Simple Subnetting Question

RouterOS General
1

Good morning all,

i’m tring to work out what seems to be a rather simple subnetting problem i have. let me explain what i’m tring to do

I have 2 Ip ranges on 2 different interfaces
202.xxx.132.1/30 on Ether 1
202.xxx.132.17/29 on Ether 2

WHat i would like to do is use the ip’s from .4 to .15 on Ether 3, i would like to use a /28 for this and i can move the 17/29 ip range up slightly but every time i try and give the router the ip of 202.xxx.132.5/28 the network shows up as 202.xxx.132.0 with a broadcast of 202.xxx.132.15

Anyone got a answer to this problem?

2

A /28 gives you an address range of 16, hence why you are getting a network of 0 and a broadcast of 15. The range of 4 to 15 is not a valid single subnet. You could make it up with two subnets( 4 to 7 and 8 to 15) but clearly this would double up on network and broadcasts.

3

The start address of a subnet has to be a multiple of the size of that subnet. For example a /28 (size=16) may start at .0 or .16 or .32 etc, but it can not start at .8 and go up to .23 etc.

–Tom