estimating this delay. Set the transmit delay according to link speed, using larger
values for lower-speed links.
If this delay is not added, the time required to transm it an LSA over the l ink is not
taken into consideration by the routing process. On slow links, the router may send
packets more quickly than devices can receive them. To avo id this proble m, you
can use the transmit delay to force the router to w ait a specifi ed inte rval betwe en
transmissions.
•
Retransmit Interval
– Sets the time between resending link-state advertisements.
(Range: 1-65535 seconds; Default: 5 seconds)
A router will resend an LSA to a neighbor if it receiv es no ackno wledgme nt after
the specified retransmit interval. The retransmit interval should be set to a
conservative value that provides an adequate flow of routing info rmat ion, but doe s
not produce unnecessary protocol traffic. Note that this valu e should b e larg er for
virtual links.
Set this interval to a value that is greater than the round-trip delay between any two
routers on the attached network to avoid unnecessary retransmissions.
• Hello Interval – Sets the interval between send ing hello p ackets on an i nterface .
This interval must be set to the same value fo r all ro uters on the networ k.
(Range: 1-65535 seconds; Default: 10)
Hello packets are used to inform other routers that the sending router is still active.
Setting the hello interval to a smaller va lue can r educe the dela y in detect ing
topological changes, but will increase routing traffic.
• Rtr Dead Interval – Sets the interval at which hello packets are not seen before
neighbors declare the router down. This interval must be set to the same value for
all routers on the network. (Range: 1-65535 seconds; D efault: 40 , or 4 times the
Hello Interval)
The dead-interval is advertised in the router's hello packets. It must be a multiple
of hello-interval and be the same for all routers on a specific networ k.
• Cost – Sets the cost of sending a protocol packet on an interface, where hi gher
values indicate slower ports. (Range: 1-65535; Default: 1)
The interface cost indicates the overhead requir ed to send packet s across a
certain interface. This is advertised as the link cost i n router link state
advertisements.
Routes are assigned a metric equal to the sum of all metrics for each interf ace lin k
in the route.
This router uses a default cost of 1 for all ports. Therefore, if you install a 10 Gigabit
module, you need to reset the cost for all of the 1 Gbps ports to a va lue greate r
than 1 to reflect the actual interface band width.
• Authentication Type – Specifi es the authe ntication type used for an int erface.
(Options: None, Simple password, MD5; Default: None)
Use authentication to prevent routers from inadvertently joining an unauthorized
area. Configure routers in the same area with the same pas sword (or key ). All
neighboring routers on the same network with the same password will exchange
routing data.
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Unicast Routing
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