Subnetting Q

Lethal` · 20 Jun 2010 at 17:02

So I've got a scenario which I need to work out an IP addressing scheme for:

Class A private network for at least 300 subnetworks
Each has at least 60 hosts

I've worked out that I'll need a 255.255.128.0 (/17) mask, which will provide 512 subnetworks, however 32768 hosts per subnetwork. This seems like far too many wasted hosts so how could I reduce it?

Thanks

Zarf · 20 Jun 2010 at 18:49

Wouldn't you just subnet a single /17 network into 512 /26's ?

Lethal` · 20 Jun 2010 at 21:31

Zarf said:
Wouldn't you just subnet a single /17 network into 512 /26's ?

Would you be able to give me a quick explanation of how this works please?
Still getting to grips with all this subnetting

kkbigal · 21 Jun 2010 at 02:13

Use variable length subnet masking?

That way you can break up a single range of 256 ip addresses into individual subnets without so much wastage.

That's if I understand the question

http://www.tcpipguide.com/free/t_IPVariableLengthSubnetMaskingVLSM.htm

FoxEye · 21 Jun 2010 at 03:14

Sure that question is right? You said:

At least 300 subnets (so you could have 1,000)
At least 60 hosts (so you could have 20,000)

So there are as many answers as numbers you can think up for subnets/hosts

Lethal` · 21 Jun 2010 at 07:34

FoxEye said:
Sure that question is right? You said:

At least 300 subnets (so you could have 1,000)
At least 60 hosts (so you could have 20,000)

So there are as many answers as numbers you can think up for subnets/hosts

Yeah it's correct alright! I thought it was strange too, as I could easily achieve that with what I proposed in the OP, just it would be quite a waste so I think I'll bring it down a bit.

Thanks kkbigal, I'll look into that. I think I read a bit about VLSM on the Cisco NetAcademy, just got to put it into practice I guess