Odd Duplex Problem - transmit speed

Gang, I have an odd problem with transmission speed. Situation:

I have a GE medical imaging device (DICOM) that GE tells me HAS to be set at 100 half duplex on the switch (this switchport is also on a vlan).

Easy enough, affer the switch config, I check the GE Imaging device, and it auto negs at 100 half.

The Tech sends an image, it takes 43 seconds to show up on our pacs server.

NOW THE ODD PART.

Switch port still configured at 100 half. We unplug the GE device from that port, and plug a small dlink hub into that port. Into the hub, we plug the GE device, the GE device auto negs on the hub at 100 full. The tech sends an image to our pacs system, and it takes 5 seconds.

I don't understand why it is doing that, ultimately, the switchport that the hub is pluggd into is still 100 half even though the hub and GE device are at 100 full.

Is the GE Tech on crack, should I be using the device at 100 full?

Also, are there any considerations, configuration changes I need to make for the DICOM protocol?

Thanks a million, I'm stumped.

The details: The Cisco switch is a 3750 running Version 12.1(19)EA1c

Reply to
troute_kilgore
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From expierence we used to have this problem on Enterasys hardware with autonegiotigation. Some PCs will not negiotigate correctly and be very slow, sometimes connecting at 10 half. Try to hard code both ends to 100 full and see if that works?

Reply to
Boxxa

What happens if you reconfigure the switch port for full duplex?

Reply to
Drake

A HUB cannot operate at full duplex, it is a hub, it only runs at half duplex. What happens when you plug it in to a switcport in auto? Does it come up at 100 full? Keep an eye on the interface counters, if you see errors it's a negotiation issue...if it's clean the GE engineer is smoking crack.

-Brian

Reply to
Brian V

To the Original Poster-

I do noted that there has been no response from you so maybe you are not reading the answers; so I will be brief.

When investigating Ethernet Duplex issues the key thing is not to believe anyone or anything that is reported. The whole issue is surrounded by magic and mystery that is difficult to unravel.

If you are measuring an enormous performance change then you have something to believe. Go with it.

I suggest:- Medical imaging equipment is not cheap $Ms. Spend $1000 on a proper managed switch. For example Cisco 2960, 3560, 3750. Whatever you fancy. I am sure that there are others however I have come to TRUST the diagnostic tools provided by Cisco.

Even then, I have more faith in the Interface error counters that I have in reported duplex settings. Interface error counters are trivialy testable, say with ipref or fping.exe

formatting link
if you organise a duplex mismatch.

In windows speak:-

c:\\>for /L %i IN (1, 1, 15) DO start cmd /c fping x.x.x.x -i -s 1400

-n 2000 -t 0 If this produces no drops than you do not have a duplex missmatch.

If you have a very fast or very long network 15 may not be enough. Ramp up 'til it melts. (Very fast and very long = Long Fat Pipe)

##/AND/## - I have even MORE faith in actual performance measurements.

Trust your numbers, make your judgements.

My conclusion is that you are being mis-informed by GE,

Trust testing more than anything and error counters more than duplex configuration setting or duplex reports.

Reply if you want more. Good luck.

Reply to
Bod43

For the avoidance of doubt the word "hub" is ambiguous in networking speak. Brian V has taken it to mean a repeater. Whilst this was common parlance at the time that 10base-T repeaters appeared it was never AFAICT a standardised term. 100base-T repeaters, what Brian V implies the OP must have connected, are almost unknown. The term "switching hub" is fairly common, meaning a small switch, and way back when "hub" was used to mean a large layer-3 switching router, the predecessors of the Cat 6500/7600 and the like. It can also be used to mean a central wiring closet ("hub room") and all sorts of other things.

Sam (who's been doing this stuff longer than he cares to remember)

Reply to
Sam Wilson

For sure, a term worth avoiding.

Unfortunately we seem to be stick with Switch.

Reply to
Bod43

Meaning a layer 2 bridge, right? :-)

Sam

Reply to
Sam Wilson

Reply to
troute_kilgore

Meaning whatever the user of the term means at the moment:)

Reply to
Bod43

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