSPF uses the bandwidth to determine the shortest path.
The drawback of IGP is that they can’t scale extremely to a large network. EGPs are designed for use between different autonomous systems that are under the control of different administration.BGP is the currently routing protocol used in internetwork.
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