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Jonathan Rioux
Asked: 2011-12-08 07:52:35 +0800 CST

Network issue - Very slow while RXing but TXing is fine

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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?

EDIT:

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.

enter image description here

EDIT 2:

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 :(

file-transfer networking switch nic

1 Answers

  1. Best Answer

    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.

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