HP HSR6800 Configuration Manual page 261

Implementation of HoVPN
Figure 78 Basic architecture of HoVPN
As shown in
user-end PEs, whereas devices that are connected to 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.
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 different requirements:
•
An SPE is required to have large-capacity routing table, high forwarding performance, and
fewer interface resources.
•
A UPE is required to have small-capacity routing table, low forwarding performance, but higher
access capability.
HoVPN makes 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.
SPE-UPE
The MP-BGP running between SPE and UPE can be either MP-IBGP or MP-EBGP. Which one to
use depends on whether the UPE and SPE belong to a same AS.
Figure 78, devices directly connected to CEs are called underlayer PEs (UPEs) or
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