download slows down upload

[oleg]

Hi everyone!

I have recently changed from ADSL to cable. Now I have 1Mbit up and down. I had terrible upload speeds (53k!!!) on the first day. Updating my NIC's (Intel PRO/100 VE) driver helped me a little, now I can upload with full speed. But: When I download and upload at the same time, my upload falls back to ca. 8-10Kb. I got a LanCity LCPET-2 modem from my ISP, running Windows Xp SP1 EN on a P4 box. Already downloaded TCP Optimizer, no changes. What can I do? What can change to get to full speed? My ISP told me, there is everything all right, they mesaured no packet loss.

Thanks for helping me!

oLEG

[mnosteele52]

Welcome to Speedguide:D, please read here (http://forums.speedguide.net/showthread.php?s=&postid=643301#post643301) so that we can properly help you, please read it carefully since it will most likely answer any questions you may have. If after reading it you still need help please post the answers to the questions at the top.:D :cool:

[oleg]

Followed the instructions, no help :-(

So the answers:

1. My connection is cable
2. The advertised speed is 1024 in both directions
3. My /IP Analyzer test results:

SpeedGuide.net TCP/IP Analyzer


TCP properties for IP = xxx.xxx.xxx.xxx
Browser/OS = Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Notes: Read the Analyzer FAQ if the above is not your IP address.

TCP options string = 020405b40103030101010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.

Default Receive Window (RWIN) = 75920
RWIN Scaling (RFC1323) = 1 bits
Unscaled Receive Window = 37960

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)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
64240 (MSS x 44)
bandwidth * delay product:

Your RcvWindow limits you to: 3036.8 kbps (379.6 KBytes/s) @ 200ms
Your RcvWindow limits you to: 1214.72 kbps (151.84 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 59 hops

TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000010

Precedence (priority) = 010 (immediate)
Delay = 0 (normal delay)
Throughput = 0 (normal throughput)
Reliability = 0 (normal reliability)
Cost = 0 (normal cost)

4. My operating system is WINDOWS XP SP1 EN

Have no spyware...
I downloaded cablenut, made the online analysis applied the changes too
I tried another NIC by the way a REALTEK based one have the same problem.

Interesting is that I have this problem only when I download at full speed. When my download is at 90k I can upload with 90k too!

According to Intel RROset I had today:
Packets sent: 4691113
Packets received: 5799391
Send errors: 0
Receive errors: 126

Is this normal?

I hope, somene can help me, because I can't limit my download speed and need the full upload speed too!

oLEG

[Kip Patterson]

You need to reduce the size of your receive window. It is too large for the latency to the site you are downloading from. When it is too large, packets are qued at the slowest point in the system, which in this case is the CMTS. When the acknowledgement packets for the upload arrive at the CMTS, they have to wait their turn in the queue, and the upload is slowed as a result.

The RWIN should be no larger than:

download speed cap / 8 (to convert bits to bytes) times the latency of the download connection.

You can't pick one RWIN that will work in every situation. The correct size depends upon the RWIN of the computer receiving the upstream and its latency as well.

[oleg]

I'm confused... What is my latency? I get even results with highest numbers like 1257! Here are two tracert results:

without load:
Tracing route to dslnuts.com [66.34.156.231]

over a maximum of 30 hops:



1 28 ms 10 ms 7 ms FE-0-0-8.dumbo.hdsnet.hu [213.157.181.1]

2 17 ms 8 ms 15 ms FE-0-0.budapest.hdsnet.hu [213.157.180.249]

3 47 ms 29 ms 28 ms fra2-cr1-atm1-350.hdsnet.hu [193.231.252.201]

4 29 ms 27 ms 27 ms fra2-cr1-atm2-210.rdsnet.ro [62.231.127.65]

5 26 ms 28 ms 26 ms so-1-3-2.ar2.FRA3.gblx.net [67.17.159.101]

6 26 ms 29 ms 27 ms pos11-0-2488M.cr2.FRA2.gblx.net [67.17.65.57]

7 109 ms 117 ms 114 ms pos0-0-2488M.cr1.JFK1.gblx.net [64.214.65.162]

8 118 ms 110 ms 111 ms so0-0-0-2488M.br1.JFK1.gblx.net [64.214.65.214]

9 115 ms 111 ms 116 ms 208.50.13.170

10 120 ms 112 ms 111 ms jfk-core-02.inet.qwest.net [205.171.30.17]

11 154 ms 169 ms 161 ms dal-core-02.inet.qwest.net [205.171.8.141]

12 163 ms 151 ms 170 ms dal-edge-07.inet.qwest.net [205.171.25.58]

13 160 ms 170 ms 151 ms ci-dfw-OC12.cust.qwest.net [65.118.50.2]

14 157 ms 172 ms 157 ms f4-g0-c1.propagation.net [66.34.255.6]

15 187 ms 161 ms 153 ms 66.34.156.231



Trace complete.

With load:
Tracing route to dslnuts.com [66.34.156.231]
over a maximum of 30 hops:

1 17 ms 6 ms 4 ms FE-0-0-8.dumbo.hdsnet.hu [213.157.181.1]
2 4 ms 3 ms 3 ms FE-0-0.budapest.hdsnet.hu [213.157.180.249]
3 32 ms 26 ms 28 ms fra2-cr1-atm1-350.hdsnet.hu [193.231.252.201]
4 35 ms 26 ms 30 ms fra2-cr1-atm2-210.rdsnet.ro [62.231.127.65]
5 206 ms 60 ms 31 ms so-1-3-2.ar2.FRA3.gblx.net [67.17.159.101]
6 413 ms 51 ms 43 ms pos11-0-2488M.cr2.FRA2.gblx.net [67.17.65.57]
7 455 ms 491 ms 128 ms pos0-0-2488M.cr1.JFK1.gblx.net [64.214.65.162]
8 488 ms 486 ms 527 ms so0-0-0-2488M.br1.JFK1.gblx.net [64.214.65.214]

9 505 ms 495 ms 488 ms 208.50.13.170
10 117 ms 384 ms 131 ms jfk-core-02.inet.qwest.net [205.171.30.17]
11 491 ms 509 ms 500 ms dal-core-02.inet.qwest.net [205.171.8.141]
12 491 ms 495 ms 513 ms dal-edge-07.inet.qwest.net [205.171.25.58]
13 488 ms 505 ms 500 ms ci-dfw-OC12.cust.qwest.net [65.118.50.2]
14 491 ms 503 ms 490 ms f4-g0-c1.propagation.net [66.34.255.6]
15 485 ms 492 ms 505 ms 66.34.156.231

Trace complete.

Thanks again!

oLEG

[mnosteele52]

Your connection is a perfect example of how checking your latency under a load really effects your connection. Your latency rised pretty high, I see you are using CableNut so try the following settings:

DefaultReceiveWindow = 131072
DefaultSendWindow = 131072
DisableAddressSharing = 1
InitialLargeBufferCount = 200
InitialMediumBufferCount = 480
InitialSmallBufferCount = 640
LargeBufferSize = 819200
MaxFastTransmit = 64000
MediumBufferSize = 150400
PriorityBoost = 0
SmallBufferSize = 12800
TransmitWorker = 32
FastSendDatagramThreshold = 4096
EnableFastRouteLookup = 1
EnablePMTUDiscovery = 1
IgnorePushBitsOnReceive = 0
GlobalMaxTcpWindowSize = 64240
MaxFreeTcbs = 8000
MaxHashTableSize = 16384
MaxNormLookupMemory = 5000000
SackOpts = 1
SynAttackProtect = 1
Tcp1323Opts = 0
TcpLogLevel = 1
TcpMaxDupAcks = 3
TcpMaxHalfOpen = 100
TcpMaxHalfRetried = 80
TcpRecvSegmentSize = 1460
TcpSendSegmentSize = 1460
TcpTimedWaitDelay = 30
TcpUseRFC1122UrgentPointer = 0
TcpWindowSize = 64240
MaxConnectionsPer1_0Server = 20
MaxConnectionsPerServer = 10
DefaultTTL = 64
DisableUserTOSSetting = 0
TcpMaxDataRetransmissions = 6
DefaultTOSValue = 90

The TcpWindowSize I gave you is based on your caps and a max latency of 500ms.


:D :cool: