I am trying to transfer a 10GB file to test my network. But when I transfer from Workstation 1 to Workstation 2, it takes 8 minutes (which is fine). But from Workstation 2 to Workstation 1, the transfer takes 50 minutes or so.

Here is the scenario:

enter image description here

10GB file transfer:

Workstation 1 -> Workstation 2 = 8 minutes
Workstation 2 -> Workstation 1 = 50 minutes (and flickering)

When I try with another switch between the 2 hosts, both side transfers are fine. So the problem resides on the Linksys Switch itself?

How can I diagnose this issue?


The switch is NOT the issue, iv changed the switch and the issue is still there. Here is a graph taken during the transfers. Red is TX and Yellow is RX. So basically, Workstation 1 is receiving data (YELLOW) very slowly, and transmits (RED) fine. And the transfers are always between the same 2 hosts. Also, Workstation 2 is RXing and TXing fine, iv tested between Workstation 2 and another Workstation other than 1. So Workstation 1 has the issue I think. How can I diagnose this?

  • Note that the network cards are set to Auto Negotiate on both workstations and both are GigaEthernet.

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I did an iperf between WS 1 and WS 2 with the -d option:

enter image description here

This is clearly showing an issue with network RXing (receiving) on workstation 1, so the disk i/o is NOT the issue here. Please help me :(

  • Other than trying other ports on the existing switch, I'd say you have diagnosed the problem. It might be the cables or the NIC's but based on the test with the other switch it sure looks like the Linksys switch.
    – dbasnett
    Dec 7 '11 at 15:58
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    I disagree. The switch is just passing traffic from one port to another. It shouldn't matter at all which direction. When you copy are you pushing or pulling in both cases? For example, when you copy from 1 to 2, on which workstation are you initiating the copy? When you copy from 2 to 1 do you initiate from the other workstation or are you doing both tests from the same box? When 'pulling' data from a remote workstation it can take longer due to having to build and transfer the index of remote files first. Dec 7 '11 at 16:04
  • Do you experience the problem with the systems plugged into different ports? Dec 7 '11 at 16:30
  • @jgoldschrafe, yes, iv changed the switch and still same problem. Dec 7 '11 at 16:32
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    I'd suggest downloading iperf (or something similar) to let you hone in a bit. If that shows fine transfer speeds, maybe there's a problem reading from disk on workstation2 or writing to disk on workstation1?
    – Bill Weiss
    Dec 7 '11 at 16:39

If the issue is not the switch, as your edit suggests, have you tried swapping out network cards (or adding a descrete network card if the ones you are currently using are built-in to the motherboards so can not be swapped)?

A while ago we had a couple ofnetwork cards "go bad" (they had worked fine for some time) in such a way, being unusually slow to transmit in one direction but up to spec in the other. Replacing them with identical cards (same make+model, bought at teh same time) fixed the issue so the cards were the problem rather than a driver (or other software) issue.

It may also be worth double-checking your cables are fine. There could be a near-break in one or more of the wires that is causing signal echo confusing the cards (which may see such echo as a collision) and causing many packet resends.

And just in case the obvious has been missed: make sure that the machine that is being slow to send doesn't have any processes sending a lot of data elsewhere already (i.e. check the network throughput gague on both machines during the test, not just one), meaning test data you send in that direction has to compete for line time to get through.

  • I have two NICs on WS 1, iv changed to the other NIC, and same problem. Dec 7 '11 at 17:28

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