When Cloud Enterprise Network (CEN) advertises Border Gateway Protocol (BGP) routes to leased lines, the original routing autonomous system (AS) paths are not supported. Therefore, in some complex topology scenarios, routing loops may occur. Starting August 1, 2018, the following limits are added to CEN:
  • Virtual border routers (VBRs) that are newly attached to a CEN instance cannot learn routes from each other. For example, virtual private cloud (VPC) 1, VPC 2, VBR 1, and VBR 2 are attached to a CEN instance. Before the limit is implemented, VPC 1, VPC 2, VBR 1, and VBR 2 can communicate with each other. After the limit is implemented, VBR 1 and VBR 2 can communicate with VPC 1 and VPC 2, but VBR 1 cannot communicate with VBR 2. If your business requires the VBRs to communicate with each other, submit a ticket. Alibaba Cloud engineers will assess your network topology and deal with your request.
  • VSwitches at the Alibaba Cloud side do not support original routing AS paths. Therefore, VBRs that belong to VSwitches at the Alibaba Cloud side cannot be attached to a CEN instance by default. If you receive error messages when you attach a VBR that belongs to such a VSwitch to a CEN instance, submit a ticket. Alibaba Cloud engineers will make migration plans for you or allow you to continue to use the VSwitch.

    The preceding limits apply to leased line VBRs that are newly attached to a CEN instance. The preceding limits do not apply to the VBRs that were attached to a CEN instance before this announcement takes effect.