Question

Your company has two Dedicated Interconnect connections in the same metropolitan area, each terminating on a different Google edge availability domain. You create one VLAN attachment on each connection, both associated with a single Cloud Router in the us-central1 region. Your on-premises router advertises the same on-premises prefix (10.50.0.0/16) over both BGP sessions with identical MED values, and both attachments have the same egress capacity. You want Google Cloud to distribute egress traffic toward on-premises across both VLAN attachments simultaneously. What must be true for Cloud Router to perform this load distribution?

Accepted Answer

The BGP sessions must advertise the on-premises prefix with equal MED values so Cloud Router installs equal-cost multipath (ECMP) routes across both attachments.

Answer

Each VLAN attachment must use a Cloud Router in a different region so ECMP can be applied across regional boundaries.

Answer

You must enable global dynamic routing mode on the VPC network, which forces traffic onto a single lowest-cost attachment.

Answer

You must configure a custom static route with equal priority pointing to each attachment, because Cloud Router does not support ECMP for dynamic routes.