Carrier's Carrier - HPE 5820X Series Configuration Manual

Figure 69 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 70 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 through the BGP session established between the routers of the Level 2 carrier. This can
greatly reduce the number of routes maintained by the Level 1 carrier network.
Multi-hop MP-EBGP
ASBR 1
EBGP
(PE)
PE 2
Multi-hop MP-EBGP
VPN LSP
LSP
VPN 1
PE 3
ASBR 2
(PE)
MPLS backbone
AS 200
PE 4
VPN 2
253
CE 3
CE 4