In this section, we will discuss IP routing and its different types.
What is IP Routing
IP routing may be defined as a process or a method of sending an IP packet from one network to another network in a reliable manner and finding the best possible path from source to destination.
The router performs the IP routing process for which it maintains the IP routing table. The routing tables contain the details of all the network addresses connected with the router. The router performs the forwarding decision from source to destination on the basis of destination address.
Every packet entering the incoming interface of the router contains the source and destination address. The router checks the destination address in the routing table. If it finds the entry in the routing table, it forwards the packet to the interface that is connected to that particular destination network. Otherwise, it simply discards the packet.
Types of IP Routing
IP routing is broadly classified into three types:
- Static Routing
- Dynamic Routing
- Default Routing
Static Routing is a form of routing process where routing table entries are made manually by the network administrator. It is also called non-adaptive routing because routing table information remains the same unless the network administrator modifies or changes the routing information.
It is more reliable and secure. It is very useful in smaller networks where numbers of routers are fixed and limited. However, when the numbers of routers increase in-network, it is difficult to manage all the routers manually.
Dynamic routing is another form of routing where routing tables are modified or updated automatically without the intervention of network administrators.
In contrast to static routing, dynamic routing is more complex and uses Routing protocols to maintain routing tables. A routing protocol is a set of a complex algorithm that seeks information from a neighbor router and update its routing table with the change in topology. The router advertises its routing information to the adjacent routers periodically.
Dynamic routing can handle very large numbers of routers, no matter how big is the network. However, it is less secure and less reliable as compared to static routing. Also, the router seems to be always busy where dynamic routing is configured, because routers talk to each other periodically to share the latest routing information.
Default Routing is used in the stub network. A stub is that network where the last end router is located and only one exit interface is available for incoming and outgoing traffic.
Difference between Static and Dynamic Routing
|S. No.||Static Routing||Dynamic Routing|
|1||The routing table is configured manually.||Automatic.|
|2||Routes are user-defined.||Routes are updated, as the topology changes.|
|3||It does not use any routing protocols.||It uses routing protocols.|
|4||It is more reliable.||Less reliable as compared to the static routing.|
|5||It is more secure.||Less secure.|
|6||Suitable for smaller networks with limited numbers of routers.||Suitable for large networks.|
|7||It does not require additional resources.||It requires additional resources like memory, bandwidth for the routing process|
|8||Link failure obstructs the rerouting.||Link failure doesn’t affect the rerouting.|