GatewaySubnet

In the Ultra Transcenders books

AZ-305AZ-104AZ-700SC-500AZ-900

Each book explains GatewaySubnet in context, with comparison tables and the common traps.

Terms in this definition

• Subnet

  A segment of a VNet's address space from which resources receive private IPs. Azure holds back five addresses per subnet (the first four and the last), leaving 251 usable in a /24 and three in a /29, the smallest IPv4 subnet.

• ExpressRoute

  A dedicated private link between on-premises networks and Azure, using Microsoft peering or private peering.

• VPN

  Traffic sent through an encrypted tunnel across a public network, as in a site-to-site connection to a VPN gateway in an Azure GatewaySubnet.

• LEAST

  Pass up to 254 expressions to this T-SQL function and it hands back whichever is smallest. Both Fabric Warehouse and SQL analytics endpoints support it.

Related terms

• ExpressRoute and S2S VPN coexistence

  Running a route-based VPN gateway (VpnGw1 or above, never Basic) alongside the ExpressRoute gateway in one VNet, sharing a GatewaySubnet of at least /27; the VPN acts as backup or links other sites.

• ExpressRoute gateway

  Connects a virtual network to an ExpressRoute circuit from inside GatewaySubnet. Only one is allowed per VNet, and VPN traffic needs a separate gateway.

• ExpressRoute gateway migration

  To turn a Standard, HighPerformance or UltraPerformance gateway into an AZ SKU, this guided experience deploys a second gateway next to it in the existing GatewaySubnet. The alternative is deleting and recreating it.

• New-AzVirtualNetworkGateway

  Cmdlet in Az.Network that deploys a VPN or ExpressRoute gateway into GatewaySubnet. Connection policies are neither created nor changed by it.

• Route table

  Resource containing user-defined routes and attached to subnets, shaping traffic that leaves them. Attaching one to GatewaySubnet steers traffic coming in over VPN.

• Virtual network gateway

  Lives in GatewaySubnet and comes in two types, ExpressRoute or VPN. Setting it as the next hop in a UDR routes traffic on-premises.

• VPN gateway

  Terminates IPsec tunnels for site-to-site, point-to-site and VNet-to-VNet connections, as a VPN-type virtual network gateway in GatewaySubnet. It gets a Standard static public IP when created, and that IP can't be swapped.

• VPN Gateway Basic SKU

  A VPN gateway SKU meant only for development, limited to 10 site-to-site tunnels and 100 Mbps, without BGP, zone redundancy, ExpressRoute coexistence or OpenVPN/Entra ID point-to-site. No other SKU can use a /29 GatewaySubnet.