Interior Gateway Routing Protocol (IGRP) is a proprietary distance-vector routing protocol developed by Cisco that is used within an autonomous system to exchange routing information. The document describes IGRP configuration and operation, including setting the autonomous system number, configuring IGRP on routers, and verifying IGRP routes and neighbor adjacencies. Key aspects of IGRP covered are metrics, timers, and network diagrams demonstrating IGRP configuration between three routers to exchange routes.

1. 1

2. Interior Gateway Routing Protocol
• Cisco proprietary protocol
• Classful routing protocol
• Updates are broadcasted via 255.255.255.255
• Administrative distance is 100
• Metric (24 bit) : Composite Metric
(BW+Delay+Load+MTU+Reliability)
• Max Hop count is 255 (100 is default)
• Load balancing of 6 equal or unequal paths
• Used for large organizations
2

3. IGRP Timers
• Update timer : 90 sec
• Invalid timer : 270 sec
• Flush timer : 630 sec
• Holddown timer : 280 sec
3

4. Autonomous System Number
• A unique number identifying the Routing domain of
the routers.
Ranges from 1- 65535
Public – 1 – 64512
Private – 64513 – 65535
•
An autonomous system is a collection of networks
under a common administrative domain
4

5. Routing Protocol Classification
IGP
• Interior Gateway
Protocol
• Routing protocols used
EGP
• Exterior Gateway
Protocol
• Routing protocol used
within an autonomous
between different
system
autonomous systems
• All routers will be
routing within the
same Autonomous
boundary
• RIP, IGRP, EIGRP,
OSPF, IS-IS
• Routers in different AS
need an EGP
• Border Gateway
Protocol is extensively
used as EGP
5

6. IGP & EGP
IGPs: RIP, OSPF,
IGRP, EIGRP
XYZ - AS 100
EGPs: BGP
IGPs: RIP, OSPF,
IGRP, EIGRP
ABC – AS 200
– IGPs operate within an autonomous system
– EGPs connect different autonomous systems
6

7. IGRP - Network Diagram
10.0.0.1/8
S0
HYD
11.0.0.1/8
S0
S1
10.0.0.2/8
E0
192.168.1.150/24
LAN - 192.168.1.0/24
CHE
S1
11.0.0.2/8
E0
192.168.2.150/24
LAN - 192.168.2.0/24
BAN
E0
192.168.3.150/2
LAN - 192.168.3.0/24
7

8. Disadvantages of IGRP
• Only works on Cisco Routers
• Slow convergence
• Formation of Routing loops
8

9. 9

10. Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.
C:> telnet 192.168.1.150
Connecting .....
================================
Welcome to Hyderabad Router
================================
User Access Verification
password : ****
Directly Connected Networks on
Directly Connected Networks on
Hyderabad> enable
HYDERABAD Router
password : ****
HYDERABAD Router
Hyderabad# configure terminal
192.168.1.0
192.168.1.0
Enter configuration commands, one per line. End with CNTL/Z.
10.0.0.0
10.0.0.0
Hyderabad(config)# interface serial 0
Hyderabad(config-if)# ip address 10.0.0.1 255.0.0.0
Hyderabad(config-if)# no shut
Hyderabad(config-if)# clockrate 64000
Hyderabad(config-if)# encapsulation hdlc
Hyderabad(config-if)# exit
Hyderabad(config)#
10

11. Hyderabad(config)# no ip routing
Hyderabad(config)# ip routing
Hyderabad(config)# router igrp 5
Hyderabad(config-router)# network 192.168.1.0
Hyderabad(config-router)# network 10.0.0.0
Hyderabad(config-router)#
Configuring IGRP
Configuring IGRP
Router(config)# router igrp <as no>
Router(config)# router igrp <as no>
Router(config-router)# network <Network ID>
Router(config-router)# network <Network ID>
11

12. Hyderabad(config)# no ip routing
Hyderabad(config)# ip routing
Hyderabad(config)# router igrp 5
Hyderabad(config-router)# network 192.168.1.0
Hyderabad(config-router)# network 10.0.0.0
Hyderabad(config-router)# ^Z
Hyderabad# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i- IS-IS, L1-IS-IS level-1, L2-IS-IS level-2,*- candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
C
10.0.0.0/8 is directly connected, Serial0
I
11.0.0.0/8 [100/10476] via 10.0.0.2, 00:00:18, Serial0
C
192.168.1.0/24 is directly connected, Ethernet0
I
192.168.2.0/24 [100/8576] viaIGRP
Metric of but
100 isMetricof but
100 isnothing IGRP
nothing 10.0.0.2, 00:00:18, Serial0
I – for IGRP routes
Administrative via Metric
I I – for IGRP routes
192.168.3.0/24 [100/10576] Distance
Composite Metric
Administrative Distance
Composite 10.0.0.2, 00:00:18, Serial0
Hyderabad#
12

13. Hyderabad# show ip protocols
Routing Protocol is "igrp 5"
Sending updates every 90 seconds, next due in 49 seconds
Invalid after 270 seconds, hold down 280, flushed after 630
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
IGRP maximum hopcount 100
IGRP maximum metric variance 1
Redistributing: igrp 5
Routing for Networks:
192.168.1.0
10.0.0.0
Routing Information Sources:
Gateway
Distance
Last Update
10.0.0.2
100
00:01:10
Distance: (default is 100)
Hyderabad#
13

14. Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.
C:> telnet 192.168.2.150
Connecting .....
================================
Welcome to Chennai Router
================================
User Access Verification
password : ****
Directly Connected Networks on
Chennai> enable Directly Connected Networks on
CHENNAI Router
password : ****
CHENNAI Router
Chennai# configure terminal
192.168.2.0
192.168.2.0
Enter configuration commands, one per line. End with CNTL/Z.
10.0.0.0
10.0.0.0
Chennai(config)# interface serial 1
11.0.0.0
11.0.0.0
Chennai(config-if)# ip address 10.0.0.2 255.0.0.0
Chennai(config-if)# no shut
Chennai(config-if)# encapsulation hdlc
Chennai(config-if)# interface serial 0
Chennai(config-if)# ip address 11.0.0.1 255.0.0.0
Chennai(config-if)# no shut
Chennai(config-if)# encapsulation hdlc
14

15. Chennai(config)# no ip routing
Chennai(config)# ip routing
Chennai(config)# router igrp 5
Chennai(config-router)# network 192.168.2.0
Chennai(config-router)# network 10.0.0.0
Chennai(config-router)# network 11.0.0.0
Configuring IGRP
Configuring IGRP
Chennai(config-router)#
Router(config)# router igrp <as no>
Router(config)# router igrp <as no>
Router(config-router)# network <Network ID>
Router(config-router)# network <Network ID>
15

16. Chennai(config)# no ip routing
Chennai(config)# ip routing
Chennai(config)# router igrp 5
Chennai(config-router)# network 192.168.2.0
Chennai(config-router)# network 10.0.0.0
Chennai(config-router)# network 11.0.0.0
^
Chennai(config-router)# Z
Chennai# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i- IS-IS, L1-IS-IS level-1, L2-IS-IS level-2,*- candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
C
10.0.0.0/8 is directly connected, Serial1
C
11.0.0.0/8 is directly connected, Serial0
I
192.168.1.0/24 [100/8576] via 10.0.0.1, 00:00:28, Serial1
C
192.168.2.0/24 is directly connected, Ethernet0
I
192.168.3.0/24 [100/8576]Metricof IGRP 00:00:54, Serial0
Metric of IGRP
100 is nothing but
100 is via 11.0.0.2,
nothing but
I – for IGRP routes
I – for IGRP routes Administrative Distance
Chennai#
Composite Metric
Administrative Distance
Composite Metric 16

17. Chennai# show ip protocols
Routing Protocol is "igrp 5"
Sending updates every 90 seconds, next due in 56 seconds
Invalid after 270 seconds, hold down 280, flushed after 630
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
IGRP maximum hopcount 100
IGRP maximum metric variance 1
Redistributing: igrp 5
Routing for Networks:
10.0.0.0
11.0.0.0
192.168.2.0
Routing Information Sources:
Gateway
Distance
Last Update
11.0.0.2
100
00:00:22
10.0.0.1
100
00:00:59
Distance: (default is 100)
Chennai#
17

18. Microsoft Windows 2000 [Version 5.00.2195]
(C) Copyright 1985-2000 Microsoft Corp.
C:> telnet 192.168.3.150
Connecting .....
================================
Welcome to Banglore Router
================================
User Access Verification
password : ****
Directly Connected Networks on
Banglore> enableDirectly Connected Networks on
Banglore Router
password : ****
Banglore Router
Banglore# configure terminal
192.168.3.0
192.168.3.0
Enter configuration commands, one per line. End with CNTL/Z.
11.0.0.0
11.0.0.0
Banglore(config)# interface serial 1
Banglore(config-if)# ip address 11.0.0.2 255.0.0.0
Banglore(config-if)# no shut
Banglore(config-if)# clockrate 64000
Banglore(config-if)# encapsulation hdlc
Banglore(config-if)# exit
Banglore(config)#
18

19. Banglore(config)# no ip routing
Banglore(config)# ip routing
Banglore(config)# router igrp 5
Banglore(config-router)# network 192.168.3.0
Banglore(config-router)# network 11.0.0.0
Banglore(config-router)#
Configuring IGRP
Configuring IGRP
Router(config)# router igrp <as no>
Router(config)# router igrp <as no>
Router(config-router)# network <Network ID>
Router(config-router)# network <Network ID>
19

20. Banglore(config)# no ip routing
Banglore(config)# ip routing
Banglore(config)# router igrp 5
Banglore(config-router)# network 192.168.3.0
Banglore(config-router)# network 11.0.0.0
Banglore(config-router)# ^Z
Banglore# show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i- IS-IS, L1-IS-IS level-1, L2-IS-IS level-2,*- candidate default
U - per-user static route, o - ODR
Gateway of last resort is not set
I
10.0.0.0/8 [100/10476] via 11.0.0.1, 00:00:01, Serial1
C
11.0.0.0/8 is directly connected, Serial1
I
192.168.1.0/24 [100/10576] of IGRP
11.0.0.1, 00:00:01, Serial1
Metric of IGRP
100 isMetric viabut
100 isnothing but
nothing
I –for IGRP routes
for IGRP routes
I I –192.168.2.0/24 [100/8576] via Metric
Administrative Distance
Composite 11.0.0.1, 00:00:01, Serial1
Administrative Distance
Composite Metric
C
192.168.3.0/24 is directly connected, Ethernet0
Banglore#
20

21. Banglore# show ip protocols
Sending updates every 90 seconds, next due in 11 seconds
Invalid after 270 seconds, hold down 280, flushed after 630
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
IGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
IGRP maximum hopcount 100
IGRP maximum metric variance 1
Redistributing: igrp 5
Routing for Networks:
192.168.3.0
11.0.0.0
Routing Information Sources:
Gateway
Distance
Last Update
11.0.0.1
100
00:01:02
Distance: (default is 100)
Banglore#
21

22. Hyderabad# ping 192.168.3.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Hyderabad# ping 192.168.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Hyderabad#
22

23. Chennai# ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Chennai# ping 192.168.3.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Chennai#
23

24. Banglore# ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Banglore# ping 192.168.2.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms
Banglore#
24