SPelham

Hi all,
What is the best way to allow me to expand the IP range we have?
Currently we have the range of 192.168.10.100 - 192.168.10.254 with a subnet of 255.255.255.0 all IP's below 100 are reserved for servers etc.
But now I have come to the point where I only have about 10 left.

Can I simply change the scope so that it distubutes IP address's from 192.168.1.0 - 192.168.10.254 and then exclude the 10.0 - 10.100 ip's

Any help would be most appreciated !

TIA

Simon

mega_stream

Are you the sys admin?!

I would check with your network guys before doing anything

Nimbus

What's the lease period? Are you getting a lot of laptop users plugging in and taking an address for 3 months when they only need it for a day?

rich101

One of two things spring to mind

- Set the lease time down to between 2 and 7 hours, that way laptops will release leases quicker .

- Recreate the scope as the original with the extended range, deactive the old and active the new.

A lot of the above may depend on the environment i.e. client and DHCP server though

rich

SPelham

Sorry there are no network guys only me !!
The lease period is set at 3 days...

SPelham

trouble is there are only about 10 - 15 laptop users so cutting the lease down to a few hours will only help in the short term as we are expecting more people to start..

MattW

Have a read

http://www.swcp.com/~jgentry/topo/unit3.htm

David_Wallis

if you drop the lease duration and your server dies, your fooked.

if you change the range of IPs which is fine, then you will need to change the subnet mask to 255.255.0.0

It would be better to do your subnetting properly based on how many hosts and how many networks you need.

How many clients and how many servers / network devices etc.

I would change the scope to do 192.168.0.1 - 192.168.10.254 change the mask to 255.255.0.0

Also you will need to make the changes on anything with a static.

SPelham

Thanks for your help guys.Think I have the right idea now

dsmith

Dont just change the mask to 255.255.0.0 unles you're really going to have 65K hosts on the single subnet

If you went for 255.255.252.0 you could have

Subnet 192.168.8.0 to 192.168.11.255 for 1000 IPs.

If your network has grown over time to around the 250 Hosts it may be time to seriously think about how its going to move on from there - and consider moving to a different toplogy now - maybe moving servers etc onto a different subnet and seperating departments or the like.

David_Wallis

hence why I said about the subnetting, I was trying to keep it simple for him. (some people can understand the 0's but anything else ***** them over) we use 255.255.240.0 and people really struggle to understand subnetting.

Correct me if im wrong but its not going to cause any ill effects having the subnet mask as 255.255.0.0? as theres not going to be anything externally accessible on that range? I know its very lazy of me and the mask should match the scope being used, but we have teams that deal with it for us...having said that we are running out of IP's in our range used for static's

Solarwinds do a nice subnet calculator.

David

stevencotton

There's no harm in assigning a /16 to so little hosts, it just looks amateurish and isn't the right way to do something.

David_Wallis

running out of addresses is amateurish Networks isnt my job.. but it helps to have a little understanding. As for subnetting on paper..no thanks.

David

stevencotton

I'd say a little knowledge was a dangerous thing if anything

David_Wallis

good point.. theres a line you can draw with little though. It helps it you know 'why' you are doing something rather than just doing it because thats what you've been told.

Knowing your own limits and not being afraid to ask counts for a lot in my book.

stevencotton

That's the defining factor, knowing one's limits. Sort of slightly related, here one of the "senior developers" thought he knew exactly what he was doing when he fired up a DHCP server on our internal office LAN for his own use. Imagine the hilarity which ensued with two DHCP servers on the same subnet

David_Wallis

I wouldnt use the word hilarity.. thank god for rouge dhcp detection

dsmith

Its all just binary - people think its harder than it is.

SPelham

Unfortunatly the last time I remember learning about subnetting and the correct use was a while back when doing my MCP and unless you are involved in networking all the time you begin to forget things (especially me with my memory )

I think I have an old learnTCPIP.com cd kicking around that I used to use when I was doing my exams, better dust it off and start learning again!!!

stevencotton

It's easy really, once you can do base 2 in your head subnetting is a snap.

jbryant

Not really - It's just that there are 10 types of people in this world; those who understand binary and those who don't.

Joolz

PS. Sorry - old joke.

dsmith

But rather sadly makes me chuckle every time I see it (and someone on another forum has it as their sig...)

Deano
IP Network designer - subnetting is my life

David_Wallis

LOL, not heard that one before

pmacFTO

http://www.thinkgeek.com/tshirts/frustrations/5aa9/