Usage Scenario
Hierarchy of VPN (HoVPN) refers to a hierarchical VPN, with multiple provider edges (PEs) functioning as different roles to form a hierarchical architecture and provide functions of a single PE. In this manner, the performance requirement on PEs is lowered. If the peer default-originate vpn-instance command is used, superstratum PE (SPE) sends the default route with the address of the next hop as the local address to underlayer PE (UPE), regardless of whether there is a default route in the local routing table. The underlayer PE (UPE) then only needs to maintain the local VPN routes, whereas all remote routes are replaced by the default route. The workload of the UPE is reduced.
Precautions
The default routes on the UPE can be obtained through the following methods:
- Run the peer default-originate vpn-instance command on the SPE to configure routes for the neighboring UPE.
- Import routes through the import-route (BGP) or network (BGP) command on the UPE.
The priority of the default route obtained through the former method is higher than that through the latter method. If the former method is adopted, the UPE sends neither update nor withdraw packets in the latter method.