Duplicating an Existing VLAN Attachment for Redundancy

If you have an existing VLAN attachment, you can create a second one to build redundancy. Google recommends redundancy so that if one VLAN attachment fails, the other one can continue to serve traffic.

To create a redundant VLAN attachment, it must connect to Google in the same metropolitan area (city) as the existing one but in a different edge availability domain.


  1. Go to the Cloud Interconnect VLAN attachments tab in the Google Cloud Console.
    Go to VLAN attachments tab
  2. Click Add VLAN attachment.
  3. Select Partner Interconnect to create Partner VLAN attachments, and then click Continue.
  4. Select I already have a service provider.
  5. Select Add a redundant VLAN to an existing VLAN.
  6. For the Select VLAN attachment field, pick the attachment that you want to build redundancy for. The new redundant attachment will use the same VPC network and region as the existing one.
  7. Specify the details of your VLAN attachments.
    • Cloud Router — Choose a Cloud Router that's not associated with the existing attachment. The Cloud Router must have an ASN of 16550. If you don't have an existing Cloud Router that you can use, create one with an ASN of 16550.
    • VLAN attachment name — A name for the attachment. This name is displayed in the console and used by the gcloud command-line tool to reference the attachment, such as my-attachment.
  8. Click Create to create the attachments, which takes a few moments.
  9. After creation is complete, copy the pairing keys. You'll need to share these keys with your service provider when you request a connection with them.
  10. Click OK to view a list of your VLAN attachments.


You must have a duplicate Cloud Router in the network and region that contains the existing VLAN attachment. The Cloud Router must have an ASN of 16550. If you don't have a duplicate Cloud Router, create one before you create a VLAN attachment. When you create the Cloud Router, use 16550 for the BGP ASN.

  1. Describe your existing VLAN attachment to view its details. Record its edge availability domain.

  2. Create a VLAN attachment of type PARTNER, specifying the name of your duplicate Cloud Router and a different edge availability domain from the existing VLAN attachment.

    The following example creates a partner attachment in edge availability domain 2 and is associated with the my-second-router Cloud Router, which is in the us-central1 region.

    gcloud compute interconnects attachments partner create my-second-attachment \
      --region us-central1 \
      --router my-second-router \
      --edge-availability-domain availability-domain-2
  3. Describe the attachment to retrieve its pairing key. You'll need to share this key with your service provider when you request a connection with them.

    gcloud compute interconnects attachments describe my-second-attachment \
      --region us-central1
    adminEnabled: false
    edgeAvailabilityDomain: AVAILABILITY_DOMAIN_2
    creationTimestamp: '2017-12-01T08:29:09.886-08:00'
    id: '7976913826166357434'
    kind: compute#interconnectAttachment
    labelFingerprint: 42WmSpB8rSM=
    name: my-second-attachment
    pairingKey: 7e51371e-72a3-40b5-b844-2e3efefaee59/us-central1/2
    region: https://www.googleapis.com/compute/v1/projects/customer-project/regions/us-central1
    router: https://www.googleapis.com/compute/v1/projects/customer-project/regions/us-central1/routers/my-second-router
    selfLink: https://www.googleapis.com/compute/v1/projects/customer-project/regions/us-central1/interconnectAttachments/my-second-attachment
    type: PARTNER
    • The pairingKey field contains the pairing key that you'll need to share with your service provider. Treat the pairing key as sensitive information until your VLAN attachment is configured.
    • The state of the VLAN attachment is PENDING_PARTNER until you request a connection with your service provider, and they complete the its configuration. Afterwards, the state of the attachment will be ACTIVE.

What's next?