Configuring OSPF
Configuring OSPF Routing
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-1
Configuring Basic OSPF
Router(config)#
router ospf process-id [vrf vpn-name]
• Enables one or more OSPF routing processes
network ip-address wildcard-mask area area-id
Router(config-router)#
• Defines the interfaces that OSPF will run on
Router(config-if)#
ip ospf process-id area area-id [secondaries none]
O i
l
h d
bl OSPF
li i l
i
f
• pt ona met o to ena e
exp c t y on an nter ace
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-2
Configuring OSPF on Internal Routers of a
Single Area
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-3
Configuring OSPF for Multiple Areas
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-4
OSPF Router ID
Th
t
i k
t OSPF b th OSPF
t
ID
b
•
e rou er s nown o
y e
rou er
num er.
• LSDBs use the OSPF router ID to differentiate one router from the
next.
• By default, the router ID is the highest IP address on an active
interface at the moment of OSPF process startup.
• A loopback interface can override the OSPF router ID. If a loopback
i t
f
i t
th
t
ID i th hi h
t IP dd
ti
n er ace ex s s, e rou er
s e g es
a
ress on any ac ve
loopback interface.
• The OSPF router-id command can be used to override the OSPF
router ID
.
• Using a loopback interface or a router-id command is recommended
for stability.
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-5
Loopback Interfaces
Router(config)#interface loopback 0
Router(config-if)#ip address 172.16.17.5 255.255.255.255
If th OSPF
i
l
d
i
th
t
t b
•
e
process s a rea y runn ng, e rou er mus e
reloaded or the OSPF process must be removed and
reconfigured before the new loopback address will take effect.
© 2006 Cisco Systems, Inc. All rights reserved.
BSCI v3.0—3-6
OSPF router-id Command
Router(config-router)#
router-id ip-address
• This command is configured under the router ospf [process-id]
command.
• Any unique arbitrary 32-bit value in