• Create a private cluster that uses VPC advanced routes.
•Set the pod and service ranges as /24.
•Set up a network proxy to access the master.

• Create a VPC-native GKE cluster using GKE-managed IP ranges.
•Set the pod IP range as /21 and service IP range as /24.
•Set up a network proxy to access the master.

• Create a VPC-native GKE cluster using user-managed IP ranges.
•Enable a GKE cluster network policy, set the pod and service ranges as /24.
•Set up a network proxy to access the master.
•Enable master authorized networks.

• Create a VPC-native GKE cluster using user-managed IP ranges.
•Enable privateEndpoint on the cluster master.
•Set the pod and service ranges as /24.
•Set up a network proxy to access the master.
•Enable master authorized networks.

Enable firewall logging, and forward all filtered egress firewall logs to the IDS.

Enable VPC Flow Logs. Create a sink in Cloud Logging to send filtered egress VPC
Flow Logs to the IDS.

Create an internal TCP/UDP load balancer for Packet Mirroring, and add a packet
mirroring policy filter for egress traffic.

Create an internal HTTP(S) load balancer for Packet Mirroring, and add a packet
mirroring policy filter for egress traffic.

Create a Cloud Armor Policy rule that denies traffic and review necessary logs.

Create a Cloud Armor Policy rule that denies traffic, enable preview mode, and review
necessary logs.

Create a VPC Firewall rule that denies traffic, enable logging and set enforcement to
disabled, and review necessary logs.

Create a VPC Firewall rule that denies traffic, enable logging and set enforcement to
enabled, and review necessary logs.

Create a managed instance group from one of the images of the on-premises servers,
and link this instance group to a target pool behind your load balancer.

Create a target pool, add all backend instances to this target pool, and deploy the target
pool behind your load balancer.

Deploy a third-party virtual appliance as frontend to these servers that will accommodate
the significant differences between these backend servers.

Use GCP's ECMP capability to load-balance traffic to the backend servers by installing
multiple equal-priority static routes to the backend servers.

Configure VPC peering in a full mesh.

Alter the routing table to resolve the asymmetric route

Create network tags to allow connectivity between all three VPCs.

Delete the legacy network and recreate it to allow transitive peering.

Double the MTU on your on-premises VPN gateway from 1460 bytes to 2920 bytes

Create two VPN tunnels on the same Cloud VPN gateway that point to the same
destination VPN gateway IP address.

Add a second on-premises VPN gateway with a different public IP address. Create a
second tunnel on the existing Cloud VPN gateway that forwards the same IP range, but
points at the new on-premises gateway IP.

Add a second Cloud VPN gateway in a different region than the existing VPN gateway.
Create a new tunnel on the second Cloud VPN gateway that forwards the same IP range,
but points to the existing on-premises VPN gateway IP address.

Peer the two VPCs, and use the default configuration for the Cloud Routers.

Peer the two VPCs, and use Cloud Router’s custom route advertisements to announce
the peered VPC network ranges to the on-premises locations.

Peer the two VPCs. Configure VPC Network Peering to export custom routes from Sales
and import custom routes on Finance's VPC network. Use Cloud Router’s custom route
advertisements to announce a default route to the on-premises locations.

Peer the two VPCs. Configure VPC Network Peering to export custom routes from Sales
and import custom routes on Finance's VPC network. Use Cloud Router’s custom route
advertisements to announce the peered VPC network ranges to the on-premises locations.

Provision Cloud Interconnect to connect both organizations together

Set up some variant of DNS forwarding and zone transfers in each organization.

Connect VPCs in both organizations using Cloud VPN together with Cloud Router.

Use Cloud DNS to create A records of all VMs and resources across all projects in both
organizations.

Create a third organization with a new host project, and attach all projects from your
company and Altostrat to it using shared VPC.