Cisco Catalyst 3750 Software Configuration Manual page 675

Chapter 28 Configuring IP Unicast Routing
These are some interface level parameters you can configure:
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Beginning in privileged EXEC mode, follow these steps to configure IS-IS interface parameters:
Command
Step 1 configure terminal
Step 2
interface interface-id
Step 3
isis metric default-metric [level-1 |
level-2]
Step 4
isis hello-interval {seconds |
minimal} [level-1 | level-2]
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The default metric on the interface, which is used as a value for the IS-IS metric and assigned when
there is no quality of service (QoS) routing performed.
The hello interval (length of time between hello packets sent on the interface) or the default hello
packet multiplier used on the interface to determine the hold time sent in IS-IS hello packets. The
hold time determines how long a neighbor waits for another hello packet before declaring the
neighbor down. This determines how quickly a failed link or neighbor is detected so that routes can
be recalculated. Change the hello-multiplier in circumstances where hello packets are lost
frequently and IS-IS adjacencies are failing unnecessarily. You can raise the hello multiplier and
lower the hello interval correspondingly to make the hello protocol more reliable without increasing
the time required to detect a link failure.
Other time intervals:
– Complete sequence number PDU (CSNP) interval. CSNPs are sent by the designated router to
maintain database synchronization
– Retransmission interval. This is the time between retransmission of IS-IS LSPs for
point-to-point links.
– IS-IS LSP retransmission throttle interval. This is the maximum rate (number of milliseconds
between packets) at which IS-IS LSPs are re-sent on point-to-point links This interval is
different from the retransmission interval, which is the time between successive retransmissions
of the same LSP
Designated router election priority, which allows you to reduce the number of adjacencies required
on a multiaccess network, which in turn reduces the amount of routing protocol traffic and the size
of the topology database.
The interface circuit type, which is the type of adjacency desired for neighbors on the specified
interface
Password authentication for the interface
Purpose
Enter global configuration mode.
Specify the interface to be configured and enter interface configuration
mode. If the interface is not already configured as a Layer 3 interface, enter
the no switchport command to put it into Layer 3 mode.
(Optional) Configure the metric (or cost) for the specified interface. The
range is from 0 to 63. The default is 10. If no level is entered, the default is
to apply to both Level 1 and Level 2 routers.
(Optional) Specify the length of time between hello packets sent by the
switch. By default, a value three times the hello interval seconds is
advertised as the holdtime in the hello packets sent. With smaller hello
intervals, topological changes are detected faster, but there is more routing
traffic.
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minimal—causes the system to compute the hello interval based on the
hello multiplier so that the resulting hold time is 1 second.
seconds—the range is from 1 to 65535. The default is 10 seconds.
Catalyst 3750 Metro Switch Software Configuration Guide
Configuring ISO CLNS Routing
28-73