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Chapter 9
Determining IP
Routes
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Objectives
Upon completion of this chapter, you willbe 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 protocolssuch 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
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To route, a router needs to know:
Destination addresses
Sources it can learn from
Possible routes
Best route
Maintain and verify routing information
What is Routing?
172.16.1.010.120.2.0
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What is Routing? (cont.)
NetworkProtocol
DestinationNetwork
ConnectedLearned
10.120.2.0172.16.1.0
ExitInterface
E0S0
Routed Protocol: IP
Routers must learn destinations that are
not directly connected
172.16.1.010.120.2.0
E0S0
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Static Route
Uses a route that anetworkadministrator entersinto the router
manually
Dynamic Route
Uses a route that anetwork routingprotocol adjustsautomatically for
topology or trafficchanges
Identifying Static and DynamicRoutes
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Defines a path to an IP destination network or subnet
Router(config)#ip route network[mask] {address| interface}[distance] [permanent]
Static Route Configuration
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Stub Network
ip route 172.16.1.0 255.255.255.0 172.16.2.1
172.16.2.1
SO
Static Route Example
172.16.1.0
B172.16.2.2
NetworkA B
This is a unidirectional route. You must have a route
configured in the opposite direction.
10.0.0.0
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Stub Network
ip route 0.0.0.0 0.0.0.0 172.16.2.2
Default 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.
10.0.0.0
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What is a Routing Protocol?
Routing protocols are
used betweenrouters to determinepaths and maintainrouting tables.
Once the path isdetermined a router canroute a routed protocol.
NetworkProtocol
DestinationNetwork
ConnectedRIP
IGRP
10.120.2.0172.16.2.0172.17.3.0
ExitInterface
E0S0S1
Routed Protocol: IPRouting protocol: RIP, IGRP
172.17.3.0
172.16.1.010.120.2.0
E0S0
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Autonomous System 100 Autonomous System 200
IGPs: RIP, IGRP EGPs: BGP
Autonomous Systems: Interior orExterior Routing Protocols
An autonomous system is a collection of networksunder a common administrative domain
IGPs operate within an autonomous system
EGPs connect different autonomous systems
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Administrative Distance:Ranking Routes
IGRPAdministrativeDistance=100
Router D
Router BRouter A
Router C
RIPAdministrativeDistance=120
E
I need to send a packet to
Network E. Both router B
and C will get it there.
Which route is best?
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Classes of Routing Protocols
Distance Vector
Hybrid Routing
Link StateC
B
A
D
C
D
B
A
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Distance Vector RoutingProtocols
Pass periodic copies of routing table to neighborrouters and accumulate distance vectors
C
D
B
A
C B AD
RoutingTable
RoutingTable
RoutingTable
RoutingTable
Distance
How farVectorIn which direction
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Routers discover the best path todestinations from each neighbor
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing Table
10.2.0.0
10.3.0.0
0
0
S0
S1
Routing Table
10.3.0.0 S0 0
10.4.0.0 E0 0
Routing Table
10.1.0.0
10.2.0.0
E0
S0
0
0
Distance VectorSources ofInformation and Discovering Routes
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Routers discover the best path todestinations from each neighbor
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing Table
10.1.0.0
10.2.0.0
10.3.0.0
Routing Table
10.2.0.0
10.3.0.0
10.4.0.0
10.1.0.0
0
0
1
1
S0
S1
S1
S0
Routing Table
10.3.0.0 S0 0
10.4.0.0 E0 0
10.2.0.0 S0 1
E0
S0
S0 1
0
0
Distance VectorSources ofInformation and Discovering Routes
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Distance VectorSources ofInformation and Discovering Routes
Routers discover the best path todestinations from each neighbor
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing Table
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
Routing Table
10.2.0.0
10.3.0.0
10.4.0.0
10.1.0.0
0
0
1
1
S0
S1
S1
S0
Routing Table
10.3.0.0 S0 0
10.4.0.0 E0 0
10.2.0.0 S0
10.1.0.0S0
1
2
E0
S0
S0
S0
1
2
0
0
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Distance VectorSelectingBest Route with Metrics
Information used to select the best path for routing
56T1
56
T1Ticks, hop count
B
A
Hop count
IPX
RIP
IGRP
Bandwidth
Delay
Load
Reliability
MTU
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Distance VectorMaintainingRouting Information
Updates proceed step-by-stepfrom router to router
A
Process toupdate this
routingtable
Topologychangecausesrouting
tableupdate
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Distance VectorMaintainingRouting Information
Updates proceed step-by-stepfrom router to router
A
Process toupdate this
routingtable
Router A sendsout this updated
routing tableafter the
next periodexpires
Topologychangecausesrouting
tableupdate
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Distance VectorMaintainingRouting Information
Updates proceed step-by-stepfrom router to router
AB
Process toupdate this
routingtable
Process toupdate this
routingtable
Topologychangecausesrouting
tableupdate
Router A sendsout this updated
routing tableafter the
next periodexpires
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Maintaining Routing InformationProblemRouting Loops
Each node maintains the distance from itself to eachpossible destination network
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0
Routing Table
10.3.0.0 S0
E0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
0
Routing Table
10.1.0.0 E0
S0
S0
S0
1
210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
10.2.0.0 S0
S1
S1
S0
1
110.1.0.0
10.4.0.0
10.3.0.0
0
0
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Maintaining Routing InformationProblemRouting Loops
Slow convergence produces inconsistent routing
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
E0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
Down
Routing Table
10.1.0.0 E0
S0
S0
S0
1
210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
10.2.0.0 S0
S1
S1
S0
1
110.1.0.0
10.4.0.0
10.3.0.0
0
0
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Router C concludes that the best path to network10.4.0.0 is through Router B
Maintaining Routing InformationProblemRouting Loops
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
2
Routing Table
10.1.0.0 E0
S0
S0
S0
1
210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
10.2.0.0 S0
S1
S1
S1
1
110.1.0.0
10.4.0.0
10.3.0.0
0
0
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Router A updates its table to reflect the new buterroneous hop count
Maintaining Routing InformationProblemRouting Loops
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
S0
S0
S0
S0
1
2
10.3.0.0
10.1.0.0
10.2.0.0
10.4.0.0
0
2
Routing Table
E0
S0
S0
S0
1
4
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
S0
S1
S1
S0
3
1
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
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Symptom: Counting to Infinity
Packets for network 10.4.0.0 bounce between routersA, B, and C
Hop count for network 10.4.0.0 counts to infinity
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
4
Routing Table
E0
S0
S0
S0
1
6
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
S0
S1
S1
S0
5
1
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
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Solution: Defining a Maximum
Define a limit on the number of hops to preventinfinite loops
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
16
Routing Table
E0
S0
S0
S0
1
16
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
S0
S1
S1
S0
16
1
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
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Solution: Split Horizon
It is never useful to send information about a route backin the direction from which the original packet came
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
XX
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
0
Routing Table
E0
S0
S0
S0
1
2
10.1.0.0
10.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
S0
S1
S1
E1
1
2
10.2.0.0
10.1.0.0
10.4.0.0
10.3.0.0
0
0
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Solution: Route Poisoning
Routers set the distance of routes that have gone downto infinity
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
Infinity
Routing Table
10.1.0.0 E0
S0
S0
S0
1
210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
10.2.0.0 S0
S1
S1
E1
1
210.1.0.0
10.4.0.0
10.3.0.0
0
0
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Solution: Poison Reverse
Poison Reverse overrides split horizon
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0X
Routing Table
10.3.0.0 S0
S0
S0
S0
1
210.1.0.0
10.2.0.0
10.4.0.0
0
Infinity
Routing Table
10.1.0.0 E0
S0
S0
S0
1
210.4.0.0
10.3.0.0
10.2.0.0
0
0
Routing Table
10.2.0.0 S0
S1
S1
E1
PossiblyDown
210.1.0.0
10.4.0.0
10.3.0.0
0
0
PoisonReverse
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Solution: Hold-Down Timers
Router keeps an entry for the network possibly downstate, allowing time for other routers to recompute forthis topology change
Network 10.4.0.0 is down
then back upthen back down
Update afterhold-down Time
Network 10.4.0.0is unreachable
A B C
10.1.0.0 10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 XUpdate after
hold-down Time
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Solution: Triggered Updates
Router sends updates when a change in its routingtable occurs
A B C
10.2.0.0 10.3.0.0 10.4.0.0
E0 S0 S0 S1 S0 E0 X
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
Network 10.4.0.0is unreachable
10.1.0.0
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Implementing Solutions inMultiple Routes
D
BE
A
X C10.4.0.0
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Implementing Solutions inMultiple Routes (cont.)
D
BE
A
CX10.4.0.0
Holddown
Holddown
Holddown
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Implementing Solutions inMultiple Routes (cont.)
D
BE
A
CX10.4.0.0
Holddown
Holddown
Holddown
Poison Reverse
Poison Reverse
Poison Reverse
Poison Reverse
S
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Implementing Solutions inMultiple Routes (cont.)
D
BE
A
CX10.4.0.0
Holddown
Holddown
Holddown
Packet forNetwork 10.4.0.0
Packet forNetwork 10.4.0.0
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Implementing Solutions inMultiple Routes (cont.)
D
BE
A
CLink up!
10.4.0.0
I l i S l i i
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Implementing Solutions inMultiple Routes (cont.)
D
BE
A
CLink up!
10.4.0.0
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Link-State Routing Protocols
After initial flood, pass small event-triggered link-stateupdates to all other routers
Link-State Packets
SPFAlgorithm
TopologicalDatabase
Shortest Path First Tree
RoutingTable
C A
D
B
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Share attributes of both distance-vectorand link-state routing
Hybrid Routing
Choose arouting path basedon distance vectors
Converge rapidly usingchange-based
updates
Balanced Hybrid Routing
IP R i
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Router configuration Select routing protocols
Specify networks orinterfaces
Network160.89.0.0
Network 172.30.0.0
IGRP,RIP
Network 172.16.0.0
RIP
RIP
IGRP
IP RoutingConfiguration Tasks
D i R i
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Defines an IP routing protocol
Router(config)#routerprotocol [keyword]
Mandatory configuration command for eachIP routing process
Identifies the physically connected networkthat routing updates are forwarded to
Router(config-router)#network network-number
Dynamic RoutingConfiguration
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19.2 kbps
T1
T1 T1
Maximum six paths (default = 4)
Hop count metric selects the path
Routes update every 30 seconds
RIP Overview
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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 Configuration
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2.3.0.0router rip
network 172.16.0.0
network 10.0.0.0
RIP Configuration Example
router rip
network 10.0.0.0
2.3.0.0router rip
network 192.168.1.0
network 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
V if i th R ti
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Verifying the RoutingProtocolRIP
RouterA#sh ip protocols
Routing 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 2Serial2 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
Di l i th
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Displaying theIP Routing Table
RouterA#sh 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
T - traffic engineered route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, Ethernet0
10.0.0.0/24 is subnetted, 2 subnets
R 10.2.2.0 [120/1] via 10.1.1.2, 00:00:07, Serial2
C 10.1.1.0 is directly connected, Serial2
R 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
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debug ip r ipCommand
RouterA#debug ip ripRIP protocol debugging is on
RouterA#
00:06:24: RIP: received v1 update from 10.1.1.2 on Serial2
00:06:24: 10.2.2.0 in 1 hops
00:06:24: 192.168.1.0 in 2 hops
00:06:33: 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 3
00:06:34: 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
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More scalable than RIP Sophisticated metric
Multiple-path support
Introduction to IGRP
IGRP
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Bandwidth
Delay
Reliability
Loading
MTU
19.2 kbps19.2 kbps
IGRP Composite Metric
Source
Destination
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Maximum six paths (default = 4)
Within metric variance
Next-hop router closer to destination
New Route
InitialRoute
Source
Destination
IGRP Unequal Multiple Paths
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Configuring IGRP
Router(config-router)#network network-number
Selects participating attached networks
Router(config)#router igrp autonomous-system
Defines IGRP as the IP routing protocol
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Configuring IGRP (cont.)
Router(config-router)#traffic-share
{ balanced | min }
Control how load-balanced traffic is distributed
Router(config-router)#variancemultiplier
Control IGRP load balancing
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router igrp 100
network 172.16.0.0
network 10.0.0.0
IGRP Configuration Example
router igrp 100
network 10.0.0.0
router igrp 100
network 192.168.1.0
network 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
Verifying the Routing
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Verifying the RoutingProtocolIGRP
RouterA#sh ip protocols
Routing 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 1Redistributing: 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
Displaying the
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Displaying theIP 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 subnets
C 172.16.1.0 is directly connected, Ethernet0
10.0.0.0/24 is subnetted, 2 subnets
I 10.2.2.0 [100/90956] via 10.1.1.2, 00:00:23, Serial2
C 10.1.1.0 is directly connected, Serial2
I 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
debug ip igrp transact ion
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debug ip igrp transact ionCommand
RouterA#debug ip igrp transactionsIGRP protocol debugging is on
RouterA#
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=88956
00:21:06: network 192.168.1.0, metric=91056
00:21:07: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.1)
00:21:07: network 172.16.0.0, metric=1100
00:21:16: 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
debug ip igrp events
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debug ip igrp eventsCommand
RouterA#debug ip igrp eventsIGRP event debugging is on
RouterA#
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: 2
00:23:44: 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: 1
00:23:48: IGRP: received update from 10.1.1.2 on Serial2
00:23:48: 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
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Updating Routing Information
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Updating Routing InformationExample (cont.)
RouterB#debug ip igrp trans
IGRP protocol debugging is on
RouterB#
1d19h: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.2)1d19h: subnet 10.2.2.0, metric=88956
1d19h: network 192.168.1.0, metric=89056
1d19h: IGRP: sending update to 255.255.255.255 via Serial3 (10.2.2.2)
1d19h: subnet 10.1.1.0, metric=88956
1d19h: network 172.16.0.0, metric=89056
1d19h: IGRP: received update from 10.1.1.1 on Serial2
1d19h: network 172.16.0.0, metric 4294967295 (inaccessible)
1d19h: IGRP: edition is now 10
1d19h: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.2)
1d19h: subnet 10.2.2.0, metric=88956
1d19h: network 172.16.0.0, metric=4294967295
1d19h: network 192.168.1.0, metric=89056
1d19h: IGRP: sending update to 255.255.255.255 via Serial3 (10.2.2.2)
1d19h: subnet 10.1.1.0, metric=88956
1d19h: 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
E0X
Updating Routing Information
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Updating Routing InformationExample (cont.)
RouterB#sh 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 - EGPi - 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 subnets
C 10.1.1.0 is directly connected, Serial2C 10.2.2.0 is directly connected, Serial3
I 192.168.1.0/24 [100/89056] via 10.2.2.3, 00:00:14, Serial3
RouterB#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
E0X
Updating Routing Information
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Updating Routing InformationExample (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 areaN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGPi - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate defaultU - per-user static route, o - ODRT - 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, Serial210.0.0.0/24 is subnetted, 2 subnets
C 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
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With ip classless Default
With no ip class less Drop
Router(config)#ip classless
ip class lessCommand
S0
Default route
172.16.0.0
E0
10.1.0.0
NetworkProtocol
DestinationNetwork
CC
RIP
10.1.0.0
10.2.0.0
172.16.0.0 via0.0.0.0
ExitInterface
E0S0
S0E0
10.2.0.0
To get to 10.7.1.1:
10.7.1.1
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Visual Objective
core_ server10.1.1.1
wg_sw_a10.2.2.11
wg_sw_l
10.13.13.11
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
s010.140.1.2/24
s0
10.140.12.2/24
s1/0 - s2/3
10.140.1.1/24 10.140.12.1/24
pod ros s0 ros e0 swA 10.140.1.2 10.2.2.3 10.2.2.11B 10.140.2.2 10.3.3.3 10.10.10.11C 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 10.9.9.11
I 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
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Visual Objective
core_ server10.1.1.1
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
s010.140.1.2/24
s0
10.140.12.2/24
s1/0 - s2/3
10.140.1.1/24 10.140.12.1/24...
pod ros s0 ros e0 swA 10.140.1.2 10.2.2.3 10.2.2.11B 10.140.2.2 10.3.3.3 10.10.10.11C 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 10.9.9.11
I 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
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Summary
After completing this chapter, you should beable 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 protocolsoperate.
Configure the RIP and IGRP routing protocols on a
Cisco router. Use showip route, show ip pro toco ls , and other show
and debug commands to verify proper routingoperation.
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Review Questions
1. What is an advantage of using a staticroute rather than a dynamic route?What is a disadvantage?
2. What is the advantage of using IGRPrather then RIP? What is a possibledisadvantage?
3. To scale up to very large IP networks,what routing protocols are recommended?