User's Manual

How HP Web Jetadmin Discovers Network Devices
HP Web Jetadmin uses several methods to find devices connected directly to the network. Regardless of the
method used, HP Web Jetadmin first gathers nodes from the network and then determines which of those
nodes is a qualified device. Qualification is always done using the SNMP protocol. Nodes found are always
queried for specific SNMP objects and then determined to be a qualified printing/imaging device. Once these
devices are qualified, HP Web Jetadmin places them in the All Devices list. Each of the methods used to find
network devices will be discussed in the following sections.
Maintaining Accurate Address Information
HP Web Jetadmin has the ability to adjust IP addresses stored for each device. In many cases, IP addresses on
devices will remain static and changes within the HP Web Jetadmin device lists won’t be needed. In a few
cases, device addresses may change due to device moves or when device addresses are assigned with DHCP.
In these cases, HP Web Jetadmin should be able to cope with the changes and quickly change its internal
record of a device’s IP address.
HP Web Jetadmin will automatically change a devices IP address anytime it has realized a change in that
address. For example, a device might have been configured with the IP address 15.62.40.203 yesterday but
today it has the IP address 15.62.42.198.
How HP Web Jetadmin Discovers PC-Connected Devices
HP Web Jetadmin can discover printers connected directly to PCs. This discovery facilitates both learning
about devices that are connected directly to PC hosts and also gathers detailed information about those
devices when the HP SNMP Proxy Agent is being used. The HP SNMP Proxy Agent is a small software package
that can be installed onto a PC and facilitates HP Web Jetadmin communications with locally connected
devices. PC-Connected discoveries can be performed without the HP SNMP Proxy Agent being installed onto
remote hosts but this type of discovery will only gather a minimal amount of device information. This
discovery queries desktop and server hosts in order to find locally connected devices. These are devices that
are not connected directly to the network, they are connected to the LPT ports or USB ports on the local host.
When one of the types of discoveries for PC-Connected devices is invoked, HP Web Jetadmin communicates
directly with the remote host in one of two ways:
●
By looking for an HP SNMP Proxy Agent on the local PC if the agent exists, HP Web Jetadmin begins to
query the device through the proxy in much the same way as it queries devices directly connected to the
network. Through the agent, many pieces of information are available including status, page count,
supply levels, and more.
●
Through WMI (Windows Management Instrumentation): WMI is a Microsoft service that runs on most
Windows operating systems and is used by remote management applications to gather information.
HP Web Jetadmin performs a query through WMI on workstations found by way of its various discovery
mechanisms. This query attempts to resolve Windows printer model details for devices that are plug
and play compatible. The WMI PC-Connected discovery solution does not gather status or other details
from the device. The WMI PC-Connected discovery also requires administrator (local) credentials on
each host queried.
PC-Connected device discoveries use different query protocols depending on the method used. The table
below shows differences in primary and secondary protocols. The primary protocol is used first and if
communication is possible through the protocol, devices are queried. The secondary protocol is used when
no communication was attained through the primary protocol.
Table 3-4 Primary and Secondary Protocols for PC-Connected Device Discoveries
PC-Connected Device Discovery Method Primary Protocol Secondary Protocol
IP broadcast SNMP WMI*
126 Chapter 3 Device Management ENWW