Introduction to RIP routing (Free Preview)

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RIP is a distance vector routing protocol that is suitable for small scale networks. It is a dynamic routing protocol that is very easy to configure.

Metric

  • Uses hop count as the only metric.
  • Each hop in the path is assigned a value of 1. When a routing advertisement is received for a destination network, the router adds 1 to the metric value specified in the advertisement and specifies the sender as the next-hop.
  • A directly connected network metric = 0.
  • Maximum hop count is 15.
  • Unreachable network metric = 16.

 

Timers

 

Timer Meaning
route update timer (30s) ·        Updates are sent every 30 seconds and when there are topology changes.

·        Sends a complete copy of the routing table.

 

Invalid after timer (180s) ·        Length of time that must pass before concluding a route is invalid.

·        By default, it’s 180 seconds.

Hold down timer (180s) ·        This is the amount of time a route is suppressed.

·        This occurs when an update is received for a particular route stating it is unreachable.

·        This continues until the hold down timer expires or an update with a route for better metric is received.

·        The default is 180 seconds.

Flushed after timer (240s) ·        This is the time between a route becoming invalid and its removal from the routing table.

·        If there is still no update after 240 seconds, the receiving router removes all routing table entries for the neighbouring router that failed to send an update.

·        The route flush timer must be greater than the value of route invalid timer.

·        The default is 240 seconds.

 

Table RIP Timers

 

 

 

How to configure RIPv1

 

SUMMARY STEPS

  1. enable

!— Enters the Privileged EXEC mode !—

  1. configure terminal

!— Enters global configuration mode. !—

  1. router rip

!— Enables a RIP routing process and enters router configuration mode —!

  1. network ip-address

!— Associates a network interface with a RIP routing process. RIP is a classful routing protocol. The network need to be followed by a classful IP address. For example, let’s assume, the router interface Fa0/1 is configured with 10.10.10.1/24 subnet IPv4 address. Then the network statement would be “network 10.0.0.0” to enable advertising 10.10.10.0/24 and to include the interface Fa0/1 in the RIP routing process. —!

  1. end

!—  Exits router configuration mode and returns to privileged EXEC mode. —!

 

R1#
R1#conf t
R1(config)#router rip
R1(config-router)#network 10.0.0.0

How to suppress RIP routing update propagation

 

When you do not want to propagation of RIP messages out a particular interface we can use the passive-interface command to suppress the rip process on that interface.

 

R1(config)#router rip

R1(config-router)#network 192.168.40.0

R1(config-router)#passive-interface fa0/0
!--- Stops propagation of RIP on the interface Fa0/0 ---!
R1(config-router)#

 

RIP Version 2 (RIPv2)

 

  • Classless
  • Supports VLSM
  • Supports MD5 authentication
  • Supports discontiguous networks
  • Unlike RIPv1 uses multicast (224.0.0.9) updates.

 

RIPv1 RIPv2
Distance Vector Distance Vector
Maximum hop count is 15 Maximum hop count is 15
Classful Classless
Broadcast Updates Multicast Updates
No VLSM support VLSM support
No authentication support MD5 authentication support
No support for discontiguous networks Support for discontiguous networks

Table RIPv1 & RIPv2 Comparison

 

How to configure RIPv2

 

SUMMARY STEPS

  1. enable

!— Enters the Privileged EXEC mode —!

  1. configure terminal

!— Enters global configuration mode. !—

  1. router rip

!— Enables a RIP routing process and enters router configuration mode —!

  1. version 2

!— Enables RIPv2 routing on the router —!

  1. network ip-address

!— Associates a network interface with a RIP routing process. RIP is a classful routing protocol. The network need to be followed by a classful IP address. For example, let’s assume, the router Fa0/1 interface is configured with 10.10.10.1/24 subnet IPv4 address. Then the network statement would be “network 10.0.0.0” to enable advertising 10.10.10.0/24 and to include the interface Fa0/1 in the RIP routing process. —!

  1. end

!— Exits router configuration mode and returns to privileged EXEC mode. —!

 

R1#
R1#conf t
R1(config)#router rip
R1(config-router)#network 10.0.0.0
R1(config-router)#version 2

How to Verify RIP routing

  • show ip route
  • show ip protocols
  • debug ip rip
Lesson tags: CCNA, Cisco, RIP, Routing
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