Question on Unusual NDT Test Results

[cholla]

I did these tests at the NDT test in Switzerland

http://cemp1.switch.ch/network/performance/web100/tcpbw100.html

I have a 56k dial-up modem.My question is about this result"Alarm: Duplex mismatch condition exists: Host set to Full and Switch set to Half duplex"

Where would the mismatch be there are no setting in my OS for this.btw I don't get this result at other NDT test sites.   

TCP/Web100 Network Diagnostic Tool v5.3.3e

click START to begin

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

running 10s outbound test (client to server) . . . . . 117.37Kb/s

running 10s inbound test (server to client) . . . . . . 115.56kb/s

Your PC is connected to a Cable/DSL modem

Alarm: Duplex mismatch condition exists: Host set to Full and Switch set to Half duplex

click START to re-test

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

running 10s outbound test (client to server) . . . . . 116.68Kb/s

running 10s inbound test (server to client) . . . . . . 116.49kb/s

Your PC is connected to a Cable/DSL modem

Alarm: Duplex mismatch condition exists: Host set to Full and Switch set to Half duplex

[netmasta]

I'm not too sure about the duplex thing, but I don't take much stock in the NDT tests. I've heard the servers aren't always configured right. Besides look at the results you got on 56K.

running 10s outbound test (client to server)[upload] . . . . . 116.68Kb/s

running 10s inbound test (server to client) {Download]. . . . . . 116.49kb/s

[cholla]

netmasta: I agree about the NDT test it usually shows that speed or close to it no matter which NDT site I use so thats what I expect.Its just the first time I ever got the alarm message.

[fred]

cholla they are talking about dsl here in this paticular test it is about trans and rec in other words you can't do both at the same time

[cholla]

fred:The reason the test says :Your PC is connected to a Cable/DSL modem is because it can't understand that a 56K dial-up modem tests that speed.I have done the NDT test at other sites & didn't get the alarm.

[fred]

oh I see I have some strange results from these NDT sites from time to time myself like auto negotiate 100MB and stuff like that or thisWEB100 Enabled Statistics:

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

running 10s outbound test (client to server) . . . . . 222.46Kb/s

running 10s inbound test (server to client) . . . . . . 1.29Mb/s

------  Client System Details  ------

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

Java data: Vendor = Sun Microsystems Inc., Version = 1.5.0_04

------  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 = 105.56 msec; the Packet size = 1460 Bytes; and

There were 11 packets retransmitted, 160 duplicate acks received, and 141 SACK blocks received

The connection was idle 0 seconds (0%) of the time

This connection is receiver limited 8.75% of the time.

This connection is network limited 91.22% 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: OFF

Packet size is preserved End-to-End

Server IP addresses are preserved End-to-End

Client IP addresses are preserved End-to-End                                  Can you explain any of this to me Cholla

[cholla]

fred: I will explain what I can I ask questions on the results myself.

running 10s outbound test (client to server) . . . . . 222.46kB/s upload speed

running 10s inbound test (server to client) . . . . . . 1.29Mb/s Download speed

Client System Details  What it detects about your OS

Round trip time = 105.56 msec latency for packet to & from the test site.

the Packet size = 1460 Bytes your MSS

11 packets retransmitted, 160 duplicate acks received, and 141 SACK blocks received all of these have to do with defragmentation of packets your os can't receive them at the time they are sent so the packet is retransmitted till your os can receive it.The 160 duplicate acks received are part of the notification to the sender that packets weren't received.

This connection is receiver limited 8.75% of the time This has to do with your RWIN in your PC.

This connection is network limited 91.22% of the time. I not sure about this one but I think it is a combination of network congestion & your connection speed(caps)

RFC 1323 Time Stamping: OFF  these 2 are set by your Tcp1323Opts yours should be 0 thats

RFC 1323 Window Scaling: OFF what the settings show 1 would turn on window scaling,2 would turn on time stamping,3 would turn on both.

RFC 2018 Selective Acknowledgment: ON  this is sackopts 1 setting

------  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.

I think sometimes this detects some of your ISP's equipment thats why it gives strange results.

Thats the best I can do.There is a contact email at the test .try that for better explanations.