upload speed drops off to nothing

[morkinva]

This is a cable modem on comcast, win98se. Upload speed should be 30KB/sec, but if I'm using FTP or yahoo's file upload, it starts off there but every 30 seconds or so, it halves its upload speed. Eventually the upload fails (on large files).

Curiously, if I use comcast's file upload via their website, there is no dropping off of speed, it keeps a constant 30KB or so.

What program might u recommend to optimize MTU and other settings? WTF goes on here?

 

[morkinva]

tried resetting the modem, both software and pinhole reset
edit>> completely disabled zonealarm pro from msconfig and rebooted
changed from usb to ethernet port on the motorola sb4100 modem, no go

 

[Big Lar]

Try DrTCP from broadbandreports,set the Rwin to 64240, and the rest at default/MTU is 1500, and TTL is left blank for now.
Ethernet is much better,What are your power/ signal levels?

Larry

 

[morkinva]

Before I give you the results, the nagging question to me is: if an ftp upload slows down and the comcast website upload doesn't, even though they go to the same webspace, do any of the following values really matter?

Tried the drtcp change, same results. I set both the network card and the cable modem to the same values. The settings are:

tcp receive: 64240
window scaling: yes
time stamping: no
selective acks: yes
path mtu discovery: no
black hole detection: no
max duplicate acks: 3
ttl: (blank)
mtu: 1500



Here's what the cable modem signal page says:


downstream -------------- value
Frequency -----------------723000000 Hz Locked
Signal to Noise Ratio ------- 34dB
Power Level -------------- 3 dBmV


upstream ------------- value
Channel ID---------------- 5
Frequency ------------------30992000 Hz Ranged
Power Level ---------------- 40 dBmV


And its been on the usb connection for a few months now, no incidents like this.

Thanks

 

[mriman]

Very Interesting.... I too am a Comcast cable subscriber and am in just the last week or two? experiencing EXACTLY the same thing.... right down to uploads slowing down then failing (4mb upload) and that strange symptom ( I just checked) an upload to Comcast runs just fine?

 

[ThePiston]

eh eh, sounds like you are victims of Comcast's no-server law. I'm not positive, but I bet when you start uploading a lot of data, their servers are aware of this and slowly back your speeds down. Not sure why it goes to zero though. Comcast in Philly did the same thing. If I tried to host a Half Life game, it would be fine at first, then go very slow until everyone was dropped. They are VERY protective of their bandwidth. In fact, they ping your PC every hour or so looking for open server ports like 80 and 21.

 

[morkinva]

Ok what you say is possible I suppose. But why is there no slowdown if I direct connect to someone on instant messenger and send them a huge file?

 

[mriman]

I called Comcast Support.... lady checked my modem & said all was good. I am behind router she could only ping modem, not my computer. I told her uploads to Comcast were uneffected.

She DID NOT offer that this was a result of any policy Comcast has against large upload traffic.

If you find a solution to this problem or hear of anyone else having the same problem you can email me from our amatuer radio website : http://www.qsl.net/carc/roster.html

I am KB9QFT