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nickjean

DHCP Windows 2008 R2 problem

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I want to put a new DHCP Server with IP 192.168.0.0 and subnet mask 255.255.252.0 that would give me following IP-Range

 

192.168.0.1 - 192.168.0.255

192.168.1.1 - 192.168.1.255

192.168.2.1 - 192.168.2.255

192.168.3.1 - 192.168.3.255

 

My question is: Have I to define 4 Scopes? If yes which Subnet mask should I use for each scope?

 

I did try to put 4 scopes but it does not work. My first scope is called 192.168.0.26 until 192.168.0.200 with subnet mask 255.255.252.0

But if want to define the secound scope with 192.168.1.26 until 192.168.1.200 with subnet mask 255.255.252.0, I get a error message:

 

" the address range and mask conflict with an existing scope".

 

Does it correct step? Or do I make a mistake

 

Thanks for help

 

Nick

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Hi,

 

Thank you for your answer. But I dont understand you. I should create a single scope with 192.168.0.0 until 192.168.0.254 subnet mask 255.255.252.0

And what is happening withe othe range 192.168.1.1 and 192.168.2.1 and 192.168.3.1? I need 1024 hosts. Your descrition I only will have 254 hosts

 

Regards

 

Nick

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Create one scope of 192.168.0.0/22, the 22 means subnet mask 255.255.252.0. Therefore a scope of 192.168.0.0 with that particular subnet mask includes:

 

192.168.0.0-192.168.0.255

192.168.1.0-192.168.1.255

192.168.2.0-192.168.2.255

192.168.3.0-192.168.3.255

 

The reason being that the 252 in the third octet converts to 11111100, the two 0's represent are the decimal figures of 2 & 1 going left to right and become part of the host section of the address, meaning you can have networks 0,1,2 & 3 (1+2) in the third octet (place of dots) as part of the same network, as normally a classfull 'C' class address would be 255 and therefore binary 11111111 (ones in the mask represents the network part of the address as opposed the host/computer). The technique is called supersubnetting, e.g. adding multiple networks together (as one).

 

Kind Regards

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Create one scope of 192.168.0.0/22, the 22 means subnet mask 255.255.252.0. Therefore a scope of 192.168.0.0 with that particular subnet mask includes:

 

192.168.0.0-192.168.0.255

192.168.1.0-192.168.1.255

192.168.2.0-192.168.2.255

192.168.3.0-192.168.3.255

 

The reason being that the 252 in the third octet converts to 11111100, the two 0's represent are the decimal figures of 2 & 1 going left to right and become part of the host section of the address, meaning you can have networks 0,1,2 & 3 (1+2) in the third octet (place of dots) as part of the same network, as normally a classfull 'C' class address would be 255 and therefore binary 11111111 (ones in the mask represents the network part of the address as opposed the host/computer). The technique is called supersubnetting, e.g. adding multiple networks together (as one).

 

Kind Regards

 

Here is an example of what you want I have excluded the first 9 addresses.

 

Kind Regards

post-9754-0-94679400-1304182210_thumb.jpg

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Hi Sabe75,

 

Thank you very much for your replay.Now I can understand you what you mean.Are you sure if I create a scope of 192.168.0.0/22 that particular IP-Range is included? I mean if I create a scope with for example:

 

192.168.0.30 until 192.168.3.200 /22, would I have 1022 hosts? Have I to create a DHCP Relay Agent too or not? I think yes

 

Kind Regards

 

Nick

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Hi Sabe75,

 

Thank you very much for your replay.Now I can understand you what you mean.Are you sure if I create a scope of 192.168.0.0/22 that particular IP-Range is included? I mean if I create a scope with for example:

 

192.168.0.30 until 192.168.3.200 /22, would I have 1022 hosts? Have I to create a DHCP Relay Agent too or not? I think yes

 

Kind Regards

 

Nick

Yes, the ranges 192.168.0-3 are one network because of the mask, they have effectively been added together. You do not need a relay agent as they are not on different networks, unless you have some sort of router between. Please try as is, am sure you will see if will work fine. In my previous network, I actually used that exact subnet. So you are effectively creating a scope from 0.31 --> 3.200 making 254-30=224 on your 0 range, 254 on your 1 and 2 range and 199 on you 3rd. Therefore, 224+254+254+199=931 (remember to exclude the 0 & 255 addresses as these would have been typically used for network ID and broadcast on classfull).

 

Kind Regards

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Yes, the ranges 192.168.0-3 are one network because of the mask, they have effectively been added together. You do not need a relay agent as they are not on different networks, unless you have some sort of router between. Please try as is, am sure you will see if will work fine. In my previous network, I actually used that exact subnet. So you are effectively creating a scope from 0.31 --> 3.200 making 254-30=224 on your 0 range, 254 on your 1 and 2 range and 199 on you 3rd. Therefore, 224+254+254+199=931 (remember to exclude the 0 & 255 addresses as these would have been typically used for network ID and broadcast on classfull).

 

Kind Regards

 

PS. Could you vote for me, to give me some good reputation. :)

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Hi again,

 

Thanks for replay. I am not sure that I dont need a DHCP relay agent. I can remember that MS has recommed me to do it.

Here is the message from Microsoft:

 

###################

Yes, we need to create 4 DHCP scopes, one for each subnet. To do so, we also need to configure DHCP relay agents for each subnet.

Generally speaking, there are two ways to configure DHCP relay agents .First, to configure routers act as a configure DHCP relay agents. In most cases, routers support DHCP relay. If your routers do not, contact your router manufacturer or supplier to find out if a software or firmware upgrade is available to support this feature.Second, we can configure a computer running Windows Server® 2008 to act as a relay agent by installing the DHCP Relay Agent service.

########################################

 

What do you mean about this resulotion?

 

Regards

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Hi again,

 

Thanks for replay. I am not sure that I dont need a DHCP relay agent. I can remember that MS has recommed me to do it.

Here is the message from Microsoft:

 

###################

Yes, we need to create 4 DHCP scopes, one for each subnet. To do so, we also need to configure DHCP relay agents for each subnet.

Generally speaking, there are two ways to configure DHCP relay agents .First, to configure routers act as a configure DHCP relay agents. In most cases, routers support DHCP relay. If your routers do not, contact your router manufacturer or supplier to find out if a software or firmware upgrade is available to support this feature.Second, we can configure a computer running Windows Server® 2008 to act as a relay agent by installing the DHCP Relay Agent service.

########################################

 

What do you mean about this resulotion?

 

Regards

 

Okay, if you want the range of 192.168.0.0 not to see 192.168.1.0 or 2.0 or 3.0 etc... as in four separate scopes/networks then you you need to create 4 scopes with the mask 255.255.255.0 for each (class C) and use a DHCP relay as these are segmented at layer 3, e.g. will need a router to communicate (layer 3). However, if you want these to be one address range with the mask 255.255.252.0 and therefore they all see each other with not router, only switches (layer 2) between the server and the clients then you do not need a DHCP relay agent and require only one scope.

 

I think it would help if you described your network infrastructure a little more, this would probably make your requirement clearer.

 

Kind Regards

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Hi,

 

Thank you for replay. We have at the time a range of 192.168.1.1 until 192.168.1.254 subnet mask 255.255.255.0.We have not enough IP now and I want to to increase my hosts to 1024.

I think you are right that it is better that I create one scope and without relay agent.

 

If you have any better idea, feel free and write me again

 

Regards

 

Nick

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I have just created an account here because I have to say something about this Microsoft "DHCP server".

 

I am trying to do one really easy thing:

 

1. I want to create one address range like "superscope" say 192.168.0.1 - 192.168.1.255 with 255.255.0.0 subnet mask

2. Then, create in this superscope some scopes for example:

192.168.0.1 - 192.168.0.19

192.168.0.20 - 192.168.0.99

192.168.0.100 - 192.168.0.255

192.168.1.1 - 192.168.1.99

192.168.1.100 - 192.168.1.255

 

3. Set for these scopes Reservations (it doesn't matter to me if it is in scopes separately or on superscope level)

4. And finally set for these scopes DIFFERENT scope dhcp options (like 003 Router, 006 DNS Servers, 150 TFTP, and so on...)

 

Why step 4?

 

Because I want to have registered things like IP phones in first scope (0.1.- 0.19.) set by Reservations and send them IP, DNS, TFTP and Subnet Mask of 255.255.0.0.

On second scope (0.20 - 0.99) let's say computer Reservations, where I want to send them IP, Gateway, DNS and Subnet Mask of 255.255.0.0.

Third scope can be set for free distribution (this setting can be done at superscope configuration probably). Here, I DO NOT want to send those computers Gateway and DNS because I don't want them to be connected to internet. But I still want to have access to whole superscope, so I want just send IP and Subnet Mask of 255.255.0.0.

 

AND SO ON...

 

Basic things are:

1. I want to send same subnet (255.255.0.0) to all things (phones, computer, printers,...) registering on this DHCP so they can communicate without any routing.

2. These Scopes differentiation lets me set options for each scope so I don't need to set every Reservation options separately.

 

With this configuration I will be able to change TFTP server for all reserved IP phones with one or two clicks..

 

Sorry for the word, but if it is true that I am unable to create more like one (1) scope on the same subnet... IT SUCKS EXTREMELY HARD

 

How can be any programmer of DHCP server so short blinded and don't see this elementary (administration) function.

I am lame programmer and I think I could program this in one week. So how could anyone from Microsoft's team, which I really admire, forget this thing?

Apparently it’s very easy to forget because I didn’t see this ability in any of Windows Server Oss.

 

Any other DHCP servers I saw, has this ability, but they are not this much robust.

 

I think that my other option is to start using LINUX.

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