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This document provides instructions for configuring a cross-region internal proxy Network Load Balancer for your services that run on Compute Engine VMs.
Before you beginBefore following this guide, familiarize yourself with the following:
PermissionsTo follow this guide, you must be able to create instances and modify a network in a project. You must be either a project owner or editor, or you must have all of the following Compute Engine IAM roles.
For more information, see the following guides:
Setup overviewYou can configure load balancer as shown in the following diagram:
Cross-region internal proxy Network Load Balancer high availability deployment (click to enlarge).As shown in the diagram, this example creates a cross-region internal proxy Network Load Balancer in a VPC network, with one backend service and two backend managed instance groups (MIGs) in region REGION_A
and REGION_B
regions.
The diagram shows the following:
A VPC network with the following subnets:
SUBNET_A
and a proxy-only subnet in REGION_A
.SUBNET_B
and a proxy-only subnet in REGION_B
.You must create proxy-only subnets in each region of a VPC network where you use cross-region internal proxy Network Load Balancers. The region's proxy-only subnet is shared among all cross-region internal proxy Network Load Balancers in the region. Source addresses of packets sent from the load balancer to your service's backends are allocated from the proxy-only subnet. In this example, the proxy-only subnet for the region REGION_B
has a primary IP address range of 10.129.0.0/23
, and for REGION_A
, has a primary IP address range of 10.130.0.0/23
, which is the recommended subnet size.
High availability setup has managed instance group backends for Compute Engine VM deployments in REGION_A
and REGION_B
regions. If backends in one region happen to be down, traffic fails over to the other region.
A global backend service that monitors the usage and health of backends.
A global target TCP proxy, which receives a request from the user and forwards it to the backend service.
Global forwarding rules, which have the regional internal IP address of your load balancer and can forward each incoming request to the target proxy.
The internal IP address associated with the forwarding rule can come from a subnet in the same network and region as the backends. Note the following conditions:
--purpose
flag set to GLOBAL_MANAGED_PROXY
.--purpose
flag to SHARED_LOADBALANCER_VIP
.Within the VPC network, configure a subnet in each region where your backends are configured. In addition, configure a proxy-only-subnet
in each region that you want to configure the load balancer.
This example uses the following VPC network, region, and subnets:
Network. The network is a custom mode VPC network named NETWORK
.
Subnets for backends.
SUBNET_A
in the REGION_A
region uses 10.1.2.0/24
for its primary IP range.SUBNET_B
in the REGION_B
region uses 10.1.3.0/24
for its primary IP range.Subnets for proxies.
PROXY_SN_A
in the REGION_A
region uses 10.129.0.0/23
for its primary IP range.PROXY_SN_B
in the REGION_B
region uses 10.130.0.0/23
for its primary IP range.Cross-region internal Application Load Balancers can be accessed from any region within the VPC. So clients from any region can globally access your load balancer backends.
Note: Subsequent steps in this guide use the network, region, and subnet parameters as outlined here. Configure the backend subnets ConsoleIn the Google Cloud console, go to the VPC networks page.
Click Create VPC network.
Provide a Name for the network.
In the Subnets section, set the Subnet creation mode to Custom.
Create a subnet for the load balancer's backends. In the New subnet section, enter the following information:
10.1.2.0/24
Click Done.
Click Add subnet.
Create a subnet for the load balancer's backends. In the New subnet section, enter the following information:
10.1.3.0/24
Click Done.
Click Create.
Create the custom VPC network with the gcloud compute networks create
command:
gcloud compute networks create NETWORK \ --subnet-mode=custom
Create a subnet in the NETWORK
network in the REGION_A
region with the gcloud compute networks subnets create
command:
gcloud compute networks subnets create SUBNET_A \ --network=NETWORK \ --range=10.1.2.0/24 \ --region=REGION_A
Create a subnet in the NETWORK
network in the REGION_B
region with the gcloud compute networks subnets create
command:
gcloud compute networks subnets create SUBNET_B \ --network=NETWORK \ --range=10.1.3.0/24 \ --region=REGION_B
To create the VPC network, use the google_compute_network
resource.
To create the VPC subnets in the lb-network-crs-reg
network, use the google_compute_subnetwork
resource.
Make a POST
request to the networks.insert
method. Replace PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/networks { "routingConfig": { "routingMode": "regional" }, "name": "NETWORK", "autoCreateSubnetworks": false }
Make a POST
request to the subnetworks.insert
method. Replace PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION_A/subnetworks { "name": "SUBNET_A", "network": "projects/PROJECT_ID/global/networks/lb-network-crs-reg", "ipCidrRange": "10.1.2.0/24", "region": "projects/PROJECT_ID/regions/REGION_A", }
Make a POST
request to the subnetworks.insert
method. Replace PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION_B/subnetworks { "name": "SUBNET_B", "network": "projects/PROJECT_ID/global/networks/NETWORK", "ipCidrRange": "10.1.3.0/24", "region": "projects/PROJECT_ID/regions/REGION_B", }Configure the proxy-only subnet
A proxy-only subnet provides a set of IP addresses that Google Cloud uses to run Envoy proxies on your behalf. The proxies terminate connections from the client and create new connections to the backends.
This proxy-only subnet is used by all Envoy-based regional load balancers in the same region as the VPC network. There can only be one active proxy-only subnet for a given purpose, per region, per network.
Important: Don't try to assign addresses from the proxy-only subnet to your load balancer's forwarding rule or backends. You assign the forwarding rule's IP address and the backend instance IP addresses from a different subnet range (or ranges), not this one. Google Cloud reserves this subnet range for Google Cloud-managed proxies. ConsoleIf you're using the Google Cloud console, you can wait and create the proxy-only subnet later on the Load balancing page.
If you want to create the proxy-only subnet now, use the following steps:
In the Google Cloud console, go to the VPC networks page.
10.129.0.0/23
.Create the proxy-only subnet in REGION_B
10.130.0.0/23
.Create the proxy-only subnets with the gcloud compute networks subnets create
command.
gcloud compute networks subnets create PROXY_SN_A \ --purpose=GLOBAL_MANAGED_PROXY \ --role=ACTIVE \ --region=REGION_A \ --network=NETWORK \ --range=10.129.0.0/23
gcloud compute networks subnets create PROXY_SN_B \ --purpose=GLOBAL_MANAGED_PROXY \ --role=ACTIVE \ --region=REGION_B \ --network=NETWORK \ --range=10.130.0.0/23Terraform
To create the VPC proxy-only subnet in the lb-network-crs-reg
network, use the google_compute_subnetwork
resource.
Create the proxy-only subnets with the subnetworks.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION_A/subnetworks { "name": " PROXY_SN_A", "ipCidrRange": "10.129.0.0/23", "network": "projects/PROJECT_ID/global/networks/NETWORK", "region": "projects/PROJECT_ID/regions/REGION_A", "purpose": "GLOBAL_MANAGED_PROXY", "role": "ACTIVE" }
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/regions/REGION_B/subnetworks { "name": "PROXY_SN_B", "ipCidrRange": "10.130.0.0/23", "network": "projects/PROJECT_ID/global/networks/NETWORK", "region": "projects/PROJECT_ID/regions/REGION_B", "purpose": "GLOBAL_MANAGED_PROXY", "role": "ACTIVE" }Configure firewall rules
This example uses the following firewall rules:
fw-ilb-to-backends
. An ingress rule, applicable to the instances being load balanced, that allows incoming SSH connectivity on TCP port 22
from any address. You can choose a more restrictive source IP address range for this rule; for example, you can specify just the IP address ranges of the system from which you initiate SSH sessions. This example uses the target tag allow-ssh
to identify the VMs that the firewall rule applies to.
fw-healthcheck
. An ingress rule, applicable to the instances being load balanced, that allows all TCP traffic from the Google Cloud health checking systems (in 130.211.0.0/22
and 35.191.0.0/16
). This example uses the target tag load-balanced-backend
to identify the VMs that the firewall rule applies to.
fw-backends
. An ingress rule, applicable to the instances being load balanced, that allows TCP traffic on ports 80
, 443
, and 8080
from the internal proxy Network Load Balancer's managed proxies. This example uses the target tag load-balanced-backend
to identify the VMs that the firewall rule applies to.
Without these firewall rules, the default deny ingress rule blocks incoming traffic to the backend instances.
The target tags define the backend instances. Without the target tags, the firewall rules apply to all of your backend instances in the VPC network. When you create the backend VMs, make sure to include the specified target tags, as shown in Creating a managed instance group.
ConsoleIn the Google Cloud console, go to the Firewall policies page.
Click Create firewall rule to create the rule to allow incoming SSH connections:
fw-ilb-to-backends
allow-ssh
0.0.0.0/0
22
for the port number.Click Create.
Click Create firewall rule a second time to create the rule to allow Google Cloud health checks:
fw-healthcheck
load-balanced-backend
130.211.0.0/22
and 35.191.0.0/16
Protocols and ports:
80
for the port number.As a best practice, limit this rule to just the protocols and ports that match those used by your health check. If you use tcp:80
for the protocol and port, Google Cloud can use HTTP on port 80
to contact your VMs, but it cannot use HTTPS on port 443
to contact them.
Click Create.
Click Create firewall rule a third time to create the rule to allow the load balancer's proxy servers to connect the backends:
fw-backends
load-balanced-backend
10.129.0.0/23
and 10.130.0.0/23
80, 443, 8080
for the port numbers.Click Create.
Create the fw-ilb-to-backends
firewall rule to allow SSH connectivity to VMs with the network tag allow-ssh
. When you omit source-ranges
, Google Cloud interprets the rule to mean any source.
gcloud compute firewall-rules create fw-ilb-to-backends \ --network=NETWORK \ --action=allow \ --direction=ingress \ --target-tags=allow-ssh \ --rules=tcp:22
Create the fw-healthcheck
rule to allow Google Cloud health checks. This example allows all TCP traffic from health check probers; however, you can configure a narrower set of ports to meet your needs.
gcloud compute firewall-rules create fw-healthcheck \ --network=NETWORK \ --action=allow \ --direction=ingress \ --source-ranges=130.211.0.0/22,35.191.0.0/16 \ --target-tags=load-balanced-backend \ --rules=tcp
Create the fw-backends
rule to allow the internal proxy Network Load Balancer's proxies to connect to your backends. Set source-ranges
to the allocated ranges of your proxy-only subnet, for example, 10.129.0.0/23
and 10.130.0.0/23
.
gcloud compute firewall-rules create fw-backends \ --network=NETWORK \ --action=allow \ --direction=ingress \ --source-ranges=SOURCE_RANGE \ --target-tags=load-balanced-backend \ --rules=tcp:80,tcp:443,tcp:8080
Create the fw-ilb-to-backends
firewall rule by making a POST
request to the firewalls.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls { "name": "fw-ilb-to-backends", "network": "projects/PROJECT_ID/global/networks/NETWORK", "sourceRanges": [ "0.0.0.0/0" ], "targetTags": [ "allow-ssh" ], "allowed": [ { "IPProtocol": "tcp", "ports": [ "22" ] } ], "direction": "INGRESS" }
Create the fw-healthcheck
firewall rule by making a POST
request to the firewalls.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls { "name": "fw-healthcheck", "network": "projects/PROJECT_ID/global/networks/NETWORK", "sourceRanges": [ "130.211.0.0/22", "35.191.0.0/16" ], "targetTags": [ "load-balanced-backend" ], "allowed": [ { "IPProtocol": "tcp" } ], "direction": "INGRESS" }
Create the fw-backends
firewall rule to allow TCP traffic within the proxy subnet for the firewalls.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/firewalls { "name": "fw-backends", "network": "projects/PROJECT_ID/global/networks/NETWORK", "sourceRanges": [ "10.129.0.0/23", "10.130.0.0/23" ], "targetTags": [ "load-balanced-backend" ], "allowed": [ { "IPProtocol": "tcp", "ports": [ "80" ] }, { "IPProtocol": "tcp", "ports": [ "443" ] }, { "IPProtocol": "tcp", "ports": [ "8080" ] } ], "direction": "INGRESS" }Create a managed instance group
This section shows how to create a template and a managed instance group. The managed instance group provides VM instances running the backend servers of an example cross-region internal proxy Network Load Balancer. For your instance group, you can define an HTTP service and map a port name to the relevant port. The backend service of the load balancer forwards traffic to the named ports. Traffic from clients is load balanced to backend servers. For demonstration purposes, backends serve their own hostnames.
ConsoleIn the Google Cloud console, go to the Instance templates page.
gil4-backendeast1-template
.apt-get
.allow-ssh
and load-balanced-backend
.Click Management. Enter the following script into the Startup script field.
#! /bin/bash apt-get update apt-get install apache2 -y a2ensite default-ssl a2enmod ssl vm_hostname="$(curl -H "Metadata-Flavor:Google" \ http://169.254.169.254/computeMetadata/v1/instance/name)" echo "Page served from: $vm_hostname" | \ tee /var/www/html/index.html systemctl restart apache2
Click Create.
Click Create instance template.
For Name, enter gil4-backendwest1-template
.
Ensure that the Boot disk is set to a Debian image, such as Debian GNU/Linux 12 (bookworm). These instructions use commands that are only available on Debian, such as apt-get
.
Click Advanced options.
Click Networking and configure the following fields:
allow-ssh
and load-balanced-backend
.Click Management. Enter the following script into the Startup script field.
#! /bin/bash apt-get update apt-get install apache2 -y a2ensite default-ssl a2enmod ssl vm_hostname="$(curl -H "Metadata-Flavor:Google" \ http://169.254.169.254/computeMetadata/v1/instance/name)" echo "Page served from: $vm_hostname" | \ tee /var/www/html/index.html systemctl restart apache2
Click Create.
In the Google Cloud console, go to the Instance groups page.
gl4-ilb-miga
.gil4-backendwest1-template
.Specify the number of instances that you want to create in the group.
For this example, specify the following options under Autoscaling:
Off:do not autoscale
.2
.Optionally, in the Autoscaling section of the UI, you can configure the instance group to automatically add or remove instances based on instance CPU use.
Click Create.
Click Create instance group.
Select New managed instance group (stateless). For more information, see Stateless or stateful MIGs.
For Name, enter gl4-ilb-migb
.
For Location, select Single zone.
For Region, select REGION_B.
For Zone, select ZONE_B.
For Instance template, select gil4-backendeast1-template
.
Specify the number of instances that you want to create in the group.
For this example, specify the following options under Autoscaling:
Off:do not autoscale
.2
.Optionally, in the Autoscaling section of the UI, you can configure the instance group to automatically add or remove instances based on instance CPU usage.
Click Create.
The gcloud CLI instructions in this guide assume that you are using Cloud Shell or another environment with bash installed.
Create a VM instance template with HTTP server with the gcloud compute instance-templates create
command.
gcloud compute instance-templates create gil4-backendwest1-template \ --region=REGION_A \ --network=NETWORK \ --subnet=SUBNET_A \ --tags=allow-ssh,load-balanced-backend \ --image-family=debian-12 \ --image-project=debian-cloud \ --metadata=startup-script='#! /bin/bash apt-get update apt-get install apache2 -y a2ensite default-ssl a2enmod ssl vm_hostname="$(curl -H "Metadata-Flavor:Google" \ http://169.254.169.254/computeMetadata/v1/instance/name)" echo "Page served from: $vm_hostname" | \ tee /var/www/html/index.html systemctl restart apache2'
gcloud compute instance-templates create gil4-backendeast1-template \ --region=REGION_B \ --network=NETWORK \ --subnet=SUBNET_B \ --tags=allow-ssh,load-balanced-backend \ --image-family=debian-12 \ --image-project=debian-cloud \ --metadata=startup-script='#! /bin/bash apt-get update apt-get install apache2 -y a2ensite default-ssl a2enmod ssl vm_hostname="$(curl -H "Metadata-Flavor:Google" \ http://169.254.169.254/computeMetadata/v1/instance/name)" echo "Page served from: $vm_hostname" | \ tee /var/www/html/index.html systemctl restart apache2'
Create a managed instance group in the zone with the gcloud compute instance-groups managed create
command.
gcloud compute instance-groups managed create gl4-ilb-miga \ --zone=ZONE_A \ --size=2 \ --template=gil4-backendwest1-template
gcloud compute instance-groups managed create gl4-ilb-migb \ --zone=ZONE_B \ --size=2 \ --template=gil4-backendeast1-template
Create the instance template with the instanceTemplates.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/instanceTemplates { "name":"gil4-backendwest1-template", "properties":{ "machineType":"e2-standard-2", "tags":{ "items":[ "allow-ssh", "load-balanced-backend" ] }, "metadata":{ "kind":"compute#metadata", "items":[ { "key":"startup-script", "value":"#! /bin/bash\napt-get update\napt-get install apache2 -y\na2ensite default-ssl\na2enmod ssl\n vm_hostname=\"$(curl -H \"Metadata-Flavor:Google\" \\\nhttp://169.254.169.254/computeMetadata/v1/instance/name)\"\n echo \"Page served from: $vm_hostname\" | \\\ntee /var/www/html/index.html\nsystemctl restart apache2" } ] }, "networkInterfaces":[ { "network":"projects/PROJECT_ID/global/networks/NETWORK", "subnetwork":"regions/REGION_A/subnetworks/SUBNET_A", "accessConfigs":[ { "type":"ONE_TO_ONE_NAT" } ] } ], "disks":[ { "index":0, "boot":true, "initializeParams":{ "sourceImage":"projects/debian-cloud/global/images/family/debian-12" }, "autoDelete":true } ] } }
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/instanceTemplates { "name":"gil4-backendeast1-template", "properties":{ "machineType":"e2-standard-2", "tags":{ "items":[ "allow-ssh", "load-balanced-backend" ] }, "metadata":{ "kind":"compute#metadata", "items":[ { "key":"startup-script", "value":"#! /bin/bash\napt-get update\napt-get install apache2 -y\na2ensite default-ssl\na2enmod ssl\n vm_hostname=\"$(curl -H \"Metadata-Flavor:Google\" \\\nhttp://169.254.169.254/computeMetadata/v1/instance/name)\"\n echo \"Page served from: $vm_hostname\" | \\\ntee /var/www/html/index.html\nsystemctl restart apache2" } ] }, "networkInterfaces":[ { "network":"projects/PROJECT_ID/global/networks/NETWORK", "subnetwork":"regions/REGION_B/subnetworks/SUBNET_B", "accessConfigs":[ { "type":"ONE_TO_ONE_NAT" } ] } ], "disks":[ { "index":0, "boot":true, "initializeParams":{ "sourceImage":"projects/debian-cloud/global/images/family/debian-12" }, "autoDelete":true } ] } }
Create a managed instance group in each zone with the instanceGroupManagers.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/{zone}/instanceGroupManagers { "name": "gl4-ilb-miga", "zone": "projects/PROJECT_ID/zones/ZONE_A", "instanceTemplate": "projects/PROJECT_ID/global/instanceTemplates/gil4-backendwest1-template", "baseInstanceName": "gl4-ilb-miga", "targetSize": 2 }
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/zones/{zone}/instanceGroupManagers { "name": "gl4-ilb-migb", "zone": "projects/PROJECT_ID/zones/ZONE_A", "instanceTemplate": "projects/PROJECT_ID/global/instanceTemplates/gil4-backendwest1-template", "baseInstanceName": "gl4-ilb-migb", "targetSize": 2 }Configure the load balancer
This example shows you how to create the following cross-region internal proxy Network Load Balancer resources:
SUBNET_A
or SUBNET_B
IP address range. If you try to use the proxy-only subnet, forwarding rule creation fails.Sometimes Google Cloud regions don't have enough proxy capacity for a new load balancer. If this happens, the Google Cloud console provides a proxy availability warning message when you are creating your load balancer. To resolve this issue, you can do one of the following:
Wait for the capacity issue to be resolved.
In the Google Cloud console, go to the Load balancing page.
Basic configuration
Configure the frontend with two forwarding rules
Reserve a proxy-only subnet
10.1.2.99
.Reserve a proxy-only subnet
10.1.3.99
.http
.gl4-ilb-miga
in REGION_A.80
.gl4-ilb-migb
in REGION_B.80
.global-http-health-check
.HTTP
.80
.Review the configuration
Define the TCP health check with the gcloud compute health-checks create tcp
command.
gcloud compute health-checks create tcp global-health-check \ --use-serving-port \ --global
Define the backend service with the gcloud compute backend-services create
command.
gcloud compute backend-services create gl4-gilb-backend-service \ --load-balancing-scheme=INTERNAL_MANAGED \ --protocol=TCP \ --enable-logging \ --logging-sample-rate=1.0 \ --health-checks=global-health-check \ --global-health-checks \ --global
Add backends to the backend service with the gcloud compute backend-services add-backend
command.
gcloud compute backend-services add-backend gl4-gilb-backend-service \ --balancing-mode=CONNECTION \ --max-connections=50 \ --instance-group=gl4-ilb-miga \ --instance-group-zone=ZONE_A \ --global
gcloud compute backend-services add-backend gl4-gilb-backend-service \ --balancing-mode=CONNECTION \ --max-connections=50 \ --instance-group=gl4-ilb-migb \ --instance-group-zone=ZONE_B \ --global
Create the target proxy.
Create the target proxy with the gcloud compute target-tcp-proxies create
command.
gcloud compute target-tcp-proxies create gilb-tcp-proxy \ --backend-service=gl4-gilb-backend-service \ --global
Create two forwarding rules, one with a VIP (10.1.2.99) in REGION_B
and another one with a VIP (10.1.3.99) in REGION_A
. For more information, see Reserve a static internal IPv4 address.
For custom networks, you must reference the subnet in the forwarding rule. Note that this is the VM subnet, not the proxy subnet.
Use the gcloud compute forwarding-rules create
command with the correct flags.
gcloud compute forwarding-rules create gil4forwarding-rule-a \ --load-balancing-scheme=INTERNAL_MANAGED \ --network=NETWORK \ --subnet=SUBNET_A \ --subnet-region=REGION_A \ --address=10.1.2.99 \ --ports=80 \ --target-tcp-proxy=gilb-tcp-proxy \ --global
gcloud compute forwarding-rules create gil4forwarding-rule-b \ --load-balancing-scheme=INTERNAL_MANAGED \ --network=NETWORK \ --subnet=SUBNET_B \ --subnet-region=REGION_B \ --address=10.1.3.99 \ --ports=80 \ --target-tcp-proxy=gilb-tcp-proxy \ --global
Create the health check by making a POST
request to the healthChecks.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/healthChecks { "name": "global-health-check", "type": "TCP", "httpHealthCheck": { "portSpecification": "USE_SERVING_PORT" } }
Create the global backend service by making a POST
request to the backendServices.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/backendServices { "name": "gl4-gilb-backend-service", "backends": [ { "group": "projects/PROJECT_ID/zones/ZONE_A/instanceGroups/gl4-ilb-miga", "balancingMode": "CONNECTION" }, { "group": "projects/PROJECT_ID/zones/ZONE_B/instanceGroups/gl4-ilb-migb", "balancingMode": "CONNECTION" } ], "healthChecks": [ "projects/PROJECT_ID/regions/global/healthChecks/global-health-check" ], "loadBalancingScheme": "INTERNAL_MANAGED" }
Create the target TCP proxy by making a POST
request to the targetTcpProxies.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/targetTcpProxy { "name": "l4-ilb-proxy", }
Create the forwarding rule by making a POST
request to the forwardingRules.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/forwardingRules { "name": "gil4forwarding-rule-a", "IPAddress": "10.1.2.99", "IPProtocol": "TCP", "portRange": "80-80", "target": "projects/PROJECT_ID/global/targetTcpProxies/l4-ilb-proxy", "loadBalancingScheme": "INTERNAL_MANAGED", "subnetwork": "projects/PROJECT_ID/regions/REGION_A/subnetworks/SUBNET_A", "network": "projects/PROJECT_ID/global/networks/NETWORK", "networkTier": "PREMIUM" }
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/forwardingRules { "name": "gil4forwarding-rule-b", "IPAddress": "10.1.3.99", "IPProtocol": "TCP", "portRange": "80-80", "target": "projects/PROJECT_ID/global/targetTcpProxies/l4-ilb-proxy", "loadBalancingScheme": "INTERNAL_MANAGED", "subnetwork": "projects/PROJECT_ID/regions/REGION_B/subnetworks/SUBNET_B", "network": "projects/PROJECT_ID/global/networks/NETWORK", "networkTier": "PREMIUM" }
Create the forwarding rule by making a POST
request to the globalForwardingRules.insert
method, replacing PROJECT_ID
with your project ID.
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/forwardingRules { "name": "gil4forwarding-rule-a", "IPAddress": "10.1.2.99", "IPProtocol": "TCP", "portRange": "80-80", "target": "projects/PROJECT_ID/global/targetTcpProxies/l4-ilb-proxy", "loadBalancingScheme": "INTERNAL_MANAGED", "subnetwork": "projects/PROJECT_ID/regions/REGION_A/subnetworks/SUBNET_A", "network": "projects/PROJECT_ID/global/networks/NETWORK", "networkTier": "PREMIUM" }
POST https://compute.googleapis.com/compute/v1/projects/PROJECT_ID/global/forwardingRules { "name": "gil4forwarding-rule-b", "IPAddress": "10.1.3.99", "IPProtocol": "TCP", "portRange": "80-80", "target": "projects/PROJECT_ID/global/targetTcpProxies/l4-ilb-proxy", "loadBalancingScheme": "INTERNAL_MANAGED", "subnetwork": "projects/PROJECT_ID/regions/REGION_B/subnetworks/SUBNET_B", "network": "projects/PROJECT_ID/global/networks/NETWORK", "networkTier": "PREMIUM" }Test the load balancer Create a VM instance to test connectivity
Create a client VM in REGION_B
and REGION_A
regions:
gcloud compute instances create l4-ilb-client-a \ --image-family=debian-12 \ --image-project=debian-cloud \ --network=NETWORK \ --subnet=SUBNET_A \ --zone=ZONE_A \ --tags=allow-ssh
gcloud compute instances create l4-ilb-client-b \ --image-family=debian-12 \ --image-project=debian-cloud \ --network=NETWORK \ --subnet=SUBNET_B \ --zone=ZONE_B \ --tags=allow-ssh
Use SSH to connect to each client instance.
gcloud compute ssh l4-ilb-client-a --zone=ZONE_A
gcloud compute ssh l4-ilb-client-b --zone=ZONE_B
Verify that the IP address is serving its hostname
Verify that the client VM can reach both IP addresses. The command should succeed and return the name of the backend VM which served the request:
curl 10.1.2.99
curl 10.1.3.99
Verify failover to backends in the REGION_A
region when backends in the REGION_B
are unhealthy or unreachable. To simulate failover, remove all backends from REGION_B
:
gcloud compute backend-services remove-backend gl4-gilb-backend-service \ --instance-group=gl4-ilb-migb \ --instance-group-zone=ZONE_B \ --global
Connect using SSH to a client VM in REGION_B
.
gcloud compute ssh l4-ilb-client-b \ --zone=ZONE_B
Send requests to the load balanced IP address in the REGION_B
region. The command output shows responses from backend VMs in REGION_A
:
{ RESULTS= for i in {1..100} do RESULTS="$RESULTS:$(curl 10.1.3.99)" done echo "***" echo "*** Results of load-balancing to 10.1.3.99: " echo "***" echo "$RESULTS" | tr ':' '\n' | grep -Ev "^$" | sort | uniq -c echo }
This section expands on the configuration example to provide alternative and additional configuration options. All of the tasks are optional. You can perform them in any order.
PROXY protocol for retaining client connection informationThe internal proxy Network Load Balancer terminates TCP connections from the client and creates new connections to the VM instances. By default, the original client IP and port information is not preserved.
To preserve and send the original connection information to your instances, enable PROXY protocol (version 1). This protocol sends an additional header that contains the source IP address, destination IP address, and port numbers to the instance as a part of the request.
Make sure that the internal proxy Network Load Balancer's backend instances are running HTTP or HTTPS servers that support PROXY protocol headers. If the HTTP or HTTPS servers are not configured to support PROXY protocol headers, the backend instances return empty responses. For example, the PROXY protocol doesn't work with the Apache HTTP Server software. You can use different web server software, such as Nginx.
If you set the PROXY protocol for user traffic, you must also set it for your health checks. If you are checking health and serving content on the same port, set the health check's --proxy-header
to match your load balancer setting.
The PROXY protocol header is typically a single line of user-readable text in the following format:
PROXY TCP4 <client IP> <load balancing IP> <source port> <dest port>\r\n
Following is an example of the PROXY protocol:
PROXY TCP4 192.0.2.1 198.51.100.1 15221 110\r\n
In the preceding example, the client IP is 192.0.2.1
, the load balancing IP is 198.51.100.1
, the client port is 15221
, and the destination port is 110
.
In cases where the client IP is not known, the load balancer generates a PROXY protocol header in the following format:
PROXY UNKNOWN\r\n
The example load balancer setup on this page shows you how to enable the PROXY protocol header while creating the internal proxy Network Load Balancer. Use these steps to change the PROXY protocol header for an existing target TCP proxy.
ConsoleIn the Google Cloud console, go to the Load balancing page.
Click editEdit for your load balancer.
Click Frontend configuration.
Change the value of the Proxy protocol field to On.
Click Update to save your changes.
In the following command, edit the --proxy-header
field and set it to either NONE
or PROXY_V1
depending on your requirement.
gcloud compute target-ssl-proxies update int-tcp-target-proxy \ --proxy-header=[NONE | PROXY_V1]Use the same IP address between multiple internal forwarding rules
For multiple internal forwarding rules to share the same internal IP address, you must reserve the IP address and set its --purpose
flag to SHARED_LOADBALANCER_VIP
.
gcloud compute addresses create SHARED_IP_ADDRESS_NAME \ --region=REGION \ --subnet=SUBNET_NAME \ --purpose=SHARED_LOADBALANCER_VIPEnable session affinity
The example configuration creates a backend service without session affinity.
These procedures show you how to update a backend service for an example load balancer so that the backend service uses client IP affinity or generated cookie affinity.
When client IP affinity is enabled, the load balancer directs a particular client's requests to the same backend VM based on a hash created from the client's IP address and the load balancer's IP address (the internal IP address of an internal forwarding rule).
ConsoleTo enable client IP session affinity:
Use the following gcloud command to update the BACKEND_SERVICE
backend service, specifying client IP session affinity:
gcloud compute backend-services update BACKEND_SERVICE \ --global \ --session-affinity=CLIENT_IPEnable connection draining
You can enable connection draining on backend services to ensure minimal interruption to your users when an instance that is serving traffic is terminated, removed manually, or removed by an autoscaler. To learn more about connection draining, read the Enabling connection draining documentation.
What's nextExcept as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2025-08-07 UTC.
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