Solved! Dell Inspiron 14R BAD File Transfer Rate Under Windows 7

[samsonluk]

I just received my 14R with Windows 7 64-bit and found Internet download problems with it.... Hardware diagnostic reported everything is fine.

Downloads from the Internet always stuck in the middle even for a 50M file, tried using IE and Firefox with the same results. In order to avoid problems of the outside Internet then I conducted another batch of file copying exercises within the local network:

1) Copying file to/from a NAS using Windows's "Copy" command, the transfer rate keep over 95Mbps (very fast, fully utilize the 100M Ethernet link)

2) Using FTP or SCP for file copying from the same NAS, transfer rate dropped to less than 8Mbps.

I suspect this maybe related with OS or drivers so I downgraded it to Windows XP - XP drivers are difficult to collect but I have a full function set now, the most tricky part is that you have to splitstream Intel HM57 AHCI / Chip set driver into the XPSP3 install CD before you can install XP in the SATA drive. I carry out the same set of tests under Windows XP and everything WORKS JUST FINE. However, the 100M LAN cannot fully utilize under XP, file transfer rate can only up to 75-80Mbps for both "Copy" and FTP / SCP operation.

I would like to know any owners of Dell Inspiron 14R / N4010 can test and confirm the Internet download issue as well as slow transfer rate using FTP / SCP kind of Internet file transfer protocol see if it also exist in your machine or I have to return mine.

 

[buwish]

I haven't heard of the issue with the specific model you have, but I suspect that it could be a driver issue. What are you using in your test- the Ethernet port or the wireless?

 

[samsonluk]

Tried both Ethernet and WiFi with the same problems under the stock OS.

In the coming week end I will try install a clean Windows 7 see if there is anything messed up by Dell in the stock image - only trouble is that Dell no longer ship OS Installation CD with this notebook.

 

[samsonluk]

Just want to report problems persist under clean install of the following OS:

Vista 32-bit
Windows 7 32-bit & 64-bit

Only no problem under XP. Maybe somethings very wrong with the hardware, not a simple driver or OS related issue. ftp, http, scp all having problems but only works fine under NetBIOS file transfer. Very strange...

 

[samsonluk]

I think I found the root cause of the problems but still cannot determine where the fault come from...

I use Wireshark to capture the network packets and found that even the machine is not transferring anything, the adapter can generate hundred of packet errors in less than 5 minutes, all related with “Bad TCP Header checksum” with the following details and packets are originated from the machine’s adapter IP:

Header checksum: 0x0000 [incorrect, should be 0x5e4a]
Header checksum: 0x0000 [incorrect, should be 0x5c54]
Header checksum: 0x0000 [incorrect, should be 0x5d8a]
Header checksum: 0x0000 [incorrect, should be 0x5d86]
...
...

After going through a simply file transfer, it will generate thousands of Bad Header checksum errors. These kind of errors also exist upon successful file transfer (the download stuck in the middle quite possible encountered excessive packet errors and give up), I have tried ftp a 30M file and the download succeed but no. of Bad Header check sum packets = 10572 out of total 31772 transferred packets, I don’t think is normal so I restore to Windwos XP and used the machine for hours with heavy file transfers and the error packet is ZERO.

How can you blame on the adapter hardware or device drivers while both LAN and Wireless adapter generated the same errors and they are fine under XP?

 

[samsonluk]

Seems the above checksum errors were due to a feature of TCP Checksum Offloading in Vista / Windows 7 so the OS doesn't apply a checksum to the TCP header and confused Wireshark. I believe Windows XP doesn't have this feature.

Actual event to stop the transfer is the server sends the message TCP Window Full and client responds with TCP ZeroWindow then the FTP / HTTP downloading stops. Any ideas why this happened and how to avoid?

 

[samsonluk]

Problem fixed by disable Windows 7 "Receive Window Auto-Tuning Level", seems this is due to my router failed to work with this Auto-Tuning feature of Windows 7.