Concept Guide

Table Of Contents
Computes routes to IPv6 destinations.
Downloads IPv6 routes to the RTM for installing in the FIB.
Accepts external IPv6 information and advertises this information in the PDUs.
The following table lists the default IS-IS values.
Table 50. IS-IS Default Values
IS-IS Parameter Default Value
Complete sequence number PDU (CSNP) interval 10 seconds
IS-to-IS hello PDU interval 10 seconds
IS-IS interface metric 10
Metric style Narrow
Designated Router priority 64
Circuit Type Level 1 and Level 2
IS Type Level 1 and Level 2
Equal Cost Multi Paths 16
Configuration Information
To use IS-IS, you must configure and enable IS-IS in two or three modes: CONFIGURATION ROUTER ISIS, CONFIGURATION
INTERFACE, and ( when configuring for IPv6) ADDRESS-FAMILY mode. Commands in ROUTER ISIS mode configure IS-IS
globally, while commands executed in INTERFACE mode enable and configure IS-IS features on that interface only. Commands
in the ADDRESS-FAMILY mode are specific to IPv6.
NOTE:
When using the IS-IS routing protocol to exchange IPv6 routing information and to determine destination
reachability, you can route IPv6 along with IPv4 while using a single intra-domain routing protocol. The configuration
commands allow you to enable and disable IPv6 routing and to configure or remove IPv6 prefixes on links.
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
Debugging 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.
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Intermediate System to Intermediate System