Jump to content

Welcome to Geeks to Go - Register now for FREE

Geeks To Go is a helpful hub, where thousands of volunteer geeks quickly serve friendly answers and support. Check out the forums and get free advice from the experts. Register now to gain access to all of our features, it's FREE and only takes one minute. Once registered and logged in, you will be able to create topics, post replies to existing threads, give reputation to your fellow members, get your own private messenger, post status updates, manage your profile and so much more.

Create Account How it Works
Photo

Windows XP SP2 File Share over Wireless


  • Please log in to reply

#1
hunk714

hunk714

    Member

  • Member
  • PipPip
  • 10 posts
I hope that a networking guru viewing these forums can answer this question, because I am intensely curious about it. The issue is this:

I have recently added a new Toshiba P11 laptop to my wireless home network, running WinXP SP2, and with an onboard IEEE 802.11n wireless adapter (Intel® Centrino® Advanced-N 6200 AGN to be specific).

I use a TP-Link TL-WR841N wireless router (in Access Point only mode, since I use another home PC as my routing "gateway" to the outside world, more specifically my Cable Modem). But I digress... the real issue is what's going on, on the _inside_ of my home network.

I noticed that my new laptop performed atrociously when I used IPX/SPX Windows file sharing (i.e. around 5-10 Mbit/sec at best in excellent signal conditions, in 802.11n mixed mode), and yet terrifically when the Windows file sharing used TCP/IP as the underlying protocol (i.e. regularly within the 45-40 Mbit/sec range). The way I first spotted this problem was to note that anything TCP/IP-based to destinations outside of the home network, were going at lightning fast rates, and yet the normal drive-mappings, and streaming of media from locally served content was terrible and unusable (i.e. I originally had it using IPX/SPX).

If this was the same story with my existing Toshiba A8 laptop (running WinXP SP2 and with an onboard IEEE 802.11g wireless adapter, Intel® PRO/Wireless 3945ABG ), then I probably wouldn't be posting this. I'd merely write it off as TCP being superior to SPX in my particular networking environment (i.e. things which come to mind are, perhaps, better error recovery due to its true sliding-window nature over SPX's burst mode, which for all I know could be set to just "1" in my case – making it a stop-and-wait protocol...). The problem is, for this older laptop with the IEEE 802.11g adapter, the situation is completely reversed!!! In most ad-hoc tests I've done (using both Windows Explorer and FTP server file up/downloads), it performs about 3-4 times better with IPX/SPX as the underlying protocol in support of Windows file sharing, as compared to TCP/IP.

So... go figure!? Why is this the case? Why should there be protocol sensitivity to the underlying wireless technology, in the case described above? i.e. seemingly, in my "radio propagation environment", for some reason the IPX/SPX and 802.11g prefer each other on one computer, while the TCP/IP and 802.11n prefer each other on the other computer. And the interesting this is, it appears to be very reproducible.

The only possible theory I have (although I admit I'm not wholly satisfied with it), is this: for some reason the 802.11n, albeit running at a far faster speed, also has more "burst errors" at the physical layer; these are then more easily dealt with in the context of a sliding window protocol, especially if running enhancements like TCP SACK.. compared a stop-and-wait behaviour of SPX (if as I suspect it is behaving in this way). Oh and the other thing which I noticed was that on the 802.11g laptop, the PING times to my gateway are reported as <1ms, while on the 802.11n laptop, they are =1ms. So the longer latency and more bursty error profile of 802.11n, would make TCP more suitable than SPX in this context.

Any thoughts/comments/alternative theories? I'd LOVE to hear from you.

Thanks for your time all,
Milo
  • 0

Advertisements


#2
hunk714

hunk714

    Member

  • Topic Starter
  • Member
  • PipPip
  • 10 posts
Hi all,

an update to the above: after some Wireshark logging of the various transfers, it turns out that the old A8 laptop was actually doing Windows file sharing using the SMB over TCP/IP protocol, and not as I suspected, NetBios over IPX/SPX. This explains why in that case, the results of the FTP and SMB varied around each other, but over a large number of tests, performed roughly equally well (i.e. both had the TCP underlay).

So the whole issue reduces down to "Why is file sharing over IPX/SPX so inferior to the same over TCP, in an 802.11G/N wireless home networking environemnt.. ??". i.e. what happened to the mantra of "NetBios over IPX/SPX is fine for very small home networks??". Curiosity more than anything else here...

Cheers,
Milo
  • 0






Similar Topics

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

As Featured On:

Microsoft Yahoo BBC MSN PC Magazine Washington Post HP