IP ROUTING IN NETWORK: RIP , IGRP
Introduction:
- IP Routing is an umbrella term for the set of protocols that determine the path that data follows in order to travel across multiple networks from its source to its destination.
- IP routing is the process of sending packets from a host on one network to another host on another, remote network. This process is done by routers.
- Routers examine the destination IP address of a packet , determine the next-hop address, and forward the packet.
- Routers use routing tables to determine a next hop address to which the packet should be forwarded.
IP Routing Process:
- When an IP packet is to be forwarded, a router uses its forwarding table to determine the next hop for the packet's destination (based on the destination IP address in the IP packet header), and forwards the packet appropriately.
- The next router then repeats this process using its own forwarding table, and so on until the packet reaches its destination. At each stage, the IP address in the packet header is sufficient information to determine the next hop; no additional protocol headers are required.
- There are many types of routing protocols.
- Routing Information Protocols(RIP)
- Interior Gateway Protocol (IGRP)
- Open Shortest Path First (OSPF)
- Exterior Gateway Protocol (EGP)
- Enhanced interior gateway routing protocol (EIGRP)
- Border Gateway Protocol (BGP)
- Intermediate System-to-Intermediate System (IS-IS
RIP (Routing Information Protocol):
- RIP (Routing Information Protocol) is a forceful protocol type used in local area network and wide area network.
- RIP (Routing Information Protocol) type is categorized interior gateway protocol within the use of distance vector algorithm.
- RIP (Routing Information Protocol) is one of the oldest distance vector routing protocols. It is usually used in small networks.
- RIP is very simple to configure and maintain, but lacks some advanced features of routing protocols like OSPF or EIGRP.
- Two versions of the protocol exists: version 1 and version 2. Both versions use hop count as a metric and have the administrative distance of 120.
- RIP version 2 is capable of advertising subnet masks and uses multicast to send routing updates, while version 1 doesn’t advertises subnet masks and uses broadcast for updates. Version 2 is backwards compatible with version 1.
- RIPv2 sends the entire routing table every 30 seconds, which can consume a lot of bandwidth. RIPv2 uses multicast address of 224.0.0.9 to send routing updates, supports authentication and triggered updates (updates that are sent when a change in the network occurs).
For example of how RIP works, consider the
following figure.
- Router R1 directly connects to the subnet 10.0.0.0/24. Network engineer has configured RIP on R1 to advertise this route. R1 sends routing updates to R2 and R3. The routing updates list the subnet, subnet mask and metric for this route. Each router, R2 and R3, receives this update and adds the route to their respective routing tables. Both routers list the metric of 1 because the network is only one hop away.
- TIP – maximum hop count for a RIP route is 15. Any route with a higher hop count is considered to be unreachable.
Interior Gateway Routing Protocol (IGRP)
- It is distance vector IGRP (Interior gateway Protocol) make-believe by Cisco.
- Router used it to exchange routing data within an independent system.
- Interior gateway routing protocol created in part to defeat the confines of RIP (Routing Information Protocol) in large networks.
- It maintains multiple metrics for each route as well as reliability, MTU, delay load, and bandwidth.
- The maximum hop of EIGRP is 255 and routing updates are transmitting 90 seconds. It measured in classful routing protocol, but it is less popular because of wasteful of IP address space.
