. This document answers the most frequently asked questions (FAQs)
related to LAN-2-LAN Software.
Symptom: File transfers on long-distance lines tend to be slower than on
A. This is because propagation delays on typical circuits are 1
millisecond per 100 miles. When you use the NetWare ping-pong file transfer
protocol, each transaction suffers the round trip propagation delay. This delay
can be further exaggerated because circuit miles can be more than twice as long
as straight-line miles.
For example, a line from Oregon to New Jersey was routed through
Seattle, Los Angeles, Chicago, and Ohio—a circuit distance of 5,402 miles. A
round-trip propagation delay on this circuit is 108 milliseconds.
This means that, for such a line, if you use the NetWare ping-pong file
transfer protocol, regardless of the line speed and data compression
effectiveness, and ignore any other delays, fewer than 10 transactions a second
can occur. If each transaction results in a payload of 512 bytes, the maximum
possible transfer rate for a file on this line is approximately 5,000
As an example, it took 40 seconds at 56 Kbps with data compression to
execute PCONSOLE when the system was set up locally with no propagation delay.
Because of the propagation delay, this time expanded to 170 seconds when
connected 5,400 miles across country.
Excessive delays can be alleviated if you use the large-packet feature
provided by LAN?LAN. If you use Ethernet, the Packet Size used by your NICs is
probably 1024. If you configure Packet Size to be 1024 on your LAN?LANs (see
your user guide), you can expect to substantially lower your file-transfer
time. The exact amount depends upon your line speed, use of compression, and
circuit mile length of your line. If you are a Thomas Conrad ARCNET or Token
Ring user, you possibly can increase the packet size even further.
A different solution to the problem will be provided by the Novell
Packet Burst NLM when it becomes available.
How do I investigate excessive delays?
A. If you need to investigate excessive delays, these suggestions are
Calculate your expected time per file transaction (in milliseconds)
which is given by:
Request transmission time + Response transmission time + Two way
Propagation delay + other delays
Request transmission time is given by:
File request size (34 bytes)/(line speed in bps/8) * 1000
Response transmission time is given by:
File response size (552 bytes)/(line speed in bps/8) * 1000
Two-way propagation delay is given by:
(Circuit miles one way * 2)/100
Other delays = 5 milliseconds
Why does the PC2LAN hang during an application program
A. PC?LAN hangs after the USERID is entered during a load of the network
version of Word Perfect v5.1 for Windows, because WP 5.1 grabs the COM1
interrupt from PC?LAN. A workaround for this problem is to move PC?LAN to the
COM2 port or use the /x option on the WP 5.1 command line to set WP 5.1 back to
its default values for the setup feature.
If you experience problems when you load similar applications in a
PC?LAN, try to use another COM port. If your application uses the COM port that
you have selected for PC?LAN, check to see if there is a way to disable or
change this selection.
How do I resolve lost interrupts with AST PREMIUM
A. You receive a message similar to this (messages can vary with earlier
Primary interrupt controller detected a lost hardware interrupt, or
Secondary interrupt controller detected a lost hardware interrupt
You can disable these messages with this SET command:
SET Display Lost Interrupt Alerts = OFF
The problem might not occur with all revisions of the motherboard and
processor module. Novell has informed AST, and the problem is under
A similar problem was experienced when you use an ALR VIESA 486/33. The
workaround was to substitute an IDE.DSK driver for the standard ISA.DSK disk
What items do I need to consider when I use a modem with
A. LAN?LAN makes minimum demands of the modem/DSU to which it is attached
and provides all the outgoing signals required by normal modems and
LAN?LAN activates output signal DTR (TR for RS422) continuously from
LAN?LAN requires the presence of the incoming modem signal DSR (DM
for RS422) before it activates the line. When DSR is present, LAN?LAN activates
output signal RTS (RS for RS422), begins to send flags to the line, and starts
the line protocol.
LAN?LAN also requires modem-supplied transmit and receive clocks to
clock data in and out. All other incoming modem signals are
LAN?LAN dynamically senses the line speed by means of periodic test
transmissions. LAN?LAN adjusts its protocol timer in accordance to the measured
Lines between LAN?LANs can be implemented with a primary leased line
and a backup dialup line. A typical example might be a leased line that
operates at 56 Kbps, backed up with a 9600 bps dial line. The switch between
primary and secondary can be activated by external equipment. In this
situation, if you assume a switch-over period of a few seconds, LAN?LAN detects
a short line outage and continues operation on the new line with the line
protocol that protects against data loss or corruption. LAN?LAN adjusts its
protocol timer for the different line speed at the next periodic speed
What is the problem and associated solution for when you use Cisco
Systems' WNIC revision "D" and "E" adapters in AST Symmetric Multi Processor
(SMP) 486/50 machines?
When you use NetWare version 2.x or version 3.11, the machine ABENDs
with a non-maskable interrupt (NMI). An error message similar to this appears
on the console screen:
System Halted Tue. Dec. 1, 1992 8:40:00 pm
ABEND: Non-maskable Interrupt
(Error Code XXXXXXXX)
The problem occurs only with the AST SMP 486/50.
On early releases of the AST SMP 486/50, I/O bus refresh is disabled.
I/O bus refresh must be enabled in order for the WNIC to properly use its 512
Kbytes of memory. Later versions of the AST SMP 486/50 are shipped with I/O bus
Run the EISA configuration program in order to enable the I/O bus
refresh. In the configuration program, in the System AST Manhattan SMP System
Board menu, I/O bus refresh can be enabled/disabled. I/O bus refresh must be
set to enabled.
What is the PC motherboard AT Bus
A. PC 386 Motherboards that use the SYMPHONY CHIP SET with a chip
identified as 461 and marked v073 do not operate properly when you do16-bit
transfers on odd byte boundaries.
This deficiency results in the incorrect operation of LAN?LAN when
installed in a PC that uses the chipset and causes the WD diagnostic to fail
during the High Speed Ports test.
If you experience a problem when you run LAN?LAN in a 386 clone, run
WD. If you get an error code in the 4141-4147 range, inspect your PC to see if
it contains the bad chip set.