HP Network Direr Software Products manual Snmp Type Detection, IP to MAC Resolution

94CHAPTER 4: DISCOVERING THE NETWORK

the Web and Telnet menu options on the right-click menu. For certain 3Com devices additional information can be obtained using HTTP – see “Web Type Recognition” and “NBX Phone Detection” on page 95

SNMP Type Detection

This stage only applies to devices that were found to support SNMP during the Device Capability Stage. 3Com Network Director reads standard SNMP MIBs in order to determine additional information about each SNMP node, in particular the type of the device (based on MIB-II sysObjectID), its IP addresses and its MAC addresses. Where a device has multiple IP addresses that respond with the same information, e.g. list of MAC addresses, 3Com Network Director ensures that it is represented as a single device on the map. Certain devices which have multiple IP addresses respond with different information. Initially they are detected as separate nodes, which 3Com Network Director attempts to resolve in the sizing stage.

If a router is detected when discovering a given subnet, that router information will be made available to any subsequent subnets included as part of the whole discovery operation. This ensures that the router is not interrogated more than once for the same information by several stages.

IP to MAC Resolution

This stage is responsible for obtaining the MAC addresses of non-SNMP nodes. For the local subnet, i.e. the one to which the 3Com Network Director PC is attached, this is achieved by reading the ARP cache of the 3Com Network Director PC. For remote subnets this is achieved by querying any routers that have been discovered on these subnets. This stage is not normally required for determining the MAC addresses of SNMP nodes, since that can be achieved in the SNMP type detection stage.

It is important for 3Com Network Director to determine the MAC addresses of nodes in order to be able to subsequently determine their position in the network topology.

End Station Type Recognition

This stage is responsible for attempting to determine the operating system type for devices that are IP-only or unrecognized (generic) SNMP.