Server Referral List

When a PXE device boots, it makes a broadcast request on the network for PXE services. The ZENworks Proxy DHCP server (novell-proxydhcp) responds to this request with information that includes the IP address of an imaging server where the device can send requests for assigned imaging work.

Because PXE devices can exist in an environment with both newer and older ZENworks systems running concurrently, the device can fail to determine its assigned imaging work if it cannot find the imaging server for its own ZENworks version.

In ZENworks 11, devices can exist in multiple Management Zones. It is essential that the PXE device contact PXE services assigned to its home zone so that it can correctly determine if there is any imaging work assigned to it. When there is only a single Management Zone, this is easy to do because all Proxy DHCP servers provide addresses to services that belong to the same zone. Any device can request imaging work from any imaging server in the same zone and get the same response.

The PXE device’s initial request for PXE services is sent as a broadcast to the network, and all Proxy DHCP servers respond with information pertaining to their respective zones (in ZENworks 11 and ZENworks Linux Management) or Proxy DHCP servers in their trees (in older ZENworks versions using Windows or NetWare imaging servers). Because it is impossible to determine which Proxy DHCP server responds first (if multiple Proxy DHCP servers respond), or which server’s response is used by the device, it is impossible to ensure that each PXE device will contact servers in its home zone or tree.

For a ZENworks environment that has PXE services, the Server Referral List configuration section provides a method for getting PXE devices to connect with their proper imaging servers. Server referral lists are only used by PXE devices, and in ZENworks 11 only one Management Zone needs to have an active Proxy DHCP server and server referral list. Because you can only have one referral list active in a network segment, if you have ZENworks Linux Management running with a referral list configured, you’ll need to disable the Proxy DHCP service for Linux Management. This allows the ZENworks referral list to be used by all PXE devices.

A server referral list allows you to ensure that all devices contact their home zone or tree for device imaging work assignments. The list should contain the IP address of an imaging server in each known Management Zone or older ZENworks system’s tree. When a device requests device imaging work from a server, the server first determines if the device belongs to the same zone or tree as the server. If it does not, that server refers the request to each server in its server referral list until it finds the device’s home zone or tree. The device is then instructed to send all future requests to the correct novell-proxydhcp.

To configure a server referral list, complete the tasks in the following sections, as applicable:

/srv/tftp

/srv/tftp