GCP Direct Connect: How It Works & When to Use It

GCP Direct Connect is Google Cloud’s dedicated network connection service that links your on-premises network directly to Google Cloud, bypassing the public internet. You get a private, high-bandwidth, low-latency connection that is more reliable and secure than a standard VPN or internet link. This article explains what GCP Direct Connect is, how it works, how to set it up, and how it compares to other connectivity options.

What Is GCP Direct Connect?

Google Cloud offers a service called Cloud Interconnect, which is the umbrella term for two types of dedicated connections: Dedicated Interconnect and Partner Interconnect. While the phrase “GCP Direct Connect” is often used informally, the official product names are these two. Dedicated Interconnect gives you a physical, private connection between your data center and Google’s network. Partner Interconnect uses a third-party service provider to establish a similar connection, often with lower upfront costs and faster deployment.

These connections are not VPNs over the internet; they are actual network links that provide higher throughput, lower latency, and more consistent performance. They are ideal for workloads that require predictable network performance, such as real-time data processing, large data transfers, or hybrid cloud architectures.

How Does GCP Direct Connect Work?

When you set up a Dedicated Interconnect, you choose a Google Cloud region and a colocation facility where Google has a presence. You then work with that facility to establish a physical cross-connect between your network equipment and Google’s. The connection is made using either 10 Gbps or 100 Gbps Ethernet ports. Once the physical link is up, you create a VLAN attachment in your Google Cloud project, which allows you to route traffic over the connection to your Virtual Private Cloud (VPC) network.

For Partner Interconnect, you don’t deal directly with the colocation facility. Instead, you choose a partner from Google’s list of approved providers. The partner provisions the connection, which can be as small as 50 Mbps or as large as 10 Gbps, and you simply configure a VLAN attachment in the Google Cloud Console. In both cases, the connection is encrypted only if you choose to enable it; by default, traffic is private but not encrypted.

Dedicated vs. Partner Interconnect

Choosing between Dedicated and Partner Interconnect depends on your bandwidth needs, budget, and deployment timeline.

Dedicated Interconnect: Best for high-volume data transfer (10 Gbps or 100 Gbps). You need to be physically near a Google Cloud colocation facility. Setup can take weeks because it involves physical cabling and coordination with the facility.
Partner Interconnect: Best for smaller bandwidth needs (50 Mbps to 10 Gbps) and faster setup. You can often get a connection in days, not weeks, because the partner handles the physical layer. It also works if you are not near a Google colocation facility, as partners have their own points of presence.

Both options provide the same private, low-latency path to Google Cloud, but they differ in operational overhead and cost. Dedicated Interconnect has a higher monthly fee but no per-GB charges; Partner Interconnect often has a lower base fee but may charge for data transfer.

Setting Up GCP Direct Connect

Here is a high-level overview of the setup process for Dedicated Interconnect:

Go to the Google Cloud Console and navigate to Hybrid Connectivity > Interconnect.
Click Create Connection and choose Dedicated Interconnect.
Select a region and a colocation facility from the list. Google shows available facilities and port speeds.
Order the connection. Google provides a service key and instructions for the colocation facility.
Contact the facility to arrange the physical cross-connect. This step may require you to have a router with compatible optics.
Once the link is active (Google verifies it), create a VLAN attachment in the console. Choose a name, a VPC network, and a region.
Configure your on-premises router with BGP (Border Gateway Protocol) settings provided by Google. This establishes the routing between your network and your VPC.
Test the connection by pinging a VM in your VPC from an on-premises machine.

For Partner Interconnect, the steps are simpler: select the partner, order the connection, and then create a VLAN attachment. The partner handles the physical setup and provides you with the BGP details.

Costs and Pricing of GCP Direct Connect

Pricing for Cloud Interconnect is based on the type of connection and the amount of data transferred. Dedicated Interconnect charges a monthly fee per 10 Gbps or 100 Gbps port, plus a separate fee for each VLAN attachment. There are no data transfer charges for traffic that stays within the same region, but if you route traffic between regions, standard egress pricing applies.

Partner Interconnect pricing is set by the partner and varies widely. Typically, you pay a monthly fee based on the bandwidth you order (e.g., 1 Gbps, 5 Gbps). Some partners also charge for data transfer. It’s important to compare quotes from multiple partners and factor in the cost of your on-premises equipment, such as routers and fiber optics.

To estimate your total cost, add the port fee, VLAN attachment fee, and any data transfer fees. Google has a pricing calculator that lets you input your expected usage to get a monthly estimate. Keep in mind that you also need to pay for the physical cross-connect at the colocation facility, which is billed by the facility, not by Google.

Common Problems and Troubleshooting

Even with a dedicated connection, issues can arise. Here are common problems and how to address them:

BGP session flapping: This usually indicates a configuration mismatch. Check that your ASN, IP addresses, and VLAN ID match what Google provided. Also verify that your router’s BGP timers are compatible.
Low throughput: If you’re not getting the expected bandwidth, check for packet loss or high latency on the link. It could be due to a faulty fiber, incorrect MTU settings, or congestion on your on-premises network.
Connection down after maintenance: If the link goes down after a power outage or maintenance, verify that the cross-connect is still physically connected and that your router has rebooted properly. Sometimes you need to re-establish the BGP session manually.
VLAN attachment not showing as active: This often means the physical link is not fully up. Confirm with the colocation facility that the cross-connect is complete and that the port is enabled.

Google Cloud provides a Connectivity Tests tool in the console that can help diagnose routing issues. You can also view logs for your VLAN attachment to see BGP events.

Alternatives to GCP Direct Connect

If a dedicated connection isn’t right for you, there are alternatives:

Cloud VPN: Uses the public internet but encrypts traffic via IPsec. It’s cheaper and faster to set up, but performance is not guaranteed and latency is higher.
Cloud NAT: Not a direct alternative, but it allows instances without external IPs to access the internet. Useful for outbound-only traffic.
Peering (Google Cloud CDN or Google Global Cache): For public content, you can use Google’s peering points to reduce latency, but this is not a private connection.
SD-WAN: Some third-party SD-WAN providers offer connectivity to Google Cloud over their own networks, which can be a middle ground between VPN and Interconnect.

For most production workloads that need consistent performance, Cloud Interconnect is the recommended choice. For development or low-traffic scenarios, Cloud VPN may suffice.

Frequently Asked Questions

Is GCP Direct Connect the same as AWS Direct Connect?

No, they are similar but different products. AWS Direct Connect is Amazon’s dedicated network connection service, while GCP’s equivalent is Cloud Interconnect. The concept is the same—a private connection to the cloud—but the setup, pricing, and features differ. If you’re familiar with AWS Direct Connect, you’ll find GCP Cloud Interconnect conceptually similar but with different console steps and terminology (e.g., VLAN attachments instead of virtual interfaces).

Can I use GCP Direct Connect with multiple VPC networks?

Yes. A single VLAN attachment connects to one VPC network, but you can create multiple VLAN attachments on the same physical connection. Each attachment can be associated with a different VPC network, allowing you to connect to multiple networks over the same dedicated link.

Does GCP Direct Connect encrypt my data?

By default, no. The connection is private and isolated from the public internet, but the data is not encrypted at the network layer. If you need encryption, you can enable MACsec on Dedicated Interconnect (for 100 Gbps links) or use an IPsec VPN over the Interconnect connection, which is a common hybrid approach.

What is the minimum bandwidth for GCP Direct Connect?

For Dedicated Interconnect, the minimum is 10 Gbps. For Partner Interconnect, you can get connections as small as 50 Mbps, making it more accessible for smaller workloads.

How long does it take to set up GCP Direct Connect?

Dedicated Interconnect can take 2-4 weeks because it involves physical cabling and coordination with a colocation facility. Partner Interconnect can be set up in a few days, as the partner handles the physical layer and often has pre-provisioned capacity.

Can I use GCP Direct Connect for internet egress?

Yes, you can route traffic from your VPC to the internet via your on-premises network using the Interconnect connection. This is called “egress through on-premises” and requires configuring specific routes. It’s useful if you want to centralize internet access through your data center for security or compliance reasons.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.

More cards in this drawer

The whole Numbers and Powers drawer →