Integrated Is-Is; Equal-Cost Multipath; Static Ppp Interfaces; Route Tags - Juniper IGP - CONFIGURATION GUIDE V11.1.X Configuration Manual

JUNOSe 11.0.x IP, IPv6, and IGP Configuration Guide

Integrated IS-IS

The E Series router supports the Integrated IS-IS version of IS-IS. Integrated IS-IS
provides a single routing algorithm to route both TCP/IP and OSI Connectionless
Network Protocol (CLNP) packets. This design adds IP-specific information to the
OSI IS-IS routing protocol. It supports IP subnetting, variable subnet masks, type of
service (ToS), and external routing.
Integrated IS-IS allows for the mixing of routing domains; that is, IP-only routers,
OSI-only routers, and dual (IP and OSI) routers. OSI and IP packets are forwarded
directly over the link-layer services without needing mutual encapsulation. The E
Series router supports IS-IS only for the routing and forwarding of TCP/IP packets.
Forwarding of OSI packets is not supported.

Equal-Cost Multipath

IS-IS supports equal-cost multipath (ECMP) and installs into the routing table multiple
entries for paths to the same destination. Each of these multiple paths to a given
destination must have the same cost as the others, but a different next hop.

Static PPP Interfaces

When IS-IS has been configured on a static PPP interface, the IS-IS neighbor does
not come up if you remove the IP address from the interface and then add the IP
address back to the interface. Consequently, when you remove and add back the IP
address, you must also remove the IS-IS configuration from the interface and then
add the configuration back to the interface by issuing the no router isis and router
isis commands.

Route Tags

E Series routers support the use of route tags, also known as administrative tags, as
a means of tagging the IP addresses on an IS-IS route before the route is propagated
to other routers in an IS-IS domain. You must reference the tag in a route map to
apply administrative policies to the IS-IS route that matches this tag.

Route Tag Applications

An administrative policy controls how a router handles the routes it receives from
and sends to neighboring routers, and governs the installation of routes in the routing
table. Examples of the types of administrative policies that you might apply with a
route tag include:
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Overview
Policies for redistributing routes received from other protocols in the routing
table to IS-IS
Policies for redistributing routes between levels in an IS-IS routing hierarchy; this
is also referred to as route leaking
Policies for summarizing routes redistributed into IS-IS or within IS-IS by creating
aggregate (summary) addresses