Operation Manual – MPLS L3VPN
H3C S9500 Series Routing Switches
Chapter 1 MPLS L3VPN Configuration
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3)
Recursion and extension of HoVPN
HoVPN supports HoPE recursion:
z
A HoPE can act as a UPE to form a new HoPE with an SPE.
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A HoPE can act as an SPE to form a new HoPE with multiple UPEs.
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HoVPN supports multi-level recursion.
With recursion of HoPEs, a VPN can be extended infinitely in theory.
Figure 1-14
Recursion of HoPEs
Figure 1-14
shows a three-level HoPE. The PE in the middle is called the middle-level
PE (MPE). MP-BGP runs between SPE and MPE, as well as between MPE and UPE.
Note:
The term of MPE does not really exist in a HoVPN model. It is used here just for the
convenience of description.
MP-BGP advertises all the VPN routes of the UPEs to the SPEs, but advertises only the
default routes of the VPN instance of the SPEs to the UPEs.
The SPE maintains the VPN routes of all sites in the HoVPN, while each UPE maintains
only VPN routes of its directly connected sites. The number of routes maintained by the
MPE is between the above two.
