IGRP (Interior Gateway Routing Protocol) is a Cisco proprietary distance vector protocol that improves upon RIP by allowing a maximum hop count of 100, addressing the limitation of 15 hops in RIP. It utilizes four timers to regulate performance, including a 90-second route update timer and a 230-second route invalid timer. IGRP focuses on metrics such as bandwidth, load, delay, reliability, and MTU to determine the best routing paths, and it is configured by specifying directly connected networks.

1. Distance vector/
90 seconds update/
100 hop counts

2. IGRP:Interior gateway routing protocol
IGRP is the cisco proprietary protocol discovered
by the cisco to overcome the problems of the RIP.
Means the network must have all cisco routers.
It is a Distance vector protocol.
IGRP is
better then the rip because it has maximum hop
count 100 as compared to the rip so the problem
of only 15 hops is resolved.
it also use
different matrix then the rip.
i.e. Bandwidth
load
delay
reliability
MTU

3. IGRP uses four types of the timers to regulate its
performance.
1.Route update timer = 90 sec
2.Route invalid timer = 230 sec
3.Holddown timer = 630 sec
4.Route flush timer = 280 sec
IGRP TIMERS

4. IGRP TIMERS
1. Route update timer:-
it is typically 30
seconds in which a router sends a complete
copy of the routing table to all neighbors.
2. Route invalid timer:-
when there is
network failure and a router didn`t get any
update about that network for 230 seconds
the router will send update to all neighbors
about the failure of that network.

5. IGRP TIMERS
3.Holddown timer:-
The routing update
table received is only store/ hold till the
hold-down timer which is 630 seconds.
means there is any routing update table
received for any route and after that for 630
seconds there is no any other update
received from that side then the table will be
discard.

6. IGRP TIMERS
4.Route flush timer:-
it is the time 280 sec
after which a route is considered as a invalid
route and the routing information about
that route is removed from the routing table
and the information is updated to the all
neighbor routers before the local routing
table is updated.

7. RIP IGRP
1.Distance vector 1.Distance vector
2.Max hop count=15 2.Max hop count=100
3.Classfull +classless 3. classless
4. No Autonomous 4.use autonomous
system number
5.FLSM+VLSM 5.FLSM
6. AD=120 6.AD=100

8. IGRP METRIX`s
1.Bandwidth:- it is the speed of link a route with
higher bandwidth is preferred always.
2. Load:- it is the amount of traffic present in the route
(minimum load maximum output). So any route with
minimum load is always used for data sending.
3. Delay :- it is the time latency between the data is
send by the sender and received by the destination.
4. Reliability :- it can find maximum 6 routes for the
destination to deliver the data packet.
5. MTU :- Maximum Transmission Units.

9. IGRP scenario

10. Example of configuring
igrp

11. Configuring the IGRP routing
To configure the IGRP routing the {ROUTER IGRP AS no.}
command is used. And we just have to mention the
directly connected networks with the router only.
Job of the IGRP is to automatically find out the all other
networks and advertise the its connecting networks to all
the connected neighbors. IGRP is classfull because the
subnet mask in all the networks is same.

12. Configure RIPv1
On router A
Router_A#config t
Router_A(config)# router igrp 10
Router_A(config)# network 10.0.0.0
Router_A(config)# network 11.0.0.0
Router_A(config)#exit
Router_A#wr
On router B
Router_B#config t
Router_B(config)# router igrp 10
Router_B(config)# network 12.0.0.0
Router_B(config)# network 11.0.0.0
Router_B(config)#exit
Router_B#wr

13. Verify IGRP
In each routers routing table there must be a
route for the directly connected networks as well
as routes from the directly connected neighbors.
To verify
Router_A# show ip route
Router_A# show ip protocols

14. IGRP
OVER