© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-2
ObjectivesObjectives
Upon completion of this chapter, you will be able to complete the following tasks:• Distinguish the use and operation of static and
dynamic routes
• Configure and verify a static route
• Identify how distance vector IP routing protocols such as RIP and IGRP operate on Cisco routers
• Enable Routing Information Protocol (RIP)
• Enable Interior Gateway Routing Protocol (IGRP)
• Verify IP routing with show and debug commands
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-3
To route a router need to know:• Destination addresses
• Sources it can learn from
• Possible routes
• Best route
• Maintain and verify routing information
What is Routing?What is Routing?
172.16.1.010.120.2.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-4
What is Routing? (cont.)What is Routing? (cont.)
NetworkProtocol
DestinationNetwork
ConnectedLearned
10.120.2.0172.16.1.0
Exit Interface
E0S0
Routed Protocol: IP
• Routers must learn destinations that are not directly connected
172.16.1.010.120.2.0
E0S0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-5
Static Route
Uses a route that a network administrator enters into the router manually
Dynamic Route
Uses a route that a network routing protocol adjusts automatically for topology or traffic changes
Identifying Static and Dynamic Routes
Identifying Static and Dynamic Routes
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-6
172.16.2.1
SO
Static RoutesStatic Routes
172.16.1.0
B172.16.2.2
Network A
Configure unidirectional static routes to and from a stub network to allow communications to occur.
B
Stub Network
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-7
Defines a path to an IP destination network or subnet
Router(config)#ip route network [mask] {address | interface}[distance] [permanent]
Static Route ConfigurationStatic Route Configuration
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-8
Stub Network
ip route 172.16.1.0 255.255.255.0 172.16.2.1
172.16.2.1
SO
Static Route ExampleStatic Route Example
172.16.1.0
B172.16.2.2
Network A B
This is a unidirectional route. You must have a route configured in the opposite direction.
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-9
Stub Network
ip route 0.0.0.0 0.0.0.0 172.16.2.2
Default RoutesDefault Routes
172.16.2.1
SO
172.16.1.0
B172.16.2.2
Network A B
This route allows the stub network to reach all known networks beyond router A.
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-10
What is a Routing Protocol?What is a Routing Protocol?
Routing protocols are used between routers to determine paths and maintain routing tables.
Once the path is determined a router can route a routed protocol.
NetworkProtocol
DestinationNetwork
ConnectedRIP
IGRP
10.120.2.0172.16.2.0172.17.3.0
Exit Interface
E0S0S1
Routed Protocol: IPRouting protocol: RIP, IGRP
172.17.3.0
172.16.1.010.120.2.0
E0S0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-11
Autonomous System 100 Autonomous System 200
IGPs: RIP, IGRP EGPs: BGP
Autonomous Systems: Interior or Exterior Routing Protocols
Autonomous Systems: Interior or Exterior Routing Protocols
• An autonomous system is a collection of networks under a common administrative domain
• IGPs operate within an autonomous system
• EGPs connect different autonomous systems
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-12
Administrative Distance: Ranking Routes
Administrative Distance: Ranking Routes
IGRPAdministrative Distance=100
Router DRouter D
Router BRouter BRouter ARouter A
Router CRouter C
RIPAdministrative Distance=120
EE
I need to send a packet to
Network E. Both router B
and C will get it there.
Which route is best?
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-13
Classes of Routing ProtocolsClasses of Routing Protocols
Distance VectorDistance Vector
Hybrid RoutingHybrid Routing
Link StateLink StateCC
BB
AA
DD
CC
DD
BB
AA
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-14
Distance Vector Routing Protocols
Distance Vector Routing Protocols
Pass periodic copies of routing table to neighbor routers and accumulate distance vectors
CC
DD
BB
AA
CC BB AADD
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
RoutingTable
Distance—How farVector—In which direction
Distance—How farVector—In which direction
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-15
Routers discover the best path to destinations from each neighbor
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
10.2.0.010.2.0.0
10.3.0.010.3.0.0
00
00
S0
S1
Routing TableRouting Table
10.3.0.010.3.0.0 S0 00
10.4.0.010.4.0.0 E0 00
Routing TableRouting Table
10.1.0.010.1.0.0
10.2.0.010.2.0.0
E0
S0
0
0
Distance Vector—Sources of Information and Discovering Routes
Distance Vector—Sources of Information and Discovering Routes
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-16
Routers discover the best path to destinations from each neighbor
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
10.1.0.010.1.0.0
10.2.0.010.2.0.0
10.3.0.010.3.0.0
Routing TableRouting Table
10.2.0.010.2.0.0
10.3.0.010.3.0.0
10.4.0.010.4.0.0
10.1.0.010.1.0.0
00
00
11
11
S0
S1
S1
S0
Routing TableRouting Table
10.3.0.010.3.0.0 S0 00
10.4.0.010.4.0.0 E0 00
10.2.0.010.2.0.0 S0
11
E0
S0
S0 11
0
0
Distance Vector—Sources of Information and Discovering Routes
Distance Vector—Sources of Information and Discovering Routes
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-17
Distance Vector—Sources of Information and Discovering Routes
Distance Vector—Sources of Information and Discovering Routes
Routers discover the best path to destinations from each neighbor
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
10.1.0.010.1.0.0
10.2.0.010.2.0.0
10.3.0.010.3.0.0
10.4.0.010.4.0.0
Routing TableRouting Table
10.2.0.010.2.0.0
10.3.0.010.3.0.0
10.4.0.010.4.0.0
10.1.0.010.1.0.0
00
00
11
11
S0
S1
S1
S0
Routing TableRouting Table
10.3.0.010.3.0.0 S0 00
10.4.0.010.4.0.0 E0 00
10.2.0.010.2.0.0 S0
10.1.0.010.1.0.0 S0
11
22
E0
S0
S0
S0
11
22
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-18
Distance Vector—Selecting Best Route with Metrics
Distance Vector—Selecting Best Route with Metrics
Information used to select the best path for routing
56T1
56
T1Ticks, hop countTicks, hop count
B
A
Hop countHop count
IPX
RIP
IGRP
Bandwidth
Delay
Load
Reliability
MTU
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-20
Distance Vector—Maintaining Routing Information
Distance Vector—Maintaining Routing Information
Updates proceed step-by-step from router to router
AA
Process to update this
routingtable
Process to update this
routingtable
TopologyTopologychange change causescausesroutingrouting
tabletableupdateupdate
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-21
Distance Vector—Maintaining Routing Information
Distance Vector—Maintaining Routing Information
Updates proceed step-by-step from router to router
AA
Process to update this
routingtable
Process to update this
routingtable
Router A sends out this updated
routing table after the
next period expires
Topologychange causesrouting
tableupdate
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-22
Distance Vector—Maintaining Routing Information
Distance Vector—Maintaining Routing Information
Updates proceed step-by-step from router to router
AABB
Process to update this
routingtable
Process to update this
routingtable
Process to update this
routingtable
Process to update this
routingtable
Topologychange causesrouting
tableupdate
Router A sends out this updated
routing table after the
next period expires
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-23
Maintaining Routing Information Problem—Routing Loops
Maintaining Routing Information Problem—Routing Loops
Each node maintains the distance from itself to each possible destination network
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing TableRouting Table
10.3.0.0S0
E0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
0
Routing TableRouting Table
10.1.0.0E0
S0
S0
S0
11
2210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
10.2.0.0S0
S1
S1
S0
11
1110.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-24
Maintaining Routing Information Problem—Routing Loops
Maintaining Routing Information Problem—Routing Loops
Slow convergence produces inconsistent routing
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
E0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
Down
Routing TableRouting Table
10.1.0.0 E0
S0
S0
S0
11
2210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
10.2.0.0 S0
S1
S1
S0
11
1110.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-25
Router C concludes that the best path to network 10.4.0.0 is through Router B
Maintaining Routing Information Problem—Routing Loops
Maintaining Routing Information Problem—Routing Loops
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
2
Routing TableRouting Table
10.1.0.0 E0
S0
S0
S0
11
2210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
10.2.0.0 S0
S1
S1
S1
11
1110.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-26
Router A updates its table to reflect the new but erroneous hop count
Maintaining Routing Information Problem—Routing Loops
Maintaining Routing Information Problem—Routing Loops
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
S0
S0
S0
S0
11
22
10.3.0.0
10.1.0.0
10.2.0.0
10.4.0.0
0
2
Routing TableRouting Table
E0
S0
S0
S0
11
44
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
S0
S1
S1
S0
33
11
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-27
Symptom: Counting to InfinitySymptom: Counting to Infinity
• Packets for network 10.4.0.0 bounce between routers A, B, and C
• Hop count for network 10.4.0.0 counts to infinity
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
4
Routing TableRouting Table
E0
S0
S0
S0
11
66
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
S0
S1
S1
S0
55
11
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-28
Solution: Defining a MaximumSolution: Defining a Maximum
Define a limit on the number of hops to prevent infinite loops
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
16
Routing TableRouting Table
E0
S0
S0
S0
11
1616
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
S0
S1
S1
S0
1616
11
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-29
Solution: Split HorizonSolution: Split Horizon
It is never useful to send information about a route back in the direction from which the original packet came
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XXXXXX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
0
Routing TableRouting Table
E0
S0
S0
S0
11
22
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
S0
S1
S1
E1
11
22
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-30
Solution: Route PoisoningSolution: Route Poisoning
Routers set the distance of routes that have gone down to infinity
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
Infinity
Routing TableRouting Table
10.1.0.0E0
S0
S0
S0
11
2210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
10.2.0.0S0
S1
S1
E1
11
2210.1.0.0
10.4.0.0
10.3.0.0
0
0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-31
Solution: Poison ReverseSolution: Poison Reverse
Poison Reverse overrides split horizon
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Routing TableRouting Table
10.3.0.0 S0
S0
S0
S0
11
2210.1.0.0
10.2.0.0
10.4.0.0
0
Infinity
Routing TableRouting Table
10.1.0.0E0
S0
S0
S0
11
2210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing TableRouting Table
10.2.0.0S0
S1
S1
E1
PossiblyDown
PossiblyDown
2210.1.0.0
10.4.0.0
10.3.0.0
0
0
PoisonReverse
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-32
Solution: Hold-Down TimersSolution: Hold-Down Timers
Router keeps an entry for the network possibly down state, allowing time for other routers to recompute for this topology change
Network 10.4.0.0 is downthen back up
then back down
Update afterhold-down Time
Update afterhold-down Time
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
AA BB CC
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XXUpdate after
hold-down TimeUpdate after
hold-down Time
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-33
Solution: Triggered UpdatesSolution: Triggered Updates
Router sends updates when a change in its routing table occurs
AA BB CC
10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XX
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
10.1.0.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-35
Implementing Solutions in Multiple Routes
Implementing Solutions in Multiple Routes
DD
BBEE
AA
XX CC
10.4.0.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-36
Implementing Solutions in Multiple Routes (cont.)
Implementing Solutions in Multiple Routes (cont.)
DD
BBEE
AA
CCXX10.4.0.0
HolddownHolddown
HolddownHolddown
HolddownHolddown
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-37
Implementing Solutions in Multiple Routes (cont.)
Implementing Solutions in Multiple Routes (cont.)
DD
BBEE
AA
CCXX10.4.0.0
HolddownHolddown
HolddownHolddown
HolddownHolddown
Poison ReversePoison Reverse
Poison ReversePoison Reverse
Poison ReversePoison Reverse
Poison ReversePoison Reverse
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-38
Implementing Solutions in Multiple Routes (cont.)
Implementing Solutions in Multiple Routes (cont.)
DD
BBEE
AA
CCXX10.4.0.0
HolddownHolddown
HolddownHolddown
HolddownHolddown
Packet for Network 10.4.0.0
Packet for Network 10.4.0.0
Packet for Network 10.4.0.0
Packet for Network 10.4.0.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-39
Implementing Solutions in Multiple Routes (cont.)
Implementing Solutions in Multiple Routes (cont.)
DD
BBEE
AA
CCLink up!Link up!
10.4.0.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-40
Implementing Solutions in Multiple Routes (cont.)
Implementing Solutions in Multiple Routes (cont.)
DD
BBEE
AA
CCLink up!
10.4.0.0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-41
Link-State Routing ProtocolsLink-State Routing Protocols
After initial flood, pass small event-triggered link-state updates to all other routers
Link-State Packets
SPFAlgorithm
TopologicalDatabase
Shortest Path First Tree
RoutingTable
RoutingTable
CC AA
DD
BB
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-42
Share attributes of both distance-vector and link-state routing
Hybrid RoutingHybrid Routing
Choose arouting path based on distance vectors
Converge rapidly using change-based
updates
Choose arouting path based on distance vectors
Converge rapidly using change-based
updates
Balanced Hybrid RoutingBalanced Hybrid Routing
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-43
Router configuration
• Select routing protocols
• Specify networks or interfaces
Network160.89.0.0
Network 172.30.0.0
IGRP,RIP
Network 172.16.0.0
RIP
RIP
IGRP
IP Routing Configuration Tasks
IP Routing Configuration Tasks
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-44
• Defines an IP routing protocol
Router(config)#router protocol [keyword]
• Mandatory configuration command for each
IP routing process
• Identifies the physically connected network that routing updates are forwarded to
Router(config-router)#network network-number
Dynamic Routing Configuration
Dynamic Routing Configuration
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-45
19.2 kbps
T1
T1 T1
• Hop count metric selects the path
• Routes update every 30 seconds
RIP OverviewRIP Overview
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-46
•Starts the RIP routing process
Router(config)#router rip
Router(config-router)#network network-number
• Selects participating attached networks• The network number must be a major classful
network number
RIP ConfigurationRIP Configuration
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-47
2.3.0.0router ripnetwork 172.16.0.0network 10.0.0.0
RIP Configuration ExampleRIP Configuration Example
router ripnetwork 10.0.0.0
2.3.0.0router ripnetwork 192.168.1.0network 10.0.0.0
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-48
Verifying the Routing Protocol—RIP
Verifying the Routing Protocol—RIP
RouterA#sh ip protocolsRouting Protocol is "rip" Sending updates every 30 seconds, next due in 0 seconds Invalid after 180 seconds, hold down 180, flushed after 240 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is Redistributing: rip Default version control: send version 1, receive any version Interface Send Recv Key-chain Ethernet0 1 1 2 Serial2 1 1 2 Routing for Networks: 10.0.0.0 172.16.0.0 Routing Information Sources: Gateway Distance Last Update 10.1.1.2 120 00:00:10 Distance: (default is 120)
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-49
Displaying the IP Routing TableDisplaying the
IP Routing Table
RouterA#sh ip routeCodes: 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 T - traffic engineered route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnetsC 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/24 is subnetted, 2 subnetsR 10.2.2.0 [120/1] via 10.1.1.2, 00:00:07, Serial2C 10.1.1.0 is directly connected, Serial2R 192.168.1.0/24 [120/2] via 10.1.1.2, 00:00:07, Serial2
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-50
debug ip rip Commanddebug ip rip Command
RouterA#debug ip ripRIP protocol debugging is onRouterA#00:06:24: RIP: received v1 update from 10.1.1.2 on Serial200:06:24: 10.2.2.0 in 1 hops00:06:24: 192.168.1.0 in 2 hops00:06:33: RIP: sending v1 update to 255.255.255.255 via Ethernet0 (172.16.1.1)00:06:34: network 10.0.0.0, metric 100:06:34: network 192.168.1.0, metric 300:06:34: RIP: sending v1 update to 255.255.255.255 via Serial2 (10.1.1.1)00:06:34: network 172.16.0.0, metric 1
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-51
• More scalable than RIP
• Sophisticated metric
• Multiple-path support
Introduction to IGRPIntroduction to IGRP
IGRP
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-52
•Bandwidth•Delay•Reliability•Loading•MTU
19.2 kbps19.2 kbps
IGRP Composite MetricIGRP Composite Metric
Source
Destination
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-54
•Maximum six paths
•Next-hop router closer to destination
•Within metric variance
New Route
Initial Route
Source
Destination
IGRP Unequal Multiple PathsIGRP Unequal Multiple Paths
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-55
Configuring IGRPConfiguring IGRP
Router(config-router)#network network-number
• Selects participating attached networks
Router(config)#router igrp autonomous-system
• Defines IGRP as the IP routing protocol
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-56
Configuring IGRP (cont.)Configuring IGRP (cont.)
Router(config-router)#traffic-share { balanced | min }
• Control how load-balanced traffic is distributed
Router(config-router)#variance multiplier
• Control IGRP load balancing
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-57
router igrp 100network 172.16.0.0network 10.0.0.0
IGRP Configuration ExampleIGRP Configuration Example
router igrp 100network 10.0.0.0
router igrp 100network 192.168.1.0network 10.0.0.0
Autonomous System = 100
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-58
Verifying the Routing Protocol—IGRP
Verifying the Routing Protocol—IGRP
RouterA#sh ip protocolsRouting Protocol is "igrp 100" Sending updates every 90 seconds, next due in 21 seconds Invalid after 270 seconds, hold down 280, flushed after 630 Outgoing update filter list for all interfaces is Incoming update filter list for all interfaces is 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 100 Routing for Networks: 10.0.0.0 172.16.0.0 Routing Information Sources: Gateway Distance Last Update 10.1.1.2 100 00:01:01 Distance: (default is 100)
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-59
Displaying the IP Routing TableDisplaying the
IP Routing Table
RouterA#sh ip routeCodes: 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 T - traffic engineered route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnetsC 172.16.1.0 is directly connected, Ethernet0 10.0.0.0/24 is subnetted, 2 subnetsI 10.2.2.0 [100/90956] via 10.1.1.2, 00:00:23, Serial2C 10.1.1.0 is directly connected, Serial2I 192.168.1.0/24 [100/91056] via 10.1.1.2, 00:00:23, Serial2
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-60
debug ip igrp transaction Command
debug ip igrp transaction Command
RouterA#debug ip igrp transactionsIGRP protocol debugging is onRouterA#00:21:06: IGRP: sending update to 255.255.255.255 via Ethernet0 (172.16.1.1)00:21:06: network 10.0.0.0, metric=8895600:21:06: network 192.168.1.0, metric=9105600:21:07: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.1)00:21:07: network 172.16.0.0, metric=110000:21:16: IGRP: received update from 10.1.1.2 on Serial200:21:16: subnet 10.2.2.0, metric 90956 (neighbor 88956)00:21:16: network 192.168.1.0, metric 91056 (neighbor 89056)
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-61
debug ip igrp events Command
debug ip igrp events Command
RouterA#debug ip igrp eventsIGRP event debugging is onRouterA#00:23:44: IGRP: sending update to 255.255.255.255 via Ethernet0 (172.16.1.1)00:23:44: IGRP: Update contains 0 interior, 2 system, and 0 exterior routes.00:23:44: IGRP: Total routes in update: 200:23:44: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.1)00:23:45: IGRP: Update contains 0 interior, 1 system, and 0 exterior routes.00:23:45: IGRP: Total routes in update: 100:23:48: IGRP: received update from 10.1.1.2 on Serial200:23:48: IGRP: Update contains 1 interior, 1 system, and 0 exterior routes.00:23:48: IGRP: Total routes in update: 2
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-62
Updating Routing Information Example
Updating Routing Information Example
RouterA# debug ip igrp trans00:31:15: %LINEPROTO-5-UPDOWN: Line protocol on Interface Ethernet0, changed state to down00:31:15: IGRP: edition is now 300:31:15: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.1)00:31:15: network 172.16.0.0, metric=429496729500:31:16: IGRP: Update contains 0 interior, 1 system, and 0 exterior routes.00:31:16: IGRP: Total routes in update: 100:31:16: IGRP: broadcasting request on Serial200:31:16: IGRP: received update from 10.1.1.2 on Serial200:31:16: subnet 10.2.2.0, metric 90956 (neighbor 88956)00:31:16: network 172.16.0.0, metric 4294967295 (inaccessible)00:31:16: network 192.168.1.0, metric 91056 (neighbor 89056)00:31:16: IGRP: Update contains 1 interior, 2 system, and 0 exterior routes.00:31:16: IGRP: Total routes in update: 3
172.16.1.1
S2E0
S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0XX
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-63
Updating Routing Information Example (cont.)
Updating Routing Information Example (cont.)
RouterB#debug ip igrp transIGRP protocol debugging is onRouterB#1d19h: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.2)1d19h: subnet 10.2.2.0, metric=889561d19h: network 192.168.1.0, metric=890561d19h: IGRP: sending update to 255.255.255.255 via Serial3 (10.2.2.2)1d19h: subnet 10.1.1.0, metric=889561d19h: network 172.16.0.0, metric=890561d19h: IGRP: received update from 10.1.1.1 on Serial21d19h: network 172.16.0.0, metric 4294967295 (inaccessible)1d19h: IGRP: edition is now 101d19h: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.2)1d19h: subnet 10.2.2.0, metric=889561d19h: network 172.16.0.0, metric=42949672951d19h: network 192.168.1.0, metric=890561d19h: IGRP: sending update to 255.255.255.255 via Serial3 (10.2.2.2)1d19h: subnet 10.1.1.0, metric=889561d19h: network 172.16.0.0, metric=4294967295
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-64
Updating Routing Information Example (cont.)
Updating Routing Information Example (cont.)
RouterB#sh ip routeCodes: 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 T - traffic engineered route
Gateway of last resort is not set
I 172.16.0.0/16 is possibly down, routing via 10.1.1.1, Serial2 10.0.0.0/24 is subnetted, 2 subnetsC 10.1.1.0 is directly connected, Serial2C 10.2.2.0 is directly connected, Serial3I 192.168.1.0/24 [100/89056] via 10.2.2.3, 00:00:14, Serial3RouterB#ping 172.16.1.1
Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:.....Success rate is 0 percent (0/5)RouterB#
172.16.1.1
S2E0
S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0XX
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-65
Updating Routing Information Example (cont.)
Updating Routing Information Example (cont.)
172.16.1.1
S2E0 S3
192.168.1.110.1.1.1 10.2.2.210.1.1.2
S2 S3
10.2.2.3
172.16.1.0 A B C192.168.1.0
E0
RouterB#debug ip igrp transactionsRouterB#1d20h: IGRP: received update from 10.1.1.1 on Serial21d20h: network 172.16.0.0, metric 89056 (neighbor 1100)RouterB#RouterB#sh ip routeCodes: 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 T - traffic engineered route
Gateway of last resort is not set
I 172.16.0.0/16 is possibly down, routing via 10.1.1.1, Serial2 10.0.0.0/24 is subnetted, 2 subnetsC 10.1.1.0 is directly connected, Serial2C 10.2.2.0 is directly connected, Serial3I 192.168.1.0/24 [100/89056] via 10.2.2.3, 00:00:18, Serial3RouterB#ping 172.16.1.1
Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 32/38/48 ms
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-66
•With ip classless Default
•With no ip classless Drop
Router(config)#ip classless
ip classless Commandip classless Command
S0
Default route
172.16.0.0E0
10.1.0.0
NetworkProtocol
DestinationNetwork
CC
RIP
10.1.0.0 10.2.0.0172.16.0.0 via0.0.0.0
Exit Interface
E0S0S0E0
10.2.0.0
To get to 10.7.1.1:
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-67
Visual ObjectiveVisual Objective
core_ server
10.1.1.1
wg_sw_a10.2.2.11
wg_sw_l10.13.13.11
wg_pc_a10.2.2.12
wg_pc_l10.13.13.12
wg_ro_a
10.13.13.3
e0/1 e0/2
e0/2
e0/1
e0
e0
fa0/23
core_sw_a10.1.1.2
10.2.2.3
wg_ro_l
core_ro10.1.1.3
fa0/24 fa0/0
s0 10.140.1.2/24
s010.140.12.2/24
s1/0 - s2/3
10.140.1.1/24 … 10.140.12.1/24
pod ro’s s0 ro’s e0 swA 10.140.1.2 10.2.2.3 10.2.2.11B 10.140.2.2 10.3.3.3 10.3.3.11C 10.140.3.2 10.4.4.3 10.4.4.11D 10.140.4.2 10.5.5.3 10.5.5.11E 10.140.5.2 10.6.6.3 10.6.6.11F 10.140.6.2 10.7.7.3 10.7.7.11G 10.140.7.2 10.8.8.3 10.8.8.11H 10.140.8.2 10.9.9.3 10.9.9.11I 10.140.9.2 10.10.10.3 10.3.3.11J 10.140.10.2 10.11.11.3 10.11.11.11K 10.140.11.2 10.12.12.3 10.12.12.11L 10.140.12.2 10.13.13.3 10.13.13.11
RIP
RIP
...
LL
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-68
Visual ObjectiveVisual Objective
core_ server
10.1.1.1
wg_sw_a10.2.2.11
wg_sw_l10.13.13.11
wg_pc_a10.2.2.12
wg_pc_l10.13.13.12
wg_ro_a
10.13.13.3
e0/1e0/2
e0/2e0/1
e0
e0
fa0/23
core_sw_a10.1.1.2
10.2.2.3
wg_ro_l
core_ro10.1.1.3
fa0/24 fa0/0
LL
s0 10.140.1.2/24
s010.140.12.2/24
s1/0 - s2/3
10.140.1.1/24 … 10.140.12.1/24...
pod ro’s s0 ro’s e0 swA 10.140.1.2 10.2.2.3 10.2.2.11B 10.140.2.2 10.3.3.3 10.3.3.11C 10.140.3.2 10.4.4.3 10.4.4.11D 10.140.4.2 10.5.5.3 10.5.5.11E 10.140.5.2 10.6.6.3 10.6.6.11F 10.140.6.2 10.7.7.3 10.7.7.11G 10.140.7.2 10.8.8.3 10.8.8.11H 10.140.8.2 10.9.9.3 10.9.9.11I 10.140.9.2 10.10.10.3 10.3.3.11J 10.140.10.2 10.11.11.3 10.11.11.11K 10.140.11.2 10.12.12.3 10.12.12.11L 10.140.12.2 10.13.13.3 10.13.13.11
IGRP
IGRP
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-69
SummarySummary
After completing this chapter, you should be able to perform the following tasks:• Determine when to use a static or dynamic route.
• Configure a static route on a Cisco Router.
• Describe how distance vector routing protocols operate.
• Configure the RIP and IGRP routing protocols on a Cisco router.
• Use show ip route, show ip protocols, and other show and debug commands to verify proper routing operation.
© 1999, Cisco Systems, Inc. www.cisco.com ICND—9-70
Review QuestionsReview Questions
1. What is an advantage of using a static route rather than a dynamic route? What is a disadvantage?
2. What is the advantage of using IGRP rather then RIP? What is a possible disadvantage?
3. To scale up to very large IP networks, what routing protocols are
recommended?