Vpns; Interface Process - Juniper M40E Hardware Manual

M40e Multiservice Edge Router Hardware Guide

VPNs

Interface Process

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Routing policy enables you to control (filter) which routes are imported into the routing
table and which routes are exported from the routing table. Routing policy also allows
you to set the information associated with a route as it is being imported into or exported
from the routing table. Routing policies applied to imported routes control the routes
used to determine active routes, whereas policies applied to exported routes control
which routes a protocol advertises to its neighbors.
You implement routing policy by defining policies. A policy specifies the conditions to
use to match a route and the action to perform on the route when a match occurs. For
example, when a routing table imports routing information from a routing protocol, a
routing policy might modify the route's preference, mark the route with a color to identify
it for later manipulation, or prevent the route from even being installed in a routing table.
When a routing table exports routes to a routing protocol, a policy might assign metric
values, modify the BGP community information, tag the route with additional information,
or prevent the route from being exported altogether. You also can define policies for
redistributing the routes learned from one protocol into another protocol.
The Junos OS supports several types of VPNs:
Layer 2 VPNs—A Layer 2 VPN links a set of sites sharing common routing information,
and whose connectivity is controlled by a collection of policies. A Layer 2 VPN is not
aware of routes within a customer's network. It simply provides private links between
a customer's sites over the service provider's existing public Internet backbone.
Layer 3 VPNs—A Layer 3 VPN links a set of sites that share common routing information,
and whose connectivity is controlled by a collection of policies. A Layer 3 VPN is aware
of routes within a customer's network, requiring more configuration on the part of the
service provider than a Layer 2 VPN. The sites that make up a Layer 3 VPN are connected
over a service provider's existing public Internet backbone.
Interprovider VPNs—An interprovider VPN supplies connectivity between two VPNs in
separate autonomous systems (ASs). This functionality could be used by a VPN
customer with connections to several various ISPs, or different connections to the
same ISP in various geographic regions.
Carrier-of-Carrier VPNs—Carrier-of-carrier VPNs allow a VPN service provider to supply
VPN service to a customer who is also a service provider. The latter service provider
supplies Internet or VPN service to an end customer.
The Junos interface process manages the physical interface devices and logical interfaces
on the router. It implements the Junos OS command-line interface (CLI) commands and
configuration statements that you use to specify interface properties such as location
(FPC location in the FPC card cage and PIC location on an FPC), the interface type (such
as SONET/SDH or ATM), encapsulation, and interface-specific properties. You can
configure both interfaces that are currently active and interfaces that might be installed
later.
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