Virtual border routers (VBRs) are an abstraction of Express Connect circuits that are isolated and virtualized by using the Layer 3 overlay and vSwitch technologies in the Software Defined Network (SDN) architecture. A VBR is deployed between a customer-premises equipment (CPE) and a virtual private cloud (VPC) to exchange data between the VPC and data center.
A VBR provides the following features:
- Exchanges data between a VPC and a data center.
- Determines the type of virtual interface of an Express Connect circuit: Layer 3 router interface or Layer 3 VLAN subinterface.
- Adds or identifies VLAN tags if a Layer 3 VLAN subinterface is used.
- Supports Border Gateway Protocol (BGP) routing.
- BGP is a dynamic routing protocol based on Transmission Control Protocol (TCP). BGP is used to exchange routing and network accessibility information across autonomous systems. When you create a connection over an Express Connect circuit, you can configure BGP routing between your data center and the associated VBR. This way, the data center and the VBR can communicate with each other through a private connection. This helps you to set up a hybrid cloud with higher efficiency, flexibility, and security.
- VBRs support BGP dynamic routing in both IPv4 and IPv6 networks.
- VBRs do not support source address-specific policy-based routes.
- Each VBR has one and only one route table.
- VBRs support only BGP-4.
- You can create at most eight BGP peers for each VBR.
- Each BGP peer supports at most 110 dynamic routes. Routes are denied when the upper limit is exceeded.
- To configure BGP when you connect to a VPC, you must specify an Autonomous System Number (ASN) for the VPC. The ASN that you specify must be different from the ASNs of the vSwitches in the VPC.