Network Throughput

As LANs evolve into 100Base-T and even Gigabit speeds, HP3000 owners consider installing additional LAN cards or upgrade to 100Base-T cards in their systems. Several factors should be examined during the decision making process. Most HP3000 systems will receive no marked increase in transfer speed from a 100MB LAN card. The fact of the matter is the majority of systems don’t have the bus speeds capable of driving a 100MB card to its full potential. Moreover, a typical screen driven application transfers very little data at a time and doesn’t use the bandwidth available on the built-in 10Base-T LAN card. I would only consider adding a 100Base-T card to a 959, 969, 979, 989, 99x, A-class, or N-class system. On low and midrange systems it is more effective to put in a second 10MB card to increase throughput than it is to install a 100Base-T card.

Will my HP3000 Benefit from an Additional Network Card?

To determine whether or not your existing LAN card is saturated you can examine the LAN throughput. During a peak usage time of day use LINKCONTROL to track the amount of data processed by the card. A simple command file like this will do it. Use the command :linkcontrol @,linkstate to obtain the correct LINKNAME and substitute it for DTSLINK in the following script.

build linkstat;rec=-80,,f,ascii;disc=50000
file linkstat,old;dev=disc;acc=append
linkcontrol DTSLINK,reset
while 1 = 1
showtime >*linkstat
linkcontrol DTSLINK,reset >*linkstat
pause 60

The first LINKCONTROL command resets the statistics to zero so you have a good baseline to start with. Next, the script goes into an infinite loop inserting the statistics for the network card into the file LINKSTAT every 60 seconds. Each entry in LINKSTAT will look like this:

MON, JUN  2, 2003, 10:08 AM
Linkname: DTSLINK   Linktype: IEEE8023  Linkstate: CONNECTED
Transmits no error           16  Receives no error          117
Transmit byte count        2642  Receive byte count        9906
Transmits error               0  Receives error               0
Transmits deferred           14  Carrier losses               0
Transmits 1 retry             2  CRC errors                   0
Transmits >1 retry            4  Frame losses                 0
Trans 16 collisions           0  Whole byte errors            0
Trans late collision          0  Size range errors            0
802 chip restarts             0  Receives dropped             0
Heartbeat losses              0  Receives broadcast         104
                                 Receives multicast           1

The important statistics here are the Transmit byte count and the Receive byte count. From these you can compute the number of bytes the card processed in a given minute, yielding a rough estimate of whether it is near capacity.

If you are still considering upgrading to a 100Base-T card you will need to purchase the network card and software from an authorized HP reseller. The driver is licensed, add-on software that does not come bundled with MPE and carries a list price up to $2000.00 depending upon system model. Additional 10Base-T LAN cards don’t require any additional software.

Configuring 100Base-T for Best Performance

BT100 network configurations default to an “autosensing” configuration for speed and duplex. This autosensing is notoriously inaccurate. Frequently the LAN card autosenses to half-duplex while the switch port is running at full duplex. The net effect is the throughput will be very poor due to miscommunication between the system and the switch. Keep this in mind if you have already installed or are going to install a 100Base-T card.

:linkcontrol @,ALL
Linkname: BT100LK   Linktype: 100BT     Linkstate: CONNECTED
Physical Path:              10/16/16
Current Station Address:    08-00-09-D3-F2-54
Default Station Address:    08-00-09-D3-F2-54
Current Multicast Addresses:

Transmit bytes                  18846    Receive bytes              9427282932
Transmits                    63251619    Receives                     86068313
Transmits no error           63215619    Receives broadcast                  0
Transmits dropped                   0    Receives multicast              13579
Transmits deferred                  0    Receives no error            86081910
Transmits 1 retry                   0    CRC or Maxsize error                0
Transmits >1 retry                  0    Code or Align error                 0
Trans 16 collisions                 0    Recv dropped: addr                 18
Trans late collision                0    Recv dropped: buffer                0
Trans underruns                     0    Recv dropped: dma                   0
Carrier losses                      0    Recv dropped: other                 0
Link disconnects                    0    Recv deferred                       0
Link speed                        100    Recv overruns                       0
Link duplex                      Half    Link auto sensed                  Yes
Link mode                  100Base-TX    Secs since clear              4086110

To force the card to run at 100MB and FULL DUPLEX requires a small change in NMMGR.

Press F1 - Open  Config
Press F2 - NS
Press F2 - Unguided Config
Press F2 - Go To Link
Enter the name of the adapter from the list and press F6 - Modify
Change the settings based on the bold items listed below and press               F6 - Save Data
Path:                 LINK.BT100LK
Physical                 path of device adapter [10/16/16 ]
>Use factory-configured local station address? [Y] (Y/N)
Local station address [FF-FF-FF-FF-FF-FF] (Hex)
>When auto-negotiation is enabled, the system can only
properly configure the link if the hub also auto-negotiates.
Use auto-negotiation to determine link settings? [N] (Y/N)
If 'N': Link speed [100 ] (100 or 10 MBits/sec)
Full Duplex mode [Y] (Y/N; N=Half)
Trace at startup? [N] (Y/N) Note : Trace reduces
Trace filename [ ] performance.

Be sure to VALIDATE both NETXPORT and DTSLINK prior to exiting NMMGR. The next time you stop and restart the network it will pick up the new settings.

The network card is just one aspect of overall network performance. Many other factors affect the throughput including cabling, network equipment, datacomm lines. We are happy to discuss your network concerns and help you plot the best course of action.