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Cisco ME 3800X and 3600X Switch Software Configuration Guide
OL-23400-01
Chapter 29 Configuring IP Unicast Routing
Configuring ISO CLNS Routing
to the default conditions for summary addressing, LSP refresh interval, LSP lifetime, LSP timers, SFP
timers, and PRC timers, use the no form of the commands. Use the no partition avoidance router
configuration command to disable the output format.
Configuring IS-IS Interface Parameters
You can optionally configure certain interface-specific IS-IS parameters, independently from other
attached routers. However, if you change some values from the defaults, such as multipliers and time
intervals, it makes sense to also change them on multiple routers and interfaces. Most of the interface
parameters can be configured for level 1, level 2, or both.
Interface level parameters:
•
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
Beginning in privileged EXEC mode, follow these steps to configure IS-IS interface parameters:
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface interface-id
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.
Step 3
isis metric default-metric [level-1 |
level-2]
(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.
