Routing Information Protocol (RIP) for IT PH-II

Routing Information Protocol (RIP)

• A distance vector protocol that measures the distance to reach a remote network by calculating hop count.
• Uses Bellman Ford algorithm to find the best route.
• A type of Interior Gateway Protocol (IGP) that works within an Autonomous System (AS).

Characteristics & Features of RIP

• RIP is a distance vector routing protocol.
• It is an IGP that works within an AS.
• Administrative distance of RIP is 120.
• Supports classless routing and VLSM (RIPv2).
• Uses metric – hop count to decide the best path to reach a destination.
• Sends periodic update messages to next RIP routers.
• Entire routing table is sent each time.
• Maximum number of hops supported by RIP is 15.
• A route with a hop count of 16 is considered an invalid route.
• A RIP update message can carry a maximum of 25 routes.

RIP Timers

• Update interval: 30 sec (routing updates are scheduled).
• Invalid timer: 180 sec (after last update, route is marked as invalid).
• Hold down timer: 180 sec (new routes are on hold).
• Flush timer: 240 sec (route is deleted).

How RIP Works

• RIP routers send their entire routing table contents to neighbor routers periodically.
• The receiving router processes the route announcements and updates its routing table if needed.

RIPv1 vs RIPv2

• RIPv1 sends entire routing table contents as broadcast messages periodically.
• RIPv1 does not support VLSM.
• RIPv2 sends entire routing table contents using multicast address 224.0.0.9.
• RIPv2 supports VLSM and routing announcements contain subnet mask details.
• RIPv2 does automatic network address summarization.

Configuring RIP

• Enable RIP by using the ROUTER RIP command.
• Disable RIPv1 and enable RIPv2 using the VERSION 2 command under RIP.
• Advertise directly connected networks as classful numbers.
• Repeat steps for all routers.

RIP Configuration Commands

• ROUTER RIP: Enables RIP protocol.
• VERSION 2: Enables RIPv2.
• NETWORK: Makes RIP advertise the network.
• SHOW IP PROTOCOLS: Displays routing protocols running on a router.
• SHOW IP ROUTE: Lists out routing table contents.

Routing Protocols

• Routing protocols exchange network information differently, based on their properties:
  • Which routers they share information with?
  • How frequently they exchange routing updates?
  • What content they exchange?

Classification of Routing Protocols

• Routing protocols can be classified into two categories:
  • Interior Gateway Protocols (IGP)
  • Exterior Gateway Protocols (EGP)

Autonomous System

• An Autonomous System (AS) is a collection of connected IP routing prefixes and their routers, controlled by a single administration that follows a defined routing policy.

Interior Gateway Protocols

• IGP is a routing protocol used to exchange routing information within routers of an AS.
• Examples of IGP include RIP, OSPF, and EIGRP.

Exterior Gateway Protocols

• EGP is a routing protocol that exchanges routing information between different AS.
• Example of EGP is BGP.

Routing Information Protocol (RIP)

• RIP is a distance vector protocol that measures the distance to reach a remote network by calculating hop count.
• RIP characteristics:
  • Uses hop count as its primary metric.
  • Is an IGP.
  • Has an administrative distance of 120.
  • Supports classless routing and VLSM (RIPv2).
  • Uses metric – hop count to decide best path to reach a destination.
  • Sends periodic update messages to next RIP routers.
  • Entire routing table is sent each time.
  • Maximum number of hops supported by RIP is 15.

RIP Timers

• RIP timers:
  • Update interval: 30 seconds
  • Invalid timer: 180 seconds
  • Hold down timer: 180 seconds
  • Flush timer: 240 seconds

How RIP Works

• RIP routers send their entire routing table contents to neighbor routers periodically.
• The receiving router processes the route announcements and updates its routing table if needed.
• This process repeats for all routers periodically.

RIP Configuration

• Steps to configure RIPv2:
  • Enable RIP on each router.
  • Disable RIPv1 and enable RIPv2.
  • Advertise directly connected networks as classful numbers.
  • Repeat steps for all routers.

RIP Configuration Commands

• Basic RIP configuration commands:
  • ROUTER RIP: Enables RIP protocol.
  • VERSION 2: Enables RIPv2.
  • NETWORK: Advertises the network.
  • SHOW IP PROTOCOLS: Displays routing protocols running on a router.
  • SHOW IP ROUTE: Lists out routing table contents.

RIP Features

• RIP is easy to implement and suitable for small networks.
• RIP has little overhead regarding used bandwidth, configuration time, and management time.
• RIP maintains only a single table – routing table.

Comparison of RIPV1 and RIPV2

• RIPv1:
  • Supports classful routing.
  • Only supports FLSM.
  • Does not carry subnet mask in route update messages.
  • Route updates are sent as broadcast messages.
  • Auto summarizes routes across major network boundaries.
• RIPv2:
  • Supports classless routing.
  • Supports FLSM and VLSM.
  • Carries subnet mask in route update messages.
  • Route updates are sent as multicast messages.
  • Supports manual route summarization.
  • Supports protocol authentication between RIPv2 routers.

RIP Metric

• RIP metric calculation:
  • Hop count refers to the number of routers a packet has to pass through to reach the destination network.

RIP Characteristics and Features

• RIP is a distance vector routing protocol.
• RIP is an IGP.
• RIP uses Bellman-Ford algorithm to find the best route.
• RIP supports equal cost load balancing by default.
• RIP supports both manual and automatic route summarization (across major networks).