Use PowerShell to Add a Vendor-Specific Class to Windows DHCP


I'm helping a customer migrate from an Infoblox appliance to Windows IPAM.

One of the tasks I've just completed is to take vendor-specific DHCP classes and option definitions from an Infoblox appliance (ISC) dump and convert it to something that Windows Server 2012 DHCP understands. A vendor-specific class ensures that vendor-specific scope options are delivered to just the vendor's devices.

Of course, I used PowerShell to import the settings… here's a sample Infoblox (ISC) setting (exhibit A):

 option vendor-class-identifier "Cisco AP c1600";
 option vendor-encapsulated-options f1:08:0a:03:0a:f1:0a:07:0a:f1;

 

And, here's what it looks like in Windows DHCP (exhibit B):

 

But, I hear you ask, how did we get from A to B?

Well, first up we need to add a vendor-specific class to the Windows DHCP server. I referenced some Cisco documentation and the key bit of information here is contained in the AsciiData property – "Cisco AP c1600" – the vendor class client identifier.

NB – It's worth giving the Cisco documentation a good read, as it details the background information relating to DHCP concepts such as client identifiers, option 60, option 43 and sub-options.

 

Here's the PowerShell for adding the vendor-specific class:

$VendorClass = @{

Name = "Cisco Aironet 1600 series"

Description = "Vendor Class Indentifier for Cisco AP c1600 Series"

Type = "Vendor"

Data = "Cisco AP c1600"

}

Add-DhcpServerv4Class @VendorClass -ComputerName HALODC01

  

Here, we're using splatting to supply the parameter values to the Add-DhcpServerv4Class. Notice how the value supplied to the -Data parameter matches that from the Infoblox configuration –  option vendor-class-identifier "Cisco AP c1600";

Next, create an option definition for our new class, again, with the aid of splatting:

$OpDef = @{

Name = "Cisco Aironet 1600 IP Provisioning"

Description = "WLAN Controller IP Address Delivery Option (43)"

OptionId = 241

Type = "IPv4Address"

VendorClass = "Cisco Aironet 1600 series"

MultiValued = $true

DefaultValue = "10.3.10.241","10.3.10.241"

}

Add-DhcpServerv4OptionDefinition @OpDef -ComputerName HALODC01

 

This option definition can be used to deliver the IP addresses of two WLAN controllers to Cisco Aironet 1660 devices from the optionID* 241. On the Infoblox appliance it looked like this – option vendor-encapsulated-options f1:08:0a:03:0a:f1:0a:07:0a:f1;

*actually it's a sub-option of option 43!

 
Let's pick the HEX apart:

  • f1 – this is the optionID 241
  • 08 – the number of IP addresses x 4
  • 0a:03:0a:f1 – IP address 1… 10.3.10.241
  • 0a:07:0a:f1 – IP address 2… 10.7.10.241

 

We need one last piece of the jigsaw, namely, adding the new option to a scope.

Set-DhcpServerv4OptionValue -OptionId 241 -VendorClass "Cisco Aironet 1600 series" -Value "10.3.10.241","10.7.10.241" -ScopeId "10.241.76.0" -ComputerName HALODC01

 

And, that's it. Here's the three steps for the conversion:

  1. Create the Class
  2. Create the Option Definition
  3. Assign the scope option

 

Now to add these steps to a script…

 

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