Monthly Archives: February 2015

Citrix PVS server Dual IP issue in multiple DHCP servers with a split scope environment

Usually, when deploy PVS servers, we only use 1 DHCP scope. But for some large environment, we have to use multiple DHCP servers with a split scope if we can’t use Windows Server 2012.

Then it’s more likely to get the dual IP issue:

1. When VDI start, first, it contacted DHCP server to get the 1st IP address, then use this IP address to connect to PVS server to start to download the image and startthe VDI.
2. And when windows is up, windows DHCP client will request an IP address from DHCP server. In multiple DHCP environment, it may request IP address from a different DHCP server and got a different IP address..

Then we got below problem:
1. VDIs may have two IP address.
2. We run out IP address. You will find that lot’s IP address are marked as ‘bad addresses’
3. DNS record issue. Because some VDIs have two IP addresses, VDIs registered the wrong IP address to DNS server.

We spent lots of times with Citrix, and Citrix can’t provide a solution for this issue. They only suggest to use PVS server in single DHCP scope environment.

But finally, we found a solution to fix this issue by ourselves.

This issue was caused by that when windows is up, Citrix PVS Device Service will inject the IP address it got during PXEboot process into system. And if Citrix PVS Device Service starts before DHCP client service, then VDI will get 1 IP address. But if DHCP client start first, Citrix will still inject the IP address, and then VDI will get two IP addresses.

There are two ways to fix this issue.

1. Disable DHCP client in VDI. This option is not good, but it works. But please be aware that after you disable DHCP client service, the VDI may not be able to get DNS server from DHCP servers. Because Citrix only inject IP address/Netmask/Gateway information to windows.

2. Make “Citrix PVS Device Service” as a dependency service of DHCP client servers to make sure that DHCP service starts after Citrix inject the IP address.

Dual to Citrix can’t fix this issue, this is the only solution we found to fix this issue.
But if you are able to use windows server 2012, then go for windows server 2012 DHCP cluster maybe another choice.