Carrier's Carrier - HP 10500 SERIES Configuration Manual

Figure 21 Network diagram for inter-AS option C
VPN 1
CE 1
PE 1
MPLS backbone
AS 100
CE 2
VPN 2
To improve the scalability, you can specify an RR in each AS, making it maintain all VPN-IPv4 routes and
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.
Figure 22 Network diagram for inter-AS option C using RRs

Carrier's carrier

It is possible that a customer of the MPLS L3VPN service provider is also a service provider. In this case,
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 redistribute the routes of the customer network
connected to a Level 2 carrier. It only redistributes 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
Multi-hop MP-EBGP
ASBR 1
(PE) EBGP
PE 2
Multi-hop MP-EBGP
VPN LSP
LSP
VPN 1
PE 3
ASBR 2
(PE)
MPLS backbone
AS 200
PE 4
VPN 2
239
CE 3
CE 4