Cloud Router is a fully distributed and managed service that programs custom dynamic routes and scales with the network traffic.
Cloud Router works with both legacy networks and VPC networks.
Cloud Router isn’t a connectivity option, but a service that works over Cloud VPN or Interconnect connections to provide dynamic routing by using the Border Gateway Protocol (BGP) for the VPC networks.
Cloud Router isn’t supported for Direct Peering or Carrier Peering connections.
Cloud Router isn’t a physical device that might cause a bottleneck, and it can’t be used by itself.
Cloud Router is required or recommended in the following cases:
Required for Cloud NAT
Required for Cloud Interconnect and HA VPN
A recommended configuration option for Classic VPN.
Cloud Router helps dynamically exchange routes between the Google Cloud networks and the on-premises network.
Cloud Router peers with the on-premises VPN gateway or router to provide dynamic routing and exchanges topology information through BGP.
Cloud Router frees you from maintaining static routes
Google Cloud recommend creating two Cloud Routers in each region for a Cloud Interconnect for 99.99% availability.
Cloud Router supports following dynamic routing mode
Regional routing mode – provides visibility to resources only in the defined region.
Global routing mode – provides has visibility to resources in all regions