If you experience problems when installing or using the ServSwitch Secure unit,
please check through this section for a possible solution. If your problem is not
listed here and you cannot resolve the issue, then please refer to the ‘Getting
assistance’ section.

No video from computer

• This is most likely to be associated with having the wrong DDC data loaded

into the ServSwitch. Computers often need read the correct DDC data
before they will output a video signal. If digital DDC data is presented
to a computer’s analog video port, a video signal will not be generated.
Conversely, if analog DDC data is presented to a computer’s digital
video port, a video signal will also not be generated. Remember that the
ServSwitch only reads the DDC data from your monitor when the ServSwitch
is first powered on. To ensure that your monitor’s DDC data is read and
stored correctly, ensure that it is attached and powered on when you switch
on your ServSwitch.

Video from some computers only

• Remember that the ServSwitch does not convert digital video signals to

analog signals and vice versa so it is not generally possible to mix digital and
analog inputs. Mixed systems are possible in certain special circumstances
but these will require specialist assistance from Black Box technical support.

SECT 5

Summary of threats and solutions

This section provides a list of potential security threats that the ServSwitch
Secure might face during operation and the special steps that have been taken
to counteract them.

Threat

Solution

Microprocessor
malfunction or
unanticipated software
bugs causing data to flow
between ports.

Unidirectional data flow is enforced by
hardware “data diodes” so data isolation
doesn’t rely on software integrity.

Subversive snooping
by means of detecting
electromagnetic radiation
emitted from the
equipment.

Carefully shielded metal case with dual
shielding in critical areas.

Detection of signals
on one computer by
monitoring for crosstalk
(leakage) signals on
another computer.

No connections to sensitive analog inputs
(such computer microphone ports) are
provided. Minimum crosstalk separation
of 60dB provided between signals from
one computer and input or I/O signals to
another computer.

Malicious modification of
microprocessor software
causing data to leak
between ports.

Data isolation is assured by hardware
and so is not compromised by any
changes to the microprocessor
software. Microprocessors use one time
programmable memory so flash upgrades
are not possible. Case uses counter-sunk
screws which can be protected by tamper
proof seals.

Buffered data within a
keyboard or mouse is sent
to the wrong computer
after switchover.

Keyboard and mouse are powered down
and reset between each switchover to
ensure that all buffers are cleared out.