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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
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Chapter 42 Configuring IP Unicast Routing
Configuring OSPF
Configuring OSPF Interfaces
You can use the ip ospf interface configuration commands to modify interface-specific OSPF
parameters. You are not required to modify any of these parameters, but some interface parameters (hello
interval, dead interval, and authentication key) must be consistent across all routers in an attached
network. If you modify these parameters, be sure all routers in the network have compatible values.
Note The ip ospf interface configuration commands are all optional.
Beginning in privileged EXEC mode, follow these steps to modify OSPF interface parameters:
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Enter interface configuration mode, and specify the Layer 3 interface
to configure.
Step 3 ip ospf cost (Optional) Explicitly specify the cost of sending a packet on the
interface.
Step 4 ip ospf retransmit-interval seconds (Optional) Specify the number of seconds between link state
advertisement transmissions. The range is 1 to 65535 seconds. The
default is 5 seconds.
Step 5 ip ospf transmit-delay seconds (Optional) Set the estimated number of seconds to wait before
sending a link state update packet. The range is 1 to 65535 seconds.
The default is 1 second.
Step 6 ip ospf priority number (Optional) Set priority to help find the OSPF designated router for a
network. The range is from 0 to 255. The default is 1.
Step 7 ip ospf hello-interval seconds (Optional) Set the number of seconds between hello packets sent on
an OSPF interface. The value must be the same for all nodes on a
network. The range is 1 to 65535 seconds. The default is 10 seconds.
Step 8 ip ospf dead-interval seconds (Optional) Set the number of seconds after the last device hello
packet was seen before its neighbors declare the OSPF router to be
down. The value must be the same for all nodes on a network. The
range is 1 to 65535 seconds. The default is 4 times the hello interval.
Step 9 ip ospf authentication-key key (Optional) Assign a password to be used by neighboring OSPF
routers. The password can be any string of keyboard-entered
characters up to 8 bytes in length. All neighboring routers on the
same network must have the same password to exchange OSPF
information.
Step 10 ip ospf message digest-key keyid md5 key (Optional) Enable MDS authentication.
• keyid—An identifier from 1 to 255.
• key—An alphanumeric password of up to 16 bytes.
Step 11 ip ospf database-filter all out (Optional) Block flooding of OSPF LSA packets to the interface. By
default, OSPF floods new LSAs over all interfaces in the same area,
except the interface on which the LSA arrives.
Step 12 end Return to privileged EXEC mode.
Step 13 show ip ospf interface [interface-name]Display OSPF-related interface information.