Cisco NCS 5500 Series

CHAPTER 2
Implementing IS-IS
Integrated Intermediate System-to-Intermediate System (IS-IS), Internet Protocol Version 4 (IPv4), is a
standards-based Interior Gateway Protocol (IGP). The Cisco software implements the IP routing capabilities
described in International Organization for Standardization (ISO)/International Engineering Consortium (IEC)
10589 and RFC 1195, and adds the standard extensions for single topology and multitopology IS-IS for IP
Version 6 (IPv6).
This module describes how to implement IS-IS (IPv4 and IPv6) on your Cisco IOS XR network.
• Enable IS-IS and Configure Level 1 or Level 2 Routing, on page 3
• Single-Topology IPv6, on page 5
• Customize Routes for IS-IS, on page 12
• Set Priority for Adding Prefixes to RIB, on page 15
• IS-IS Interfaces, on page 16
• Limit LSP Flooding, on page 19
• IS-IS Authentication, on page 23
• Nonstop Forwarding, on page 26
• ISIS NSR, on page 29
• Multiprotocol Label Switching Traffic Engineering, on page 31
• IS-IS Overload Bit Avoidance, on page 37
• Configuring Global Weighted SRLG Protection, on page 39
• References for IS-IS, on page 41
Enable IS-IS and Configure Level 1 or Level 2 Routing
This task explains how to enable IS-IS and configure the routing level for an area.
Configuring the routing level in Step 4 is optional, but is highly recommended to establish the proper level
of adjacencies.
Note
Before you begin
Although you can configure IS-IS before you configure an IP address, no IS-IS routing occurs until at least
one IP address is configured.
Routing Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release 6.3.x
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