Usage 
Information
By default, the dead interval is four times the default hello-interval.
Related 
Commands
ip ospf hello-interval – sets the time interval between the hello packets.
ip ospf hello-interval
Specify the time interval between the hello packets sent on the interface.
C-Series, E-Series, S-Series, Z-Series, S4810
Syntax
ip ospf hello-interval seconds
To return to the default value, use the no ip ospf hello-interval command.
Parameters
seconds
Enter the number of seconds for the interval. The range is 1 to 65535. 
The default is 10 seconds.
Defaults 10 seconds
Command Modes INTERFACE
Command History
Version 8.3.11.1 Introduced on the Z9000.
Version 8.3.7.0 Introduced on the S4810.
Version 7.6.1.0 Introduced on the S-Series.
Version 7.5.1.0 Introduced on the C-Series.
pre-Version 
6.1.1.1
Introduced on the E-Series.
Usage 
Information
The time interval between the hello packets must be the same for routers in a network.
Related 
Commands
ip ospf dead-interval – sets the time interval before a router is declared dead.
ip ospf message-digest-key
Enable OSPF MD5 authentication and send an OSPF message digest key on the interface.
C-Series, E-Series, S-Series, Z-Series, S4810
Syntax
ip ospf message-digest-key keyid md5 key
To delete a key, use the no ip ospf message-digest-key keyid command.
Parameters
keyid
Enter a number as the key ID. The range is 1 to 255.
key
Enter a continuous character string as the password.
Defaults No MD5 authentication is configured.
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