Reference Guide

Multi-topology IS-IS adds TLVs:
● MT TLV — contains one or more Multi-Topology IDs in which the router participates. This TLV is included in IIH and the first
fragment of an LSP.
● MT Intermediate Systems TLV — appears for every topology a node supports. An MT ID is added to the extended IS
reachability TLV type 22.
● MT Reachable IPv4 Prefixes TLV — appears for each IPv4 an IS announces for a given MT ID. Its structure is aligned with
the extended IS Reachability TLV Type 236 and it adds an MT ID.
● MT Reachable IPv6 Prefixes TLV — appears for each IPv6 an IS announces for a given MT ID. Its structure is aligned with
the extended IS Reachability TLV Type 236 and add an MT ID.
By default, the system supports dynamic host name exchange to assist with troubleshooting and configuration. By assigning a
name to an IS-IS NET address, you can track IS-IS information on that address easier. The system does not support ISO CLNS
routing; however, the ISO NET format is supported for addressing.
To support IPv6, the Dell Networking implementation of IS-IS performs the following tasks:
● Advertises IPv6 information in the PDUs.
● Processes IPv6 information received in the PDUs.
● 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 28. 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
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Intermediate System to Intermediate System