IP subnets for internal traffic

Primary tabs

introduction

The LIC uses three ranges of IP addresses. Two ranges are for external use and one range is internal.

Each block is split into smaller chunks called IP subnets using a technique called CIDR.

what it is

The LIC uses the 192.168.0.0/16 network for all its private addresses. There are three data networks in the LIC: biz01, biz02 and adm01.

Figuring out CIDR and IP address ranges can fry the brain of a normal person. Use the handy IP calculator web site (http://jodies.de/ipcalc) and save your head.

The diagrams show these subnets on network topology diagrams. They show the various chunks of the LIC, the colours of the network cables connecting the computers, some of the computer names and where the IP addresses get used.

IP subnets for internal traffic

I split the 192.168.0.0/16 network into 32 subnets.

  • 192.168.0.0/16 -> 192.168.0.0/21, 192.168.8.0/21 and so on up to 192.168.248.0/21

I only use three subnets. Each subnet is used to cover one area of the LIC. The table below summarises what is going on. There are gaping great holes in this table to allow more DMZs to be added at a later date (the LIC can be expanded to a much bigger and more complex setup).

Each of the 32 subnets contains 2,046 host IP addresses.

LIC table: IP subnets for LIC internal traffic
Description Address Netmask Prefix
LIC Network 192.168.0.0 255.255.0.0 /16
biz01      
Internet DMZ 192.168.0.0/21 192.168.0.0 255.255.248.0 /21
192.168.8.0 255.255.248.0 /21
192.168.16.0 255.255.248.0 /21
  192.168.24.0 255.255.248.0 /21
192.168.32.0 255.255.248.0 /21
biz02      
Internet DMZ 192.168.40.0/21 192.168.40.0 255.255.248.0 /21
  192.168.48.0 255.255.248.0 /21
  192.168.56.0 255.255.248.0 /21
  192.168.64.0 255.255.248.0 /21
  192.168.72.0 255.255.248.0 /21
adm01      
Internet DMZ 192.168.80.0/21 192.168.80.0 255.255.248.0 /21
  192.168.88.0 255.255.248.0 /21
  192.168.96.0 255.255.248.0 /21
  192.168.104.0 255.255.248.0 /21
  192.168.112.0 255.255.248.0 /21
  ...    
  192.168.248.0 255.255.248.0 /21