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27-16
Cisco ASA 5500 Series Configuration Guide using ASDM
Chapter 27 Configuring OSPF
Customizing OSPF
Step 6 Click Advanced to edit advanced virtual link properties,
The Advanced OSPF Virtual Link Properties dialog box appears. You can configure the OSPF properties
for the virtual link in this area. These properties include authentication and packet interval settings
Step 7 In the Authentication area, choose the Authentication type by clicking the radio button next to one of the
following options:
• None to disable OSPF authentication.
• Authentication Password to use clear text password authentication. This is not recommended
where security is a concern.
• MD5 to use MD5 authentication (recommended).
• Area (Default) to use the authentication type specified for the area. See the “Configuring OSPF Area
Parameters” section on page 27-11 for information about configuring area authentication. Area
authentication is disabled by default. Therefore, unless you have previously specified an area
authentication type, interfaces set to area authentication have authentication disabled until you
configure this setting.
Step 8 In the Authentication Password area, enter and re-enter a password when password authentication is
enabled. Passwords must be a text string of up to 8 characters.
Step 9 In the MD5 IDs and Key area, enter the MD5 keys and parameters when MD5 authentication is enabled.
All devices on the interface using OSPF authentication must use the same MD5 key and ID. Specify the
following settings:
a. In the Key ID field, enter a numerical key identifier. Valid values range from 1 to 255. The Key ID
displays for the selected interface.
b. In the Key field, enter an alphanumeric character string of up to 16 bytes. The Key ID displays for
the selected interface.
c. Click Add or Delete to add or delete the specified MD5 key to the MD5 ID and Key table.
Step 10 In the Interval area, specify the interval timing for the packet by choosing from the following options:
• Hello Interval to specify the interval, in seconds, between hello packets sent on an interface. The
smaller the hello interval, the faster topological changes are detected, but the more traffic is sent on
the interface. This value must be the same for all routers and access servers on a specific interface.
Valid values range from 1 to 65535 seconds. The default value is 10 seconds.
• Retransmit Interval to specify the time, in seconds, between LSA retransmissions for adjacencies
belonging to the interface. When a router sends an LSA to its neighbor, it keeps the LSA until it
receives the acknowledgement message. If the router receives no acknowledgement, it will resend
the LSA. Be conservative when setting this value, or needless retransmission can result. The value
should be larger for serial lines and virtual links. Valid values range from 1 to 65535 seconds. The
default value is 5 seconds.
• Transmit Delay to specify the estimated time, in seconds, required to send an LSA packet on the
interface. LSAs in the update packet have their ages increased by the amount specified by this field
before transmission. If the delay is not added before transmission over a link, the time in which the
LSA propagates over the link is not considered. The value assigned should take into account the
transmission and propagation delays for the interface. This setting has more significance on very
low-speed links. Valid values range from 1 to 65535 seconds. The default value is 1 second.
• Dead Interval to specify the interval, in seconds, in which no hello packets are received, causing
neighbors to declare a router down. Valid values range from 1 to 65535. The default value of this
field is four times the interval set by the Hello Interval field.