Key Terminology

Read the following key terms to understand the concepts on which Cloud Interconnect is built. These terms might apply to Dedicated Interconnect, Partner Interconnect, or both.

Colocation facility (also known as an Interconnect location)

For Dedicated Interconnect, a colocation facility is where Google has a point of presence, allowing you to connect your on-premises network with Google's network. In the colocation facility, work with the facility provider to provision your routing equipment before using Dedicated Interconnect. For a list of facilities and their supported regions, see Colocation Facility Locations.

For Partner Interconnect, supported service providers will have connected to Google in at least one of these facilities.

Edge availability domain

Each metropolitan area (metro) has at least two zones called edge availability domains. These domains provide isolation during scheduled maintenance, meaning that two domains in the same metro won't be down for maintenance at the same time. This isolation is important when you're building for redundancy.

Edge availability domains span a single metro, not across metros. To maintain availability and an SLA, you must build duplicate interconnects in different domains in the same metro. For example, building interconnects in dfw-zone1-4 and dfw-zone2-4 provides redundancy across different Edge availability domains, whereas dfw-zone1-4 and dfw-zone1-505 do not because they are in the same Edge availability domain.

Maintenance windows are not co-ordinated across metros. For instance, the edge availability domains dfw-zone1-4 and ord-zone1-7 could experience overlapping maintenance events. When connecting to multiple metros for redundancy, it is important to connect to different Edge availability domains in each of those metros, as described in the production topology.


A Letter of Authorization and Connecting Facility Assignment (LOA-CFA) identifies the connection ports that Google has assigned for your connection and grants permission for a vendor in a colocation facility to connect to them. LOA-CFA documents are required when you order Dedicated Interconnect connections in a colocation facility.

When you order dedicated connections, Google allocates resources for your interconnects and then generates an LOA-CFA document for each one. The LOA-CFA lists the demarcation points that Google allocated for your interconnects. Submit this form to the facility vendor to provision cross connects between Google's equipment and your own. Once the status of an interconnect changes to PROVISIONED, the LOA-CFA is no longer valid, necessary, or available in the Cloud Console.

For more information about the provisioning flow, see the Dedicated Interconnect Provisioning overview.

Metropolitan area

A metropolitan area (metro) is the city where a colocation facility is located. When you create an interconnect, you select the colocation facility and metro where the interconnect will live.

The metro you choose depends on the location of your on-premises network and the location of your VM instances (their GCP region). Typically, you might want to pick a metro that's geographically close to your on-premises network to reduce latency. For redundancy, you might choose a metro that is further away.

In regards to the GCP region, each metro supports a subset of regions. You can create VLAN attachments in these supported regions only. For example, if you pick a facility in Ashburn, you can only create VLAN attachments in the North American regions. Assuming your VM instances are also in these regions, you can create VLAN attachments in the same regions to reduce latency and egress costs. Otherwise, traffic would have to travel between regions to reach your VM instances or on-premises network.

For more information, see Colocation Facility Locations.

Metropolitan availability zone

See edge availability domain.

Pairing key

Pairing keys are used only for Partner Interconnect. It's a unique identifier that allows service providers to identify particular VLAN attachments without anyone sharing potentially sensitive information about their VPC network or GCP project. Treat the pairing key as sensitive information until your VLAN attachment is configured. If it's discovered, it's possible for other parties to use it to connect to your network. The key is one-time use and can't be modified. If you need a new pairing key, delete your VLAN attachment and then create a new one.

Pairing keys use the following format: <random>/<vlan-attachment-region>/<edge-availability-domain>. For example, 7e51371e-72a3-40b5-b844-2e3efefaee59/us-central1/2 is a pairing key for a VLAN attachment in the us-central1 region and edge availability domain 2.

Service provider

A network service provider. To use Partner Interconnect, you're required to connect to a supported service provider. The service provider provides connectivity between your on-premises network and your VPC network.