Setting up an Azure Big IP F5 device

Occasional Visitor


I've inherited an Azure F5 implementation. 

Below is the subnet layout. 

external (234 Addresses)


internal (244 Addresses)
*F5 Route configuration = Gateway


management (244 Addresses)


GatewaySubnet (59 Addresses)



The *F5 Route configuration is a configuration item in the F5 operating system.


The subnet layout and F5 configuration above is currently in production and functioning as expected. 

I've inherited the F5 subnet layout below. 

Looking at the subnet layout below, what is the "internal" subnet gateway?

How is this determined?


external (32 addresses)


internal (32 addresses)

Gateway Address (??????)


management (248 addresses)


GatewaySubnet (59 addresses)






Subnet FAQ's

Are there any restrictions on using IP addresses within these subnets?

Yes. Azure reserves 5 IP addresses within each subnet. These are x.x.x.0-x.x.x.3 and the last address of the subnet. x.x.x.1-x.x.x.3 is reserved in each subnet for Azure services.


  • x.x.x.0: Network address
  • x.x.x.1: Reserved by Azure for the default gateway
  • x.x.x.2, x.x.x.3: Reserved by Azure to map the Azure DNS IPs to the VNet space
  • x.x.x.255: Network broadcast address



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