Network Help

[JdotK]

Hello, I live in California, USA, and have had Comcast High Speed for about a year and a half. I was subscribed to their 6Mbps service, and was receiving these speeds consistantly:

http://www.gritalian.com/comcast.png


But as of last Monday my internet has dropped to about 1/6th of that.

I have had 2 technicians come and check my line this week, both saying that everything looked fine. One connected with his laptop and also downloaded at the same speed as my computer (a constant 768k/sec).

Today the 2nd technician came and reported that everything was fine, but suggested moving to the 8Mbps plan, which I did.

Now my download speed is:

http://www.gritalian.com/comcastnow.jpg

As you can see in the graph the speed does pick up at first, to about 1600KB/s, then immediately drops to a constant 1012KB/sec

I'm hoping someone can explain to me what possibly could have happened and what I can do to fix it, seeing how Comcast has said everything is fine.


The first technician was convinced that different websites put a Cap on me... he doesn't believe me that the videos on IGN.com are ok to download and that my Insider membership is legit... that and I can tell he really doesn't know what to say or do.


Any help is appreciated. Thanks.

[trogers]

1012 KB/s = 8096 kbps.

1 Kilo Byte = 8 kilobits.

So you are getting your 8 mbps speed. I do not see any problem here.

[JdotK]

Hmm, I just found a conversion chart.

I guess I thought the comcast 6Mbps ment 6MB/s


So I thought I should be getting 6000KB/s, since I was getting 3800KB/sec


I guess it turns out 3800KB/sec is really 30.4Mbps

So it appears for the last few months comcast has been messing up and giving me insane speeds.

I upgraded to the 8Mbps, which now I am getting 1014KB/sec, which is:

8.112 Mbps or 8112 Kbps.


Is this correct?

[trogers]

Yes. ComCast does have some periodic speed burst. Post your TCP Analyzer and we can check if your settings is optimum.

[JdotK]

« SpeedGuide.net TCP Analyzer Results »
Tested on: 01.27.2007 23:00
IP address: 67.188.x.xxx

TCP options string: 020405b40103030301010402
MSS: 1460
MTU: 1500
TCP Window: 513920 (multiple of MSS)
RWIN Scaling: 3
Unscaled RWIN : 64240
Reccomended RWINs: 64240, 128480, 256960, 513920
BDP limit (200ms): 20557kbps (2570KBytes/s)
BDP limit (500ms): 8223kbps (1028KBytes/s)
MTU Discovery: ON
TTL: 50
Timestamps: OFF
SACKs: ON
IP ToS: 00100000 (32)
Precedence: 001 (priority)
Delay: 0 (normal delay)
Throughput: 0 (normal throughput)
Reliability: 0 (normal reliability)
Cost: 0 (normal cost)
Check bit: 0 (correct)
DiffServ: CS1 001000 (8) - class 1 (RFC 2474). Similar forwarding behavior to the ToS Precedence field.

____


Thanks for your help

[trogers]

« SpeedGuide.net TCP Analyzer Results »
Tested on: 01.27.2007 23:00
IP address: 67.188.x.xxx

TCP options string: 020405b40103030301010402
MSS: 1460
MTU: 1500
TCP Window: 513920 (multiple of MSS)
RWIN Scaling: 3
Unscaled RWIN : 64240
Reccomended RWINs: 64240, 128480, 256960, 513920
BDP limit (200ms): 20557kbps (2570KBytes/s)
BDP limit (500ms): 8223kbps (1028KBytes/s)
MTU Discovery: ON
TTL: 50
Timestamps: OFF
SACKs: ON
IP ToS: 00100000 (32)
Precedence: 001 (priority)
Delay: 0 (normal delay)
Throughput: 0 (normal throughput)
Reliability: 0 (normal reliability)
Cost: 0 (normal cost)
Check bit: 0 (correct)
DiffServ: CS1 001000 (8) - class 1 (RFC 2474). Similar forwarding behavior to the ToS Precedence field.

____


Thanks for your help

TCP Window (RWIN) set to 513920 may let you enjoy the periodic speed burst of ComCast.

If you find your speed fluctuates at 6-7 mbps, try setting RWIN to 256960.