Configuration Options For The Backbone And Customer Carriers; Customer Carrier: Isp With Ip Core - Cisco CRS Configuration Manual

Implementing MPLS Layer 3 VPNs
• Customer carriers can use any link layer technology to connect the CE routers to the PE routers and the
• The customer carrier can use any addressing scheme and still be supported by a backbone carrier.
Benefits of Implementing MPLS VPN CSC Using BGP
The benefits of using BGP to distribute IPv4 routes and MPLS label routes are:
• BGP takes the place of an IGP and LDP in a VPN forwarding and routing instance (VRF) table.
• BGP is the preferred routing protocol for connecting two ISPs.

Configuration Options for the Backbone and Customer Carriers

To enable CSC, the backbone and customer carriers must be configured accordingly:
• The backbone carrier must offer BGP and MPLS VPN services.
• The customer carrier can take several networking forms. The customer carrier can be:
An IGP in the customer carrier network is used to distribute next hops and loopbacks to the CSC-CE.
Note
IBGP with label sessions are used in the customer carrier network to distribute next hops and loopbacks
to the CSC-CE.

Customer Carrier: ISP with IP Core

The following figure shows a network configuration where the customer carrier is an ISP. The customer carrier
has two sites, each of which is a point of presence (POP). The customer carrier connects these sites using a
VPN service provided by the backbone carrier. The backbone carrier uses MPLS or IP tunnels to provide
VPN services. The ISP sites use IP.
Figure 36: Network: Customer Carrier Is an ISP
The links between the CE and PE routers use eBGP to distribute IPv4 routes and MPLS labels. Between the
links, the PE routers use multiprotocol iBGP to distribute VPNv4 routes.
PE routers to the P routers.
◦An ISP with an IP core (see the
◦An MPLS service provider with or without VPN services (see
Provider").
Cisco IOS XR Virtual Private Network Configuration Guide for the Cisco CRS Router, Release 6.1.x
Configuration Options for the Backbone and Customer Carriers
"Customer Carrier: ISP with IP
Core").
"Customer Carrier: MPLS Service
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