R21xx-HP FlexFabric 11900 MPLS Configuration Guide

Figure 34 Network diagram for inter-AS option C

To improve the scalability, you can specify an RR in each AS to maintain all VPN-IPv4 routes and to

exchange VPN-IPv4 routes with PEs in the AS. The RRs in two ASs establish an inter-AS VPNv4

connection to advertise VPN-IPv4 routes, as shown in Figure 35.

Figure 35 Network diagram for inter-AS option C u

sing RRs

Carrier's carrier

If a customer of the MPLS L3VPN service provider is also a service provider, the MPLS L3VPN service

provider is called the provider carrier or the Level 1 carrier, while the customer is called the customer

carrier or the Level 2 carrier. This networking model is referred to as carrier's carrier. In this model, the

Level 2 service provider serves as a CE of the Level 1 service provider.

For good scalability, the Level 1 carrier does not learn the routes of the customer network connected to

a Level 2 carrier. It only learns the routes for delivering packets between different sites of the Level 2

carrier. Routes of the customer networks connected to a Level 2 carrier are exchanged through the BGP

VPN 1

CE 1

PE 1

PE 3

VPN 1

CE 3

CE 2

VPN 2 VPN 2

PE 2

PE 4

ASBR 1

(PE)

ASBR 2

(PE)

VPN LSP

CE 4

EBGP

AS 100 AS 200

MP-IBGP

-IBGP

Multi-hop MP-EBGP

MPLS backbone MPLS backbone

LSP