Reference Guide

Except where identified, the commands described in this chapter apply to both IPv4 and IPv6 versions of IS-IS.
Configuration Tasks for IS-IS
The following describes the configuration tasks for IS-IS.
• Enabling IS-IS
• Configure Multi-Topology IS-IS (MT IS-IS)
• Configuring IS-IS Graceful Restart
• Changing LSP Attributes
• Configuring the IS-IS Metric Style
• Configuring IS-IS Cost
• Changing the IS-Type
• Controlling Routing Updates
• Configuring Authentication Passwords
• Setting the Overload Bit
• Debuging IS-IS
Enabling IS-IS
By default, IS-IS is not enabled.
The system supports one instance of IS-IS. To enable IS-IS globally, create an IS-IS routing process and assign a NET
address. To exchange protocol information with neighbors, enable IS-IS on an interface, instead of on a network as with
other routing protocols.
In IS-IS, neighbors form adjacencies only when they are same IS type. For example, a Level 1 router never forms an
adjacency with a Level 2 router. A Level 1-2 router forms Level 1 adjacencies with a neighboring Level 1 router and
forms Level 2 adjacencies with a neighboring Level 2 router.
NOTE: Even though you enable IS-IS globally, enable the IS-IS process on an interface for the IS-IS process to
exchange protocol information and form adjacencies.
To configure IS-IS globally, use the following commands.
1. Create an IS-IS routing process.
CONFIGURATION mode
router isis [tag]
tag: (optional) identifies the name of the IS-IS process.
2. Configure an IS-IS network entity title (NET) for a routing process.
ROUTER ISIS mode
net network-entity-title
Specify the area address and system ID for an IS-IS routing process. The last byte must be 00.
For more information about configuring a NET, refer to IS-IS Addressing.
3. Enter the interface configuration mode.
CONFIGURATION mode
interface interface
Enter the keyword interface then the type of interface and slot/port information:
– For a 1-Gigabit Ethernet interface, enter the keyword GigabitEthernet then the slot/port information.
– For the Loopback interface on the RPM, enter the keyword loopback then a number from 0 to 16383.
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