Subnetting / supernetting

[scrimmy]

I am getting confused with supernetting. Can someone please help.

If I need to further subnet off a class c subnet such that
Subnet 1 to have 100 hosts
Subnet 2 to have 50 hosts
Subnet 3 to have 20 hosts
Subnet 4 to have 10 hosts
subnet 5 to have 10 hosts

These fit nicely into the range using subnet mask
/25 for subnet 1 (126 hosts available)
/26 for subnet 2 (62 hosts available)
/27 for subnet 3 (30 hosts available)
/28 for subnet 4 and subnet 5 (14 hosts available)

I have been allocated 172.16.118.0/24, do I need to split the IP addresses as:

172.16.118.128/25 - subnet 1
172.16.118.64/26 - subnet 2
172.16.118.32/27 - subnet 3
172.16.118.16/28 - subnet 4
172.16.118.0/28 - subnet 5

or

172.16.118.0/25 - subnet 1
172.16.118.128/26 - subnet 2
172.16.118.192/27 - subnet 3
172.16.118.224/28 - subnet 4
172.16.118.240/28 - subnet 5

Many thanks

 

[burtsbees]

Either way---just make sure the device can use subnet zero. On a Cisco, subnet zero is enabled by default.

You can also use the 24 bit mask for purposes of route maps, acl's, NAT, etc. to cover all subnets. You are actually using VLSM, or "subnetting a subnet" as some refer to it as the thing of which to be that. I am trying to not end that previous sentence with a preposition.

There is no supernetting in this scenario...VLSM=Variable Length Subnet Mask, as covered in CCNA ICND (or ICND2...).

/

tim@tim-laptop ~ $ sudo apt-get install windows
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Couldn't find package windows...Thank Goodness!