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dlai

Need Help With Slow Comcast Connection on One Laptop

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I'm hoping someone can help me with some speed issues I'm having. I have two laptops using XP connecting to a 6mb Comcastconnection via wireless G. I've loaded cablenut and TCP optimizer on both and have the settings equal on both computers.  However, one is able to connect at 7mb and the other only at 387 kbps. Upload is slow too. I can't figure out for the life of me why this one laptop is so slow. Hopefully someone can help out with some suggestions.

Here's some data:

TCP properties for IP = (xxxxxx)

Browser/OS = Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.12) Gecko/20050915 Firefox/1.0.7

Notes: Read the Analyzer FAQ if the above is not your IP address.

TCP options string = 020405b40103030201010402

MTU = 1500

MTU is fully optimized for broadband.

MSS = 1460

Maximum useful data in each packet = 1460, which equals MSS.

Default TCP Receive Window (RWIN) = 256960

RWIN Scaling (RFC1323) = 2 bits (scale factor of 4)

Unscaled TCP Receive Window = 64240

RWIN is a multiple of MSS

Other values for RWIN that might work well with your current MTU/MSS:

513920 (MSS x 44 * scale factor of 8)

128480 (MSS x 44 * scale factor of 2)

64240 (MSS x 44)

bandwidth * delay product (Note this is not a speed test):

Your TCP Window limits you to: 10278.4 kbps (1284.8 KBytes/s) @ 200ms

Your TCP Window limits you to: 4111.36 kbps (513.92 KBytes/s) @ 500ms

MTU Discovery (RFC1191) = OFF

Time to live left = 51 hops

TTL value is ok.

Timestamps (RFC1323) = OFF

Selective Acknowledgements (RFC2018) = ON

IP type of service field (RFC1349) = 00100000 (32)

Precedence (priority) = 001 (priority)

Delay = 0 (normal delay)

Throughput = 0 (normal throughput)

Reliability = 0 (normal reliability)

Cost = 0 (normal cost)

Check bit = 0 (correct, 8th checking bit must be zero)

DiffServ (RFC 2474) = CS1 001000 (8) - class 1 (RFC 2474). Similar forwarding behavior to the ToS Precedence field.

More stuff:

:::.. Download Stats ..:::

Connection is:: 387 Kbps about 0.4 Mbps (tested with 748 kB)

Download Speed is:: 47 kB/s

Tested From:: https://testmy.net (server2)

Test Time:: Tue Feb 07 2006 16:38:27 GMT-0800 (Pacific Standard Time)

Bottom Line:: 7X faster than 56K 1MB download in 21.79 sec

Diagnosis: May need help : running at only 8.13 % of your hosts average (comcast.net)

Validation Link:: https://testmy.net/stats/id-TWRMQE7CP

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Statistics:

WEB100 Enabled Statistics:

Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done

running 10s outbound test (client to server) . . . . . 365.75Kb/s

running 10s inbound test (server to client) . . . . . . 523.94kb/s

------  Client System Details  ------

OS data: Name = Windows XP, Architecture = x86, Version = 5.1

Java data: Vendor = Sun Microsystems Inc., Version = 1.5.0_06

------  Web100 Detailed Analysis  ------

Cable modem/DSL/T1 link found.

Link set to Full Duplex mode

No network congestion discovered.

Good network cable(s) found

Normal duplex operation found.

Web100 reports the Round trip time = 2023.33 msec; the Packet size = 1460 Bytes; and

No packet loss was observed.

This connection is receiver limited 37.47% of the time.

  Increasing the the client's receive buffer (196.0 KB) will improve performance

This connection is network limited 62.51% of the time.

Web100 reports TCP negotiated the optional Performance Settings to:

RFC 2018 Selective Acknowledgment: ON

RFC 896 Nagle Algorithm: ON

RFC 3168 Explicit Congestion Notification: OFF

RFC 1323 Time Stamping: OFF

RFC 1323 Window Scaling: ON

Packet size is preserved End-to-End

Server IP addresses are preserved End-to-End

More Details:

WEB100 Kernel Variables:

Client: localhost/127.0.0.1

AckPktsIn: 193

AckPktsOut: 0

BytesRetrans: 0

CongAvoid: 0

CongestionOverCount: 0

CongestionSignals: 0

CountRTT: 192

CurCwnd: 202940

CurMSS: 1460

CurRTO: 6740

CurRwinRcvd: 201480

CurRwinSent: 16304

CurSsthresh: 2147483647

DSACKDups: 0

DataBytesIn: 0

DataBytesOut: 747520

DataPktsIn: 0

DataPktsOut: 512

DupAcksIn: 0

ECNEnabled: 0

FastRetran: 0

MaxCwnd: 202940

MaxMSS: 1460

MaxRTO: 6740

MaxRTT: 4980

MaxRwinRcvd: 201480

MaxRwinSent: 16304

MaxSsthresh: 0

MinMSS: 1460

MinRTO: 270

MinRTT: 70

MinRwinRcvd: 50370

MinRwinSent: 16304

NagleEnabled: 1

OtherReductions: 0

PktsIn: 193

PktsOut: 512

PktsRetrans: 0

X_Rcvbuf: 103424

RcvWinScale: 7

SACKEnabled: 3

SACKsRcvd: 0

SendStall: 0

SlowStart: 137

SampleRTT: 4980

SmoothedRTT: 4770

X_Sndbuf: 103424

SndWinScale: 2

SndLimTimeRwin: 4075299

SndLimTimeCwnd: 6798850

SndLimTimeSender: 2574

SndLimTransRwin: 1

SndLimTransCwnd: 1

SndLimTransSender: 1

SndLimBytesRwin: 157680

SndLimBytesCwnd: 589840

SndLimBytesSender: 0

SubsequentTimeouts: 0

SumRTT: 388480

Timeouts: 0

TimestampsEnabled: 0

WinScaleRcvd: 2

WinScaleSent: 7

DupAcksOut: 0

StartTimeUsec: 659258

Duration: 10880006

c2sData: 2

c2sAck: 2

s2cData: 9

s2cAck: 2

half_duplex: 0

link: 100

congestion: 0

bad_cable: 0

mismatch: 0

spd: 0.00

bw: 5.51

loss: 0.000001000

avgrtt: 2023.33

waitsec: 0.00

timesec: 10.00

order: 0.0000

rwintime: 0.3747

sendtime: 0.0002

cwndtime: 0.6251

rwin: 1.5372

swin: 64.0000

cwin: 1.5483

rttsec: 2.023333

Sndbuf: 8388608

aspd: 1.85072

Checking for mismatch on uplink

(speed > 50 [0>50], (xmitspeed < 5) [0.36<5]

(rwintime > .9) [0.37>.9], (loss < .01) [1.0E<.01]

Checking for excessive errors condition

(loss/sec > .15) [1.0E>.15], (cwndtime > .6) [0.62>.6],

(loss < .01) [1.0E<.01], (MaxSsthresh > 0) [0>0]

Checking for 10 Mbps link

(speed < 9.5) [0<9.5], (speed > 3.0) [0>3.0]

(xmitspeed < 9.5) [0.36<9.5] (loss < .01) [1.0E<.01], (mylink > 0) [3.0>0]

Checking for Wireless link

(sendtime = 0) [2.0E=0], (speed < 5) [0<5]

(Estimate > 50 [5.51>50], (Rwintime > 90) [0.37>.90]

(RwinTrans/CwndTrans = 1) [1/1=1], (mylink > 0) [3.0>0]

Checking for DSL/Cable Modem link

(speed < 2) [0<2], (SndLimTransSender = 0) [1=0]

(SendTime = 0) [2.0E-4=0], (mylink > 0) [3.0>0]

Checking for half-duplex condition

(rwintime > .95) [0.37>.95], (RwinTrans/sec > 30) [0.1>30],

(SenderTrans/sec > 30) [0.1>30], OR (mylink <= 10) [3.0<=10]

Checking for congestion

(cwndtime > .02) [0.62>.02], (mismatch = 0) [0=0]

(MaxSsthresh > 0) [0>0]

estimate = 5.51 based on packet size = 11Kbits, RTT = 2023.33msec, and loss = 1.0E-6

The theoretical network limit is 5.51 Mbps

The NDT server has a 8192.0 KByte buffer which limits the throughput to 31.63 Mbps

Your PC/Workstation has a 196.0 KByte buffer which limits the throughput to 0.75 Mbps

The network based flow control limits the throughput to 0.76 Mbps

Client Data reports link is 'T1', Client Acks report link is 'T1'

Server Data reports link is '10 Gig', Server Acks report link is 'T1'

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Your have a serious problem in your connection. Signals are facing huge latency and this is causing the slowdown.

"Web100 reports the Round trip time = 2023.33 msec; the Packet size = 1460 Bytes; and

No packet loss was observed.

This connection is receiver limited 37.47% of the time.

  Increasing the the client's receive buffer (196.0 KB) will improve performance

This connection is network limited 62.51% of the time."

RTT = 2023.33msec

This high latency is limiting your throughput to only 0.75 Mbps.

Check the condition of your connection; cables, loose plug/socket, modem/router, any nearby electrcial devices emitting electromagnetic interference, etc...

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BUT, here's the results from my other laptop, much different results:

WEB100 Kernel Variables:

Client: localhost/127.0.0.1

AckPktsIn: 3154

AckPktsOut: 0

BytesRetrans: 102200

CongAvoid: 2940

CongestionOverCount: 0

CongestionSignals: 5

CountRTT: 2983

CurCwnd: 40880

CurMSS: 1460

CurRTO: 270

CurRwinRcvd: 921600

CurRwinSent: 16304

CurSsthresh: 5840

DSACKDups: 0

DataBytesIn: 0

DataBytesOut: 8957100

DataPktsIn: 0

DataPktsOut: 6135

DupAcksIn: 142

ECNEnabled: 0

FastRetran: 5

MaxCwnd: 91980

MaxMSS: 1460

MaxRTO: 300

MaxRTT: 110

MaxRwinRcvd: 921600

MaxRwinSent: 16304

MaxSsthresh: 45260

MinMSS: 1460

MinRTO: 220

MinRTT: 20

MinRwinRcvd: 57600

MinRwinSent: 16304

NagleEnabled: 1

OtherReductions: 0

PktsIn: 3154

PktsOut: 6135

PktsRetrans: 70

X_Rcvbuf: 103424

RcvWinScale: 7

SACKEnabled: 3

SACKsRcvd: 160

SendStall: 0

SlowStart: 41

SampleRTT: 30

SmoothedRTT: 70

X_Sndbuf: 103424

SndWinScale: 4

SndLimTimeRwin: 0

SndLimTimeCwnd: 10039806

SndLimTimeSender: 2584

SndLimTransRwin: 0

SndLimTransCwnd: 1

SndLimTransSender: 1

SndLimBytesRwin: 0

SndLimBytesCwnd: 8957100

SndLimBytesSender: 0

SubsequentTimeouts: 0

SumRTT: 151380

Timeouts: 0

TimestampsEnabled: 0

WinScaleRcvd: 4

WinScaleSent: 7

DupAcksOut: 0

StartTimeUsec: 727412

Duration: 10045535

c2sData: 2

c2sAck: 2

s2cData: 9

s2cAck: 3

half_duplex: 0

link: 100

congestion: 1

bad_cable: 0

mismatch: 0

spd: 0.00

bw: 7.69

loss: 0.000814996

avgrtt: 50.75

waitsec: 0.00

timesec: 10.00

order: 0.0450

rwintime: 0.0000

sendtime: 0.0003

cwndtime: 0.9997

rwin: 7.0312

swin: 64.0000

cwin: 0.7018

rttsec: 0.050748

Sndbuf: 8388608

aspd: 19.86236

Checking for mismatch on uplink

(speed > 50 [0>50], (xmitspeed < 5) [0.40<5]

(rwintime > .9) [0>.9], (loss < .01) [8.14<.01]

Checking for excessive errors condition

(loss/sec > .15) [8.14>.15], (cwndtime > .6) [0.99>.6],

(loss < .01) [8.14<.01], (MaxSsthresh > 0) [45260>0]

Checking for 10 Mbps link

(speed < 9.5) [0<9.5], (speed > 3.0) [0>3.0]

(xmitspeed < 9.5) [0.40<9.5] (loss < .01) [8.14<.01], (mylink > 0) [3.0>0]

Checking for Wireless link

(sendtime = 0) [3.0E=0], (speed < 5) [0<5]

(Estimate > 50 [7.69>50], (Rwintime > 90) [0>.90]

(RwinTrans/CwndTrans = 1) [0/1=1], (mylink > 0) [3.0>0]

Checking for DSL/Cable Modem link

(speed < 2) [0<2], (SndLimTransSender = 0) [1=0]

(SendTime = 0) [3.0E-4=0], (mylink > 0) [3.0>0]

Checking for half-duplex condition

(rwintime > .95) [0>.95], (RwinTrans/sec > 30) [0>30],

(SenderTrans/sec > 30) [0.1>30], OR (mylink <= 10) [3.0<=10]

Checking for congestion

(cwndtime > .02) [0.99>.02], (mismatch = 0) [0=0]

(MaxSsthresh > 0) [45260>0]

estimate = 7.69 based on packet size = 11Kbits, RTT = 50.75msec, and loss = 8.14996E-4

The theoretical network limit is 7.69 Mbps

The NDT server has a 8192.0 KByte buffer which limits the throughput to 1261.13 Mbps

Your PC/Workstation has a 900.0 KByte buffer which limits the throughput to 138.55 Mbps

The network based flow control limits the throughput to 13.82 Mbps

Client Data reports link is 'T1', Client Acks report link is 'T1'

Server Data reports link is '10 Gig', Server Acks report link is 'Ethernet'

The slow laptop is an IBM Thinkpad T42 running XP Pro.  The faster one is a Sony PCG K45 running XP Pro as well.  I really think there's someone going on with the IBM...

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Will do.  I just went to the IBM website and noticed there's some new drivers related to the networking components, including a new one for the nic.  It's downloading now (remembering that it's slow on that computer), so it will take a while, but I'll retest things when it's done.  I really appreciate your help, and steering me in the right direction....

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Fallow, thanks for the link.  It's not the case with the problem I'm experiencing.  Signal strength is at the max, and I don't experience the same issues with the other laptops I have, only with the one in question.  My wap has a 7db antenna as well, and the problem still occurs if I'm sitting right next to the wap with this one laptop in question.

I did load the new drivers last night with no improvements in the performance, sad to say.  So I'm inclined to think that there is something wrong with the built-in wireless nic in the laptop. This morning I did a direct connect to my router via an ethernet cable and got 7mb right away, so that pretty much seals it in my mind that it's the wireless nic that's at fault.

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Here's an interesting update.  It appears that some IBM Thinkpads use an Intel Pro 2200BG mini pci card which has a problem connecting to Linksys routers.  The symptoms are slow wireless access, and transmit speeds that start at 54 Mbps and then slows down to 24 mpbs, exactly the problems I'm having.  This problem is widespread and the fix is replacing that card with a newer IBM a/b/g card based on the Atheros chipset.  This is what I'm going to do and have contacted an IBM warranty center already.  So for anyone that has a Thinkpad with speed issues or connection drops, that is the fix...

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Here's an interesting update.  It appears that some IBM Thinkpads use an Intel Pro 2200BG mini pci card which has a problem connecting to Linksys routers.  The symptoms are slow wireless access, and transmit speeds that start at 54 Mbps and then slows down to 24 mpbs, exactly the problems I'm having.  This problem is widespread and the fix is replacing that card with a newer IBM a/b/g card based on the Atheros chipset.  This is what I'm going to do and have contacted an IBM warranty center already.  So for anyone that has a Thinkpad with speed issues or connection drops, that is the fix...

Good to know.  Thanks for the tip.

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