Administrator Guide

not take eect immediately after the authentication change wait timer expires; OSPF accepts both the old as well as new
authentication schemes for a time period that is equal to two times the congured authentication change wait timer. After this time
period, OSPF accepts only the new authentication scheme.
This transmission stops when the period ends.
The default is 0 seconds.
Conguring Virtual Links
Areas within OSPF must be connected to the backbone area (Area ID 0.0.0.0).
If an OSPF area does not have a direct connection to the backbone, at least one virtual link is required. Congure virtual links on an ABR
connected to the backbone.
• hello-interval — help packet
• retransmit-interval — LSA retransmit interval
• transmit-delay — LSA transmission delay
• dead-interval — dead router detection time
• authentication-key — authentication key
• message-digest-key — MD5 authentication key
To congure virtual links, use the following command.
• Congure the optional parameters of a virtual link.
CONFIG-ROUTEROSPF- id mode
area area-id virtual-link router-id [hello-interval seconds | retransmit-interval seconds |
transmit-delay seconds | dead-interval seconds | authentication-key key | message-digest-key
keyid md5 key]
• area ID: assigned earlier (the range is from 0 to 65535 or A.B.C.D).
• router ID: IP address associated with the virtual link neighbor.
• hello interval seconds: the range is from 1 to 8192 (the default is 10).
• retransmit interval seconds: the range is from 1 to 3600 (the default is 5).
• transmit delay seconds: the range is from 1 to 3600 (the default is 1).
• dead interval seconds: the range is from 1 to 8192 (the default is 40).
• authentication key: eight characters.
• message digest key keyid: the range is from 1 to 255.
• md5 key: 16 characters.
If you do not enter other parameters, the defaults are used.
Only the area ID and router ID require conguration to create a virtual link.
Use EITHER the Authentication Key or the Message Digest (MD5) key.
Example of Viewing Virtual Links
Use the show ip ospf process-id virtual-links command to view the virtual link.
Dell#show ip ospf 1 virtual-links
Virtual Link to router 192.168.253.5 is up
Run as demand circuit
Transit area 0.0.0.1, via interface TenGigabitEthernet 13/16, Cost of using 2
Transmit Delay is 1 sec, State POINT_TO_POINT,
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
644
Open Shortest Path First (OSPFv2)