Chapter 7 Determining IP Routes

1
Chapter 7Determining IP Routes

• Routing Overview
• Distance Vector Routing
• Link-State and Balanced Hybrid Routing
• Enabling Rip
• Enabling IGRP
• Enabling EIGRP
• Enabling OSPF
• Variable-Length Subnet Masks

2

• Routing Overview

• Static Routing? Dynamic Routing? ???? ????.
• Classless Routing Protocol? ????.
• Static Routes, Default Routes Forwarding ??? ? ?
  ??.
• Static Routing? ??? ??? ? ??.
• Dynamic Routing Protocol? ??? ? ??.
• Inter-VLAN Routing? ??? ? ? ??.

3
Introducing Ruting
What Is Routing?
10.120.2.0
172.16.1.0

• ????? Layer3(Network Layer)?? ????.

• ???? ???? ?? ???? ? ?? ????? ????.
• ??? (???) ?? (Destination Address)
• ??? (??? ??? ?? Source) (Information
  Source, Exit Interface)
• ??? ?? (Possible Routes, 1 ??? ??)
• ??? ?? (Best Route)
• ??? ??? ?? ? ?? ?/? ??

4
What Is Routing? (Cont.)

• ???? ??? ????? ?? ???? ?? ??? ??? ??? ????? ???
  ??? ??? ??.

5
Comparing Static and Dynamic Routes
Identify Static and Dynamic Routes
Static Route (????) ???? ???? ???? ??? ??? ????.

• ???? ????? ??? ???, ???? ???? Static Route?
• Update?? ??, ????? ?? ???? ???? ??? ??? ??
• (redistribute static) ???? ? ? ??. ?? ??? ????
  (directly
• connected networks) ? ?? ??? ???? ???? ??? ????
  
• ????.

Dynamic Route (????) ??? ????? ???? ??? ????
????? ??? ??? ????.

• ??? ????? ???? ???? ????? ??? ?? ???? ???? ????
  Update??.

6
Configuring Static Routes
Static Routes
Stub Network
172.16.1.0
SO
Network
A
B
B
172.16.2.1
172.16.2.2

• Static Route? ????? ?? ????? ?? ??? ??.
• ??? ????? ???? ?? ??? ???? ??? ? ??.
• Static Route? ?? Stub Network?? ?? ????.

7
Configuring Static Routes
Static Routes Configuration
Router(config) ip route network mask
address interface distance permanent

• Network ??? ???? ?? Subnet??.
• Mask Network? ??? ?????.
• Address Next Hop Router? IP Address??.
• Interface Next Hop Router? Exit Interface??.
• Distance Administrative Distance???.
  Optional??.
• administrative distance?? ?? ?? ?? ??? ??.
• Permanent ?? Interface? Shutdown ???, ???
• ????? ??? ???? ?? ??. Optional??.

8
Static Routes Example
Stub Network
172.16.1.0
SO
Network
B
A
B
172.16.2.1
172.16.2.2
Router(config) ip route 172.16.1.0 255.255.255.0
172.16.2.1
9
Configuring Default Route Forwarding
Default Routes

• Default route? ??? IP Network Address? ??
  route? ??? ????
• ?? ? ?? IP Packet? ??? route? ???.
• Default Route? Static Route? ????? Gateway of
  last Resort??
• ??? ??.

Stub Network
172.16.1.0
SO
Network 10.0.0.0
B
A
B
172.16.2.1
172.16.2.2
Router(config) ip route 0.0.0.0 0.0.0.0
172.16.2.2

• ip route? ?? ?? ???? ????.
• 0.0.0.0? ???? ?? ???? ?? ????(??? ???? ??? ???
• ?????? ?? ???? ??.
• 0.0.0.0? ?? ??? ???? ??? ??? ??.
• 172.16.2.2? ?? ???? ?? ???? ???? next-hop ???? IP
  
• ??? ????.

10
Verifying the Static Route Configuration
Verifying the Static Route Configuration

• Router 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, ia - IS-IS inter area
• - candidate default, U - per-user static
  route, o - ODR
• P - periodic downloaded static route
• Gateway of last resort is 0.0.0.0 to network
  0.0.0.0
• 10.0.0.0/24 is subnetted, 1 subnets
• C 10.1.1.0 is directly connected, Serial0
• S 0.0.0.0/0 is directly connected, Serial0

• asterisk()? ??? ????? ??? ??? ????.

11
Inter-VLAN Routing
VLAN-to-VLAN Overview
Router on a stick
Fast E0/0
ISL
VLAN 2
VLAN 1
Application
TCP
IP
10.1.1.2
10.2.2.2
ISL
Ethernet

• Network Layer ???? ??? ?????? ????? ?? ?? ? ??.

12
Dividing a Physical Interface into Subinterfaces

• ???? ??????? ??? ???????? ??? ? ? ??.

13
Routing Between VLANs with ISL Trunks
FastE0/0
ISL
VLAN 2
VLAN 1
interface fastethernet 0/0 no ip
address!interface fastethernet 0/0.1 ip
address 10.1.1.1 255.255.255.0 encapsulation isl
1 interface fastethernet 0/0.2 ip address
10.2.2.1 255.255.255.0 encapsulation isl 2
10.1.1.2
10.2.2.2
14
Routing Between VLANs with 802.1Q Trunks
FastE0/0
802.1Q
VLAN 2
VLAN 1
interface fastethernet 0/0 ip address 10.1.1.1
255.255.255.0interface fastethernet 0/0.2 ip
address 10.2.2.1 255.255.255.0 encapsulation
dot1q
10.1.1.1
10.2.2.1

• ?????????? switchport trunk encapsulation dot1q
  ???? ????.
• Trunk? major ?????? ??? ????.

15
Introducing Dynamic Routing Protocols
What Is a Routing Protocol?
10.120.2.0
172.16.2.0
E0
S0

• ??? ????? ????? ??? ???? ??? ???? ????? ????.
• - ???? ??? ????
• - ???? ??? ??
• - ??? ?? ??
• - ???? ?? ????
• ?? ?? ??

NetworkProtocol
DestinationNetwork
Exit Interface
172.17.3.0
10.120.2.0172.16.2.0172.17.3.0
E0S0S1
ConnectedRIPIGRP
Routed Protocol IPRouting protocol RIP, IGRP
16
Autonomous Systems Interior or Exterior Routing
Protocols
Autonomous System 100

• Autonomous System? ??? ?? ????? ?????? ????.
• IGP(Interior Gateway Protocol) ?? ??? ??? ???
  ??? ????? ????. RIP, IGRP ?? ? ???.
• EGP(Exterior Gateway Protocol) ?? ?????? ???
  ??? ????? ????. BGP(Border Gateway Protocol)?
  EGP? ??.

17
Administrative Distance Ranking Routes
18
Default Administrative Distance
IS-IS 115
19
Dynamic Routing Protocol? ??
Distance Vector-????
B
C
A
???? ?? ??? ??(vector)? ??(distance)? ??? ????
????
D
Hybrid Routing-?????
Distance vector? Link state? ??? ??? ?? ????
Link State-????
B
SPF (Shortest Path First) ??? ???? ??? ???? ???
Topology DB (???? ??)? ??? DB? ??? ?? ? ??? ????
???? ??? ?? ??? ???? ??? ????
C
A
D
20
Classful Routing Overview

• Classful Routing? Routing Protocol? ???? ??? ??
  ? ?????
• ? ??? ??? ???.
• ???? ??? ???? ?? Default Subnet Mask? ????.
• Classful Routing Protocol? ???? ??? Major
  Network Number? ?
• ? ?? ???? ??? ??????? ????? ??.(FLSM Fixed
• Length Subnet Mask)
• ?? ?? ??????? Summary routes ??? ????.
• Classful Routing Protocol? ?
• RIP Version 1 (RIPv1)
• IGRP

21
Classless Routing Overview

• Classless Routing Protocol? Route? Advertise ?
  ?, Routing Mask (subnet mask, Prefix)? ????
  ????. Prefix Routing???? ??.
• Classless Routing Protocol? variable-length
  subnet mask(VLSM)? ????.
• ??? ?? Route? Summarize ? ? ??.
• Classless Routing Protocol? ?
• RIP Version 2 (RIPv2)
• EIGRP
• OSPF
• IS-IS

22
Using the ip classless Command
Using the ip classless Command
Stub Network
172.16.3.0
172.16.1.0
SO
Network
A
B
B
A
10.1.1.1
10.1.1.2
10.2.2.0
Router(config) ip route 0.0.0.0 0.0.0.0
10.1.1.2 Router(config) ip classless
23
??? ????? ???
?? RIP-1 IGRP EIGRP IS-IS OSPF
????
????
???? ???
???? ???
VLSM ??
??
???? ?? ?? ?? ?? ?? ?? ?? ??
24

• Distance Vector Routing

• Distance Vector Routing? ????.
• Routing ??? ?? ??? ??.
• Routing Loop? ?? ?? ? ?? ??? ????.
• Static Routing? ?? ??? ? ? ??.
• Distance Vector ???? ????.

25
Selecting Distance Vector Routes
Distance Vector Routing Protocols

• ???? ?? ?? ? ???? ???? ??? ?? ?? ??? ??? ????
  ???? ??? ????
• ????? ????? ??? ??? ?????? ??? ??? ??? ???? ???
  ??? distance (??, Hop)?? ??? ???? ??? ??????.
• ????? ?? RIP, IGRP

26
Sources of Information and Discovering Routes
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
A
B
C
E0
S0
S0
S1
S0
E0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
E0
0
10.3.0.0
1
10.4.0.0
1
10.2.0.0
S0
1
10.4.0.0
2
10.1.0.0
1
10.1.0.0
2

• ?? ?? ???? ?? ??? ???? ????? ???? ?? ??? ???
  ??????? ??? ??? ? ???? ?? ??? ??? ???? ???? ??.

27
Selecting the Best Route with Metrics
IGRP
A

Bandwidth Delay Load Reliability MTU
56
RIP
Hop count
T1
56
T1
B

• Hop count ??? ???? ???? ?
• Bandwidth ??? ??? ??, ?? ?? ?????? 10Mbps ???
  ??? 64Kbps ??? ?? ??.
• Delay ??? ????? ????? ???? ?? ??? ??
• Load ???? ??? ?? ???? ??? ?? ???
• Reliability ? ???? ??? ?? ?? ??
• MTU ?? ?? ??(Maximum transmission unit), ?? ???
  ?? ??? ??? ??? ?? ???? ????.

28
??? ???? ???
??? ???? ???
RIP-1 ? ???
RIP-2 ? ???
IGRP ??? ???? ?? ??? ??? ?? ???, ??, MTU ?? ??
EIGRP 256?? ??? ?? ????, IGRP? ??
OSPF ???? ????? ??? ???
?? IS-IS ???? ????? ??? ???
29
Maintaining Routing Information
Maintaining Routing Information
Process to Update This Routing Table
Process to Update This Routing Table
Topology Change Causes Routing Table Update
Router A sends Out This Updated Routing Table
After the Next Period Expires
A
B

• ???? ?? ????? ??? ???? ???? ???? ?? ???? ???
  ???? ???? ??? ??? ???? ????.
• ???? ?? ???? ???? ??? ???? ??? ?? ??? ??? ??? ???
  ???? ??.
• ?? ??? ????? ??? ? ?? ??? ???? ?? ???, ???? ???
  ??? ???? ?????? ??.
• ? ??? B? ?? ?? ????? ???? ??? ???? ???? ???, ??
  ???? ??? B? ??? A? ??? 1???, ??? B? ??? A? ???
  ??? ?? ??? 1? ??? ??.

30
How Routing Inconsistencies Occur In Distance
Vector
Inconsistent Routing Entries
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
A
B
C
E0
S0
S0
S1
S0
E0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
E0
0
10.3.0.0
1
10.4.0.0
1
10.2.0.0
S0
1
10.4.0.0
2
10.1.0.0
1
10.1.0.0
2

• ???? ???? ? ???? ???? ?? ?? ??? ? ?????? ?? ???
  ????.
• ???? 10.4.0.0? ???? ??? ?? ????? ??? ??? ??? ???
  ???? ????. ?? ????? ??(Convergence) ???? ??.

31
Inconsistent Routing Entries (Cont.)
10.4.0.0
10.1.0.0
10.2.0.0
10.3.0.0
X
A
B
C
E0
S0
S0
S1
S0
E0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
E0
Down
10.3.0.0
1
10.4.0.0
1
10.2.0.0
S0
1
10.4.0.0
2
10.1.0.0
1
10.1.0.0
2

• ?? Convergence(??)? ???? ???? ???.
• ???? 10.4.0.0 ? ?? ??? ? ??? C? ??? ???? ??? E0
  ?????? ??? ?? ??? ??.
• ???, ??? A? B? ? ??? ?? ?? ? ????, ??? A? ???
  10.4.0.0? ??? B? ??? ? ? ??? ?? ??.
• ??? A? ??? ???? ??? 10.4.0.0 ????? ?? ???
  Distance 2?? ???? ??.

32
Inconsistent Routing Entries (Cont.)
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
X
A
B
C
E0
S0
S0
S1
S0
E0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
S0
2
10.3.0.0
1
10.4.0.0
1
10.2.0.0
S0
1
10.4.0.0
2
10.1.0.0
1
10.1.0.0
2

• ??? B? ??? ???? 10.4.0.0 ????? ?? ??? ???? ??
  ??? ??? C? 10.4.0.0 ????? ?? ??? ??? B? ?? ?????
  ????.
• ??? C? 10.4.0.0 ????? ?? ??? 2??? ???? ??? ????
  ??????.

33
Inconsistent Routing Entries (Cont.)
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
X
A
B
C
E0
S0
S0
S1
S0
E0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
S0
2
10.3.0.0
1
10.4.0.0
3
10.2.0.0
S0
1
10.4.0.0
4
10.1.0.0
1
10.1.0.0
2

• ??? B? ??? C(3?)?? ??? ??? ???? ???? ????.
• ??? A? ??? B?? ??? ??? ???? ????, 10.4.0.0 ?????
  ??? ?? ??? ???? 10.4.0.0? ?? ??? 4? ????.

34
Defining a Maximum to Prevent Count to Infinity
Count to Infinity
10.4.0.0

• ??? ??? ????? ?? ??? ?? ??? ?? 10.4.0.0? ?? ????
  ??? Loop? ????? ??? ??? Count-to-Infinity? ??.

35
Defining a Maximum
10.4.0.0

• ?? ??? ???? ???? ????? ?? ????.
• 16? Unreachable??? ????. ??? 10.4.0.0 hop-count?
  16?? ????? ??? ??? ???? ???? ?? ???? ???? ???
  ???? ??? ? ?? ????.

36
Solutions to Eliminate Routing Loops
Routing Loops
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
X
A
B
C
E0
S0
S0
S1
S0
E0
Packet for Network 10.4.0.0
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
S0
2
10.3.0.0
10.4.0.0
3
1
10.2.0.0
S0
1
10.4.0.0
10.1.0.0
1
4
10.1.0.0
2

• ???? 10.4.0.0?? ?? ??? ??? B? ??? C ??? ???.

37
Split Horizon
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
A
B
C
E0
S0
S0
S1
S0
E0
X
X
Routing Table
Routing Table
Routing Table
10.1.0.0
10.2.0.0
0
0
10.3.0.0
0
S0
10.2.0.0
10.3.0.0
0
0
10.4.0.0
S0
0
10.3.0.0
1
10.4.0.0
1
10.2.0.0
S0
1
10.4.0.0
2
10.1.0.0
1
10.1.0.0
2

• ??? ???? ??? ?? ????? ??? ?? ??? ??? ???? ??? ??

38
Route Poisoning
10.4.0.0

• ??? C? 10.4.0.0? ?? ????? unreachable??? ?? ?????
  ??? ???? ??? A,B? ????? ? ??? ?? ??? ????? ????.
  ??? ??? C? ??? ?? ??? ?? Unreachable??? ???? ???
  ??? B?? ? ??? ?? ????? ?? ???? ????.

39
Poison Reverse
10.1.0.0
10.2.0.0
10.3.0.0
10.4.0.0
X
A
B
C
E0
S0
S0
S1
S0
E0
PoisonReverse
Routing Table
Routing Table
Routing Table
10.1.0.0
10.3.0.0
0
10.2.0.0
0
E0
0
S0
10.2.0.0
10.4.0.0
S0
0
10.3.0.0
Infinity
S1
0
S0
1
10.3.0.0
PossiblyDown
10.4.0.0
1
10.2.0.0
S1
S0
2
10.4.0.0
E1
2
10.1.0.0
2
10.1.0.0

• ??? B? 10.4.0.0? ??? inaccessible??? ?? ??? C???
  ??? ??? ??? C?? ?? ?? ???? Poison Reverse? ???
  ????? ??? C? ???. Poison Reverse? split horizon??
  ???? ?? ??? ???? ??? ??? C? ??? ? ??.

40
Holddown Timers

• ??? ??? ??? ????? ??? ???? ???? ?? ???? ??? ???
  ???? ????? ? ?? ??? ??? ? ?????? ?? ?? ????
  topology??(Link Down)? ??? ??? ? ??? ??.
• ???? ???? ?? ???? ??? ??? ?? ???(inaccessible)???
  ????? ?? ?? ?? ?? ?????? ???? ??? hold-down
  timers? ?????.
• ??? ???? ?? ??? ??? ??? ??? ?? ?? metric?? ??
  ????? ?? ?? ?? ? ??? ??? ?? ????? ???? hold-down
  timers? ????.
• Hold-down Timers ??? ???? ?? ?? ?? metric?? ??
  ????? ?? ????? ???? ??? ????.
• Hold-down timers ?? ???? ?? ??? possibly down
  ??? ???? ??? ???? ????.

41
Triggered Updates

• ??? loops? ??? ????, slow convergence, timing? ??
  ???? ???? ??? ??? ????. ????? ??? ??? ???? ?? ???
  ?? ?? ??? ???? ???? ? ??? Triggered update? ???
  ???? ??? ?? ??? ???? ?? ????.
• Triggered update? ?? ??? ???? ?????? ?? ??? ???
  ??? ??? ???? ??? ???? ???? ???? ??? ?? ???? ??
  ??? ???? ???? ??? ?? ?? ?? ???? ??? ?? ???? ????
  ??? loops? ??? ? ??.

42
Distance Vector Operations
Distance Vector Operation
Triggered Update
route poisoning?? ???? Triggered Update??.
10.4.0.0
X
C
Triggered Update

• ??? B? 10.4.0.0? ?? ??? ?? ??? ???? ?? ??? ????
  ???? ?? ??? route poisoning???? ????.
• ??? ??? ???? A,D? 10.4.0.0? ?? ??? ? ?? ???? ???
  ???? triggered update? ?? ????.

43
Distance Vector Operation (Cont.)

• ??? A,D? triggered update? ?? ?? ?? ??? hold-down
  timers? ?? ??? 10.4.0.0 ??? down???? ????.
• ??? A,D? 10.4.0.0? ?? ??? down???? ?? ??? E?
  triggered Update? ??? ??? E? ?? ??? hold-down
  timers? ?????.

44
Distance Vector Operation (Cont.)

• Router A,D? 10.4.0.0 ??? inaccessible??? ??? B?
  Poison Reverse? ???.
• ??? E? ??? A,D??? 10.4.0.0? ?? ?????? triggered
  update? ??? ??? poison reverse? ??? A,D? ???.

45
Distance Vector Operation (Cont.)

• ?? ???? ??? A,D,E? ?? ?? ????? ?? ???? ?? ??? ???
  ??? ??? ?? ??? ???? ???? hold-down timers? ?????.
• 1. Hold-down timers? ??? ?
• 2. ?? ?? metric ?? ?? update? ??? ?
• 3. ??? ???? ????? Flush timers? ???? ??? ?????
  
• 10.4.0.0 ??? ??? ?

46
Distance Vector Operation (Cont.)

• 10.4.0.0 ??? ?? ???? ?? ??? B? ?? triggered
  update ??? ??? A,D? ??? ??? A,D? triggered
  update? ??? E? ???.
• Triggered update? ?? ?? ???? hold-down timers?
  ???? ?? 10.4.0.0? ?? ??? ?? ????? ?? ??? ????
  update??.

47
Distance Vector Operation (Cont.)

• ?? ???? 10.4.0.0 ????? ?? ??? ?? ????? ?? ?? ??
  ????? 10.4.0.0 ????? ??? ??? ??? ?? ?? ??? ? ?? ??

48

• Link-State and Balanced Hybrid Routing

• Link State ??? ??? ???? ? ?? ??? ??.
• Link State Routing? ??? ??? ??.
• Balanced-Hybrid Routing? ??? ??.

49
How Routing Information Is Maintained with Link
State
Link-State Routing Protocols

• ? ???? ??? ??? Link? ??(Link State Bandwidth,
  Address, Up-Down State?)? ?????? LSA(Link State
  Advertisement) Packet? ???? ????.
• LSA? ?? ???? ??? Topology Database? Update? ?
  LSA? ?? ?????? Flooding??.
• ? ???? Topology Database? ????? Short-Path-First
  Algorithm? ??, ??? ???? ????. Link State Routing
  Protocol?? OSPF(Open short Path First),
  IS-IS(Intermediate System-to-Intermediate System)
  ?? ??.

50
Link-State Network Hierarchy Example

• Area ??? ?????? ??? ???. AS? ? ?? ????? ?? ?
  ??.
• Autonomous System(AS) Autonomous System? ???
  ?? ????? ?????? ???? ??? ??? ??? ????. ??
  Domain?? ????? ??.

• ???? ??
• 1. ??? ???? ??? ?? ??.
• 2. Link State Advertisement? ??? Area ?? ?? ??
  ? ??.

51
Link-State Routing Protocol Algorithms
Link-State Routing Protocol Algorithms
New York
Boston
Network 10.0.0.0
Network 192.168.33.0
Cost 1
Cost 1
Cost 1
Cost 1
Cost 1
Network 185.134.0.0
Network 192.168.157.0
San Francisco
Los Angeles
52
Benefits and Drawbacks of Link-State Routing
Benefits of Link-State Routing

• Fast convergence Network Topology? ??? ??? ??,
  ?? ???? ??? Topology? ?? ???? ??? ???? ??? ??.
• ??? ?? ??
• ???? Network Topology? ???? ??.
• LSA(Link-state Advertisement)? Routing Domain? ??
  Device? ?? ??? ????? ?? Network? ?? ??? ??? ?? ?
  ? ??.
• Hierarchical Design (??? ???)? ??, Network ???
  ???? ??, ?? ? ? ??.

53
Caveats of Link-State Routing

• ??? ??? ??? ??.
• Memory ??? ????? ??? adjacency database,
  topology database, forwarding database? ?? ???
  ??.
• CPU Dijkstras algorithm? ?? CPU ??? ??? ??.
  ?? Network? ????? ?? ??? ???? ?? ??.
• CPU? ??? ???? ??? Network Design? ?? ??.
• Area ?? ? ???? ??? ??.
• Backbone area? ??? ?? area? ??? ??? ?? ??? Area?
  ?????? ???.
• ???? Configuration? ????, ???? ???? ???? ? ??
  Configuration? ??? ??.
• Distance Vector Routing? ??? Troubleshooting? ??.

54
Drawbacks to Link-State Routing Protocols

• ??? ???? ??? ?? ??? ???
• ?? ?? ??
• ??? ??? ???? ??
• ????? ?? ?? ??? ???? ??? ?? ??? ????
• SPF ??? ??? ??? ? ?? ??? ? ??.

• ?? Discovery Process? ???? ?? LSA? ?? Neighboring
  Router? Flooding ??.(Network Traffic ??)
• ?? Memory ? CPU? ??
• ??? ??? ???? ??? ??
• ???? ??? ??? ?? ?? ?? ????? ?????? ??
• ????? ??
• ???? ?????? ?????? ??.
• RIP ? IGRP?? ? ? ????? ??

55
Balanced Hybrid Routing
Balanced Hybrid Routing
Choose a routing path based on distance
vectors Converge rapidly using change-based
updates
Balanced Hybrid Routing

• Distance Vector Routing ? Link-State Routing? ???
  ??

56

• Enabling RIP

• RIP? ??? ?? ??? ? ??.
• RIP? ??? ???? ??? ??? ? ? ??.

57
Configuring Dynamic Routing Protocols
IP Routing Configuration Tasks
Network 172.16.0.0

• ??? ??? ????? enable?? ???? ??? ?? ???? ????? ??.
• RIP?? IGRP? ?? ??? ????? ????.
• ????? IP????? ????.
• ?? ????/??? ??? ??? ??? ???? ?????? ?? ??? ??.

RIP
IGRP, RIP
IGRP
Network 160.89.0.0
RIP
Network 172.30.0.0
58
RIP Features
RIP Overview

• ?? ?? ??? ??????.
• ? ?? ?? ??? ?? ??? ????.
• ?? ??? ? ?? 15??.
• ??? ???? ???? ????? ? 30? ?? ????.
• RIP? ?? 6?? ?? ?? ????? load-balancing? ? ?
  ??.(default4)
• RIPv1? ??? ???? ??? ?? ? ??? ??? ??? ??? ???.
• RIPv2? ??? ???? ??? ?? ? ??? ??? ??? ?? ???.
• RIPv1? ??? ????? ???? ???, RIPv2? ????.
• RIPv2? VLSM? ????.

59
Dynamic Routing Configuration
Router(config)router protocol keyword

• Protocol? RIP, IGRP, OSPF ?? EIGRP? ??.
• Keyword? ?? ???? ?????, ??? IGRP? ?? ?? ???? ???
  ?? ????? ?? ????.

Router(config-router)network network-number

• RIP? IGRP? ?? network-number ??? ??? ?? ?? ?? ???
  ??? ?? ??? ???? ??? ??? ??? ??.
• ???? ??? ?? ???? ????? ?? ????? ???? ??? ???? ??.

60
Configuring RIP
RIP Configuration

• RIP ??? ????? ????.

• Network ???? ? ???? ??? ???? ?? ??? ?? ????.
• ??? ????? ????? ??? ??? ???? ??? ????? ???? ???
  ??????? ????? ??.

61
RIP Configuration Example
192.168.100.0
E0
192.168.100.1
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
router rip network 172.16.0.0 network 10.0.0.0
2.3.0.0
2.3.0.0
router rip network 10.0.0.0 network
192.168.100.0
62
Verifying the RIP Configuration
Verifying the RIP Configuration
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 2 Serial0
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
000010 Distance (default is 120)
63
Displaying the IP 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,
000007, Serial0 C 10.1.1.0 is directly
connected, Serial0 R 192.168.1.0/24 120/2
via 10.1.1.2, 000007, Serial0
64
Displaying the IP Routing Table (Cont.)
R 192.168.1.0/24 120/2 via 10.1.1.2,
000007, Serial0
Output ??
R or C ???? ?? ??? ??? ???? ????. C ?? ?????? ?? ?? R ???? ?? ??? dynamic routing protocol? RIP? ??? ?? S ???? ?? ??? static route? ??? ????? ?? ?? I IRGP? ??? ???? ?? ??? ??
192.168.1.0 ???? ????? ????.
120/1 ?? 120? Administrative distance???? 120? RIP? ??? ???? ?? ??? ???? ?? ???? 1? dynamic routing protocol? RIP? ???? ?? metric? hop count? ???? ??? ???? ? ?? hop-count(router) ??? ??? ?? ? ? ??.
Via 10.1.1.2 ???? ?? ??? ??? ???? IP address 30.1.1.2? ??? ???? ?? ????.
000007 ???? ?? ??? ?? ?? ???? ???? ????.
Serial0 ???? ??? ? ???? ?? ?????? ????? ? ? ??. ?? ??? Serial 0? ??? ???? ??? ? ??.
65
Troubleshooting the RIP Configuration
debug ip rip Command
RouterA debug ip rip RIP protocol debugging is
on RouterA 000624 RIP received v1 update
from 10.1.1.2 on Serial0 000624 10.2.2.0
in 1 hops 000624 192.168.1.0 in 2
hops 000633 RIP sending v1 update to
255.255.255.255 via Ethernet0 (172.16.1.1) 00063
4 network 10.0.0.0, metric 1 000634
network 192.168.1.0, metric 3 000634 RIP
sending v1 update to 255.255.255.255 via Serial0
(30.1.1.1) 000634 network 172.16.0.0,
metric 1 RouterA no debug ip rip
66

• Enabling IGRP

• IGRP? ??? ?? ??? ? ??.
• Unequal-Cost Load Balancing? ??? ?? ??? ? ??.
• IGRP? ??? ???? ??? ??? ? ? ??.

67
IGRP Features
Introducing IGRP
IGRP

• ??? ???
• ??? ???
• ?? ?? ??

• Interior gateway protocol??. Cisco??? ??? ??? ???
  ?????? ??? ? ??.
• Distance vector routing protocol??. Metric
  factor? Bandwidth, Delay, Reliability, Load, MTU?
  ????.(Composite Metric?? ??.) Hop Count?
  255?(Default 100?) ??? ????.( Metric
  maximum-hops?? ??? Router Configuration Mode ??
  ????.)
• IGRP? 6?? Unequal Cost Path? ????.(Default?
  4???.) maximum path 1 ??? ?? Loadbalancing?
  Disable??. maximum path 6? ????.
• 90??? routing information? ????. routing
  information ??? ???? full update ??? ????.
• administrative distance? 100 ??.
• AS Number? ??? ??. AS Number? ??? ?????? IGRP
  routing information? ????.

68
IGRP Metrics
IGRP Composite Metric

• IGRP ??? ??? ?? ????? ????.
• ??? ???? ?? ????
• ???? ??? ?? ??? ?????? ?? ??
• ??? Keepalive? ???? ??? ??? ??? ??? ???
• ?? ? ? ?? ??? ???? ??? ??? ??
• MTU ??? Maximum Transfer Unit ?

69
Supporting Multiple Paths with IGRP
IGRP Unequal Multiple paths

• IGRP? Source Address? Destination Address ??? ??
  ? ??? ??? ? ?? ??? ?? Metric? ?? ??? ?? ? ???
  ???? round-robin??? ??? ??? ????.
• Round-robin? ?????? ??? ?? ? ?? ?? ??? ???? ???
  ??? ?? ??? ?? ?? ??? ??? ??? ??? ? ??? ????? ???
  ??? ?? ???.
• IGRP? ??? ??? ?? ?? metric?? ???? ???? ???
  ??(variance) ?? ???? ??? Unequal Path? ??? ? ??.

70
IGRP Unequal-Cost Load Balancing
Router(config-router) variance 2

• Router E? Router C? ???? ?? FD 20 ??? Network
  Z? ??? Router C? ????.
• Variance ?? 2? ?? , Router E? Router B? Network
  Z? ?? ??? ????. (20 10) lt (2 x FD)
• Variance ?? 2? ?? Router E? Network Z? ?? ???
  Router D? ???? ???. (20 25) gt (2 x FD)

• ?? FD Feasible Distance

71
Configuring IGRP
Configuring IGRP

• ???? IGRP Enable ??.
• IGRP? AS? ??? ?? ?? ??? IANA? ??? ??? ?? ????.
• ? ??? ??? AS? ??? ?? ???? ??? AS ??? ???? ??.
• ???? ?? AS ??? ??? ???? ???? ??? ??? ?? ?? ???.

• Network ???? ???? ?? ??? ? ???? ??? ????.

• ?? IANA (Internet Assigned Numbers Authority)
  ??? ?? ?? ?? ??

72
Configuring IGRP (Cont.)

• Variance? Traffic-Share Balanced ??? ?? Best
  Metric? ? ???? Metric ?? ?? ??? ??? ???? ????.

• traffic-share balanced? ???? ?? ?? metric ??
  ??? ?? Balancing??.
• traffic-share min? ???? ?? ?? unequal path?
  ????? ???? ????? ??? ??? ???? ??? ??? ??(metric??
  ?? ??)?? ???? ???.

73
IGRP Configuration Example
192.168.100.0
Autonomous System 100
E0
192.168.100.1
S0
E0
S0
S0
S1
E0
S0
S0
S1
172.16.1.0
192.168.1.0
A
B
C
10.1.1.1
172.16.1.1
10.1.1.2
10.2.2.2
192.168.1.1
10.2.2.3
router igrp 100 network 10.0.0.0 network
192.168.100.0
74
Verifying the IGRP Configuration
Verifying the IGRP Configuration
192.168.100.0
192.168.100.1
E0
S0
E0
S0
S0
S1
E0
172.16.1.0
192.168.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
10.2.2.2
192.168.1.1
10.2.2.3
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 K11, K20,
K31, K40, K50 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 000101
Distance (default is 100)
75
Displaying the IP Routing Table
192.168.100.0
192.168.100.1
E0
S0
E0
S0
S0
S1
E0
172.16.1.0
192.168.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
10.2.2.2
192.168.1.1
10.2.2.3
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 I 10.2.2.0 100/90956 via
10.1.1.2, 000023, Serial0 C 10.1.1.0 is
directly connected, Serial0 I 192.168.1.0/24
100/91056 via 10.1.1.2, 000023, Serial0
76
Troubleshooting the IGRP Configuration
Debug ip igrp transactions Command
192.168.100.0
192.168.100.1
E0
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
RouterA debug ip igrp transactions IGRP protocol
debugging is on RouterA 002106 IGRP sending
update to 255.255.255.255 via Ethernet0
(172.16.1.1) 002106 network 10.0.0.0,
metric88956 002106 network 192.168.1.0,
metric91056 002107 IGRP sending update to
255.255.255.255 via Serial0 (10.1.1.1) 002107
network 172.16.0.0, metric1100 002116
IGRP received update from 10.1.1.2 on
Serial0 002116 subnet 10.2.2.0, metric
90956 (neighbor 88956) 002116 network
192.168.1.0, metric 91056 (neighbor 89056)
77
Debug ip igrp events Command
192.168.100.0
192.168.100.1
E0
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
RouterA debug ip igrp events IGRP event
debugging is on RouterA 002344 IGRP sending
update to 255.255.255.255 via Ethernet0
(172.16.1.1) 002344 IGRP Update contains 0
interior, 2 system, and 0 exterior
routes. 002344 IGRP Total routes in update
2 002344 IGRP sending update to
255.255.255.255 via Serial0 (10.1.1.1) 002345
IGRP Update contains 0 interior, 1 system, and 0
exterior routes. 002345 IGRP Total routes in
update 1 002348 IGRP received update from
10.1.1.2 on Serial0 002348 IGRP Update
contains 1 interior, 1 system, and 0 exterior
routes. 002348 IGRP Total routes in update 2
78
Updating Routing Information Example
192.168.100.0
192.168.100.1
E0
E0
X
S0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
RouterA debug ip igrp trans 003115
LINEPROTO-5-UPDOWN Line protocol on Interface
Ethernet0, changed state to down 003115 IGRP
edition is now 3 003115 IGRP sending update
to 255.255.255.255 via Serial0 (10.1.1.1) 003115
network 172.16.0.0, metric4294967295 003
116 IGRP Update contains 0 interior, 1 system,
and 0 exterior routes. 003116 IGRP Total
routes in update 1 003116 IGRP broadcasting
request on Serial0 003116 IGRP received
update from 10.1.1.2 on Serial0 003116
subnet 10.2.2.0, metric 90956 (neighbor
88956) 003116 network 172.16.0.0, metric
4294967295 (inaccessible) 003116 network
192.168.1.0, metric 91056 (neighbor
89056) 003116 IGRP Update contains 1
interior, 2 system, and 0 exterior
routes. 003116 IGRP Total routes in update 3
79
Updating Routing Information Example (Cont.)
S0
E0
S0
S0
S1
E0
172.16.1.0
192.168.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
10.2.2.2
192.168.1.1
10.2.2.3
RouterB debug ip igrp trans IGRP protocol
debugging is on RouterB 1d19h IGRP sending
update to 255.255.255.255 via Serial0
(10.1.1.2) 1d19h subnet 10.2.2.0,
metric88956 1d19h network 192.168.1.0,
metric89056 1d19h IGRP sending update to
255.255.255.255 via Serial1 (10.2.2.2) 1d19h
subnet 10.1.1.0, metric88956 1d19h
network 172.16.0.0, metric89056 1d19h IGRP
received update from 10.1.1.1 on Serial0 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 Serial0 (10.1.1.2) 1d19h subnet
10.2.2.0, metric88956 1d19h network
172.16.0.0, metric4294967295 1d19h
network 192.168.1.0, metric89056 1d19h IGRP
sending update to 255.255.255.255 via Serial1
(10.2.2.2) 1d19h subnet 10.1.1.0,
metric88956 1d19h network 172.16.0.0,
metric4294967295
80
Updating Routing Information Example (Cont.)
E0
X
S0
S0
S0
S1
E0
172.16.1.0
192.168.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
10.2.2.2
192.168.1.1
10.2.2.3
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 - 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, Serial0 10.0.0.0/24 is
subnetted, 2 subnets C 10.1.1.0 is directly
connected, Serial0 C 10.2.2.0 is directly
connected, Serial1 I 192.168.1.0/24
100/89056 via 10.2.2.3, 000014,
Serial1 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
81
Updating Routing Information Example (Cont.)
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
RouterB debug ip igrp transactions RouterB 1d20h
IGRP received update from 10.1.1.1 on
Serial0 1d20h network 172.16.0.0, metric
89056 (neighbor 1100) RouterB 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 - 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, Serial0 10.0.0.0/24 is
subnetted, 2 subnets C 10.1.1.0 is directly
connected, Serial0 C 10.2.2.0 is directly
connected, Serial1 I 192.168.1.0/24
100/89056 via 10.2.2.3, 000018,
Serial1 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 100 percent (5/5), round-trip
min/avg/max 32/38/48 ms
82
?? Ip classless Command
Default route
E0
S0
172.16.0.0
10.1.0.0
10.2.0.0
Router(config)ip classless
NetworkProtocol
DestinationNetwork
Exit Interface
10.1.0.0 10.2.0.0 172.16.0.0 via0.0.0.0
To get to 10.7.1.1 ip classless Default Route?
?? no ip classless Drop
CCRIP
E0S0 S0E0

• 10.0.0.0? 255.255.255.0? subnetting ? ??,
  10.0.0.0 ????? subnet?? ?? Destination? 10.7.1.1?
  ??? ?? Drop ??.
• 10.7.0.0 network? ?? path? routing table? ?? ?,
  ? network ?? packet? Default Route? ????? ????
  Packet? ??? ???? ???? Packet? Drop ???.
• ??? ??? 10.0.0.0? ??????? ?? ?? ??? 10.0.0.0? ??
  ???? ???? ??? ??? ????. ??? 10.7.0.0 ????? ??
  ??? ???? ??? Default Route? ???? ???.

83
Ip classless Command (Cont.)
S0 10.1.2.1/24
S0 10.1.2.2/24
10.1.1.0/24
10.7.0.1
10.1.2.0/24
Router B
Router A
interface Serial 0 ip address 10.1.2.2
255.255.255.0 interface Ethernet 0 ip address
10.1.1.1 255.255.255.0 ip route 0.0.0.0 0.0.0.0
10.1.2.1 no ip classless
interface Serial 0 ip address 10.1.2.1
255.255.255.0 interface Ethernet 0 ip address
10.7.0.1 255.255.255.0 no ip classless
RouterB??? ping 10.7.0.1? ??? ?
84

• Enabling EIGRP

• EIGRP? ??? ?? ??? ? ??.
• EIGRP? IGRP? ???? ? ? ??.
• EIGRP? ??? ???? ??? ??? ? ? ??.

85
EIGRP Features
Introducing EIGRP
Cisco?? IGRP? ??? ??? ??? routing protocol??.
IP RoutingProtocols
IP RoutingProtocols
AppleTalk Routing Protocol
EnhancedIGRP
AppleTalk Routing Protocol
IPX RoutingProtocols
IPX RoutingProtocols

• EIGRP supports
• Rapid convergence
• Reduced bandwidth usage
• Multiple network-layer protocols

86
Introducing EIGRP (Cont.)

• ??? ??(Cisco Proprietary) Routing Protocol??.
• Hybrid Protocol??. Link State? Distance Vector
  Routing Protocols? ??? ????. Advanced Distance
  Vector Routing Protocol??.
• Rapid Convergence Rapid Convergence? ???
  DUAL(Diffusing Update Algorithm)? ????.
• Bandwidth ?? ????.
• ???? ????? ?? ???. Destination? ?? Path? Metric?
  ??? ?? ??(Incremental updates) ?? Partial Update?
  ??.??? Link? ?? Routing Information Update? ??.
• Routing Information? ??? ????? Update?
  ??.(Multicast Update)
• Topology Database?? ??? Path? ?? ??? 100 Loop
  Free Routing Protocol??.
• Configuration? ??.
• VLSM? Discontiguous Network? ????.
• Multiple Network Layer Support IP Routing???
  IPX, AppleTalk Routing? ????.
• IGRP? ???? ??.

87
EIGRP Terminology
Neighbor TableAppleTalk Destination Next Hop
Router
Neighbor TableIPX Destination Next Hop
Router
Neighbor TableIP Next-Hop Interface Router
88
EIGRP Terminology (Cont.)

• Neighbor Table EIGRP ???? ?????(?? ???
  Neighbor Router)? ?? Table? ???? ?? ????? ??? ???
  ????. ???? ????(IP, IPX, AppleTalk)?? ???
  Neighbor Table? ????.
• Topology Table EIGRP ???? ??? ????? ??? ?? ? ??
  ????? ?? Topology Table? ????.???? ???? ?? ???
  Topology Table? ????.
• Routing Table EIGRP ???? Topology Table? ???
  ??, Destination? ?? ??? ??? ??? ???? ????. ????
  ???? ?? ??? Routing Table? ????.
• Successor Destination? ?? Primary Route??. ???
  ???? ????.
• Feasible Successor Destination? ?? Backup
  Route??. Feasible Successor? Successor? ??? ?????
  Topology Table? ?? ??. Destination? ??? ?? ??
  Feasible Successor? ??? ? ??.

89
Comparing EIGRP and IGRP
Comparing EIGRP and IGRP

• EIGRP? IGRP? ??? metric? ????.
• IGRP? ?? Unequal Cost Path Load Balancing? ??.
• IGRP??? Convergence Time? ?????.
• IGRP ??? Network Overhead? ?? ???.

90
Configuring EIGRP Protocol
Configuring EIGRP

• EIGRP? Enable ???, AS Number? ????.

• EIGRP? ??? ????? Major Class? ????. (Cisco IOS
  12.0?? mask Option? ?? Classless Network? ??? ?
  ??.)

91
EIGRP Configuration Example
192.168.100.0
Autonomous System 100
192.168.100.1
E0
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
router eigrp 100 network 172.16.0.0 network
10.0.0.0
router eigrp 100 network 192.168.1.0 network
10.0.0.0
router eigrp 100 network 10.0.0.0 Network
192.168.100.0
92
Verifying the EIGRP configuration
Verifying the EIGRP Configuration

• EIGRP? ??? ??? Neighbor ???? ?? ??.

• EIGRP topology table? ?? ??. ???? ???, ??? ?? ??
• ????, ??? ??, ????? ??? ??? ????.

• ??? ??? ? ?? EIGRP ???? ?? ??.

• ???? routing protocol? ?? Parameter ? ??? ?? ??.

• ???? ???? EIGRP ??? ?? ?? ??. Hello, ????, ??,
  ??,
• ????? ????.

93
Troubleshooting the EIGRP Configuration
debug ip eigrp Command
Router debug ip eigrp IP-EIGRP processing
incoming UPDATE packet IP-EIGRP Ext 192.168.3.0
255.255.255.0 M 386568 256000 130560 SM
360960 256000 104960 IP-EIGRP Ext 192.168.0.0
255.255.255.0 M 386560 256000 130560 SM
360960 256000 104960 IP-EIGRP Ext
192.168.3.0 255.255.255.0 M 386560 256000
130560 SM 360960 256000 104960 IP-EIGRP
172.69.43.0 255.255.255.0, - do advertise out
Ethernet0/1 IP-EIGRP Ext 172.69.43.0
255.255.255.0 metric 371200 256000 115200
94
debug ip eigrp ????
?? ??
IP-EIGRP ?? ??? IP EIGRP ?? ??? ?? ????.
Ext ? ??? ?? ????? ?? ???? ??? ?? ????? ?? ??? ?? ??? ??? Int? ???.
M ?? ???(computed metric)? ????, ??? ?? ???? ??? ??? ???? SM? ????. ? ?? ??? ?? ?????, ? ?? ? ??? ?? ? ???? ????.
SM ???? ?? ??? ?? ??? (stated metric)? ????.
95

• Enabling OSPF

• OSPF? ??? ?? ??? ? ??.
• ?? ?? ?????? ???? ? ? ??.
• Shortest Path Algorithm? ?? ? ? ??.
• OSPF? ??? ???? ??? ?? ? ? ??.

96
OSPF Features
Introducing OSPF

• OSPF(Open Shortest Path First)? IETF(Internet
  Engineering Task Force)? IGP(Interior Gateway
  Protocol) Working Group? ??, IP ???? ?? ?????. ?
  Working Group? ???, ???, ??? ??????? ??? ??
  SPF(Shortest Path First ?? ???? ??? ? Dijkstra
  ?????? ???) ????? ??? IGP? ??? ?? ?? 1988??
  ?????.
• OSPF? ??? ?? ???? ????? ?? ?? ???.RIP? ??? ????
  ??? ?? ???.(???? 50? ??? ???? OSPF? ??? ??? ? ???
  ??.)
• OSPF? Link State Routing Protocol?? ??? ???
  OSPF version 2??.(RFC 2328 April 1998, RFC 1247
  1991)
• IGP(Interior Gateway Protocol)??.

97
Comparing OSPF with Distance Vector Protocols
OSPF as a Link-State Protocol

• Convergence? ?? Routing Change? ?? Flooding
  ?? ? ????? Parallel?? ?? ??? ??? ???.
• VLSM ? CIDR? ????.
• Network Reachability OSPF? Reachability
  Limitation? ??.
• Use of Bandwidth ????? ??? ?? ?? Multicast?
  Link State Update? ??.(? 30? ???? ?? ????? sync?
  ???? ?? Update? ??. ?? LSA?? ?? Aging
  Timer(Default 30?)? ?? Timeout? ?? LSA? ?????
  ???? LSA? ?? ???.
• Method of path selection OSPF? Bandwidth? ???
  Cost Value? Path Selection? ????.OSPF? Equal-Cost
  Multiple Path? ????.
• OSPF? ?????? ?? ?? ??? ??? SPF algorithm? ?? ??.
• Link router interface
• State description of an interface and its
  relationship to neighboring routers

98
OSPF Hierarchical Routing

• AS(autonomous system)? Area? ????.
• Routing Update Traffic? ??? ??
• ??? SPF calculations? ??
• ?? ??? ???
• Link-State update overhead? ??

99
Shortest Path Algorithm
Shortest Path First Algorithm
Router A
Router D
10
10
1
Router B
128.213.0.0
5
10
10
Router C
128.213.11.0
5
222.211.10.0

• ????? ? ????? ??? Cost? ??? ?? ??? ????.
• ?? ??? ????? (Dijkstra)? ????? ???? ????.
• Cost 10000 0000/bandwith(bps)

100
Configuring Single Area OSPF
Configuring Single Area OSPF

• OSPF? enable ???.
• ???? ID? ?? ??? ??? ??? OSPF ?????? ???? ?? ????
  1?? 65,535??? ??? ???.
• ? ??? ?? ?? ?? ??.

• address? major network, subnet ?? interface? ???
  ??? ? ??.
• wildcard-mask? network ??? ??? ???? ???? ???
  ????. 0?? ???? ?? ????? ??, 1? ???? ?? ????. ??
  ??, 0.0.0.0? 32bit? ?? ??? ???? ????? ??.
• area-id? ??? ????, ?? ??? ?? 0?? ????.
• ?? Area_ID? 4 Octet? Dotted Decimal Format?? ???
  ? ??. ?? ?? Backbone Area? 0.0.0.0?? ?? Area?
  192.168.1.0 ??? ???? IP ??? ???? ? ? ??.

101
OSPF Configuration Example
192.168.100.0
Area 0
E0
192.168.100.1
S0
E0
S0
S0
S1
E0
192.168.1.0
172.16.1.0
A
B
C
172.16.1.1
10.1.1.1
10.1.1.2
192.168.1.1
10.2.2.2
10.2.2.3
router ospf 100 network 10.1.1.0 0.0.0.255 area
0 network 172.16.1.0 0.0.0.255 area 0
router ospf 100 network 10.0.0.0 0.255.255.255
area 0 network 192.168.1.0 0.0.0.255 area 0
router ospf 100 network 10.1.1.2 0.0.0.0 area
0 network 10.2.2.2 0.0.0.0 area 0 network
192.168.100.0 0.0.0.255 area 0
102
Configuing Loopback Interfaces
Advertised Loopback Address Ex 172.16.17.5
In OSPF table Uses address space Can use
ping
Unadvertised Loopback Address Ex
192.168.255.254 Not in OSPF table Saves
address space Cannot use ping
Network 172.16.0.0

• Router ID

• ???? OSPF? ???? Number??.
• Default OSPF Process? Startup?? Active
  Interface? IP Address? ?? ?? IP Address? Router
  ID? ??.
• Loopback Interface? ??? Override??. ? ?? Active
  Loopback Interface ? ?? ?? IP Address? Router ID?
  ??.
• Router? Router ID? ???? ???? show ip ospf
  interface ??? ????.

103
Verifying the OSPF Configuration
Verifying the OSPF Configuration

• OSPF ??? ????.

• ???? ?? ?? ?? Route? Display??.

• Area ID? adjacency information, OSPF Timers?
  Statistics ? Display??.

• DR, BDR,Neighbor? ?? ??? ?? ??.

104
Troubleshooting the OSPF Configuration
OSPF debug Commands
105
OSPF debug Commands

• ??? ????? ?? ????? ?? IP ??? ????? ???? ???.
• ???? ?? OSPF Hello ??? ???? ??? ?? ???? ???.
• ???? ?? OSPF dead ??? ???? ??? ?? ???? ???.

106
OSPF debug Commands
Routerdebug ip ospf packet OSPF rcv. V2 T1
148 rid200.0.0.117 aid0.0.0.
chk6AB2 aut0 auk
?? ??
V OSPF ??
T OSPF ?? ??, ??? ?? ??? ??? ??. 1 Hello 2 ??? ?? 3 ?? ?? ?? 4 ???? ???? 5 ???? ??
L OSPF ?? ??, ??? ??
Rid OSPF ??? ???
Aid OSPF ?? ???
chk OSPF ???
Aut OSPF ?? ??, ??? ?? ??? ??? ??. 0 ???? 1 ?????? 2 MD5
Auk OSPF ?? ?
Keyid MD5 ? ???
Seq ????
107

• Variable-Length Subnet Masks

• VLSM? ??? ??.
• VLSM? ???? Route Summarization? ? ? ??.

108
VLSM Features
What Is a Variable-length Subnet Mask?
172.16.14.32/27
172.16.14.132/30
A
172.16.1.0/24
172.16.14. 64/27
172.16.14.136/30
B
172.16.0.0/16
HQ
HQ
172.16.14.96/27
172.16.2.0/24
C
172.16.14.140/30

• Subnet 172.16.14.0/24? ? ?? Subnet?? ?? ? ??.
• 27bit? Subnet?? ????.
• 27bit Subnet?? ???? ??? Subnet? ? ?? ?? ?? 30bit
  Subnet?? ????.

109
Calculating VLSMs
110
A Working VLSM Example
172.16.32.0/26
172.16.33.0/30
172.16.32.64/26
172.16.33.4/30
172.16.33.8/30
172.16.32.128/26
172.16.33.12/30
172.16.32.192/26
26-Bit Mask (62 Hosts)
30-Bit Mask (2 Hosts)
111
Route Summarization with VLSM
What Is Route Summarization?

• Routing Protocol? ?? ?? Subnet? ??? Route?
  Summarize? ? ??.

112
Summarizing Within an Octet
172.16.168.0/24 10101100 . 00010000 .
10101 000 . 00000000
172.16.169.0/24 172 . 16
. 10101 001 . 0
172.16.170.0/24 172 . 16
. 10101 010 . 0
172.16.171.0/24 172 . 16
. 10101 011 . 0
172.16.172.0/24 172 . 16
. 10101 100 . 0
172.16.173.0/24 172 . 16
. 10101 101 . 0
172.16.174.0/24 172 . 16
. 10101 110 . 0
172.16.175.0/24 172 . 16
. 10101 111 . 0
Number of Common Bits 21Summary
172.16.168.0/21
Noncommon Bits 11
113
Summarizing Addresses in a VLSM Designed Network
172.16.128.0/20
B
172.16.128.0/20
172.16.32.64/26
172.16.32.0/24
CorporateNetwork
A
C
172.16.0.0/16
172.16.32.128/26
172.16.64.0/20
D
172.16.64.0/20
114
Implementation Considerations

• ?? ?? IP address? ??? highest-order bit? ???
  ??.
• Routing decision? Longest Match? ??? ?? ??.
• Routing protocol? Prefix (subnet mask) Length?
  ??? ? ??? ??.

115
Route Summarization Operation in Cisco Routers
172.16.5.33 /32        Host 172.16.5.32 /27 Subnet
172.16.5.0 /24 Network 172.16.0.0 /16 Block of
Networks 0.0.0.0 /0 Default

• Routing Protocol? Host-specific route,
  Network-Specific
• Route, Default route? ????.
• Router? Longest Match? ????.

116
Summarizing Routes in a Discontiguous Network

• RIPv1? IGRP? Subnet Mask ??? ??? ??? ?????
  Subnet(discontiguous subnet)? ???? ???. (???? ??
  ???? ??? Receiving Interface? ????? ??? Major
  ????? ??, ?????? ???? ????? ?? ??? ???? ? ?,
  Receiving Interface? ??? ??????? ??? ???????
  ???? Update ??? ???.gt Subnet Mask ??? ??? ????
  ???.)
• OSPF, EIGRP,RIP v.2 ?? Subnet Mask ??? ??? ???
  ????? Subnet(discontiguous subnet)? ????.

117
Distance Vector Routing Protocol Comparison Chart

Characteristic RIPv1 RIPv2 IGRP EIGRP Count
to infinity X X X Split
horizon X X X X Hold-down
timer X X X Triggered updates with
route poisoning X X X X Load
balancingEqual paths X X X
X Load balancingUnequal paths X
X VLSM support X X Routing
algorithm B-F B-F B-F DUAL Metric
Hops Hops Comp Comp Hop count limit 16
16 100 100 Scalability Small Small
Med Large
EIGRP is an advanced distance vector protocol
B-F Bellman-Ford Algorithm DUAL Diffusing
Update Algorithm
118
Link State Routing Protocol Comparison Chart

Characteristic OSPF
IS-IS EIGRP Hierarchical topology
X X Retains knowledge of
all possible routes X X
X Manual Route summarization
X X X Automatic Route
summarization
X Event-triggered announcements X
X X Equal paths Load balancing X
X X Unequal paths Load balancing
X VLSM support X X
X Routing algorithm Dijkstra
IS-IS DUAL Metric Cost Cost Comp Hop
count limit 200 1024
100 Scalability Large VryLg Large

For comparison purposes only, not a part of
this course EIGRP has some link-state features
119
LAB Test (1)

• Static Route LAB

Router config terminal Router(config) ip route
192.168.1.0 255.255.25.0 172.16.1.2 Router(config)
ip classless Router(config) exit Router show
running-configuration Router show ip
route Router ping 192.168.1.1
Router config terminal Router(config) ip route
10.1.1.0 255.255.25.0 Serial 0 Router(config) ip
classless Router(config) exit Router show
running-configuration Router show ip
route Router ping 10.1.1.2
120
LAB Test (2)

• Default Route LAB

Router config terminal Router(config) ip route
192.168.1.0 255.255.255.0 serial
0 Router(config) exit Router show
running-configuration Router show ip
route Router ping 192.168.1.1
Router config terminal Router(config) ip route
0.0.0.0 0.0.0.0 serial 0 Router(config)
exit Router show running-configuration Router
show ip route Router ping 10.1.1.2
121
LAB Test (3)

• RIP Routing LAB

Router config terminal Router(config) router
rip Router(config) network 10.0.0.0 Router(config
) network 172.16.0.0 Router show ip
route Router show ip protocols Router ping
192.168.1.1 Router debug ip rip Router no debug
ip rip
Router config terminal Router(config) router
rip Router(config) network 192.168.1.0 Router(con
fig) network 10.0.0.0 Router show ip
route Router show ip protocols Router ping
10.1.1.1 Router debug ip rip Router no debug ip
rip
122
LAB Test (4)

• IGRP Routing LAB

Router config terminal Router(config) router
igrp 100 Router(config) network
10.0.0.0 Router(config) network
172.16.0.0 Router show ip route Router show ip
protocols Router ping 192.168.1.1 Router debug
ip igrp Router no debug ip igrp
Router config terminal Router(config) router
igrp 100 Router(config) network
192.168.1.0 Router(config) network
10.0.0.0 Router show ip route Router show ip
protocols Router ping 10.1.1.1 Router debug ip
igrp Router no debug igrp
123
LAB Test (5)

• EIGRP Routing LAB

Router config terminal Router(config) router
eigrp 100 Router(config) network
10.1.1.1 Router(config) network
172.16.0.0 Router show ip route eigrp Router
show ip protocols Router ping 192.168.1.1 Router
debug ip eigrp Router no debug ip eigrp
Router config terminal Router(config) router
eigrp Router(config) network 192.168.1.0 Router(c
onfig) network 10.0.0.0 Router show ip route
eigrp Router show ip protocols Router ping
10.1.1.1 Router debug ip eigrp Router no debug
ip eigrp
124
LAB Test (6)

• OSPF Routing LAB

Router-A config terminal Router_A(config)
router ospf 100 Router_A(config) network
10.1.1.0 0.0.0.255 area 0 Router_A(config)
network 172.16.1.0 0.0.0.255 area 0 Router_A
show ip route ospf Router_A show ip
protocols Router_A ping 192.168.1.1 Router_A
debug ip ospf events Router_A no debug ip ospf
events
Router_B config terminal Router_B(config)
router ospf 100 Router_B(config) network
192.168.1.0 0.0.0.255 area 0 Router_B(config)
network 172.16.1.0 0.0.0.255 area 0 Router_B
show ip route ospf Router_B show ip
protocols Router_B ping 10.1.1.1 Router_B debug
ip ospf events Router_B no debug ip ospf events