Juniper IGP - CONFIGURATION GUIDE V11.1.X, Configuration Manual

Page: 359 / 454

Route Tag Structure
On E Series routers, an IS-IS route tag is a 32-bit (4-octet) nonzero number that is
stored as sub-TLV 1 inside the extended IP reachability TLV (type 135). TLV type 135,
in turn, is part of an IS-IS LSP. The route tag is therefore advertised when LSPs are
transmitted in an IS-IS network.
Because TLV type 135 is a new-style TLV tuple, it has a data structure that includes
a wide metric field of four octets. As a result, to use IS-IS route tags you must issue
the metric-style wide command (in Router Configuration mode) to specify that the
router generate and accept only new-style TLV tuples.
For a discussion of IS-IS support for TLV tuples, see “Extensions for Traffic
Engineering” on page 333.
Setting Route Tags
You can set IS-IS route tags in any of the following ways:
■
Tagging a route for IP addresses on an IS-IS passive interface
■
Tagging a route for IP addresses on an IS-IS interface
■
Tagging IS-IS routes by using an associated route map to set the tag
■
Tagging an IS-IS summary address
For instructions and examples on configuring IS-IS route tags, see the sections listed
in Table 14 on page 335.
Table 14: Configuration Tasks for Setting IS-IS Route Tags
See Using This Command To Learn About
“Configuring Passive
Interfaces” on page 352
“passive-interface” on
page 352
Setting a route tag for an IS-IS passive
interface
“Configuring Route Tags for
IS-IS Interfaces” on page 354
“isis tag” on page 355 Setting a route tag for an IS-IS
interface
“Configuring Redistribution”
on page 359
“redistribute” on
page 361
Setting a route tag for a route
redistributed from another protocol
to IS-IS by using an associated route
map
“Redistributing Routes
Between Levels” on page 362
“redistribute isis ip” on
page 363
Setting a route tag for a route
redistributed from one IS-IS level to
another IS-IS level by using an
associated route map
“Configuring Default Routes”
on page 367
“default-information
originate” on page 367
Setting a route tag for an IS-IS default
route by using an associated route
map
Overview
■ 335
Chapter 6: Configuring IS-IS