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RIP (Routing Information Protocol)

RIP (Routing Information Protocol)

It is an open standard, distance vector, classfull routing protocol. Rip version 2 supports classless.

It sends the complete routing table out to all active interfaces every 30 seconds. Rip only uses hop count to determine the best way to a remote network, but it has a maximum allowable hop count of 15 by default, meaning that 16 is deemed unreachable. RIP works well in small networks, but it’s inefficient on large networks with slow WAN links or on networks with a large number of routers installed.

RIP version 1, uses only classfull routing. This means that all devices in the network must use the same subne mask. This is because RIP version 1 doesn’t send updates with subnet mask information in tow.

RIP version 2, provides something called prefix routing, and does send subnet mask information with the route updates. This is called Classless Routing.

  • It broadcasts routing updates to its neighbor router using ip
  • Multicast Address-
  • It forward updates periodically and sends complete routing table to each active interface.
  • Update timer is 30 sec.
  • Invalid timer is 180 sec.
  • Hold down timer is 180 sec.
  • Flush timer is 240 sec.
  • Metric – Hop count
  • Max Hop count – 15
  • By default Max-path 4 (1 to 16)
  • AD – 120
  • It performs automatic route summarization with default subnet mask.
  • It doesn’t support manual summarization.
  • It doesn’t support manual route summarization.
  • It support equal cost load balancing.
  • It use bellman-ford Algorithm
  • It use UDP port number 520
  • RIP is an Application Layer Protocol.
  • RIP Version 1 – Classfull, RIP Version 2 Classless
  • RIP Version 1 doesn’t support Authentication but RIP Version 2 Supports MD5 authentication.
  • The Network command tells the routing protocol which network to advertise.

Split-Horizon: A method of preventing routing loops in distance-vector routing protocols by prohibiting a router from advertising a route back onto the interface from which it was learned.

Route Poisoning: Route poisoning is a method of preventing a network from sending packets through a route that has become invalid. When the routing protocol detects an invalid route (such as can be caused by a severed cable or the failure of a network node), all of the routers in the network are informed that the bad route has a hop count of 16, which stands for infinity. This makes all nodes on the invalid route appear infinitely distant, thereby preventing any of the routers from sending packets over the invalid route.

Updates: Updates are sent every 30 seconds by default to the address

Invalid Timer: Invalid timer means a timer which starts when a router didn’t receive an update about a route in a specified time.

Holddown: The timer for holddown will be activated when the route goes into an invalid state. This is set to 180 by default.

Flush: This timer is set to 240 seconds, when a route is 240 seconds old it is flushed from the routing table.

Differences between Rip v1 and Rip v2

Rip version 1 Rip version 2
Updates Broadcast No
Multicast (No) Yes (
Classfull Classless
Manual summary (No) Yes
Authentication (No) Yes


RIP Example
RIP Example

Assign ip add on required interfaces

Router (config) #host r1
r1 (config) #no ip domain look up
r1 (config) #line con 0
r1 (config) #logg syn
r1 (config) #exec-t 0 0
r1 (config) #int fa0/0
r1 (config-if) #ip add
r1 (config-if) #no shut
r1 (config-if) #int s0/0
r1 (config-if) #ip add
r1 (config-if) #no shut

Router (config) #host r2
r2 (config) #no ip domain look up
r2 (config) #line con 0
r2 (config) #logg syn
r2 (config) #exec-t 0 0
r2 (config) #int fa0/0
r2 (config-if) #ip add
r2 (config-if) #no shut
r2 (config-if) #int s0/0
r2 (config-if) #ip add
r2 (config-if) #no shut
r2 (config-if) #int s0/1
r2 (config-if) #ip add
r2 (config-if) #no shut

Router (config) #host r3
r3 (config) #no ip domain look up
r3 (config) #line con 0
r3 (config) #logg syn
r3 (config) #exec-t 0 0
r3 (config) #int fa0/0
r3 (config-if) #ip add
r3 (config-if) #no shut
r3 (config-if) #int s0/0
r3 (config-if) #ip add
r3 (config-if) #no shut

Now here we will configure RIP Version 2

r1 (config) #router rip
r1 (config-router) #version 2
r1 (config-router) #network
r1 (config-router) #network
r1 (config-router) #no auto summary
r1 (config-router) #passive interface fa0/0

r2 (config) #router rip
r2 (config-router) #version 2
r2 (config-router) #network
r2 (config-router) #network
r2 (config-router) #network
r2 (config-router) #no auto summary
r2 (config-router) #passive interface fa0/0

r3 (config) #router rip
r3 (config-router) #version 2
r3 (config-router) #network
r3 (config-router) #network
r3 (config-router) #no auto summary
r3 (config-router) #passive interface fa0/0

To advertise all connected interfaces we use this command also

Router (config) #router rip
Router (config-router) Network

To check all the route

Router#show ip route

To check the internal rip events

Router#debug ip rip

To turn off this command

Router#undebug all

To stop automatic Summarization

Router (config) #router rip
Router (config-router) #no auto summary

To check the RIP Timers

Router#show ip protocols

To stop update on LAN

Router (config) #router rip
Router (config-router) #passive interface fa0/0

To clear the ip route

Router#clear ip route *

To check the load balancing

(To discover the path of a packet)

To change the Rip Timers

Router (config) #router rip
Router (config-router) # timers basic 10 10 10 10

(Timers basic update invalid hold flush)

To change the maximum path value

Router (config) # router rip
Router (config-router) #maximum path 10

To change the AD value

Router (config) # router rip
Router (config-router) #distance 100

IP Rip authentication

We will run this command on each routers serial interface one which we want to implement authentication.

Router (config) #key chain Mani
Router (config-keychain) #key?
<0-2147483647> key identifier
Router (config-keychain) #key 5
Router (config-keychain-key) #key-string cisco

Remember that, Key number and key string must match on both routers. But we can use key chain name different. Now we will implement this authentication on the serial interface.

Router (config) #int s0/0
Router (config-if) #Ip rip authentication mode md5
Router (config-if) #ip rip authentication key-chain Mani

Mannual route summarization

We will create some loopback on first router

r1 (config) # int loo 1
r1 (config-if) # ip add
r1 (config-if) # int loo 2
r1 (config-if) # ip add
r1 (config-if) # int loo 3
r1 (config-if) # ip add
r1 (config-if) # int loo 4
r1 (config-if) # ip add
r1 (config-if) # int loo 5
r1 (config-if) #ip add

Now here we will advertise all the routes via this command

r1 (config-router) # network

This command would advertise all the loopback interfaces to another router. We will create some loopback on second router

r2 (config) # int loo 1
r2 (config-if) # ip add
r2 (config-if) # int loo 2
r2 (config-if) # ip add
r2 (config-if) # int loo 3
r2 (config-if) # ip add
r2 (config-if) # int loo 4
r2 (config-if) # ip add
r2 (config-if) # int loo 5
r2 (config-if) # ip add

Now here we will advertise all the routes via this command

r2 (config-router) # network

This command would advertise all the loopback interfaces to another router.We will create some loopback on third router

r3 (config) # int loo 1
r3 (config-if) # ip add
r3 (config-if) # int loo 2
r3 (config-if) # ip add
r3 (config-if) # int loo 3
r3 (config-if) # ip add
r3 (config-if) #int loo 4
r3 (config-if) # ip add
r3 (config-if) # int loo 5
r3 (config-if) # ip add

r3 (config-router) #network

This command would advertise all the loopback interfaces to another router. Now here, once we advertise all the routes then routing table become larger. It would use more processor and memory of router.

To reduce the load of router here we will create manual route summarization

r1 (config) #int s0/0
r1 (config-if) #ip summary-address rip
r1 (config) #int s0/1
r1 (config-if) #ip summary-address rip

Now we can check the routes of r1 on another router

r2#clear ip route*
r2#sh ip route


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