Hierarchy VPN (HVPN) is a VPN technology applied to hierarchical networks. Conventional BGP/MPLS IP VPN adopts a flat network model and requires all provider edges (PEs) to have the same performance. If the performance of some PEs is not so high, the performance of the entire network is affected, limiting the number of access users. To solve this problem, HVPN converts the flat network model into a hierarchical network model to lower the requirements on device performance level by level, improve network scalability, and facilitate the planning and design of large-scale networks.
Why Do We Need HVPN?
Background of HVPN
A BGP/MPLS IP VPN adopts a flat network model. It uses the Border Gateway Protocol (BGP) to advertise VPN routes and Multiprotocol Label Switching (MPLS) to forward VPN packets on the service provider's backbone network. On the network shown in the following figure, PEs refer to edge devices on the service provider network. All PEs are on the same plane.
BGP/MPLS IP VPN model
On a BGP/MPLS IP VPN, the pressure of VPN service deployment is concentrated on PEs, which are all required to deliver the same level of performance. As the network grows in both scale and service diversity, the access capabilities of some PEs fail to meet requirements. On a flat network, the performance issues of some PEs may affect the performance and scalability of the entire network, which is not conducive to large-scale VPN deployment. Moreover, hierarchical architectures are currently used in most networking design scenarios. For example, metro networks typically use a three-layer architecture consisting of the access layer, aggregation layer, and core layer. To deploy VPN functions on a hierarchical network, hierarchy VPN (HVPN) is introduced.
To prevent the low performance levels of some PEs from affecting the performance of the entire network and limiting the number of access users, the BGP/MPLS IP VPN needs to shift from the flat model to the hierarchical model. In other words, HVPN needs to be deployed. On the network shown in the following figure, HVPN distributes PE functions across multiple PEs that play different roles.
HVPN Networking and Advantages
HVPN networking
