HP Web Jetadmin 10.3 - User Guide

IP Range Discovery is effective when the administrator has knowledge of IP segments. Administrators use IP
Range Discovery settings to map IP segments or groups of IP segments into HP Web Jetadmin discovery. This
method efficiently sweeps selected portions of the network or WAN. IP Range address pairs consist of
beginning and ending IP addresses. IP Range discoveries first ping (send ICMP echo requests) specific IP
addresses as defined by range address pairs. If the device responds, HP Web Jetadmin follows with SNMP
queries. Multiple ranges can be specified in IP Range discoveries. HP Web Jetadmin pings in bursts of 30
queries to the first set of addresses from the first range and then waits one second before sending the next
burst of 30 queries.
Setting Realistic Ranges
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Setting Ranges Based on Subnets or Contiguous Subnets
Most networks are divided up into subnets, which can be used to describe a network IP addressing scheme
and are sometimes referred to as IP maps. A subnet within a large network can be described with a network
number and a subnet mask. This is an example of one subnet with an IP range of 15.5.188.1 through
15.5.191.254:
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Network number example: 15.5.188.0
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Subnet mask example: 255.255.252.0
There are 1,022 possible addresses on this subnet. It may take HP Web Jetadmin only about 10 minutes to
discover devices on this network depending on the network, the number of devices on that network, and the
host on which HP Web Jetadmin is installed.
NOTE: IP address calculators are an easy way to analyze IP networks. Many free versions of IP calculators
exist and can be obtained on the Internet.
IP Range discovery can perform to expectations when the range data has been correctly developed. It is easy
to configure ranges that are larger than needed and actually cause the discovery to take a long time and
perhaps even yield little in the way of devices. For example, a class A range could easily be developed for the
HP intranet but would literally take weeks to complete. On most large networks, the majority of the IP
addresses won’t answer the HP Web Jetadmin query and will cause timeouts to occur; these translate into
very long discovery times.
If you specify an IP range that is very large, your network might crash if that IP range is for a class A or class B
network (when the first two octets of the IP range are not the same). HP Web Jetadmin will display a warning
message stating that a large range might cause a large amount of network traffic; you can choose to
continue or change the range.
You can choose to specify a large subnet range using the larger subnet address feature (Tools > Options >
Shared > Discovery > Methods > IP Range > General). Large networks are considered any network bigger
than a Class B network, which has up to 65,000 nodes.
Setting Ranges Based on Subnets or Contiguous Subnets
Since large IP ranges can cause HP Web Jetadmin discovery to take long periods of time to complete, it can be
useful to use subnet ranges rather than the entire network for a discovery. These subnets, when put together
into one list, represent an IP map. This type of a map can be obtained from an IT or Network Infrastructure
team. It is also a good idea to work with these teams to discuss plans for implementing HP Web Jetadmin
discoveries.
NOTE: Hewlett-Packard strongly recommends that you discuss HP Web Jetadmin discoveries with your
information technology or network administration team.
Here is an example of IP range planning. Assume we have 20 subnets on our hypothetical network. All of
these subnets use the same subnet mask of 255.255.255.0. Here are the network numbers that represent
our 20 subnets:
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