A virtual border router (VBR) is a product mapping of the leased line that you have applied to access a VSwitch. You can think of it as a router between your customer-premises equipment (CPE) and the VPC, which serves as a bridge for exchanging data between the on-premises IDC and the VPC.
VBR provides following functions:
Exchange data between a VPC and an on-premises IDC as a router.
In the layer-3 subinterface mode, VBR can identify or bind VLAN tags.
Decide the port mode for the leased line: layer-3 interface or VLAN-based layer-3 subinterface.
Support BGP routing.
Each VBR have only one routing table.
The maximum number of custom routing entries in one routing table is 48.
Source address-based policy routing is not supported.