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Routing Basics : Distance Vector vs Link State Routing Protocol

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Today i am going to talk about the basics of the dynamic routing protocol. As some of you already knew the about the types of routing protocols and what is the difference ? The reason why I am talking about this due to lot of basics questions asked by the readers of the blog. I am happy to share the information with you guys.

Let's talk about the routing protocols which we are using in our network and then we will check how they actually works in the network. These all protocols are dynamic routing protocols and these routers are
  • RIP- Routing Information Protocol
  • OSPF- Open Shortest Path First
  • IGRP- Interior gateway routing Protocol
  • EIGRP- Enhanced  Interior gateway routing Protocol
  • IS-IS- Intermediate system to intermediate System
  • BGP- Border Gateway Protocol
These are the dynamic routing protocol which can be distance vector or can be Link state except BGP. BGP is a path vector routing protocol and we are not going to talk BGP here.

Distance Vector Routing Protocol:-
In this routing scheme, each router periodically shares its knowledge about the entire network with its neighbours. Each router has a table with information about network. These tables are updated by exchanging information with the immediate neighbours. 
Fig 1.1- Distance Vector Routing Protocol

For IP RIP, the maximum hop is 15. A hop count of 16 indicates an unreachable network. Two versions of RIP exist: version 1 and version 2.IGRP is another example of a distance vector protocol with a higher hop count of 255 hops.Periodic updates are sent at a set interval. For IP RIP, this interval is 30 seconds.Updates are sent to the broadcast address 255.255.255.255



So I hope you understand the way how distance vector routing protocol works in actual means, now the question is which of the routing protocol is work link distance vector. So the protocols are RIP, IGRP are the distance vector routing protocol.

Link State Routing Protocol:-
In the case of Link state routing protocol, you can send the full information once in the network and if there is some update and changes next time, you are going to send only the changes across the network and that is way of working of the Link State Routing Protocol. Link-State router tells ALL other routers about ONLY its neighbours and links. In Link-State protocols Update and Decision processes are independent. Link-State are fast loop-free convergence protocols .

Fig 1.2- Link State Routing Protocol
So there is no any concept of HOP count as what we are using in the distance vector routing protocol. In the case of Link state routing protocol, it maintains 3 tables and these tables are Neighbour table, Routing Table and Topology Table. Mainly OSPF and IS-IS are the Link state routing protocol. 

In the case if you are looking about the EIGRP and BGP routing protocols, EIGRP is a Hybrid routing protocol and is a mix of Link state and Distance Vector what experts say and on the other side BGP is a Path Vector Routing Protocol and is works differently.

And if you are interested to look back about the article which i wrote some weeks ago about the difference between the OSPF and RIP protocol, you can go to the below link

Below is the basic table shows the difference between the Distance Vector and Link State routing protocol. Please let me know if you have any queries. I will come up with one by one topic in details which includes all these routing protocol.

Fig 1.1- Distance Vector vs Link State routing Protocols