ndt-users list created

[Dale Blount <>]

Hello again,

I've just upgraded my old web100/ndt server to new hardware with onboard
gigE (instead of a card) and a xeon instead of a p2.  The new server is
also running 2.6.15 (the old one was running 2.6.11 or so).  It seems to
run fine on the lan (my workstation only has 100mbps, and it clocks
around 94mbps both ways).  However, any distant connection -
DSL/Cable/dialup seems to test horribly in the downstream direction.  

I've tweaked the sysctl params the same they were on the other server,
but they don't seem to help much.

Downloading a file from the server appears to travel at normal speed.

Below are the logs from a 5mb/5mb cable modem connection, 3 hops from
the ndt server.

Thanks for any pointers and/or tuning advice.

Dale







Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client to server) . . . . . 3.73Mb/s
running 10s inbound test (server to client) . . . . . . 72.66kb/s
The slowest link in the end-to-end path is a 10 Mbps Ethernet subnet
Information: The receive buffer should be 73.99 Kbytes to maximize
throughput

********************************************************************

WEB100 Enabled Statistics:
Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client to server) . . . . . 3.73Mb/s
running 10s inbound test (server to client) . . . . . . 72.66kb/s

        ------  Client System Details  ------
OS data: Name = Windows 2003, Architecture = x86, Version = 5.2
Java data: Vendor = Sun Microsystems Inc., Version = 1.5.0_04

        ------  Web100 Detailed Analysis  ------
10 Mbps Ethernet 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 = 60.62 msec; the Packet size = 1460
Bytes; and 
There were 201 packets retransmitted, 18 duplicate acks received, and 20
SACK blocks received
The connection stalled 1 times due to packet loss
The connection was idle 0.26 seconds (0.76%) of the time
This connection is network limited 99.64% 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
Information: Network Address Translation (NAT) box is modifying the
Client's IP address
        Server says [W.X.Y.Z] but Client says [Z.Y.X.W]


*******************************************************************

WEB100 Kernel Variables:
Client: localhost/127.0.0.1
AckPktsIn: 231
AckPktsOut: 0
BytesRetrans: 293460
CongAvoid: 0
CongestionOverCount: 0
CongestionSignals: 2
CountRTT: 13
CurCwnd: 1460
CurMSS: 1460
CurRTO: 264
CurRwinRcvd: 17520
CurRwinSent: 5840
CurSsthresh: 16060
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 3403472
DataPktsIn: 0
DataPktsOut: 2248
DupAcksIn: 18
ECNEnabled: 0
FastRetran: 1
MaxCwnd: 21900
MaxMSS: 1460
MaxRTO: 264
MaxRTT: 100
MaxRwinRcvd: 17520
MaxRwinSent: 5840
MaxSsthresh: 146000
MinMSS: 1460
MinRTO: 224
MinRTT: 24
MinRwinRcvd: 17520
MinRwinSent: 5840
NagleEnabled: 1
OtherReductions: 0
PktsIn: 231
PktsOut: 2248
PktsRetrans: 201
X_Rcvbuf: 4194304
RcvWinScale: 2147483647
SACKEnabled: 3
SACKsRcvd: 20
SendStall: 0
SlowStart: 0
SampleRTT: 100
SmoothedRTT: 64
X_Sndbuf: 4194304
SndWinScale: 2147483647
SndLimTimeRwin: 0
SndLimTimeCwnd: 34764344
SndLimTimeSender: 126942
SndLimTransRwin: 0
SndLimTransCwnd: 1
SndLimTransSender: 1
SndLimBytesRwin: 0
SndLimBytesCwnd: 3403472
SndLimBytesSender: 0
SubsequentTimeouts: 0
SumRTT: 788
Timeouts: 1
TimestampsEnabled: 0
WinScaleRcvd: 2147483647
WinScaleSent: 2147483647
DupAcksOut: 0
StartTimeUsec: 464790
Duration: 34893925
c2sData: 3
c2sAck: 3
s2cData: 1
s2cAck: 1
half_duplex: 0
link: 100
congestion: 0
bad_cable: 0
mismatch: 0
spd: -1.78
bw: 6.16
loss: 0.000889680
avgrtt: 60.62
waitsec: 0.26
timesec: 34.00
order: 0.0779
rwintime: 0.0000
sendtime: 0.0036
cwndtime: 0.9964
rwin: 0.1337
swin: 32.0000
cwin: 0.1671
rttsec: 0.060615
Sndbuf: 4194304
aspd: 0.19621

Checking for mismatch on uplink
        (speed > 50 [-1.78>50], (xmitspeed < 5) [3.73<5]
        (rwintime > .9) [0>.9], (loss < .01) [8.89<.01]
Checking for excessive errors condition
        (loss/sec > .15) [2.61>.15], (cwndtime > .6) [0.99>.6], 
        (loss < .01) [8.89<.01], (MaxSsthresh > 0) [146000>0]
Checking for 10 Mbps link
        (speed < 9.5) [-1.78<9.5], (speed > 3.0) [-1.78>3.0]
        (xmitspeed < 9.5) [3.73<9.5] (loss < .01) [8.89<.01], (mylink > 0)
[10.0>0]
Checking for Wireless link
        (sendtime = 0) [0.00=0], (speed < 5) [-1.78<5]
        (Estimate > 50 [6.16>50], (Rwintime > 90) [0>.90]
         (RwinTrans/CwndTrans = 1) [0/1=1], (mylink > 0) [10.0>0]
Checking for DSL/Cable Modem link
        (speed < 2) [-1.78<2], (SndLimTransSender = 0) [1=0]
         (SendTime = 0) [0.0036=0], (mylink > 0) [10.0>0]
Checking for half-duplex condition
        (rwintime > .95) [0>.95], (RwinTrans/sec > 30) [0>30],
         (SenderTrans/sec > 30) [0.02>30], OR (mylink <= 10) [10.0<=10]
Checking for congestion
        (cwndtime > .02) [0.99>.02], (mismatch = 0) [0=0]
        (MaxSsthresh > 0) [146000>0]

estimate = 6.16 based on packet size = 11Kbits, RTT = 60.62msec, and
loss = 8.8968E-4
The theoretical network limit is 6.16 Mbps
The NDT server has a 4096.0 KByte buffer which limits the throughput to
527.92 Mbps
Your PC/Workstation has a 17.0 KByte buffer which limits the throughput
to 2.20 Mbps
The network based flow control limits the throughput to 2.75 Mbps

Client Data reports link is 'Ethernet', Client Acks report link is
'Ethernet'
Server Data reports link is 'Dial-up', Server Acks report link is
'Dial-up'