DHCP Scope vs IP Helper

Hi @all,
SCCM 2012 R2 on W2K8R2 Server with SQL 2012 SP1 included all CU's and Hotfixes.
It's only for a LAB so i have installed all on one Server.
Problem is now, that when i install W8.1 i need other bootfile than when i install W7 cause of EFI.
How did you manage this with Windows Server DHCP? cause with Scope options i only can set one Boot File (=067)
Greetz Stoney

Hi,
This is exactly the reason why it isn't supported or recommended to use DHCP options instead IP Helpers should be used. Ip Helpers will assign the boot file dynamically. Moving the DHCP role to a separate server will solve it.
In your setup you have another challenge as well, WDS in Windows 2008r2 will only support PXE boot from an uefi x64-based machine and not 32bit.
http://ccmexec.com/2013/05/configmgr-2012-uefi-and-pxe-boot-support/
Regards,
Jörgen
-- My System Center blog ccmexec.com -- Twitter
@ccmexec

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Windows 2008 R2 DHCP scope change - Netsh Exec not working

OK, there seems to be a disconnect between Netsh documentation and how it actually works. We are in the process of re-addressing ALL our DHCP scopes (joys of a buy-out) and using the steps outlined in numerous MS articles and Blogs etc... we should
be able to use "Netsh dhcp server scope 192.168.1.0 dump > scope1.cfg" then modify the cfg file with the new scope address (i.e. change all 192.168.1. to lets say 10.10.5.). Then use netsh exec scope1.cfg (yes, the file modified) to
create the new scope which would contain all the "stuff" the current scope has (reservations, options, etc).
Well, all we get is the response "The following command was not found: |".
Environment is as follows:
Account is a domain admin
working on a RDP session on the DHCP server
Server is Windows 2008 R2 (current functioning DHCP server)
Using administrative CMD (elevated)
have tried changing context into Netsh | DHCP | Server and default CMD - all "no go"
supporting link from MS: http://technet.microsoft.com/en-us/library/cc772372(v=ws.10).aspx#BKMK_1
There's a lot of discussions around this, but I haven't seen any response that says how to actually do it. export/import won't work for us since we have to update the scope info. With almost 100 scopes to update, we really need this functionality!
(or similar method)
Any assistance would be greatly appreciated.

OK... It seems the issue is with the dump file. I actually got exec to run once with a dump file which wasn't modified.  The stupid part is it only ran one time, I could not duplicate it.   Since
I've beat this thing to death and no one could offer any assistance (Hello MS?), I'm not wasting any more time on it.   Luckily, I was able to figure out an alternate method.
Looking at the dump file I realized all the lines are just a straight NetSh commands, which means all I needed to do is grab the lines and preface them with NetSh. Like this...
for /f "tokens=*" %a in ('type scope.cfg ^| find /i "dhcp"') do NetSh %a
where scope.cfg is your dump file.   This runs perfect and seems to be the exact thing that exec should be doing. I did flip the "SET STATE 1" to "0" so the scope was deactivated (Don't forget to run it in an elevated
prompt).
Hope this helps someone else so they aren't spending days for nothing!

Internal DHCP scope for AP on WLC 7.0 (on diff subnet)

hi All,
I would like to know if it is possible to assign dhcp pool on a different subnet to the WLC management interface?
Eg: Management Interface is on 172.16.4.100 /24
I would like to use the WLC Internal DHCP to assign IP to my APs on the a different range 172.16.2.x /24
Is that possible?
I have tried assigning dhcp scope for the AP within the same subnet as the management interface and it works. But that is not my requirement
Apparently i need my AP to be sitting on a different vlan
please advise

No its not possible.. this works only if the AP and the WLC management interface is in the same subnet!! to ur issue we use something called as DHCP OPTION 43, google search DHCP OPTION 43 + cisco, the first link that u get wil help you!!
Please dont forget to rate the usefull posts!!
Regards
Surendra

Best place to create the DHCP scope for Guest SSID for remote office connected to HQ Foreign-Anchor controller

Hi Experts ,
Need help with the respect to understand the best practice to place/create the DHCP scope for remote site Guest SSID which will be connected to HQ Foeign-Anchor controller set-up.
how about internet traffic for Guest SSID , which one will be recommanded :
1) Guest SSID gets authenticated from HQ ISE and exposed to the local internet
2) Guest SSID gets authenticated from HQ ISE and exposed to the HQ internet
Thanks

Hi George ,
Thanks for your reply ...So you mean, best design would be to create the DHCP scope into DMZ for guest and let it get exposed to HQ internet ...
how about if I have another anchor controller in lets say in other office and I need to anchor the traffic or load balance from HQ foreign controller , in that case if I create DHCP scope into HQ anchor controller and if its down , I will loose the connectivity , how do I achieve fail-over to another anchor ?
Do I need to create secondary scope into another anchor controller and let the client get reauthenticated from other location ISE and get ip address as well from another anchor controller . Is it what you are proposing ?

How to check particular DHCP Scope all Details.

How to check particular one DHCP Scope ALL Details. Server is Windows 2003 so Powershell.
Any Command like Netsh or anything? For a particular Scope.
Also How to export & import a particular DHCP Scope?
AliahMurfy

Hi,
With netsh command you can manage your DHCP server.
For more information you can refer to:
Netsh commands for DHCP
http://technet.microsoft.com/en-us/library/cc787375.aspx#BKMK_export
Especially for subtitle Netsh DHCP server
Hope this helps.

IPAM does not show all the dhcp scopes

Hello,
I have the following strange behavior.
I've installed IPAM on a new server (2012 R2), all the acces rules are completed. But when i'm looking to the DHCP scope, not all off the scopes are included.
For the moment its not possible to upload screenshots, but only 3 off the 4 scopes are included in IPAM.
Has anyone an idee what the problem can be?
Thank you in advance!
Regards,
Kevin

Hi,
Check the selections you have made for viewing first. To see IPv4 scopes, click DHCP Scopes in the upper navigation pane and IPv4 in the lower navigation pane. To see IPv6 scopes click IPv6 in the lower nav pane, etc.
You can also view scopes by clicking DNS and DHCP Servers and choosing Server Type = DHCP and View = Scope Properties. Again, you must click IPv4 or IPv6 in the lower nav pane. You can't view IPv4 and IPv6 scopes at the same time.
Also check and see if the scopes are shown in IP Address Blocks when you choose the Current View = IP Address Ranges.
If a scope was recently created on a DHCP server, or the server was recently added, then all data might not yet be gathered. Right-click the server in SERVER INVENTORY and then click Retrieve All Server Data, and be sure to refresh the view using the display
pane refresh button or F5.
Let me know if this helps.
Thanks,
-Greg

DHCP scope full, event ID 1020

Hi, one of our Windows 2008 R2 Domain controllers is returning the following warning message on almost a daily basis:
Log Name:      System
Source:        Microsoft-Windows-DHCP-Server
Date:          19/11/2014 11:32:41 AM
Event ID:      1020
Task Category: None
Level:         Warning
Keywords:      Classic
User:          N/A
Computer:      computername.domain.x.x
Description:
Scope, 10.x.x.0, is 83 percent full with only 39 IP addresses remaining.
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
    <Provider Name="Microsoft-Windows-DHCP-Server" Guid="{xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}" EventSourceName="DhcpServer" />
    <EventID Qualifiers="0">1020</EventID>
    <Version>0</Version>
    <Level>3</Level>
    <Task>0</Task>
    <Opcode>0</Opcode>
    <Keywords>0x80000000000000</Keywords>
    <TimeCreated SystemTime="2014-11-19T00:32:41.000000000Z" />
    <EventRecordID>12980</EventRecordID>
    <Correlation />
    <Execution ProcessID="0" ThreadID="0" />
    <Channel>System</Channel>
    <Computer>computer.domain.x.x</Computer>
    <Security />
</System>
<EventData>
    <Data>10.x.x.x</Data>
    <Data>83</Data>
    <Data>39</Data>
</EventData>
</Event>
Upon review of Microsoft Support online, I found the following article which illustrates a few options:
http://support.microsoft.com/kb/255999/en-au
What would be the logical choice for us, having the 10.x.x network?
Ideally, it would be good not having to re-subnet anything if possible, or re-create the scope.
Would a scope extension require a reboot of the server? Never done this before, so thought I should ask.

Hi,
According to your description, my understanding is that DC prompts an warning event ID 1020, indicate 83% full with DHCP scope.
By default, the threshold value for firing of event 1020 is 80%. Estimate devices number, contrast with the number of IP address in this scope, if the percentage is less than 80%, you may try to reduce the lease duration and decrease the cleanup interval.
This can help to speed the reclaiming of expired scope IP addresses.
To reduce the lease duration:
1.At the DHCP server, click Start, point to Administrative Tools, and then click
DHCP.
2.In the DCHP console tree, right-click the scope you want to configure, and then click
Properties.
3.On the General tab, under Lease duration for DHCP clients, type the new lease duration.
To use a Netsh command to set the cleanup interval time:
1.At the DHCP server, click Start, click Run, type
cmd, and then press ENTER.
2.Type netsh dhcp set databasecleanupinterval <NewInterval> (where "NewInterval" is the amount of time in minutes between DHCP database cleanups).
As an existing DHCP scope, its subnet mask can’t be changed. If the Start Address and
End Address do not currently include all addresses for your specific subnet, you can increase the number of addresses in the scope by extending the
Start Address or End Address in the scope properties. This operation needn’t reboot.
If neither of above 2 suggestions is applicable, new a DHCP scope or reference
KB255999 (resubnetting and superscoping). At the same time, you need to change your network topology.
Best Regards,
Eve Wang

DHCP scope options: How TO

Hi,
I have a 10.4 server as DHCP for several VLANs. I need to setup DHCP scope options on two VLANs to be able to direct DHCP requests from a specific device (IP phones) to the relevant VLAN for obtianing IP addresses.
I cannot see bootpd.plist in /etc and not much information available online about this.
Found these two relevant posts but not much of help:
http://discussions.apple.com/message.jspa?messageID=7200952
http://discussions.info.apple.com/message.jspa?messageID=5054131
I can export the serveradmin settings out and can see the entries but where and how do I make the scope entries? plist editor won't open the file and if i convert to csv in excel the existing data is there and logical but where do i enter my scope options?
any help in the right direction will be much appreciated.
cheers
Muhammad

You didn't try hard enough... ;). You need to use the Get-DhcpServerv4OptionValue cmdlet (or ...v6...).
Get-DhcpServerv4OptionValue -ComputerName <computername> | Where-Object OptionID -eq 6 | Select-Object Value
Edit: I think it's important that you know how I solved this problem. Perhaps you can put it to use yourself some time. The first thing I did was return all the 'get' DHCP cmdlets using this command: Get-Command -Module dhcp* -Name get-*. I quick scanned
the cmdlets (actually, they're functions) and found the word 'option.' I jumped over to the DHCP MMC snap-in and quickly figured out why that sounded familiar. In the GUI, you right-click Server Options to get to this setting. I then ran the function in my
example without piping it to the Where-Object cmdlet, and it return a value property. I then added the | Where-Object to filter down what was returned.
In writing this edit, I determined there's actually an -OptionID parameter, which means I could have better written my example. Here's that now:
Get-DhcpServerv4OptionValue -ComputerName <computername> -OptionID 6 | Select-Object Value
Always filter as close to the left as possible. That's means we don't want to pipe to something when we can filter with a built-in parameter.

Getting "Error in setting DHCP Scope Network and Netmask"

Hello Cisco Experts - I'm trying to setup a new DHCP scope on my Cisco 2504 and am getting the error referenced above. Here are the settings I am using:
I have another range setup in exactly the same way only it runs from 10.35.209.65 through 10.35.209.90. Can anyone point me in the right direction for what I'm doing wrong? Thanks in advance!

Good question.
Here is the screeshot of the scope I just activated:
What IOS Version are you running? I have 7.4.100.0 on mine.
Please Rate Helpful posts and mark this question as answered if, in fact, this does answer your question. Otherwise, feel free to post follow-up questions.
Charles Moreton

WDS Server - PXE + Diffrent DHCP Scope + Diffrent Network

Dear All,
I have a WDS Server + DHCP on one server and OS Deployment is working properly.
but i have a different network with different DHCP Server + DHCP Scope and wanted to deploy the WDS images on that.
so please guide me how to do this..
Explanation : DHCP + WDS on 172.27.11.XX (OS Deployment working properly)
DHCP on 172.27.3.XX (Not Able to find PXE Server on this..) all ports are open and tried to add 66 and 67 port with WDS name or IP but did not work.. please help..
Thanks in advance
Dhiraj Gaikawd

Hi,
You should configure IP helper on your router to point to your DHCP and WDS server.
And make sure port 4011 on WDS is reachable accross router.
Hope this helps.

How DHCP scope will work between two Wireless contoller

Dear All,
I would like to inform you that we are going to deploy Wireless Network with redundancy of Wireless LAN Controller and we need to figure out how DHCP scope would work during fail over any one of Wireless LAN controller and DHCP Server .I have two site where Two Differenet DHCP Server would be palced with different DHCP socpe.So My query is that if Site-A(according to attached diagram) DHCP Server and controller fails how Wireless client will take the DHCP scope from Site-B(according to attached diagram) DHCP Server as it has been configured different DHCP Scope.Can any one tell me whether i can configure same DHCP Scope at Both Site's DHCP Server.
Is there any way to configure same DHCP Scope for two sites.For your infromation client wants two Different DHCP Server with different scope for Two Site and how redundancy would be ensured if any one WLC or DHCP goes down.
I am eagerly waiting for your reply as early as possible.Please help to figure out the solution.
I am going to attached Sample Design for your reference.
Thanks and regards
Erfan

Erfan:
My query was that if one wireless client already associated
WLC-A with one IP block of Location-A (DHCP Server) using SSID named TEST. If DHCP-A or WLC-A goes down then how that same client would associate with WLC-B and get the IP Block from Location-B (DHCP Server) using same SSID name TEST.
In this case the clinets connected to the APs in location A will disconnect (if the WLC went down) and they have to connect again when the APs join WLC-B. They will get IP address from location B block then.
If DHCP went down when new clinets try to connect the primary DHCP is down so they are referred to the secondary DHCP. connected clinets will disconnect only when their DHCP lease times out. They will try to renew but the DHCP server is not available. They will disconnect then and connect again and getting IP from B site.
1. How we will create same policy for that two different block using same SSID.
what policy? where?..etc?
2. client would be connected with Access point but they will get the IP through VLAN interface of the Controller and we have to assign IP helper address in the interface vlan.So how the the client would get the IP block if we assign two IP helper address in the interface vlan in case of failure of DHCP and WLC of one location.
3. If we assign two IP helper address then which DHCP Server will release the IP for client and we can make delay between two DHCP Server to release the IP address.
If two IP helpers are configured the switch will send them both the client's request and they client receives two offers. The clients chooses one of the offers. Usually the clinet will accept the faster DHCP server to respond.
If you are using the DHCP on the WLC then it is different. The WLC will always try to reach the primary DHCP server as long as it is reachable. If the primary DHCP is not reachable then it falls back to the secondary DHCP server.
Note that when you use IP helper then you usually disable DHCP Proxy feature on the controller. Do you have it disabled?

WLC dhcp scope issue

Hi,
We are facing this problem
we are using guest SSID with captive portal authentication.
We are using below step to conect to network
1) User will click on guest SSID & get IP from DHCP scope
2) User will open google.com & then it will redirect to authentication page - we need to provide userid/pass & then we will able to access internet
Problem
Assume user only do Step -1 , Then My dhcp scope is utilizing
How can we restrict the same to 'geneuine' user, any option/workaround ?
br/subhojit

I have to agree with e. Shortening theeaae will help.
But the kny way to keep people off the WLAN would be to use a PSK so that only authorized users can get on.
HTH
Steve

How to check whether DHCP scope is fully leased/ exhausted on CUCM Publisher?

Hi All,
we have few new 7942 phones deployed and they are not registering.
we suspect that dhcp scope configured on cucm pub do not have any free ips to assign.
we need to know a way to confirm DHCP indeed is the issue.
Any suggestions will be very helpful.
Thank you

Hi,
I do not have any customers who run DHCP on CUCM servers but I would suggest that you look at using RTMT to collect log files from the DHCPMON service.
You could also check out the blog below:
http://bhatkoti.com/2009/02/16/how-to-check-call-manager-6x-5x-7x-dhcp-lease/
The solution proposed is kind of neat but may not be something that you would be comfortable with.
Hope this helps

DHCP scope increase and changes in wlc

hi,
i am using wlc 4402 with a mgt ip 172.26.150.x/24 and ap manager ip 172.26.150.x/24, my all ap get the ip address from dhcp . currently in dhcp server 172.26.150.3 to 254 dhcp scope is configured. at mysite some devices are configured like ipad,iphone or galaxy tab with mac binding in dhcp server. now this pool is almost full. i have a policy configured for these devices for mac binding is done in DHCP. to increase pool what are the changes i need to do in wlc. what are the changes i need to do in dhcp server . is policy made for mac binding in dhcp server will get affected by this ?
regards
rajat

Hi Rajat,
Use a /23 range ip address rather than using 172.26.150.x/24. So at first this change need to be carried out on the L3 device (which will the default gateway of the WLC managment interface). Accordingly the AP managment ip and ap manager ip's subnet mask is going to change from /24 to /23.
Then ensure that on the dhcp server you expand the scope from /24 to /23. This is will not affect the MAC bindings as long as you are using the same ip range with a different subnet mask.
Hope that helps
Regards
Najaf
Please rate when applicable or helpful !!!

When editing DHCP Scope in IPAM, get "Error: 5 - Access is denied"

Hello all!
I have a pair of Server 2012 DHCP servers configured for Failover. I also have a Server 2012 IPAM server that manages the first server in that pair, but not the second one. The reason is that I have the DHCP Failover Auto Config Sync tool running
on the first server and it can only be installed on one server of a Failover pair.
So, my diagram would look something like this:
IPAM --manages--> DHCP 1 <--Failover/Auto Sync--> DHCP 2
So, here is my problem. I can make a change to a DHCP Scope directly on DHCP 1 and it is instantaneously replicated to DHCP 2. That is no problem.
But, when I try to edit the same Scope through IPAM, it fails and returns the following error: (Error:5 - Access is denied.)
Any help would be greatly appreciated.
Thanks!

Hi,
One of our service engineers here was able to reproduce the problem by removing the
IPAM computer account from the IPAMUG security group in Active Directory.
Interestingly, doing this does not change the status of the server from green to red in terms of manageability.
Can you please check and see if this is the problem?
Thanks,
-Greg
P.S. If this is not the problem, please answer a few more questions:
Is the IPAM and DHCP server joined to the same domain?
Are they multihomed servers or have only one NIC?
Are you using the same user account on IPAM and DHCP server?
Note: I tried reproducing this and when the IPAM server is removed from the IPAMUG group it does cause Error 5 - Access is denied, however I was able to get the status to turn red after doing this. I think it is critical that an Active Directory update
occur, so you should try running gpupdate /force on your DC, DHCP server, and IPAM server.

DHCP Scope vs IP Helper

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