Juniper JUNOSE 11.2.X BGP AND MPLS User Manual

multiple tiers of VPNs—the tier-1 backbone VPN of the provider carrier and the tier-2
VPNs of the customer carrier.
In a hierarchical carrier-of-carriers VPN environment, each carrier (or ISP) maintains the
internal routes of its customers in VRF tables on its PE routers. Therefore, the customer
carrier’s internal routes are installed into the VRF routing tables of the provider carrier’s
PE routers and advertised across the provider carrier’s core. Similarly, the internal routes
of the customer carrier’s customers are installed into the VRF routing tables of the
customer carrier’s PE routers. The customer carrier’s external routing information is
exchanged by its PE routers (which connect to the provider carrier’s VPN) over their own
IBGP session.
NOTE: To the customer carrier, the router it uses to connect to the provider carrier’s
VPN is a PE router. However, the provider carrier views this device as a CE router.
Carrier-of-carriers VPNs provide the following benefits to the customer carriers:
•
Reduced VPN administration—The VPN backbone is managed by the provider carrier.
•
Reduced routing management—Intersite routing issues are the responsibility of the
provider carrier.
•
Flexibility—The VPN backbone can be used to deliver both VPN services and Internet
connectivity services.
The following benefits are provided to the provider carriers:
•
Reduced VPN administration—Provider carriers do not have to maintain separate VPNs
for each customer carrier’s end customer.
•
Reduced router management—Customer carriers manage their own CE routers.
•
Scalability—The provider carrier’s PE routers do not maintain the end customer’s
external routes (as required in a traditional networking environment); the
carrier-of-carriers network easily scales as the number of external routes and VPNs
increases.
The following sections describe the two types of carrier-of-carriers environments.
Customer Carrier as an Internet Service Provider
The provider carrier’s VPN can function as the backbone for a customer carrier that
provides Internet services for its customers at multiple sites. In this type of
carrier-of-carriers environment, MPLS label-switched paths are established among the
customer carrier’s PE routers that connect to the provider carrier at each site. Routes are
learned and maintained as follows:
•
The customer carrier’s internal routes are learned and advertised across the provider
carrier’s VPN. The customer carrier’s external routes are not installed in the provider’s
VPN.
Copyright © 2010, Juniper Networks, Inc.470
JunosE 11.2.x BGP and MPLS Configuration Guide

Juniper JUNOSE 11.2.X BGP AND MPLS Specifications

General

Brand	Juniper
Model	JUNOSE 11.2.X BGP AND MPLS
Category	Software
Language	English