Using DHCPUtil

 

Topic Last Modified: 2012-10-17

This topic describes how to use DHCPUtil.

DHCPConfigScript.bat

DHCPUtil does not configure the DHCP servers by itself. It delegates that responsibility to a script which can be changed to suit the organization’s need. After it calculates the values for various options, DHCPUtil passes these values to a script, which can then take appropriate action.

DHCPConfigScript.bat is one such script and is the one that ships with DHCPUtil. (It is in the same location as DHCPUtil.) This script uses netsh dhcp server commands that configure DHCP server with the options required for Lync Server deployment.

Note

DHCPConfigScript.bat cannot be used against any DHCP server other than the DHCP server feature included with Windows Server operating systems, unless you modify it.

Here is what the script contains:

netsh dhcp server delete optionvalue 120 
netsh dhcp server delete optiondef 120 
netsh dhcp server delete class MSUCClient 
if /i %1 EQU Cleanup goto :EOF 
netsh dhcp server add optiondef 120 UCSipServer Binary 0 comment="Sip Server Fqdn" 
netsh dhcp server set optionvalue 120 Binary %3 
netsh dhcp server add class MSUCClient "UC Vendor Class Id" "%2" 1 
netsh dhcp server add optiondef 1 UCIdentifier Binary 0 Vendor=MSUCClient comment="UC Identifier 
"netsh dhcp server set optionvalue 1 Binary vendor=MSUCClient %4 
netsh dhcp server add optiondef 2 URLScheme Binary 0 Vendor=MSUCClient comment="URL Scheme" 
netsh dhcp server set optionvalue 2 Binary vendor=MSUCClient %5 
netsh dhcp server add optiondef 3 WebServerFqdn Binary 0 Vendor=MSUCClient comment="Web Server Fqdn" 
netsh dhcp server set optionvalue 3 Binary vendor=MSUCClient %6 
if nt %7 == NULL (netsh dhcp server add optiondef 4 WebServerPort Binary 0 Vendor=MSUCClient comment="Web Server Port") 
if not %7 == NULL (netsh dhcp server set optionvalue 4 Binary vendor=MSUCClient %7) 
netsh dhcp server add optiondef 5 CertProvRelPath Binary 0 Vendor=MSUCClient comment="Cert Prov Relative Path" 
netsh dhcp server set optionvalue 5 Binary vendor=MSUCClient %8 

The first three commands clean up a DHCP server so that values for various options can be set correctly. If the script is run in cleanup mode, no further action is taken. Otherwise, the definition for option 120 is created and set to the supplied value.

Next, a vendor with vendor class identifier MS-UC-Client (%2 will always have this value) is created. Then, the script sets sub-options for option 43 one at a time. You’ll notice that the following sub-options are created for the vendor class:

netsh dhcp server add optiondef 3 WebServerFqdn Binary 0 Vendor=MSUCClient comment="Web Server Fqdn"

For details about netsh dhcp, see Deploying Lync Phone Edition, Configuring DHCP Options to Enable Sign-in for IP Phones, and the MSDN Library at https://go.microsoft.com/fwlink/p/?LinkId=205011.

Configuring DHCP Server by Using DHCPUtil

At the command prompt, run:

DHCPUtil -SipServer <FQDN of the Sip Server> [-WebServer <FQDN of the web server> | 
-CertProvUrl <Url of the Certificate Provisioning Service>] [-RunConfigScript [<Path of the script>]]

Only the last parameter RunConfigScript is not part of DHCPConfigScript.bat. This parameter causes DHCPUtil to generate the values for option 120 and 43 and then pass the values to the configuration script. If RunConfigScript is specified without any path, then DHCPConfigScript.bat is run. If a valid file path is specified, then that file is run. This file can be a script or an executable.

The following parameters are passed to the script, in this order:

• Mode: Possible values are Cleanup and Configure

• Value of the vendor class identifier

• Value of option 120

• Value of sub-option 1 for option 43

• Value of sub-option 2 for option 43

• Value of sub-option 3 for option 43

• Value of sub-option 4 for option 43

• Value of sub-option 5 for option 43

Administrators can use the content in this topic to write custom scripts. For example, to configure a DHCP server, the following command needs to be run on the DHCP server:

DHCPUtil.exe -SipServer sip.contoso.com -WebServer web.contoso.com -RunConfigScript

This will invoke DHCPConfigScript.bat with the appropriate parameters, which in turn will invoke various netsh dhcp server commands.

You might also want to edit DHCPConfigScript.bat (or, write a different one) so that it can run netsh commands to a remote DHCP server, thereby removing the need to run DHCPUtil on the DHCP server itself.

Testing DHCP Server Configuration

DHCPUtil can also be used to test the configuration on DHCP server. In this scenario, DHCPUtil sends out DHCP packets, as Lync Server clients would do, and then parses the received packet. If an appropriate response is received, the retrieved values are shown as follows:

DHCPUtil -EmulateClient

Note that this may require appropriate exclusions in the firewall and that generally, this won’t work if run on the DHCP server. It should be run on a computer that is served by the DHCP server whose configuration is to be tested.

To enable exclusions, run the following commands from an administrator command prompt:

netsh advfirewall firewall add rule name="DHCPClientIn"  dir=in action=allow localport=68 protocol=udp
netsh advfirewall firewall add rule name="DHCPClientOut"  dir=out action=allow localport=68 protocol=udp

After you’re done, run the following commands (from an elevated command prompt) to remove the exclusions:

netsh advfirewall firewall delete rule name="DHCPClientIn"
netsh advfirewall firewall delete rule name="DHCPClientOut"

Output: Starting Discovery
Sending Packet (Size: 280, Network Adapter: 192.168.0.244, Attempt Type: Broadcast only)
--Begin Packet--
DHCP: INFORM (xid=D2FFB17A)
DHCP: Op Code (op) = 1
DHCP: Hardware Type (htype) = 6
DHCP: Hops (hops) = 0
DHCP: Transaction ID (xid) = 3539972474
DHCP: Seconds (secs) = 0
DHCP: Flags (flags) = 0000
DHCP: Client IP Address (ciaddr) = 192.168.0.244
DHCP: Your IP Address (yiaddr) = 0.0.0.0
DHCP: Server IP Address (siaddr) = 0.0.0.0
DHCP: Relay IP Address (giaddr) = 0.0.0.0
DHCP: Client HW Address (chaddr) = 122222222222
DHCP: Server Host Name (sname) = 
DHCP: Boot File Name (file) = 
DHCP: Magic Cookie = 99.130.83.99
DHCP: Option Field
DHCP: DHCP MESSAGE TYPE( 53) = (Length: 1) DHCP INFORM
DHCP: Server Identifier( 54) = (Length: 0) 0.0.0.0
DHCP: Client Identifier( 61) = (Length: 7) """"" (01122222222222)
DHCP: SIP Server( 120) = (Length: 0) enc:0 ()
DHCP: Host Name( 12) = (Length: 6) Client
DHCP: Vendor Identifier( 60) = (Length: 12) MS-UC-Client
DHCP: Param Req List( 55) = (Length: 2) 120 43
DHCP: Vendor Info( 43) = (Length: 0) ()
DHCP: End of this option field
--End Packet--
Received Packet
Sender:192.168.0.238:67, Size:365
--Begin Packet--
DHCP: ACK (xid=D2FFB17A)
DHCP: Op Code (op) = 1
DHCP: Hardware Type (htype) = 6
DHCP: Hops (hops) = 0
DHCP: Transaction ID (xid) = 3539972474
DHCP: Seconds (secs) = 0
DHCP: Flags (flags) = 0000
DHCP: Client IP Address (ciaddr) = 192.168.0.244
DHCP: Your IP Address (yiaddr) = 0.0.0.0
DHCP: Server IP Address (siaddr) = 0.0.0.0
DHCP: Relay IP Address (giaddr) = 0.0.0.0
DHCP: Client HW Address (chaddr) = 122222222222
DHCP: Server Host Name (sname) = 
DHCP: Boot File Name (file) = 
DHCP: Magic Cookie = 99.130.83.99
DHCP: Option Field
DHCP: DHCP MESSAGE TYPE( 53) = (Length: 1) DHCP ACK
DHCP: Server Identifier( 54) = (Length: 4) 192.168.0.238
DHCP: Client Identifier( 61) = (Length: 0) ()
DHCP: SIP Server( 120) = (Length: 18) enc:0 sip.contoso.com 
(0003736970076578616D706C6503636F6D00)
DHCP: Host Name( 12) = (Length: 0) 
DHCP: Vendor Identifier( 60) = (Length: 0) 
DHCP: Param Req List( 55) = (Length: 0) 0 0
DHCP: Vendor Info( 43) = (Length: 87) MS-UC-
Clienthttps web.contoso.com
443/CertProv/CertProvisioningService.svcÜ NAP 
(010C4D532D55432D436C69656E7402056874747073030F7765622E6578616D706C652E636F6D040334343305252F4365727450726F762F4365727450726F766973696F6E696E67536572766963652E737663DC034E4150)
DHCP: End of this option field
--End Packet--
Result: Success
DHCP Server : 192.168.0.238
Sip Server : sip.contoso.com
CertProv Url : https://web.contoso.com:443/CertProv/CertProvisioningService.svc

When there is a success result, the output shows the DHCP server that responded, the value for SIP server, and the certificate provisioning service URL.

Configuring DHCP Servers Manually

After you have the values for various options (generated using DHCPUtil), you need to manually do the same tasks that the script does using netsh dhcp server commands.

To create the definition for option 120

1. Open the DHCP Management console.

2. Go to appropriate domain.

3. Right-click IPv4.

4. Click Set Predefined Options to open the Predefined Options and Values dialog box.

5. Click Add to open the Option Type dialog box.

6. Do the following:

   • In Name, type the SIP server name.

   • In Data type, click Binary.

   • In Code, type 120.

   • In Description, type SIP Server List.

7. Click OK to accept and close the dialog box.

To set the value for option 120

1. In the navigation tree, under IPv4, click Server Options.

2. Right-click Server Options, and click Configure Options to open the Server Options dialog box.

3. Select the 120 Sip Server check box. This lets you edit the value in the Data Entry box.

4. Carefully enter the value generated by DHCPUtil.

5. Click OK to accept and close the dialog box.

To create a new vendor class with the value MS-UC-Client

1. Right-click IPv4 again, and click Define Vendor Classes… to open the DHCP Vendor Classes dialog box.

2. Click Add to open the New Class dialog box.

3. Do the following:

   • In Display Name, type MSUCClient.

   • In Description, type the UC Vendor Class Id.

   • Under ASCII, click MS-UC-Client.

4. Click OK to accept and close the dialog box.

To create a definition for each of the sub-options in option 43, for the vendor class created in the previous procedure

1. Right-click IPv4, and click Set Predefined Options to open the Predefined Options and Values dialog box.

2. In Option Class, click MSUCClient.

3. Click Add to open the Option Type dialog box.

4. Do the following: (the following example is for sub-option 1 only)

   • In Name, type UCIdentifier.

   • In Data type, click Binary. (This is true for all five sub-options.)

   • In Code, click 1. (Other sub-options will have corresponding code, such as 2, 3, 4 or 5.)

   • In Description, type UC Identifier.

5. Click OK to accept and close the dialog box.

6. Repeat this process for all five sub-options.

To set the values for each of the sub-options

1. Under IPv4, click Server Options.

2. Right-click Server Options, and click Configure Options to open Server Options dialog box.

3. Click the Advanced tab.

4. In the Vendor class box, click MSUCClient.

5. Check each sub-option, and fill in appropriate values.

6. Click OK to accept values and close the dialog box.

Manual configuration of the DHCP server is now complete. You can test the configuration using DHCPUtil –EmulateClient.

Cleaning up Lync Server Related Configuration from DHCP Server

Use the DHCPUtil command DHCPUtil –CleanDHCPConfig to clean up Lync Server configuration information from the DHCP server.

This command should be run on the DHCP server and requires that DHCPConfigScript.bat be in the same directory as DHCPUtil. As is the case with RunConfigScript, administrators can modify DHCPConfigScript.bat so that the netsh commands are issued to remote DHCP servers. This removes the need to run DHCPUtil on the DHCP server itself.

To clean up the configuration manually, the DHCP server administration console can be used. The value for option 120 and new vendor class and various sub-options for option 43 (corresponding to Vendor MS-UC-Client) are required to clean up configuration.

Enabling Lync Server DHCP Server

You can use Lync Server, DHCP Server to supply DHCP options 43 and 120 to phones during bootstrapping, for example, in a branch office where the local DHCP server might be unable to provide these options. We do not recommend using Lync Server, DHCP Server for data centers, which should be configured manually.

Note that Lync Server, DHCP Server does not participate in the IP acquisition process and can be used alongside other DHCP servers in your organization.

To enable Lync Server, DHCP Server on a single Registrar, run the following command:

Note

If you enable DHCP Server on a Lync Server that’s in a different subnet from the devices running Lync Phone Edition, you might need to configure appropriate BOOTP relay agents to forward the DHCP packets to the Lync Server, DHCP Server. For details about how to do this, see the next section.  

Set-CSRegistrarConfiguration -Identity <Service Identity of the Registrar> -EnableDHCPServer $true

If service-level Registrar configuration for this Registrar doesn’t exist, run this cmdlet also:

New-CSRegistrarConfiguration -Identity <Service Identity of the Registrar> -EnableDHCPServer $true

Note

To disable DHCP Server, use the Set-CsRegistrarConfigurationcmdlet again, and set the value for EnableDHCPServer to $false.

Configuring Microsoft BOOT Relay Agents

For details, see Configure the DHCP Relay Agent at https://go.microsoft.com/fwlink/p/?LinkId=205013.

The following two pages in the TechNet Library are particularly useful:

• "Configure global DHCP Relay Agent properties" at https://go.microsoft.com/fwlink/p/?LinkId=205015

• "Enable the DHCP Relay Agent on a router interface" at https://go.microsoft.com/fwlink/p/?LinkId=205016

Make sure that the Boot Threshold and Hop Count Threshold are configured correctly; otherwise the relay agent will drop the packets.

The packets sent by Lync Server clients have the secs parameter (seconds elapsed since the client started discovery process; for details, see RFC 2131) set to 0, so Boot Threshold in the DHCP relay agents must be set to 0.