IP routing is one of the important topics in computer networks. IP routing is performed on the data which describes the path that data follows to reach from source to destination in the network. Through IP routing only the shortest path for the data is determined to reach the destination which decreases cost and data is sent in minimum time. IP routing uses different protocols and technologies for different networks. For IP routing we require some basics of IP addresses, routers, and different networks.
IP Routing:
IP routing is the process that defines the shortest path through which data travels to reach from source to destination. It determines the shortest path to send the data from one computer to another computer in the same or different network. Routing uses different protocols for the different networks to find the path that data follows. It defines the path through which data travel across multiple networks from one computer to other. Forwarding the packets from source to destination via different routers is called routing. The routing decision is taken by the routers.
IP Routing
Terminologies:
- Autonomous System (AS): The collection of networks managed and supervised by a single entity or organization is called an autonomous system.
- Router: A router is a device that forwards the data using routing through multiple networks.
- Routing Table: A routing table is a table present in the router which stores the routing information.
Different Types of Routing:
There are three different types of routing:
- Static Routing
- Dynamic Routing
- Default Routing
Static Routing: In this type of routing the routing table is updated by the network administrator.
Dynamic Routing: In this type of routing the routing table is automatically updated using routing protocols.
Default Routing: In this type of routing the router is configured to send all the data towards a specific router. This routing is generally used with the stub routers.
How does IP routing work?
When the data is sent from the source to the destination the TCP and other protocols of the source work and form an IP packet that is sent to the network. When an IP packet is sent to the network from the source it has to pass through multiple routers to reach the destination. The router in the network gets the destination address from the packet and through its routing table identifies the next router information to which the data packet has to be passed. The routing table of the router includes various information about the next router, its cost, and other necessary information. The router takes the routing decision with the help of routing protocols and a routing table to which next router the packet has to be sent to find the best route to reach the destination. Different packets can be sent through different paths but all the packets reach their intended destination. When the packets reach the destination through different routers it sends them to the TCP for further processing.
Routing Protocols:
For taking routing decisions router needs various routing protocols and a routing table. The routing protocols are divided into two domains:
- Interdomain Routing protocols
- Intradomain Routing protocols
Interdomain Routing Protocols:
This routing is used among the autonomous networks and it includes Path Vector Routing(PVR).
Path Vector Routing:
- Path vector routing uses path vectors for routing.
- Border Gateway Protocol(BGP) is used in PVR for making routing decisions.
Types of Routing Protocol
Intra domain Routing Protocols:
This routing is used within the autonomous networks and it includes two types of routing: Distance Vector Routing(DVR) and Link State Routing(LSR).
Distance Vector Routing:
- Distance vector routing uses distance vectors for routing.
- It uses the Bellman-Ford algorithm for the computation of various distances.
- Routing Information Protocol(RIP) is used in DVR for making routing decisions.
- DVR suffers from count to infinity problem which can be solved using split-horizon or route poisoning.
Link State Routing:
- Link State routing uses the state of the link for routing.
- It uses the Dijkstra algorithm for the computation of various distances.
- Open Shortest Path First(OSPF) is used in LSR for making routing decisions.
- LSR suffers from heavy traffic due to flooding which can be solved by the TTL field.