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Configuring DHCP in windows 2003

Hi,
I was searching to find out a way to distribute IP addresses depends on the client type. Windows clients will get IP from our main DHCP scope while the mobile devices will get from a different scope. I read through some of the documents in regards to this but i didnt know how to find out the vendor class ids for mobile devices like iphone and android phones. is there any way to find it out?

I would like to know a working solution to provide clients IP addresses as nowadays each user consumes more than one ip for his laptop and mobile, which consumes most of the ips n the pool. Please suggest a good working way to be used in corporate environment.

Thanks for the help
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abafadel
Asked:
abafadel
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2 Solutions
 
Steve KnightIT ConsultancyCommented:
You could just run wired and wireless on different vlan / subnets.... Or increase your subnet size if feasible?
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chris_martin62Commented:
try this it may help

http://www.coffer.com/mac_find/
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pwindellCommented:
A simple option is to shorten the DHCP Scope Lease period to one day rather than the default of 8 days.  This will allow an address to be freed up sooner and reused by someone else.  Client renew their lease at 50% of the scope life,...so they would renew every 12 hours,...but if an address is not renewed then it becomes available to someone else in 24 hours.

If your subnets are sized at 6 hosts, 14 host, 30 host, 62 host, or 126 host, then you can upsize them to 254 host segments,....but do not make them larger than 254 host. Ethernet looses efficiency at around 300 hosts per segment and the next jump above 254 Host is a 510 host segment which is way to big.

I think the suggestion you were given by dragon-it to put the wireless access points on a different IP Segment is the best solution and the one I would go with,...this would obviously mean you may have to add a new segment to your LAN..
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abafadelAuthor Commented:
Pwindell, thanks for your suggestion, i have already done making the lease period to 1 day, thats the way i am surviving now. Is there any document to get help on adding a different subnet segment?

Thanks to all commented
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pwindellCommented:
There is not going to be a simple document for that.  I'm not sure what to tell you there,..that is just something that an IT person at a place just "knows" how to do.  It can effect cabling and it would mean configuring, reconfiguring, or installing a new LAN Router.  You can also use a Layer3 Switch as a Router/Switch combination where it is doing both jobs of a Router and Switch at the same time.

If you only mean that question in the context of the DHCP,...all you do is create a new Scope (just a normal regular Scope,..no Superscopes!) for the new IP Segment.  It is the job of the LAN Router to handle the rest and forward the DHCP Queries to the DHCP Server properly.
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Steve KnightIT ConsultancyCommented:
well said there.  how many devices have you got in total btw and what ip range / subnet mask are you using.

I always setup a scope on dhcp to be x.x.x.1 to x.x.x.254 and then exclude areas for fixed ip devices at top and bottom of range so for a client range you should be able to get 240 addresses maybe.

As to whether you want that many on single subnet.... With switched network not so much of an issue, especially if all going back to communicate with same servers / internet connection etc anyway.

As has been said above you need a router or layer 3 switch to handle the routing... Or at a oush if only one server involved and no internet direct fromdesk then two network cards inserver.

Would invest in a layer 3 switch personally and split each office / department or whatever into different vlan, maybe 100 or so on each.

Tht also means you could run two dhcp servers with scope split between them, one giving 100 to 200 say other 1 to 100 for redundancy.

Anyway if not sure maybe worth bringing someone in to help split it up, we can advise but is diffivcult to know specifics of your enviornment.

Sorry for typos etc. This train bumping all over the place!

steve
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pwindellCommented:
I'll "second that".

I always make Scopes the entire subnet range and then use Exclusions to mold it to what I want.  I keep Reservations to a bare minimum,...if you have a lot of those then you may as well forget DHCP and go static and have one less running "sever service" to go wrong or maintain.

I also use an L3 Switch here.

I also run a pair of DHCP Servers with identical Scopes apart form where the Exclusions create a 50/50 split in the addresses each hand out.
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abafadelAuthor Commented:
Thanks to all of your comments. We are using windows 2003 server for DHCP, presently i have one superscope in network ID 192.168.10.0 starting range 111 to 254. Upto 110 i have to use as static for different network equipments and servers. So, i have only 143 addresses to lease for clients. (it was enough for some time, but days changed people used iphone and all sort of smart phones besides their laptop, also required IP.)

I came across with the Vendor/user class ID method for distributing IPs, do you think its suggested way? If so, how do I find the vendor class IDs of smartphones?

Thanks for your helps
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Steve KnightIT ConsultancyCommented:
do you really need so many fixed ip devices for a 140 user network?!  what  have you.... A couple of servers, nas, managed switches, half a dozen printers, access points etc i suppose?

Unless you can increase your subnet size vendor class etc. Is irrelevant.

Options:

1. Increase subnet size, i.e. Change subnet mask
2. Reduce no. Of fixed ip entries area and increase dhcp issued addresses.
3. Add further subnet(s).
4. unless they are company phones tell you users to get them off the wifi network and use their 3.5G!

 No. 3. Will see you into any amount of new vlans and split and expand as needed.
No. 2 is short term fix - issue whole 1 ... 254 scope and make sure all fixed devices are excluded.
no. 1 meand changing submet mask on all fixed ip devices for starters.
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pwindellCommented:
Why do you have a Superscope!?!?!

Get rid of the Superscope,...Superscopes are for Multi-Netting and you are not Multi-netting.

Having server 2003 means nothing,...it could just as easily be Linux,..it doesn't change anything.

We have given you everything you need to remedy the situation,...you just have to do it,...and follow proper network design principles when you do it.
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abafadelAuthor Commented:
Thank you all for your support. In this case, i wll be trying to expand the host IPs to 510. does this affect the releasing time of the IPs? I mean it may delay obtaining IP as the range is huge?

Thanks.
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Steve KnightIT ConsultancyCommented:
no it will make no difference in that respect.  you just need to change the subnet mask on every fixed ip device such as routers, switches, server, access points, printers etc.

Puit the scope lease time down to 30 mins now.  pick an evening or whatever when ypu can have down time and nobody will therefore have any valid dhcp ip addresses.  remove the scope and rebuild it. Like was said you don't need superscope, just make one scope covering all addresses in range and add some eclusions in for your fixed ip areas.

If you have more than one server there run dhcp on both.... Put same scope on both 1...510 and then:

1 - 110  excluded from both for your fixed ip stuff
111 - 300 excluded from server B (so server A gives them out)
301 - 510 excluded from Server A (so server B gives them out)

make sure server nic has correct subnet mask too of course.

Good luck!
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pwindellCommented:
Thank you all for your support. In this case, i wll be trying to expand the host IPs to 510.

So you will not fix it "right",..you are just going to create a future mess for someone else to worry about?.

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Steve KnightIT ConsultancyCommented:
Thanks for the points.... but what did you do in the end?
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abafadelAuthor Commented:
Thanks to all of your support. I removed the existing scope and created a scope with range of 255.255.252.0 subnet range, excluding some important static address which i had already used here. Changed almost all static ip subnets from 255.255.255.0 to 255.255.252.0. (eventhough i didnt change on the servers, i still get connection from clients to those subnets are 255.255.255.0). Anyhow i get around 900 something ips for lease to clients.

Again, thanks to all of your help, especially dragon-it, pwindell. Keep up good helps!
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Steve KnightIT ConsultancyCommented:
glad you got working, be careful running mixed subnet masks mind, will make you scatch your head once a pc gets and adddress outside the original range and can communicate with internet say but not a sefver or new printer ypu put in say....

Anyway as long as you are happy.... Good luck with it!


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abafadelAuthor Commented:
Thanks for your concern. Actually i put them all in a single subnet (255.255.255.252) including servers and clients, but exluded the servers and appliances in DHCP. does it make sense or not a good practice?
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Steve KnightIT ConsultancyCommented:
No that sounds a good plan.  Set the whole IP range as scope, add exclude range for your servers etc. on fixed IP's.
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abafadelAuthor Commented:
Thank you for your support.
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