Hierarchical Mpls L3Vpn Implementation - H3C S9500 Series Operation Manual

Operation Manual – MPLS L3VPN
H3C S9500 Series Routing Switches
Configuring BGP on the MPLS backbone network (create IBGP peers between
provider PEs).
Configuring basic MPLS capability on user-end network (including customer PEs).

1.1.4 Hierarchical MPLS L3VPN Implementation

As PE is required to aggregate multiple VPN routes on a MPLS L3VPN, it is prone to
forming a bottleneck in a large-scale deployment or in the case that PE capacity is
small. To solve the problem, Hangzhou H3C Technologies Co., Ltd. introduced the
HoVPN (Hierarchy of VPN, Hierarchical MPLS L3VPN) solution.
Hierarchical MPLS L3VPN divides an MPLS VPN into several MPLS VPNs in a
hierarchical network structure. Each VPN takes on a role depending on its level. There
are high performance requirements in routing and forwarding on the PEs at the higher
level of MPLS VPN, because they are primarily used for connecting the backbone
networks and providing access service for huge VPN clients. However, such
requirements are relatively low for PEs at the lower level of the network as they
primarily function to access the VPN clients at the edges. Congruous with the IP
network model, HoVPN model improves the scalability of MPLS L3VPN, and hence
allows lower-layer MPLS VPNs comprising low-end equipment to provide MPLS VPN
accessing and interconnect through the high-end MPLS VPN backbone.
As shown in
(underlayer PE or user-end PE); the devices in the core network connected with the
UPEs are called SPE (superstratum PE or service-provider-end PE).
Hierarchical PEs have the same appearance as that of the traditional PEs and can
coexist with other PEs in the same MPLS network.
UPEs are responsible for user access; they only maintain the routes of directly
connected VPN sites, but not that of the remote sites. SPEs, however, are responsible
for the maintenance and advertisement of VPN routes; they maintain all the routes of
the VPNs connected by their UPEs, including the routes in both local and remote sites.
UPE and SPE are relative concepts. In a multi-layer PE architecture, an upper layer PE
is an SPE for its lower layer PE, and a lower layer PE is an UPE for its upper layer PE.
The MBGP runs between SPE and UPE can be either MP-IBGP or MP-EBGP,
depending on whether the SPE and the UPE are in the same AS.
Figure 1-5, the PEs directly connected with user devices are called UPE
Chapter 1 MPLS L3VPN Configuration
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