Two Dedicated Interconnects attach to Cloud Routers in us-west1 and us-east1. You want default ingress from on-prem to prefer us-west1 and fail over to us-east1 if us-west1 fails. How set MED values?

To achieve default ingress preference for us-west1 and failover to us-east1, you must use global routing. Global routing allows traffic to enter your VPC network through the closest Cloud Router advertising the route, regardless of the region where the resource is located. Setting the base priority on the Cloud Router influences the Multi-Exit Discriminator (MED) value advertised to your on-premises network. A lower MED value is preferred. Therefore, setting us-west1's base priority to 1 makes it the preferred path, while us-east1's base priority of 1000 acts as a higher-cost, failover path. Regional routing would restrict traffic to only enter through Cloud Routers in the same region as the destination, which doesn't support the desired failover across regions.