Dedicated Interconnect overview

Dedicated Interconnect provides direct physical connections between your on-premises network and Google's network. Dedicated Interconnect enables you to transfer large amounts of data between networks, which can be more cost-effective than purchasing additional bandwidth over the public internet.

Before you use Dedicated Interconnect

Ensure that you meet the following requirements:

  • Be familiar with basic network interconnections so that you can order and configure circuits.
  • Be familiar with Cloud Interconnect terminology.
  • Your network must physically meet Google's network in a colocation facility. You must provide your own routing equipment. Your on-premises router is typically located in the colocation facility. However, you can also extend your connection to a router outside of the colocation facility.
  • In the colocation facility, your network devices must support the following technical requirements:

    • 10-Gbps circuits, single mode fiber, 10GBASE-LR (1310 nm), or 100-Gbps circuits, single mode fiber, 100GBASE-LR4

    • IPv4 link local addressing

    • LACP, even if you're using a single circuit

    • EBGP-4 with multi-hop

    • 802.1Q VLANs

How does Dedicated Interconnect work?

For Dedicated Interconnect, you provision a Dedicated Interconnect connection between the Google network and your own network. The following example diagram shows a single Dedicated Interconnect connection between a Virtual Private Cloud (VPC) network and your on-premises network.

A Dedicated Interconnect connection (click to enlarge).
Dedicated Interconnect connection (click to enlarge)

For the basic setup shown in the diagram, a Dedicated Interconnect connection is provisioned between the Google network and the on-premises router in a common colocation facility. Your setup might be different if your on-premises router is not in the same colocation facility as your Dedicated Interconnect demarcation.

When you create a VLAN attachment, you associate it with a Cloud Router. This Cloud Router creates a BGP session for the VLAN attachment and its corresponding on-premises peer router. The Cloud Router receives the routes that your on-premises router advertises. These routes are added as custom dynamic routes in your VPC network. The Cloud Router also advertises routes for Google Cloud resources to the on-premises peer router.

IPv6 support

You have the option of specifying dual-stack IPv4 and IPv6 as a stack type when you create or update a VLAN attachment for Dedicated Interconnect. Configuring your attachment to be dual-stack allows you to exchange IPv6 addresses between your on-premises network and your VPC network.

To enable IPv6 traffic exchange in Dedicated Interconnect, you must also enable IPv6 prefix exchange in the IPv4 BGP sessions that are configured on the associated Cloud Router. Your IPv6-enabled VPC networks must include dual-stack subnets. In addition, the subnets must be assigned internal IPv6 ranges.

You must also configure IPv6 addresses on the VMs in the subnet.

After you configure IPv6 in your VPC network, subnets, and VMs, you can configure dual-stack VLAN attachments. For more information, see Create VLAN attachments and Modify VLAN attachments.

For information about using internal IPv6 ranges in your VPC network and subnets, see Internal IPv6 specifications.


To create and configure a Dedicated Interconnect connection, you start by deciding where you want a Dedicated Interconnect connection and whether you want MACsec for Cloud Interconnect. Then, you order a Dedicated Interconnect connection so that Google can allocate the necessary resources and send you a Letter of Authorization and Connecting Facility Assignment (LOA-CFA). After you receive the LOA-CFA, you need to submit it to your vendor so that they can provision the connections between Google's network and your network.

You then need to configure and test the connections with Google before you can use them. After they're ready, you can create VLAN attachments to allocate a VLAN on the connection.

For detailed steps to provision a Dedicated Interconnect connection, see the Provisioning overview.

Redundancy and SLA

Depending on your availability needs, you can configure Dedicated Interconnect to support mission-critical services or applications that can tolerate some downtime. To achieve a specific level of reliability, Google has two prescriptive configurations:

For the highest level availability, we recommend the configuration for 99.99% availability as the base configuration, as shown in the following diagram. Clients in the on-premises network can reach the IP addresses of virtual machine (VM) instances in the us-central1 region through at least one of the redundant paths. If one path is unavailable, the other paths can continue to serve traffic.

Redundant connections for 99.99% availability (click to enlarge).
Redundant connections for 99.99% availability (click to enlarge)

We recommend that you use the 99.99% availability configuration for production-level applications with a low tolerance for downtime. If your applications aren't mission-critical and can tolerate some downtime, you can use the 99.9% availability configuration.

The SLA requires properly configured topologies that are defined by the 99.99% and 99.9% configurations. These configurations ensure availability and provide an SLA.

Balance egress traffic with redundant connections

When you have a redundant topology similar to the 99.99% configuration, there are multiple paths for traffic to traverse from the VPC network to your on-premises network.

Google Cloud uses ECMP to balance the egress traffic across connections. To use ECMP, the Cloud Routers used by the VLAN attachments must receive the same announcement with equal cost (the same CIDR range and the same MED values).

Dedicated Interconnect does the following to balance traffic across connections:

  • All VLAN attachments operate on Dataplane v1. Traffic is balanced approximately, according to the configured capacity. Traffic balancing might not work optimally when VLAN attachment capacities are different.

  • All VLAN attachments operate on Dataplane v2. Google Cloud balances the traffic between the VLAN attachments based upon the configured capacity of each VLAN attachment.

  • VLAN attachments operate on a mix of Dataplane v1 and v2. Egress traffic might be misbalanced between the VLAN attachments. Misbalanced traffic is most noticeable for attachments with under 1 Gpbs of configured capacity.

    Google is migrating all existing VLAN attachments to use Dataplane v2 without any action required on your part. If you need to migrate to Dataplane v2 to resolve misbalanced VLAN attachments, contact Google Cloud Support.

Create redundant connections with sufficient capacity

The Best practices document describes best practices for creating redundant Cloud Interconnect connections that have sufficient capacity in a failover scenario. Following these practices helps ensure that events such as planned maintenance or hardware failures do not cause loss of connectivity.

Dedicated Interconnect availability

A Dedicated Interconnect connection is considered available if you can send and receive packets (ICMP ping) between a VM in a specific Google Cloud region and a correctly configured machine in your on-premises network. You should be able to send and receive packets through at least one of your redundant connections.

Restrict Dedicated Interconnect usage

By default, any VPC network can use Cloud Interconnect. To control which VPC networks can use Cloud Interconnect, you can set an organization policy. For more information, see Restrict Cloud Interconnect usage.

What's next?