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

  • You must be familiar with basic network interconnections. You'll be ordering and configuring circuits.
  • You must be familiar with the Cloud Interconnect terminology that's described in Key Terminology.
  • Your network must physically meet Google's network in a colocation facility. You must provide your own routing equipment.
  • In the colocation facility, your on-premises network devices must support the following technical requirements:
    • 10G circuits, single mode fiber, 10GBASE-LR (1310 nm), or 100G 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 cross connect between the Google network and your own router in a common location. The following example shows a single Dedicated Interconnect connection between a Virtual Private Cloud (VPC) network and your on-premises network:

Diagram of a Dedicated Interconnect (click to enlarge)
Dedicated Interconnect (click to enlarge)

For this basic setup, a cross connect is provisioned between the Google network and the on-premises router in a common colocation facility. This cross connect is a Dedicated Interconnect connection.

When you create an interconnect attachment (VLAN), you associate it with a Cloud Router. This Cloud Router creates a BGP session for the interconnect attachment (VLAN) and its corresponding on-premises peer router. Routes that your on-premises router advertises are received by this Cloud Router and 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.

Elements of Dedicated Interconnect

The following definitions explain the different elements that were introduced in the basic setup.


The Cloud Interconnect connection represents a specific physical connection between Google and an on-premises network. This connection exists in a colocation facility where the on-premises network and Google's network meet.

A single connection can be a single 10G link, a single 100G link, or a link bundle, connected to a single Cloud Router. If you have multiple connections to Google at different locations or to different devices, you must create separate Cloud Interconnect connections.

Interconnect attachment (VLAN)

An interconnect attachment, also known as a VLAN attachment, is a logical layer 2 connection between your premises and a VPC network. An attachment allocates a specific 802.1Q VLAN on your Cloud Interconnect connection and connects that VLAN to a VPC network that you specify. Cloud Router establishes a point-to-point BGP session over the VLAN to your on-premises router.

You can create multiple attachments (VLANs) on a single Cloud Interconnect connection. Each attachment is associated with a VPC network and a Google Cloud region:

  • When you associate an attachment for Dedicated Interconnect with a VPC network, this network must be in a project that resides in the same organization as the project that contains the Cloud Interconnect connection.
  • The set of valid regions for an attachment depends upon the colocation facility used by the Cloud Interconnect connection.

You can set the capacity of each attachment. For a list of capacities, see the Pricing page. The default attachment capacity is 10 Gbps.

The capacity setting limits the maximum bandwidth an attachment can use. If you have multiple attachments on a single Cloud Interconnect connection, the capacity limitation might be helpful in cases where you want to prevent network congestion on your connection. The maximum bandwidth is approximate, so it's possible for a attachment to use more bandwidth than the selected capacity.

Since the capacity setting only limits the egress bandwidth from Google Cloud to the colocation facility for the Cloud Interconnect connection, it's recommended that you configure an egress rate limiter on your router for your connection. Configuring this limiter enables you to cap the maximum ingress bandwidth to your VPC network for traffic using that connection.

Interconnect location

The interconnect location is the colocation facility where the Cloud Interconnect connection is provisioned. This is where your on-premises routing equipment meets Google's peering edge.

Each interconnect location supports a subset of Google Cloud regions. For example, the lga-zone1-16 location supports interconnect attachments in the northamerica-northeast1, us-east1, us-west1, us-west2, us-east4, and us-central1 regions.

100 Gbps circuits are not available in all Cloud Interconnect locations. To find out if a location is supported, contact your sales representative.

For a list of all locations and their supported regions, see Choosing colocation facility locations.

Cloud Router

Cloud Router dynamically exchanges routes between your VPC network and your on-premises network through BGP. When you create an interconnect attachment (VLAN), you associate it with a Cloud Router. The Cloud Router creates a BGP session that connects to your on-premises (peer) router.

Unless you configure custom route advertisements, Cloud Router advertises the following routes:

  • If your VPC network uses regional dynamic routing mode, subnet routes in the same region as the Cloud Router.
  • If your VPC network uses global dynamic routing mode, subnet routes in all regions.

Cloud Router also creates custom dynamic routes in your VPC network for destinations it learns from your on-premises peer router. According to the dynamic routing mode of the VPC network (regional or global), Cloud Router makes those routes available to either just the Cloud Router's region or to all regions. For more information about Cloud Router, see the Cloud Router overview.

VLAN attachment

See interconnect attachment.

Provisioning overview

Start by ordering an Cloud Interconnect connection so that Google can allocate the necessary resources and send you an LOA-CFA. After you receive the LOA-CFA, you'll need to submit it to your vendor so that they can provision the cross connects between Google's network and your network.

You'll 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 Cloud Interconnect connection.

For information about all the steps required to provision a Dedicated Interconnect, see the Provisioning Overview in the Creating Dedicated Interconnect how-to guide.


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, one for 99.99% availability and another for 99.9% availability.

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

Base configuration

For the highest level availability, Google recommends the configuration for 99.99% availability, as shown in the following diagram. Clients in the on-premises network can reach the IP addresses of VM instances in the us-central1 region through at least one of the redundant paths and vice versa. If one path is unavailable, the other paths can continue to serve traffic.

Diagram of redundant interconnects for 99.9% availability (click to enlarge)
Redundant interconnects for 99.99% availability (click to enlarge)


Balancing egress traffic with redundant Cloud Interconnect 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. If the Cloud Routers receive the same announcement with equal cost (same CIDR range and same MED values), Google Cloud uses ECMP to balance the egress traffic across connections.

Dedicated Interconnect availability

A Dedicated Interconnect connection is considered available if you can send and receive packets (ICMP Ping) between a VM instance 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.

Frequently-asked questions

For answers to common questions about Cloud Interconnect architecture and features, see the Cloud Interconnect FAQ.

What's next?