HP 12500 Series Configuration Manual page 215

Basic architecture of HoVPN
Figure 60 Basic architecture of HoVPN
VPN 1
CE
As shown in
whereas routers that are connected with UPEs and are in the internal network are called superstratum PEs
(SPE) or service provider-end PEs.
The hierarchical PE consists of multiple UPEs and SPEs, which function together as a traditional PE.
NOTE:
With the HoVPN solution, PE functions are implemented hierarchically. Hence, the solution is also called
hierarchy of PE (HoPE).
UPEs and SPEs play the following different roles:
A UPE allows user access. It maintains the routes of the VPN sites that are directly connected with
•
it, It does not maintain the routes of the remote sites in the VPN, or only maintains their summary
routes. A UPE assigns inner labels to the routes of its directly connected sites, and advertises the
labels to the SPE along with VPN routes through MP-BGP.
An SPE manages and advertises VPN routes. It maintains all the routes of the VPNs connected
•
through UPEs, including the routes of both the local and remote sites. An SPE advertises routes
along with labels to UPEs, including the default routes of VPN instances or summary routes and the
routes permitted by the routing policy. By using routing policies, you can control which nodes in a
VPN can communicate with each other.
Different roles mean the following different requirements:
SPE: An SPE is required to have large-capacity routing table, high forwarding performance, and
•
fewer interface resources.
• UPE: A UPE is required to have small-capacity routing table, low forwarding performance, but
higher access capability.
HoVPN takes full use of both the high performance of SPEs and the high access capability of UPEs.
The concepts of SPE and UPE are relative. In the hierarchical PE architecture, a PE may be the SPE of its
underlayer PEs and a UPE of its SPE at the same time.
The HoPE and common PEs can coexist in an MPLS network.
PE
MPLS network
UPE SPE
VPN 2
Site 1
CE
Figure 60, routers directly connected to CEs are called underlayer PEs (UPEs) or user-end PEs,
PE
UPE
VPN 1 VPN 2
Site 2
CE
207
CE