H3C Technologies H3C S12500-X Series Switches - Manual (Page 122)

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Figure 40 Scenario where the Level 2 carrier is an MPLS L3VPN service provider
NOTE:
If equal cost routes exist between the Level 1 carrier and the Level 2 carrier, H3C recommends that you
establish equal cost LSPs between them.
Nested VPN
The nested VPN technology exchanges VPNv4 routes between PEs and CEs of the ISP MPLS L3VPN and
allows a customer to manage its own internal VPNs. Figure 41 shows a nested VPN network. On the
service provider's MPLS VPN network, there is a customer VPN named VPN A. The customer VPN
contains two sub-VPNs, VPN A-1 and VPN A-2. The service provider PEs consider the customer's network
as a common VPN user and do not join any sub-VPNs. The service provider CE devices (CE 1 and CE
2) exchange VPNv4 routes including sub-VPN routing information with the service provider PEs, which
implements the propagation of the sub-VPN routing information throughout the customer network.