Keysight Technologies N5244/5B Service Manual page 122

Troubleshooting
Rear Panel Troubleshooting
If the analyzer can talk to the network, but the network can not talk to the
analyzer, then the computer or device used from the network may have a
subnet mask that excludes communication with the IP address chosen for the
analyzer. Any subnet mask other than 0.0.0.0 will exclude operation from
some addresses. Changing the subnet mask of a computer or other device
should only be attempted by a qualified network administrator. Failure to
communicate due to a subnet mask incompatibility does not indicate any
failure of the analyzer.
If the analyzer fails to ping in either direction, and assuming the subnet masks
are set properly, then the fault must be isolated to the analyzer or to the
network. Contact a qualified network administrator.
Testing Between Two Analyzers
The ability of the analyzer's LAN to function can be easily tested by connecting
two analyzers together using a "crossover cable" (a short length of cable with
an RJ-45 connector on each end).
Some network hubs have the capability to make a crossover connection using
two normal, or straight-through, cables. If this capability is not available and a
crossover cable is not available, a crossover cable can be made by following
the directions in "Constructing a Crossover Cable" on page 4-28.
Set the IP addresses on two analyzers. The addresses can be set to anything,
but they must be different. Make sure the subnet mask and gateway addresses
are set to 0.0.0.0 and that the LAN is active on both analyzers. Connect the
two analyzers together using either a crossover cable or a crossover hub.
Now follow the steps in "How to Ping from the Analyzer to the Local Area
Network (LAN)" on page 4-26 to have the first analyzer ping the second
analyzer. When done, repeat the procedure having the second analyzer ping
the first. If both procedures function properly, the LAN circuitry on both
analyzers is verified.
If neither function properly:
— One or both IP addresses could be wrong.
— One or both LAN states could be set to off.
— The crossover cable could be miswired.
— One or both analyzers could be defective.
If possible, eliminate the possibility of a defective analyzer by substitution of a
known working unit. Once the analyzer has been proven to be working
properly, concentration can be placed on the network itself to determine the
cause of the failure.
Constructing a Crossover Cable
A crossover cable can be made from a standard LAN cable by connecting pin 1
from each connector to pin 3 of the other connector, and pin 2 from each
connector to pin 6 of the other connector.
4-28 Keysight N5244B/45B Service Guide