HP Network Direr Software Products manual Purpose of each stage is described below, IP Ping

Key Concepts 93

9Device Sizing

With the exception of the sizing stage (explained below), each of the stages runs sequentially, and the sequence is repeated for each subnet that is being discovered. The sizing stage runs once only, when all the other stages have been executed for all of the subnets being discovered.

The purpose of each stage is described below:

IP Ping

In order to detect which IP nodes exist, this stage performs an IP Ping over the specified ranges of addresses for the subnet. If no ranges are specified, a default range is deduced from the subnet address and subnet mask of the subnet being discovered. This range excludes the subnet address itself (lowest address value) and the subnet broadcast address (highest address value).

Device Capability Detection

This stage is applied to each device that responded to a ping in the previous stage. Its purpose is to determine if a device supports certain network protocols. Specifically, these are:

■SNMP

■HTTP

■Telnet

The most detailed information is generally obtained from devices that support SNMP. For these devices 3Com Network Director initially starts the communication using the read community string as originally specified in the Network Discovery wizard. Having successfully communicated using the read community string it then attempts communication using the write community string(s), again obtained from the Network Discovery wizard. While the write community string is not heavily used by the discovery process (except a small part of topology), it is used extensively by other features of 3Com Network Director. Consequently, if the write community cannot be successfully determined, discovery will continue, but add a warning to the report provided at the end of discovery.

3Com Network Director detects HTTP and Telnet capabilities by attempting to open a TCP connection to the device using ports 80 and 23 respectively. The purpose of this detection is to decide whether to enable