Modify VLAN attachments

This document describes how to modify Partner Interconnect VLANattachments and their Border Gateway Protocol (BGP) sessions.

Note: For definitions of terms used on this page, seeCloud Interconnect key terms.

The following table lists VLAN attachment and BGP session properties. Italso provides information about how to modify them.

PropertyHow to modify
CapacityWork with your service provider as described in theModify capacity section in this document.
Description and MTU

See theModify the description and MTU section in this document.

Modifications are immediate and in rare cases can cause traffic disruption. If traffic is disrupted, the disruption lasts less than a minute.

Stack type

See theModify the stack type section in this document. Modifying the stack type from IPv4 and IPv6 (dual stack) to IPv4 only (single stack) removes the IPv6 BGP session from the associated Cloud Router, and removes the IPv6 address from the VLAN attachment. Changing the stack type on an IPv4 only (single stack) attachment to IPv4 and IPv6 (dual stack) adds a default-configured IPv6 BGP session to the associated Cloud Router. The following describes the behavior of the IPv6 BGP session:

  • The attachment is active and the peer router already has an IPv6 BGP configuration: the IPv6 BGP session establishes and starts routing IPv6 traffic immediately.
  • The attachment isn't active or the peer router doesn't have an IPv6 BGP configuration: the IPv6 BGP session doesn't establish and you can modify the BGP session before activating the attachment or configuring the peer router.

To change the stack type of an IPv4 only (single stack) attachment without immediately accepting IPv6 traffic, de-activate the attachment or disable the peer router's IPv6 BGP configuration first.

Whether a VLAN attachment is enabled or disabledTo disable or re-enable a VLAN attachment, seeDisable VLAN attachments.

VLAN ID

BGP IP addresses (Cloud Router IP address, on-premises router IP address)

You can't modify these properties for existing attachments. Instead, you must recreate the VLAN attachment.

To create VLAN attachments for Partner Interconnect, seeCreate VLAN attachments.

Custom learned routesFollow the steps inUpdate an existing session to use custom learned routes.
MD5 authenticationIf you have a Layer 2 connection, follow the steps inAdd authentication to an existing session. If you have a Layer 3 connection, contact your service provider for instructions.

The peer ASN is not a property of the VLAN attachment—it is part of theBGP configuration of the Cloud Router. If you have a Layer 2 connectionand you want to modify the peer ASN, update the Cloud Router's BGPsession for the VLAN attachment.

For more information, see the following resources:

Modify capacity

For an existing VLAN attachment, Google Cloud supports increasing or decreasingthe attachment's capacity as your capacity demands rise or fall. Becausecapacity changes can affect your service provider's network, you must work withthem to change your attachment's capacity. Changes in capacity, in rare cases,can cause traffic disruption. If traffic is disrupted, the disruption lasts lessthan a minute.

After the service provider has updated your attachment, your service providerworks with Google to update the attachment's capacity in your Google Cloud project.At that time, Google updates the charges for the attachment based on the newcapacity.

If you modify the capacity of an encrypted VLAN attachment, you might need to addHA VPN tunnels to accommodate increased traffic. For more information,seeConfigure HA VPN over Cloud Interconnect.

For a list of all the service providers, seeSupported service providers.

Modify the description and MTU

This section provides instructions for updating the description andmaximum transmission unit (MTU) of aVLAN attachment. In rare cases, changing the attributes of a VLAN attachmentcan cause traffic disruption. If traffic is disrupted, the disruption lasts lessthan a minute.

To make use of a 1460-, 1500-, or 8896-byte MTU,the VPC networkthat uses the attachment must have the same MTU value. Inaddition, the on-premises virtual machine (VM) instances and routers must havethe same MTU value. If your network has the default MTU of1460, then selectan MTU of1460 for your VLAN attachment.

You cannot modify the MTU (1440) of an encrypted VLAN attachmentthat is used in an HA VPN over Cloud Interconnect deployment.

Console

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

    Go to VLAN attachments

  2. Select the VLAN attachment to modify.

  3. On the attachment's detail page, clickEdit.

  4. Modify theDescription of your VLAN attachment.

  5. Optional: Update themaximum transmission unit (MTU) ofthe attachment.

  6. ClickSave.

gcloud

Modify aninterconnectAttachment by specifying the name of the existingVLAN attachment and the attributes to modify:

gcloud compute interconnects attachments partner updateNAME \    --region=REGION \    --description=DESCRIPTION \    --mtu=MTU

Replace the following:

  • NAME: the name of the existing VLAN attachment
  • REGION: the region of the attachment
  • DESCRIPTION: a description of the attachment
  • MTU: the maximum transmission unit (MTU) of theattachment

For more information, see thegcloud compute interconnects attachments partner update reference.

Modify the stack type

This section describes modifying the stack type of a VLAN attachment. You canchange between either IPv4 only (single stack), or IPv4 and IPv6 (dual stack).

Modifying the stack type from IPv4 and IPv6 (dual stack) to IPv4 only (singlestack) removes the BGP session from the associated Cloud Router, andremoves the IPv6 address from the VLAN attachment.

Important: Downgrading from IPv4 and IPv6 (dual stack) to IPv4 only (singlestack) results in dropped packets.

Console

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

    Go to VLAN attachments

  2. Select the VLAN attachment to modify.

  3. On the attachment's detail page, clickEdit.

  4. In theIP stack type section, select the IP stack type, eitherIPv4 (single-stack) orIPv4 and IPv6 (dual-stack).

  5. (Optional): You can specify custom IP address ranges when you change yourattachment's stack type.

    Note: The following instructions describe how to configure customIP address ranges for a Layer 2 connection. If you want to usecustom IP address ranges with a Layer 3 connection, you create aVLAN attachment and then your service provider configures thecustom IP address ranges during their VLAN attachmentconfiguration process. If you have a Layer 3 connection, contactyour service provider for instructions.

    For more information about prerequisites, limitations andwhy you might use custom IP address ranges, seeCustom IP address ranges.

    In theCloud Router IPv6 orPeer IPv6 sections, enter thefollowing information:

    • In theCloud Router IPv6 field, enter the IPv6 CIDRaddress that you want to assign to the Cloud Router end of yourVLAN attachment, like2001:db8::1/125.
    • In thePeer IPv6 field, enter the IPv6 CIDR address that youwant to assign to the customer router end of your VLAN attachment.

  6. ClickSave.

gcloud

Run the following command:

gcloud compute interconnects attachments partner updateNAME \  --region=REGION \  --stack_type=STACK_TYPE

Replace the following:

  • NAME: the name of the existing VLAN attachment.

  • REGION: the region of your VLAN attachment.

  • STACK_TYPE: the stack type for your VLANattachment. The stack type can be one of the following:

    • IPV4_ONLY: selects IPv4 only (single stack).

    • IPV4_IPV6: selects IPv4 and IPv6 (dual stack).

Note: When you switch the stack type fromIPV4_IPV6 (dual stack) toIPV4_ONLY (single stack), a warning indicates that theIPv6 only BGP session is removed.

The output is similar to the following when changing the stack type fromIPV4_ONLY toIPV4_IPV6:

adminEnabled: trueedgeAvailabilityDomain: AVAILABILITY_DOMAIN_1bandwidth: BPS_1GcloudRouterIpAddress: 169.254.67.201/29cloudRouterIpv6Address: 2600:2d00:0:1::1/125creationTimestamp: '2017-12-01T08:31:11.580-08:00'customerRouterIpAddress: 169.254.67.202/29customerRouterIpv6Address: 2600:2d00:0:1::2/125description: Interconnect for location 1id: '7193021941765913888'interconnect: https://www.googleapis.com/compute/alpha/projects/partner-project/global/interconnects/lga-2kind: compute#interconnectAttachmentlabelFingerprint: 42WmSpB8rSM=name: partner-attachmentpartnerMetadata:interconnectName: New York (2)partnerName: Partner IncportalUrl: https://partner-portal.comregion: https://www.googleapis.com/compute/alpha/projects/partner-project/regions/REGIONselfLink: https://www.googleapis.com/compute/alpha/projects/partner-project/regions/REGION/interconnectAttachments/ATTACHMENT_NAMEstackType:STACK_TYPEstate: ACTIVEtype: PARTNERvlanTag8021q: 1000

The output is similar to the following when changing the stack type fromIPV4_IPV6toIPV4_ONLY:

adminEnabled: trueedgeAvailabilityDomain: AVAILABILITY_DOMAIN_1bandwidth: BPS_1GcloudRouterIpAddress: 169.254.67.201/29creationTimestamp: '2017-12-01T08:31:11.580-08:00'customerRouterIpAddress: 169.254.67.202/29description: Interconnect for location 1id: '7193021941765913888'interconnect: https://www.googleapis.com/compute/alpha/projects/partner-project/global/interconnects/lga-2kind: compute#interconnectAttachmentlabelFingerprint: 42WmSpB8rSM=name: partner-attachmentpartnerMetadata:interconnectName: New York (2)partnerName: Partner IncportalUrl: https://partner-portal.comregion: https://www.googleapis.com/compute/alpha/projects/partner-project/regions/REGIONselfLink: https://www.googleapis.com/compute/alpha/projects/partner-project/regions/REGION/interconnectAttachments/ATTACHMENT_NAMEstackType:STACK_TYPEstate: ACTIVEtype: PARTNERvlanTag8021q: 1000

Add custom IP address ranges when upgrading to dual stack

When you update your stack type from IPv4 only to dual stack on a Layer 2connection, you can provide custom IPv6 address ranges by using the--candidate-cloud-router-ipv6-address and--candidate-customer-router-ipv6-address flags.

gcloud compute interconnects attachments partner updateATTACHMENT_NAME \    --project=PROJECT_ID \    --region=REGION \    --router=ROUTER_NAME \    --stack-type=IPV4_IPV6 \    --candidate-cloud-router-ipv6-address=CANDIDATE_CLOUD_ROUTER_IP_ADDRESS \    --candidate-customer-router-ipv6-address=CANDIDATE_CUSTOMER_ROUTER_IP_ADDRESS

Replace the following:

  • ATTACHMENT_NAME: the name of your VLAN attachment
  • PROJECT_ID: the ID of your Google Cloud project
  • REGION: the region of your VLAN attachment
  • ROUTER_NAME: the name of the Cloud Router
  • CANDIDATE_CLOUD_ROUTER_IP_ADDRESS: the IPv6 CIDR addressthat you want to assign to the Cloud Router end of your VLAN attachment;for example,2001:db8::1/125
  • CANDIDATE_CUSTOMER_ROUTER_IP_ADDRESS: the IPv6 CIDRaddress that you want to assign to the customer router end

If you use a Layer 3 connection, your service provider can configure custom IPaddresses when you upgrade the stack type.

What's next

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Last updated 2026-02-19 UTC.