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Lync Server 2010 – Cannot Connect to Sharing Server | Elan Shudnow’s Blog

Configuring Lync DHCP using Cisco DHCP Servers (VLAN and PIN Auth)

I recently had a project where all DHCP Servers were Cisco switches. During the configuration, we noticed that a certain DHCP Configuration worked on certain Cisco switches but not the rest but a configuration was found that worked on all switches. More on the specifics in the VLAN section below. In this article, I will show you how to figure out how to configure the 120 and 43 options on a Cisco switch as well as how to configure the VLAN ID using the two different methods mentioned above. Thanks to Dave Howe from Microsoft for helping out with the PIN Authentication Settings for Cisco DHCP.

PIN Authentication Settings

Run DHCPUtil.exe to find out hex data values for DHCP Options 120 and 43

C:\Program Files\Microsoft Lync Server 2010\> DHCPUtil.exe -sipserver pool01.contoso.com

Sip Server FQDN: pool01.contoso.com

Certificate Provisioning Service URL: https://pool01.contoso.com:443/CertProv/CertProvisioningService.svc

Option 120: 00076578616D706C6503636F6D00

Vendor Class Identifier: MS-UC-Client

Option 43 (for vendor=MS-UC-Client):

Sub-Option 1 : 4D532D55432D436C69656E74

Sub-Option 2 : 6874747073

Sub-Option 3 : 6578616D706C652E636F6D

Sub-Option 4 : 343433

Sub-Option 5 : 2F4365727450726F762F4365727450726F7669736



Build DHCP Option 120 hex value for Cisco DHCP using DHCPUtil.exe output info

Option 120 = hex 00076578616D706C6503636F6D00


Build DHCP Option 43 hex value for Cisco DHCP using DHCPUtil.exe output info

Note: Format of DHCP Option 43 hex value:

Sub-Option 1 Sub-Option 2 Sub-Option 3 Sub-Option 4 Sub-Option 5
01 Length Data 02 Length Data 03 Length Data 04 Length Data 05 Length Data

1. Compile Sub-Option 1 from DHCPUtil.exe output:

Length of data is hex value for (number of characters of Data) divided by 2 ( # of chars / 2 )

2. Compile Sub-Option 2 from DHCPUtil.exe output:
02 Length of data Data
02 05 6874747073
3. Compile Sub-Option 3 from DHCPUtil.exe output:
03 Length of data Data
03 0B 6578616D706C652E636F6D
4. Compile Sub-Option 4 from DHCPUtil.exe output:
04 Length of data Data
04 03 343433
5. Compile Sub-Option 5 from DHCPUtil.exe output:
05 Length Data
05 25 2F4365727450726F762F4365727450726F766973696F6E696E67536572766963652E737663


Combine the five Sub-Option values to build the DHCP Option 43 hex value for Cisco DHCP:

Compiled DHCP Option 43:

Sub-Option1 Sub-Option2 Sub-Option3 Sub-Option4 Sub-Option5
01 Length Data 02 Length Data 03 Length Data 04 Length Data 05 Length Data
VLAN ID Settings with PIN Authentication Settings

There are a few ways to make this work:

* Link Layer Discovery Protocol (LLDP)
* Two different ways to make it work on DHCP. DHCP is what this article will cover.

Now let’s say we have two VLAN IDs: 208 (Data) and 209 (Voice) on the same ports. The idea here is swap the phone from the Data VLAN to the Voice VLAN. As stated earlier, we found two methods in configuring the VLAN ID Settings. The first I will show is how it worked on a switch that supported LLDP – Catalyst 4507R – SUP-IV IOS version (cat4500-ENTSERVICESK9-M), Version 12.2(54)SGI. The second is how it worked on the switch that was not LLDP Capable – Catalyst 6513 SUP720 (S72033_rp-PK9SV-M), Version 12.2(18)SXD7 – or higher. Thanks to my client for enduring the painful process of figuring out the below and providing me with information and explanations on what he did to get the Cisco DHCP configured for VLAN ID as well as the switch information provided which you can see in the first two comments in this article.

LLDP Switch Data Scope (Comments in Red)

ip dhcp pool Data14_Lync (VLAN 208)

option 10 hex 00d0 (Decimal 209)

option 60 ascii “CPE-OCPHONE”

LLDP Switch Voice Scope (Comments in Red)

ip dhcp pool Voice14_Lync (VLAN 209)

option 10 hex 00d0 (Decimal 209)

option 60 ascii “CPE-OCPHONE”

option 43 hex 010C4D532D55432D436C69656E7402056874747073030B6578616D706C652E636F6D040334343305252F4365727450726F762F4365727450726F766973696F6E696E67536572766963652E737663

option 120 hex 00076578616D706C6503636F6D00

Non-LLDP Switch Data Scope (Comments in Red)

When we noticed the LLDP Switch Scope configuration wouldn’t work on a non-LLDP Switch, we tried running this on Windows DHCP. My client sniffed the traffic and found that Windows DHCP had some 43 option information passed back to the client for the VLAN ID information. So what we did in option 43 is specify an option 10 sub-option. The oa is the sub option. The 02 is the length of the data field divided by 2. The 00d1 is the hex value of the data vlan.

ip dhcp pool Data14_Lync

option 43 hex 0a0200d1

Non-LLDP Switch Voice Scope

ip dhcp pool Voice14_Lync

option 120 hex 00076578616D706C6503636F6D00

option 43 010C4D532D55432D436C69656E7402056874747073030B6578616D706C652E636F6D040334343305252F4365727450726F762F4365727450726F766973696F6E696E67536572766963652E737663



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