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VPC Subnet Configuration in vCenter

This section describes the procedures for configuring a VPC Subnet using the vSphere Client.

VPC Subnets are Logical Subnets for workload (VMs / K8s) connection.

There are 2 types of VPC Subnets:

vCenter VPC Connectivity

VPC Subnet Overlay

Tenant creates subnet-overlay and share to namespace

Overview of Overlay Types

Different Subnet Overlay types are available:

Type Use Case Routing Logic
Public Provide Public IPs to workloads with direct access to the physical network (No-NAT). External visibility is high; direct ingress/egress.
Private-TGW Provide Private IPs to workloads with no access to the physical network (requires NAT), but routably accessible to other VPCs in the same Transit Gateway. Best for shared internal services across the enterprise.
Private-VPC Provide Private IPs to workloads with no access to the physical network and other VPCs in the same Transit Gateway (requires NAT). Maximum isolation; workloads are "hidden" even from other VPCs.

VPC Subnet Option

Configuration

  • Step1. Create new VPC Subnet (Overlay) vCenter Create VPC

  • Step2. Configure new VPC Subnet vCenter Create VPC

    • VLAN Extensions
      "No" for a VPC-Subnet Overlay.
      Note: VLAN Extension is detailed in a the section below.

    • Access Mode
      Select VPC Subnet mode based (Public / Private TGW / Private VPC) based on the VM connectivity you need.

    • IP Block
      Choose "Any", or select a specific IP Block for that VPC Subnet.

    • Auto allocate Subnet CIDR from IP Blocks
      . "Yes" to let VCF Networking choose the VPC Subnet CIDR,
      . "No" to choose manually the CIDR to use (you can see the "Available Ranges" when clicking on "View IPs..." - not showed in the screenshot).

    • Subnet size
      Choose the number of IPs you'll need in that subnet to connect your workloads.
      Keep in mind, 3 IP will be consumed by the VPC Gateway (subnet IP, default gateway, broadcast IP) + optionally a 4th IP if you enable DHCP Server.

    • VPC Gateway Connectivity
      . "Yes": The VPC Subnet will be connected to the VPC Gateway and so workloads connected on that VPC Subnet will have access to outside of that VPC Subnet.
      . "No": The VPC Subnet will NOT be connected to the VPC Gateway and so workloads connected on that VPC Subnet will NOT have access outside of that VPC Subnet.

    • DHCP Config
      . "None": No DHCP Service.
      . "DHCP Server": VPC Subnet will have a DHCP Server to offer DHCP service to the workloads connected to that VPC Subnet.
      . "DHCP Relay": VPC Gateway will forward DHCP requests for workloads connected to that VPC Subnet to an external DHCP Server.This option is not available if the VPC Gateway is connected to a Distributed Transit Gateway.

Monitoring

Topology

You can see the VPC Subnets Overlay in a graphical way under Topology: vCenter Validation VPC Subnet

VPC Subnet VLAN-Extension

Org creates subnet-VLAN and share to Org => Subnet available in Tenant Subnets. then Tenant share to namespace Note: That subnet-VLAN can be shared in multiple Orgs.

Org creates DTGW-VLAN-Dedicated and add "Dedicated VLAN Connection" to Org => DTGW available in Tenant. then Tenant adds that DTGW-VLAN-Dedicated to a VPC (public mode only) Note: That subnet-VLAN can NOT be shared in multiple Orgs.

Overview of VLAN Options

Different Subnet VLAN options are available:

Type Use Case Routing Logic
L2-Only Provides direct access to a physical VLAN. Access to Public VPC Subnets is via the external network only. No access to Private VPC Subnets.
Public - No VPC Connectivity The VPC Gateway is aware of the VLAN subnet, but provides no routing services to it. In vCenter, this option provides the exact same functionality as the L2-Only mode (designed for VCF Automation).
Public - VPC Connectivity Provides access to the physical VLAN via the VPC Gateway (bridges). Enables simultaneous access to the Physical VLAN and internal Overlay VPC Subnets.

VPC Subnet VLAN Option

Configuration

  • Step1. Create new VPC Subnet VLAN-Extension vCenter Create VPC

  • Step2. Choose the VPC Subnet name + VLAN Extension + Access Mode + VLAN ID (+ Gateway IP + Connectivity) vCenter Create VPC

    • VLAN Extensions
      "Yes" for a VPC-Subnet VLAN-Extension.

    • Access Mode
      Select Access Mode (L2-Only / Public - No VPC Connectivity / Public - VPC Connectivity) based on the VM connectivity you need.

    • VLAN ID
      Enter the physical VLAN ID.

    • Gateway CIDR IPv4 Address (only for the Access Mode Public)
      Enter the default gateway of that VLAN (configured in the physical network).

    • VPC Gateway Connectivity (only for the Access Mode Public)
      . "No": The VPC Subnet VLAN-Extension will NOT be connected to the VPC Gateway, but directly to the physical VLAN.
      . "Yes": The VPC Subnet VLAN-Extention will be connected to the VPC Gateway and bridged to the physical VLAN.

Monitoring

Topology

You can see the VPC Subnets VLAN-Extension in a graphical way under Topology: vCenter Validation VPC Subnet