Establish 99.9% availability for Dedicated Interconnect

The topology for 99.9% availability is suitable for non-critical applications that can tolerate some downtime. For example, your organization might do batch uploads for which the timing of the operation isn't critical. If a connection isn't available, the operation continues when connectivity is restored.

For Cloud Interconnect terminology used on this page, see Key terms.

For information about creating redundant Cloud Interconnect connections that have sufficient capacity in a failover scenario, see Best practices.


The following resources and settings are required to achieve 99.9% availability:

  • At least two Cloud Interconnect connections. The connections must be located in the same metropolitan area (metro), but in different edge availability domains (metro availability zones). It doesn't matter if the connections are in the same facility or in different facilities, as long as they are located in two different edge availability domains.

  • At least one Cloud Router. Each Cloud Interconnect connection must be attached to the Cloud Router.

Example topology

The following example topology shows two Cloud Interconnect connections in the same metro but in different colocation facilities: lga-zone1-16 and lga-zone2-1422. The Cloud Router is in the vpc1 network in the us-central1 region.

Redundant connections for 99.9% availability (click to enlarge).
Redundant connections for 99.9% availability (click to enlarge)

Creating a 99.9% topology

The following sections walk through the steps for creating this topology. To create a topology that's tailored for you, replace the sample input values with your own. For example, replace the vpc1 network name with your VPC network name.

Order Cloud Interconnect connections

Order duplicate connections by using the Google Cloud console or the Google Cloud CLI.


  1. In the Google Cloud console, go to the Interconnect Hybrid Connectivity page.

    Go to Interconnect Hybrid Connectivity

  2. Click Get started.

  3. Select Dedicated Interconnect, and then click Continue.

  4. Select Order new Dedicated Interconnect, and then click Continue.

  5. Specify the details for the Cloud Interconnect connection:

    • Name: Enter int-lga1.
    • Description: Enter Example Cloud Interconnect connection in LGA ZONE1.
    • Location: Choose Digital Realty | Telx New York (111 8th Ave), which is the PeeringDB name for the lga-zone1-16 location.
    • Capacity: Use the default capacity (10 Gb/s).
  6. Click Next.

  7. Specify the details for the redundant Cloud Interconnect connection:

    • Name: Enter int-lga2.
    • Description: Enter Example Cloud Interconnect connection in LGA ZONE2.
    • Location: Choose zColo New York - 60 Hudson St, which is the PeeringDB name for the lga-zone2-1422 location.
    • Capacity: Use the default capacity (10 Gb/s).
  8. Click Next.

  9. Specify your contact information:

    • Company name: Enter The Customer. This name is used in the LOA-CFA as the party authorized to request a Cloud Interconnect connection.
    • Technical contact: Enter You don't need to enter your own address; you are included in all notifications.
  10. Click Next.

  11. Review your order. Check that your Cloud Interconnect connections details and contact information are correct. If everything is correct, click Place order. If not, go back and edit the connection details.

  12. On the order confirmation page, review the next steps, and then click Done.


  • Order two Cloud Interconnect connections with the names int-lga1 and int-lga2:

    gcloud compute interconnects create int-lga1 \
      --customer-name "The Customer" \
      --description "Example Cloud Interconnect connection in LGA ZONE1" \
      --interconnect-type DEDICATED \
      --link-type ETHERNET_10G_LR \
      --location lga-zone1-16 \
      --requested-link-count 1 \
    gcloud compute interconnects create int-lga2 \
      --customer-name "The Customer" \
      --description "Example Cloud Interconnect connection in LGA ZONE2" \
      --interconnect-type DEDICATED \
      --link-type ETHERNET_10G_LR \
      --location lga-zone2-1422 \
      --requested-link-count 1 \

After you order Cloud Interconnect connections, Google emails you a confirmation and allocates ports for you. When the allocation is complete, Google generates LOA-CFAs for your connections and emails them to you. All the automated emails are sent to the NOC contact and the person who ordered the connections.

You are able to use the Cloud Interconnect connections only after your connections have been provisioned and tested. For more information about the provisioning process, see the Provisioning overview.

Create a Cloud Router

To create a Cloud Router, follow the instructions in this section.


  1. In the Google Cloud console, go to the Create a Cloud Router page.

    Go to Create a Cloud Router

  2. Specify the Cloud Router details:

    • Name: Enter router1 for the name of the Cloud Router.
    • Network: Select vpc1, which is the name of the network where the on-premises network extends to.
    • Region: Select us-central1, which is the region where the Cloud Router advertises all subnets, as shown in the example topology.
    • Google ASN: Enter 64513, which is the ASN for the example Cloud Router.
  3. Under Routes, select Advertise all subnets visible to the Cloud Router (default), and then click Create.


  • Create a Cloud Router in the vpc1 network in the us-central1 region; use ASN 64513:

    gcloud compute routers create router1 \
      --asn 64513 \
      --network vpc1 \
      --region us-central1

Create VLAN attachments

After your Cloud Interconnect connections are ready to use (in the ACTIVE state), create VLAN attachments to connect the connections with Cloud Router. Create duplicate attachments, one for each connection. In the example, int-lga1 and int-lga2 are connected to router1.


  1. In the Google Cloud console, go to the VLAN attachments tab.

    Go to VLAN attachments

  2. Click Add VLAN attachment.

  3. Select Dedicated Interconnect, and then click Continue.

  4. Select In this project.

  5. Select the int-lga1 Cloud Interconnect connection, and then click Continue.

  6. Select Add VLAN attachment:

    • Name: Enter attachment-lga1-central1.
    • Router: Select the router1 Cloud Router.
  7. Click Create. The attachment takes a few moments to create.

  8. For the attachment, to add a BGP session to router1, click Configure. The VLAN attachment has already populated the Google and Peer BGP IP addresses.

  9. Record the IP addresses, ASNs, and VLAN tag for each attachment. This information is required to configure the on-premises router.

  10. To add the BGP session, click Save configuration. The BGP sessions are inactive until you configure BGP on your on-premises router.

  11. Create another attachment named attachment-lga2-central1 for the int-lga2 connection. Use router1 for the attachment's Cloud Router.


  1. Create two attachments, one for the int-lga1 Cloud Interconnect connection and the router1 Cloud Router and another for the int-lga2 connection and router1:

    gcloud compute interconnects attachments create attachment-lga1-central1 \
       --interconnect int-lga1 \
       --router router1
    gcloud compute interconnects attachments create attachment-lga2-central1 \
       --interconnect int-lga2 \
       --router router1
  2. Describe the attachment-lga1-central1 attachment to retrieve the resources that it allocated, such as the VLAN ID and BGP peering addresses; use these values to configure the Cloud Router and on-premises router:

    gcloud compute interconnects attachments describe attachment-lga1-central1 \
       --region us-central1

    The previous command outputs the following information:

    creationTimestamp: '2017-08-15T08:34:11.137-07:00'
    id: '5630382895290821276'
    kind: compute#interconnectAttachment
    name: attachment-lga1-central1
    operationalStatus: ACTIVE
      tag8021q: 1000
  3. Record the following values:

    • tag8021q: Specifies the VLAN ID, which is 1000. The VLAN ID identifies traffic that goes across this attachment. Use this value to configure a tagged VLAN subinterface on the on-premises router.
    • cloudRouterIpAddress: The Cloud Router IP address, which is Assign this address to a Cloud Router interface, and specify this address as the BGP neighbor on the on-premises router.
    • customerRouterIpAddress: The customer router IP address, which is On the Cloud Router, specify this address as the BGP peer address on the interface that has the Cloud Router IP address assigned to it. Assign this address to the VLAN subinterface on the on-premises router.
  4. On the router1 Cloud Router, add an interface for the attachment-lga1-central1 attachment:

    gcloud compute routers add-interface router1 \
      --interface-name router1-1 \
      --interconnect-attachment attachment-lga1-central1 \
      --ip-address \
      --mask-length 29 \
      --region us-central1
  5. Add a BGP peer to the interface; for this example, the on-premises ASN is 12345:

    gcloud compute routers add-bgp-peer router1 \
      --interface router1-1 \
      --peer-name central1 \
      --peer-ip-address \
      --peer-asn 12345 \
      --region us-central1
  6. Describe the attachment-lga2-central1 attachment, and then configure another BGP session on the router1 Cloud Router.

Configure on-premises routers

To configure the on-premises routers, use the information from the VLAN attachments. The following example is an excerpt from a Juniper router configuration. Use the sample as a starting point for configuring your own routers. For more information, see Configuring on-premises routers.

interface ae20 {
  native-vlan-id 1;
  aggregated-ether-options {
    lacp {
  unit 1000 {
    vlan-id 1000;
    family inet {

protocols bgp {
  group google {
    type external;
    multihop {
      ttl 4;
    hold-time 60;
    peer-as 64513;
    local-as 12345;
    neighbor {

What's next