cisco 640 802 ccna portable command guide 2008 phần 5 pptx
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Configuring a Default Route on a Router 71
By default, a static route is always used rather than a routing protocol. By adding an AD
number to your ip route statement, however, you can effectively create a backup route
to your routing protocol. If your network is using EIGRP, and you need a backup route, add
a static route with an AD greater than 90. EIGRP will be used because its AD is better
(lower) than the static route. If EIGRP goes down, however, the static route will be used in
its place. This is known as a floating static route.
If a static route refers to an exit interface rather than a next-hop address, the destination is
considered to be directly connected and is therefore given an AD of 0 rather than 1.
Configuring a Default Route on a Router
Exterior Border Gateway Protocol (eBGP) 20
EIGRP (internal) 90
Open Shortest Path First Protocol (OSPF) 110
Intermediate System-to-Intermediate
System Protocol (IS-IS)
115
RIP 120
Exterior Gateway Protocol (EGP) 140
On-Demand Routing 160
EIGRP (external) 170
Internal Border Gateway Protocol (iBGP)
(external)
200
Unknown 255
Router(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
11
11
77
77
22
22
11
11
66
66
11
11
00
00
22
22
Send all packets destined for
networks not in my routing
table to 172.16.10.2.
Router(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
//
//
00
00
Send all packets destined for
networks not in my routing
table out my serial 0/0
interface.
72 Configuration Example: Static Routes
Verifying Static Routes
To display the contents of the IP routing table, enter the following command:
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
NOTE: The codes to the left of the routes in the table tell you from where the
router learned the routes. A static route is described by the letter S.
Configuration Example: Static Routes
Figure 7-1 illustrates the network topology for the configuration that follows, which shows
how to configure static routes using the commands covered in this chapter.
Figure 7-6 Network Topology for Static Route Configuration
NOTE: The host names, passwords, and interfaces have all been configured
using the commands shown in the configuration example in Chapter 6,
“Configuring a Single Cisco Router.”
Boston Router
Boston>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Boston#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global
configuration mode
s0/0/1
DCE
172.16.40.2
s0/0/0
172.16.40.1
Network 172.16.50.0/24
fa0/0
172.16.50.50
Bangor
Network 172.16.10.0/24
Network 172.16.20.0/30 Network 172.16.40.0/30
s0/0/1
DCE
172.16.20.2
s0/0/0
172.16.20.1
fa0/0
Boston
172.16.10.10
Network 172.16.30.0/24
fa0/0
172.16.30.30
Buffalo
172.16.10.1
172.16.30.1 172.16.50.1
Configuration Example: Static Routes 73
Buffalo Router
Bangor Router
Boston(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
11
11
77
77
22
22
11
11
66
66
33
33
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
11
11
77
77
22
22
11
11
66
66
22
22
00
00
22
22
Configures a static route
using the next-hop address
Boston(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
11
11
77
77
22
22
11
11
66
66
44
44
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
11
11
77
77
22
22
11
11
66
66
22
22
00
00
22
22
Configures a static route
using the next-hop address
Boston(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
11
11
77
77
22
22
11
11
66
66
55
55
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
11
11
77
77
22
22
11
11
66
66
22
22
00
00
22
22
Configures a static route
using the next-hop address
Boston(config)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to privileged mode
Boston#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to
NVRAM
Buffalo>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Buffalo#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global
configuration mode
Buffalo(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
11
11
77
77
22
22
11
11
66
66
11
11
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
//
//
11
11
Configures a static route
using the exit interface
Buffalo(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
11
11
77
77
22
22
11
11
66
66
55
55
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
//
//
00
00
Configures a static route
using the exit interface
Buffalo(config)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to privileged mode
Buffalo#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to
NVRAM
Bangor>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Bangor#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global
configuration mode
Bangor(config)#ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
00
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
//
//
11
11
Configures a static route
using the default route
Bangor(config)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to privileged mode
Bangor#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to
NVRAM
This page intentionally left blank
CHAPTER 8
RIP
This chapter provides information and commands concerning the following topics:
• The ip classless command
• RIP routing: mandatory commands
• RIP routing: optional commands
• Troubleshooting RIP issues
• Configuration example: RIPv2 routing
The ip classless Command
NOTE: A supernet route is a route that covers a range of subnets with a
single entry.
NOTE: The ip classless command is enabled by default in Cisco IOS Soft-
ware Release 11.3 and later.
RIP Routing: Mandatory Commands
Router(config)#ii
ii
pp
pp
cc
cc
ll
ll
aa
aa
ss
ss
ss
ss
ll
ll
ee
ee
ss
ss
ss
ss
Instructs Cisco IOS Software
to forward packets destined for
an unknown subnet to the best
supernet route
Router(config)#nn
nn
oo
oo
ii
ii
pp
pp
cc
cc
ll
ll
aa
aa
ss
ss
ss
ss
ll
ll
ee
ee
ss
ss
ss
ss
Turns off the ip classless
command
Router(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
rr
rr
ii
ii
pp
pp
Enables RIP as a routing
protocol.
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
w.x.y.z
w.x.y.z is the network number
of the directly connected
network you want to advertise.
76 RIP Routing: Optional Commands
NOTE: You need to advertise only the classful network number, not a subnet:
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
not
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
11
11
00
00
00
00
If you advertise a subnet, you will not receive an error message,
because the router will automatically convert the subnet to the
classful network address.
RIP Routing: Optional Commands
Router(config)#nn
nn
oo
oo
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
rr
rr
ii
ii
pp
pp
Turns off the RIP routing
process.
Router(config-router)#nn
nn
oo
oo
nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
w.x.y.z
Removes network w.x.y.z
from the RIP routing process.
Router(config-router)#vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
RIP will now send and
receive RIPv2 packets
globally.
Router(config-router)#vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
11
11
RIP will now send and
receive RIPv1 packets only.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
ss
ss
ee
ee
nn
nn
dd
dd
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
11
11
The interface will send only
RIPv1 packets.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
ss
ss
ee
ee
nn
nn
dd
dd
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
The interface will send only
RIPv2 packets.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
ss
ss
ee
ee
nn
nn
dd
dd
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
11
11
22
22
The interface will send both
RIPv1 and RIPv2 packets.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
rr
rr
ee
ee
cc
cc
ee
ee
ii
ii
vv
vv
ee
ee
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
11
11
The interface will receive
only RIPv1 packets.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
rr
rr
ee
ee
cc
cc
ee
ee
ii
ii
vv
vv
ee
ee
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
The interface will receive
only RIPv2 packets.
Router(config-if)#ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
rr
rr
ee
ee
cc
cc
ee
ee
ii
ii
vv
vv
ee
ee
vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
11
11
22
22
The interface will receive
both RIPv1 and RIPv2
packets.
Router(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
RIPv2 summarizes networks
at the classful boundary.
This command turns auto-
summarization off.
Troubleshooting RIP Issues 77
Troubleshooting RIP Issues
Router(config-router)#pp
pp
aa
aa
ss
ss
ss
ss
ii
ii
vv
vv
ee
ee
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
00
00
//
//
00
00
//
//
00
00
RIP updates will not be sent
out this interface.
Router(config-router)#nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
a.b.c.d
Defines a specific neighbor
with which to exchange
information.
Router(config-router)#nn
nn
oo
oo
ii
ii
pp
pp
ss
ss
pp
pp
ll
ll
ii
ii
tt
tt
hh
hh
oo
oo
rr
rr
ii
ii
zz
zz
oo
oo
nn
nn
Turns off split horizon (on
by default).
Router(config-router)#ii
ii
pp
pp
ss
ss
pp
pp
ll
ll
ii
ii
tt
tt
hh
hh
oo
oo
rr
rr
ii
ii
zz
zz
oo
oo
nn
nn
Reenables split horizon.
Router(config-router)#tt
tt
ii
ii
mm
mm
ee
ee
rr
rr
ss
ss
bb
bb
aa
aa
ss
ss
ii
ii
cc
cc
33
33
00
00
99
99
00
00
11
11
88
88
00
00
22
22
77
77
00
00
33
33
66
66
00
00
Changes timers in RIP:
30 = Update timer (in
seconds)
90 = Invalid timer (in
seconds)
180 = Hold-down timer (in
seconds)
270 = Flush timer (in
seconds)
360 = Sleep time (in
milliseconds)
Router(config-router)#mm
mm
aa
aa
xx
xx
ii
ii
mm
mm
uu
uu
mm
mm
pp
pp
aa
aa
tt
tt
hh
hh
ss
ss
x
Limits the number of paths
for load balancing to x (4 =
default, 6 = maximum).
Router(config-router)#dd
dd
ee
ee
ff
ff
aa
aa
uu
uu
ll
ll
tt
tt
ii
ii
nn
nn
ff
ff
oo
oo
rr
rr
mm
mm
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
oo
oo
rr
rr
ii
ii
gg
gg
ii
ii
nn
nn
aa
aa
tt
tt
ee
ee
Generates a default route
into RIP.
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
Displays all RIP activity in
real time
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
rr
rr
ii
ii
pp
pp
dd
dd
aa
aa
tt
tt
aa
aa
bb
bb
aa
aa
ss
ss
ee
ee
Displays contents of the RIP
database
78 Configuration Example: RIPv2 Routing
Configuration Example: RIPv2 Routing
Figure 8-1 illustrates the network topology for the configuration that follows, which shows
how to configure RIPv2 using the commands covered in this chapter.
Figure 8-7 Network Topology for RIPv2 Routing Configuration
NOTE: The host name, password, and interfaces have all been configured as per
the configuration example in Chapter 6, “Configuring a Single Cisco Router.”
Cancun Router
Cancun>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Cancun#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration
mode
Cancun(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
rr
rr
ii
ii
pp
pp
Enables RIP routing
Cancun(config-router)#vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
Enables RIPv2
Cancun(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
Advertises directly connected
networks (classful address only)
Cancun(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Turns off auto-summarization
s0/0/1
DCE
172.16.40.2
s0/0/0
172.16.40.1
Network 172.16.50.0/24
fa0/0
172.16.50.50
Mazatlan
Network 172.16.10.0/24
Network 172.16.20.0/30 Network 172.16.40.0/30
s0/0/1
DCE
172.16.20.2
s0/0/0
172.16.20.1
fa0/0
Cancun
172.16.10.10
Network 172.16.30.0/24
fa0/0
172.16.30.30
Acapulco
172.16.10.1
172.16.50.1172.16.30.1
Configuration Example: RIPv2 Routing 79
Acapulco Router
Mazatlan Router
Cancun(config-router)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration
mode
Cancun(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode
Cancun#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
Saves the configuration to
NVRAM
Acapulco>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Acapulco#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration
mode
Acapulco(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
rr
rr
ii
ii
pp
pp
Enables RIP routing
Acapulco(config-router)#vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
Enables RIPv2
Acapulco(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
Advertises directly connected
networks (classful address only)
Acapulco(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Turns off auto-summarization
Acapulco(config-router)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to global configuration
mode
Acapulco(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode
Acapulco#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to
NVRAM
Mazatlan>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode
Mazatlan#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration
mode
Mazatlan(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
rr
rr
ii
ii
pp
pp
Enables RIP routing
Mazatlan(config-router)#vv
vv
ee
ee
rr
rr
ss
ss
ii
ii
oo
oo
nn
nn
22
22
Enables RIPv2
Mazatlan(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
Advertises directly connected
networks (classful address only)
80 Configuration Example: RIPv2 Routing
Mazatlan(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Turns off auto-summarization
Mazatlan(config-router)#ee
ee
xx
xx
ii
ii
tt
tt
Moves to global configuration
mode
Mazatlan(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode
Mazatlan#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to
NVRAM
CHAPTER 9
EIGRP
This chapter provides information and commands concerning the following topics:
• Configuring Enhanced Interior Gateway Routing Protocol (EIGRP)
• EIGRP auto-summarization
• Load balancing: variance
• Bandwidth use
• Authentication
• Verifying EIGRP
• Troubleshooting EIGRP
• Configuration example: EIGRP
Configuring Enhanced Interior Gateway Routing Protocol (EIGRP)
Router(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
Turns on the EIGRP process.
100 is the autonomous system
number, which can be a
number between 1 and
65,535.
All routers in the same
autonomous system must use
the same autonomous system
number.
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
00
00
00
00
00
00
00
00
Specifies which network to
advertise in EIGRP.
Router(config-if)#bb
bb
aa
aa
nn
nn
dd
dd
ww
ww
ii
ii
dd
dd
tt
tt
hh
hh
x
Sets the bandwidth of this
interface to x kilobits to allow
EIGRP to make a better
metric calculation.
TIP: The bandwidth
command is used for metric
calculations only. It does not
change interface
performance.
Router(config-router)#nn
nn
oo
oo
nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
00
00
00
00
00
00
00
00
Removes the network from
the EIGRP process.
82 EIGRP Auto-Summarization
NOTE: tos is a reference to the original Interior Gateway Routing Protocol
(IGRP) intention to have IGRP perform type-of-service routing. Because this
was never adopted into practice, the tos field in this command is always
set to zero (0).
NOTE: With default settings in place, the metric of EIGRP is reduced to the
slowest bandwidth plus the sum of all the delays of the exit interfaces from the
local router to the destination network.
TIP: For two routers to form a neighbor relationship in EIGRP, the k values must
match.
CAUTION: Unless you are very familiar with what is occurring in your network,
it is recommended that you do not change the k values.
EIGRP Auto-Summarization
Router(config)#nn
nn
oo
oo
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
Disables routing process 100.
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
00
00
00
00
00
00
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
Identifies which interfaces or
networks to include in
EIGRP. Interfaces must be
configured with addresses
that fall within the wildcard
mask range of the network
statement. A network mask
can also be used here.
Router(config-router)#mm
mm
ee
ee
tt
tt
rr
rr
ii
ii
cc
cc
ww
ww
ee
ee
ii
ii
gg
gg
hh
hh
tt
tt
ss
ss
tos
k1 k2 k3 k4 k5
Changes the default k values
used in metric calculation.
These are the default values:
tos=0, k1=1, k2=0, k3=1,
k4=0, k5=0
Router(config-router)#aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Enables auto-summarization for the
EIGRP process.
NOTE: The default behavior of auto-
summarized changed from enabled to
disabled was introduced in Cisco IOS
Software Release 12.2(8)T.
Router(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Turns off the auto-summarization
feature.
Load Balancing: variance 83
CAUTION: EIGRP automatically summarizes networks at the classful boundary.
A poorly designed network with discontiguous subnets could have problems
with connectivity if the summarization feature is left on. For instance, you
could have two routers advertise the same network—172.16.0.0/16—when in
fact they wanted to advertise two different networks—172.16.10.0/24 and
172.16.20.0/24.
Recommended practice is that you turn off automatic summarization if
necessary, use the ip summary-address command, and summarize manually
what you need to.
Load Balancing: variance
NOTE: The behavior of the auto-
summary command is disabled by
default, beginning in Cisco IOS
Software Release 12.2(8)T. This means
that Cisco IOS Software will now send
subprefix routing information across
classful network boundaries.
Router(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt
00
00
//
//
00
00
Enters interface configuration mode.
Router(config-if)#ii
ii
pp
pp
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
11
11
00
00
11
11
00
00
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
00
00
00
00
77
77
55
55
Enables manual summarization for
EIGRP autonomous system 100 on this
specific interface for the given address
and mask. An administrative distance of
75 is assigned to this summary route.
NOTE: The administrative-distance
argument is optional in this command.
Without it, an administrative distance of
5 is automatically applied to the
summary route.
Router(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
Creates routing process 100
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
00
00
00
00
00
00
00
00
Specifies which network to advertise in
EIGRP
Router(config-router)#vv
vv
aa
aa
rr
rr
ii
ii
aa
aa
nn
nn
cc
cc
ee
ee
n
Instructs the router to include routes
with a metric less than or equal to n
times the minimum metric route for that
destination, where n is the number
specified by the variance command
84 Authentication
NOTE: If a path is not a feasible successor, it is not used in load balancing.
NOTE: EIGRP supports up to six unequal-cost paths.
Bandwidth Use
NOTE: By default, EIGRP is set to use only up to 50 percent of the bandwidth of
an interface to exchange routing information. Values greater than 100 percent
can be configured. This configuration option might prove useful if the bandwidth
is set artificially low for other reasons, such as manipulation of the routing metric
or to accommodate an oversubscribed multipoint Frame Relay configuration.
NOTE: The ip bandwidth-percent command relies on the value set by the
bandwidth command.
Authentication
Router(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
Enters interface configuration mode.
Router(config-if)#bb
bb
aa
aa
nn
nn
dd
dd
ww
ww
ii
ii
dd
dd
tt
tt
hh
hh
22
22
55
55
66
66
Sets the bandwidth of this interface
to 256 kilobits to allow EIGRP to
make a better metric calculation.
Router(config-if)#ii
ii
pp
pp
bb
bb
aa
aa
nn
nn
dd
dd
ww
ww
ii
ii
dd
dd
tt
tt
hh
hh
pp
pp
ee
ee
rr
rr
cc
cc
ee
ee
nn
nn
tt
tt
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
55
55
00
00
11
11
00
00
00
00
Configures the percentage of
bandwidth that may be used by
EIGRP on an interface.
50 is the EIGRP autonomous system
number.
100 is the percentage value.
100% * 256 = 256 kbps.
Router(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
Enters interface configuration mode.
Router(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
mm
mm
oo
oo
dd
dd
ee
ee
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
mm
mm
dd
dd
55
55
Enables Message Digest 5 algorithm
(MD5) authentication in EIGRP packets
over the interface.
Router(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
rr
rr
oo
oo
mm
mm
ee
ee
oo
oo
Enables authentication of EIGRP
packets.
romeo is the name of the key chain.
Router(config-if)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
Authentication 85
NOTE: For the start time and the end time to have relevance, ensure that the
router knows the correct time. Recommended practice dictates that you run
Network Time Protocol (NTP) or some other time-synchronization method if you
intend to set lifetimes on keys.
Router(config)#kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
rr
rr
oo
oo
mm
mm
ee
ee
oo
oo
Identifies a key chain. The name must
match the name configured in interface
configuration mode above.
Router(config-keychain)#kk
kk
ee
ee
yy
yy
11
11
Identifies the key number.
NOTE: The range of keys is from
0 to 2147483647. The key identification
numbers do not need to be consecutive.
At least 1 key must be defined on a key
chain.
Router(config-keychain-key)#kk
kk
ee
ee
yy
yy
ss
ss
tt
tt
rr
rr
ii
ii
nn
nn
gg
gg
ss
ss
hh
hh
aa
aa
kk
kk
ee
ee
ss
ss
pp
pp
ee
ee
aa
aa
rr
rr
ee
ee
Identifies the key string.
NOTE: The string can contain from
1 to 80 uppercase and lowercase
alphanumeric characters, except that the
first character cannot be a number.
Router(config-keychain-
key)#aa
aa
cc
cc
cc
cc
ee
ee
pp
pp
tt
tt
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
start-time
{ii
ii
nn
nn
ff
ff
ii
ii
nn
nn
ii
ii
tt
tt
ee
ee
|
end-time
| dd
dd
uu
uu
rr
rr
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
seconds
}
Optionally specifies the period during
which the key can be received.
NOTE: The default start time and the
earliest acceptable date is January 1,
1993. The default end time is an infinite
period.
Router(config-keychain-key)#ss
ss
ee
ee
nn
nn
dd
dd
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
start-time
{ii
ii
nn
nn
ff
ff
ii
ii
nn
nn
ii
ii
tt
tt
ee
ee
|
end-
time
| dd
dd
uu
uu
rr
rr
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
seconds
}
Optionally specifies the period during
which the key can be sent.
NOTE: The default start time and the
earliest acceptable date is January 1,
1993.
The default end time is an infinite
period.
86 Troubleshooting EIGRP
Verifying EIGRP
Troubleshooting EIGRP
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
ss
ss
Displays the neighbor table.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
ss
ss
dd
dd
ee
ee
tt
tt
aa
aa
ii
ii
ll
ll
Displays a detailed neighbor table.
TIP: The show ip eigrp neighbors
detail command verifies whether a
neighbor is configured as a stub router.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
Shows information for each interface.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
Shows information for a specific interface.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
11
11
00
00
00
00
Shows information for interfaces running
process 100.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
tt
tt
oo
oo
pp
pp
oo
oo
ll
ll
oo
oo
gg
gg
yy
yy
Displays the topology table.
TIP: The show ip eigrp topology
command shows you where your feasible
successors are.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
tt
tt
rr
rr
aa
aa
ff
ff
ff
ff
ii
ii
cc
cc
Shows the number and type of packets
sent and received.
Router#ss
ss
hh
hh
oo
oo
ww
ww
ii
ii
pp
pp
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
Shows a routing table with only EIGRP
entries.
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ff
ff
ss
ss
mm
mm
Displays events/actions related to
EIGRP feasible successor metrics
(FSM)
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
pp
pp
aa
aa
cc
cc
kk
kk
ee
ee
tt
tt
Displays events/actions related to
EIGRP packets
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
Displays events/actions related to your
EIGRP neighbors
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
Displays events/actions related to your
EIGRP neighbors
Router#dd
dd
ee
ee
bb
bb
uu
uu
gg
gg
ii
ii
pp
pp
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
nn
nn
oo
oo
tt
tt
ii
ii
ff
ff
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
ss
ss
Displays EIGRP event notifications
Configuration Example: EIGRP 87
Configuration Example: EIGRP
Figure 9-1 illustrates the network topology for the configuration that follows, which shows
how to configure EIGRP using the commands covered in this chapter.
Figure 9-8 Network Topology for EIGRP Configuration
Austin Router
Austin>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode.
Austin#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode.
Austin(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
Enters interface configuration mode.
Austin(config-if)#ii
ii
pp
pp
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
11
11
77
77
22
22
11
11
66
66
22
22
00
00
11
11
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
Assigns the IP address and netmask.
Austin(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
mm
mm
oo
oo
dd
dd
ee
ee
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
mm
mm
dd
dd
55
55
Enables MD5 authentication in
EIGRP packets.
Austin(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
ss
ss
uu
uu
ss
ss
aa
aa
nn
nn
nn
nn
aa
aa
hh
hh
Enables authentication of EIGRP
packets. susannah is the name of the
key chain.
Austin(config-if)#nn
nn
oo
oo
ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
Austin(config-if)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt
00
00
//
//
11
11
Enters interface configuration mode.
Austin(config-if)#ii
ii
pp
pp
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
11
11
77
77
22
22
11
11
66
66
11
11
00
00
11
11
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
Assigns the IP address and netmask.
Austin(config-if)#nn
nn
oo
oo
ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
Austin(config-if)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
Enables EIGRP routing.
s0/0
HoustonAustin
s0/0
172.16.20.1/24
Corporate
Network
EIGRP Routing with
MD5 Authentication
Between Routers
fa0/1
172.16.10.1/24
fa0/1
172.16.30.1/24
s0/1
172.16.20.2/24
172.16.10.10/24
172.16.30.30/24
DCE
88 Configuration Example: EIGRP
Houston Router
Austin(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Disables auto-summarization.
Austin(config-router)#ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ll
ll
oo
oo
gg
gg
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
cc
cc
hh
hh
aa
aa
nn
nn
gg
gg
ee
ee
ss
ss
Changes with neighbors will be
displayed.
Austin(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
Advertises directly connected
networks (classful address only).
Austin(config-router)#kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
ss
ss
uu
uu
ss
ss
aa
aa
nn
nn
nn
nn
aa
aa
hh
hh
Identifies a key chain name, which
must match the name configured in
interface configuration mode.
Austin(config-keychain)#kk
kk
ee
ee
yy
yy
11
11
Identifies the key number.
Austin(config-keychain-key)#kk
kk
ee
ee
yy
yy
ss
ss
tt
tt
rr
rr
ii
ii
nn
nn
gg
gg
tt
tt
oo
oo
ww
ww
ee
ee
rr
rr
Identifies the key string.
Austin(config-keychain-key)#aa
aa
cc
cc
cc
cc
ee
ee
pp
pp
tt
tt
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
00
00
66
66
::
::
33
33
00
00
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
ii
ii
nn
nn
ff
ff
ii
ii
nn
nn
ii
ii
tt
tt
ee
ee
Specifies the period during which the
key can be received.
Austin(config-keychain-key)#ss
ss
ee
ee
nn
nn
dd
dd
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
00
00
66
66
::
::
33
33
00
00
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
00
00
99
99
::
::
44
44
55
55
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
Specifies the period during which the
key can be sent.
Austin(config-keychain-key)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration mode.
Austin(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode
Austin#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to NVRAM.
Houston>ee
ee
nn
nn
aa
aa
bb
bb
ll
ll
ee
ee
Moves to privileged mode.
Houston#cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
uu
uu
rr
rr
ee
ee
tt
tt
ee
ee
rr
rr
mm
mm
ii
ii
nn
nn
aa
aa
ll
ll
Moves to global configuration mode.
Houston(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
11
11
Enters interface configuration mode.
Houston(config-if)#ii
ii
pp
pp
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
11
11
77
77
22
22
11
11
66
66
22
22
00
00
22
22
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
Assigns the IP address and netmask.
Houston(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
mm
mm
oo
oo
dd
dd
ee
ee
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
mm
mm
dd
dd
55
55
Enables MD5 authentication in
EIGRP packets.
Houston(config-if)#ii
ii
pp
pp
aa
aa
uu
uu
tt
tt
hh
hh
ee
ee
nn
nn
tt
tt
ii
ii
cc
cc
aa
aa
tt
tt
ii
ii
oo
oo
nn
nn
kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
ee
ee
dd
dd
dd
dd
ii
ii
ee
ee
Enables authentication of EIGRP
packets. eddie is the name of the key
chain.
Configuration Example: EIGRP 89
Houston(config-if)#cc
cc
ll
ll
oo
oo
cc
cc
kk
kk
rr
rr
aa
aa
tt
tt
ee
ee
55
55
66
66
00
00
00
00
00
00
Sets the clock rate.
Houston(config-if)#nn
nn
oo
oo
ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
Houston(config-if)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ff
ff
aa
aa
ss
ss
tt
tt
ee
ee
tt
tt
hh
hh
ee
ee
rr
rr
nn
nn
ee
ee
tt
tt
00
00
//
//
11
11
Enters interface configuration mode.
Houston(config-if)#ii
ii
pp
pp
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
11
11
77
77
22
22
11
11
66
66
33
33
00
00
11
11
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
00
00
Assigns the IP address and netmask.
Houston(config-if)#nn
nn
oo
oo
ss
ss
hh
hh
uu
uu
tt
tt
dd
dd
oo
oo
ww
ww
nn
nn
Enables the interface.
Houston(config-if)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
11
11
00
00
00
00
Enables EIGRP routing.
Houston(config-router)#nn
nn
oo
oo
aa
aa
uu
uu
tt
tt
oo
oo
ss
ss
uu
uu
mm
mm
mm
mm
aa
aa
rr
rr
yy
yy
Disables auto-summarization.
Houston(config-router)#ee
ee
ii
ii
gg
gg
rr
rr
pp
pp
ll
ll
oo
oo
gg
gg
nn
nn
ee
ee
ii
ii
gg
gg
hh
hh
bb
bb
oo
oo
rr
rr
cc
cc
hh
hh
aa
aa
nn
nn
gg
gg
ee
ee
ss
ss
Changes with neighbors will be
displayed.
Houston(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
00
00
00
00
Advertises directly connected
networks (classful address only).
Houston(config-router)#kk
kk
ee
ee
yy
yy
cc
cc
hh
hh
aa
aa
ii
ii
nn
nn
ee
ee
dd
dd
dd
dd
ii
ii
ee
ee
Identifies a key chain name, which
must match the name configured in
interface configuration mode.
Houston(config-keychain)#kk
kk
ee
ee
yy
yy
11
11
Identifies the key number.
Houston(config-keychain-key)#kk
kk
ee
ee
yy
yy
ss
ss
tt
tt
rr
rr
ii
ii
nn
nn
gg
gg
tt
tt
oo
oo
ww
ww
ee
ee
rr
rr
Identifies the key string.
Houston(config-keychain-key)#aa
aa
cc
cc
cc
cc
ee
ee
pp
pp
tt
tt
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
00
00
66
66
::
::
33
33
00
00
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
ii
ii
nn
nn
ff
ff
ii
ii
nn
nn
ii
ii
tt
tt
ee
ee
Specifies the period during which the
key can be received.
Houston(config-keychain-key)#ss
ss
ee
ee
nn
nn
dd
dd
ll
ll
ii
ii
ff
ff
ee
ee
tt
tt
ii
ii
mm
mm
ee
ee
00
00
66
66
::
::
33
33
00
00
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
00
00
99
99
::
::
44
44
55
55
::
::
00
00
00
00
AA
AA
pp
pp
rr
rr
11
11
99
99
22
22
00
00
00
00
77
77
Specifies the period during which the
key can be sent.
Houston(config-keychain-key)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to global configuration
mode.
Houston(config)#ee
ee
xx
xx
ii
ii
tt
tt
Returns to privileged mode.
Houston#cc
cc
oo
oo
pp
pp
yy
yy
rr
rr
uu
uu
nn
nn
nn
nn
ii
ii
nn
nn
gg
gg
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
ss
ss
tt
tt
aa
aa
rr
rr
tt
tt
uu
uu
pp
pp
cc
cc
oo
oo
nn
nn
ff
ff
ii
ii
gg
gg
Saves the configuration to NVRAM.
This page intentionally left blank
CHAPTER 10
Single Area OSPF
This chapter provides information and commands concerning the following topics:
• Configuring OSPF: Mandatory commands
• Using wildcard masks with OSPF areas
• Configuring OSPF: Optional commands
— Loopback interfaces
— Router ID
— DR/BDR elections
— Modifying cost metrics
— Authentication: Simple
— Authentication: Using MD5 encryption
— Timers
— Propagating a default route
• Verifying OSPF configuration
• Troubleshooting OSPF
• Configuration example: Single area OSPF
Configuring OSPF: Mandatory Commands
Router(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
oo
oo
ss
ss
pp
pp
ff
ff
11
11
22
22
33
33
Starts OSPF process 123. The process
ID is any positive integer value
between 1 and 65,535. The process
ID is not related to the OSPF area.
The process ID merely distinguishes
one process from another within the
device.
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
11
11
00
00
00
00
00
00
00
00
00
00
22
22
55
55
55
55
aa
aa
rr
rr
ee
ee
aa
aa
00
00
OSPF advertises interfaces, not
networks. Uses the wildcard mask to
determine which interfaces to
advertise. Read this line to say “Any
interface with an address of
172.16.10.x is to be put into area 0.”
92 Using Wildcard Masks with OSPF Areas
Using Wildcard Masks with OSPF Areas
When compared to an IP address, a wildcard mask identifies which addresses get matched
for placement into an area:
• A 0 (zero) in a wildcard mask means to check the corresponding bit in the address for
an exact match.
• A 1 (one) in a wildcard mask means to ignore the corresponding bit in the address—
can be either 1 or 0.
Example 1: 172.16.0.0 0.0.255.255
172.16.0.0 = 10101100.00010000.00000000.00000000
0.0.255.255 = 00000000.00000000.11111111.11111111
result = 10101100.00010000.xxxxxxxx.xxxxxxxx
172.16.x.x (Anything between 172.16.0.0 and 172.16.255.255 will
match the example statement.)
TIP: An octet of all 0s means that the octet has to match exactly to the address.
An octet of all 1s means that the octet can be ignored.
NOTE: The process ID number of
one router does not have to match the
process ID of any other router.
Unlike Enhanced Interior Gateway
Routing Protocol (EIGRP), matching
this number across all routers does not
ensure that network adjacencies will
form.
Router(config-router)#ll
ll
oo
oo
gg
gg
aa
aa
dd
dd
jj
jj
aa
aa
cc
cc
ee
ee
nn
nn
cc
cc
yy
yy
cc
cc
hh
hh
aa
aa
nn
nn
gg
gg
ee
ee
ss
ss
dd
dd
ee
ee
tt
tt
aa
aa
ii
ii
ll
ll
Configures the router to send a syslog
message when there is a change of
state between OSPF neighbors.
TIP: Although the log-adjacency-
changes command is on by default,
only up/down events are reported
unless you use the detail keyword.
Configuring OSPF: Optional Commands 93
Example 2: 172.16.8.0 0.0.7.255
172.168.8.0 = 10101100.00010000.00001000.00000000
0.0.0.7.255 = 00000000.00000000.00000111.11111111
result = 10101100.00010000.00001xxx.xxxxxxxx
00001xxx = 00001000 to 00001111 = 8–15
xxxxxxxx = 00000000 to 11111111 = 0–255
Anything between 172.16.8.0 and 172.16.15.255 will match the
example statement.
Configuring OSPF: Optional Commands
The following commands, although not mandatory, enable you to have a more controlled
and efficient deployment of OSPF in your network.
Loopback Interfaces
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
11
11
00
00
11
11
00
00
00
00
00
00
00
00
aa
aa
rr
rr
ee
ee
aa
aa
00
00
Read this line to say “Any interface
with an exact address of 172.16.10.1
is to be put into area 0.”
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
11
11
77
77
22
22
11
11
66
66
11
11
00
00
00
00
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
aa
aa
rr
rr
ee
ee
aa
aa
00
00
Read this line to say “Any interface
with an address of 172.16.x.x is to be
put into area 0.”
Router(config-router)#nn
nn
ee
ee
tt
tt
ww
ww
oo
oo
rr
rr
kk
kk
00
00
00
00
00
00
00
00
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
aa
aa
rr
rr
ee
ee
aa
aa
00
00
Read this line to say “Any interface
with any address is to be put into area
0.”
Router(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ll
ll
oo
oo
oo
oo
pp
pp
bb
bb
aa
aa
cc
cc
kk
kk
00
00
Creates a virtual interface named
loopback 0, and then moves the
router to interface configuration
mode.
Router(config-if)#ii
ii
pp
pp
aa
aa
dd
dd
dd
dd
rr
rr
ee
ee
ss
ss
ss
ss
11
11
99
99
22
22
11
11
66
66
88
88
11
11
00
00
00
00
11
11
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
22
22
55
55
55
55
Assigns the IP address to the
interface.
NOTE: Loopback interfaces are
always “up and up” and do not go
down unless manually shut down.
This makes loopback interfaces
great for use as OSPF router IDs.
94 Configuring OSPF: Optional Commands
Router ID
DR/BDR Elections
Router(config)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
oo
oo
ss
ss
pp
pp
ff
ff
11
11
Starts OSPF process 1.
Router(config-router)#rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ii
ii
dd
dd
11
11
00
00
11
11
11
11
11
11
Sets the router ID to 10.1.1.1. If
this command is used on an OSPF
router process that is already active
(has neighbors), the new router ID
is used at the next reload or at a
manual OSPF process restart.
Router(config-router)#nn
nn
oo
oo
rr
rr
oo
oo
uu
uu
tt
tt
ee
ee
rr
rr
ii
ii
dd
dd
11
11
00
00
11
11
11
11
11
11
Removes the static router ID from
the configuration. If this command
is used on an OSPF router process
that is already active (has
neighbors), the old router ID
behavior is used at the next reload
or at a manual OSPF process
restart.
Router(config)#ii
ii
nn
nn
tt
tt
ee
ee
rr
rr
ff
ff
aa
aa
cc
cc
ee
ee
ss
ss
ee
ee
rr
rr
ii
ii
aa
aa
ll
ll
00
00
//
//
00
00
Changes the router to interface
configuration mode.
Router(config-if)#ii
ii
pp
pp
oo
oo
ss
ss
pp
pp
ff
ff
pp
pp
rr
rr
ii
ii
oo
oo
rr
rr
ii
ii
tt
tt
yy
yy
55
55
00
00
Changes the OSPF interface
priority to 50.
NOTE: The assigned priority can
be between 0 and 255. A priority
of 0 makes the router ineligible to
become a designated router (DR)
or backup designated router BDR).
The highest priority wins the
election. A priority of 255
guarantees a tie in the election. If
all routers have the same priority,
regardless of the priority number,
they tie. Ties are broken by the
highest router ID.
