ndt-users list created

[Clarke Morledge <>]

I need some help decoding the "This connection is sender limited x% of the 
time", particularly when the value of x is greater than 80%.

What does the statement actually mean, and what are some potential 
troubleshooting remedies?

In this case, I am using NDT v.5.5.4a.

I am including the statistics output of a test below, where this example 
is sender limited 88.14% of the time....

Clarke Morledge
College of William and Mary
Information Technology - Network Engineering
Jones Hall (Room 18)
Williamsburg VA 23187

-------------------------------------------------------

checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client-to-server [C2S]) . . . . . 93.43Mb/s
running 10s inbound test (server-to-client [S2C]) . . . . . . 93.04Mb/s
Client: localhost/127.0.0.1
CurMSS: 1448
X_Rcvbuf: 33554432
X_Sndbuf: 33554432
AckPktsIn: 45541
AckPktsOut: 0
BytesRetrans: 0
CongAvoid: 0
CongestionOverCount: 0
CongestionSignals: 0
CountRTT: 45542
CurCwnd: 99912
CurRTO: 205
CurRwinRcvd: 63712
CurRwinSent: 6144
CurSsthresh: 2147483647
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 120854968
DataPktsIn: 0
DataPktsOut: 83303
DupAcksIn: 0
ECNEnabled: 0
FastRetran: 0
MaxCwnd: 99912
MaxMSS: 1448
MaxRTO: 207
MaxRTT: 9
MaxRwinRcvd: 66608
MaxRwinSent: 6144
MaxSsthresh: 0
MinMSS: 1428
MinRTO: 201
MinRTT: 1
MinRwinRcvd: 55024
MinRwinSent: 5792
NagleEnabled: 1
OtherReductions: 0
PktsIn: 45541
PktsOut: 83303
PktsRetrans: 0
RcvWinScale: 10
SACKEnabled: 3
SACKsRcvd: 0
SendStall: 0
SlowStart: 66
SampleRTT: 4
SmoothedRTT: 5
SndWinScale: 1
SndLimTimeRwin: 1223997
SndLimTimeCwnd: 5595
SndLimTimeSender: 9140777
SndLimTransRwin: 3624
SndLimTransCwnd: 10
SndLimTransSender: 3634
SndLimBytesRwin: 86086656
SndLimBytesCwnd: 123528
SndLimBytesSender: 34644784
SubsequentTimeouts: 0
SumRTT: 214553
Timeouts: 0
TimestampsEnabled: 1
WinScaleRcvd: 1
WinScaleSent: 10
DupAcksOut: 0
StartTimeUsec: 411289
Duration: 10370730
c2sData: 5
c2sAck: 5
s2cData: 5
s2cAck: 5
half_duplex: 0
link: 100
congestion: 0
bad_cable: 0
mismatch: 0
spd: 93.23
bw: 2344.96
loss: 0.000001000
avgrtt: 4.71
waitsec: 0.00
timesec: 10.00
order: 0.0000
rwintime: 0.1180
sendtime: 0.8814
cwndtime: 0.0005
rwin: 0.5082
swin: 256.0000
cwin: 0.7623
rttsec: 0.004711
Sndbuf: 33554432
aspd: 0.00000
CWND-Limited: 22054.01
minCWNDpeak: -1
maxCWNDpeak: -1
CWNDpeaks: -1
The slowest link in the end-to-end path is a 100 Mbps Full duplex Fast 
Ethernet subnet

Web100 reports the Round trip time = 4.71 msec; the Packet size = 1448 
Bytes; and
No packet loss was observed.
This connection is receiver limited 11.79% of the time.
This connection is sender limited 88.14% of the time.
Server '128.239.22.8' is not behind a firewall. [Connection to the 
ephemeral port was successful]
Client is probably behind a firewall. [Connection to the ephemeral port 
failed]
The theoretical network limit is 2344.96 Mbps
The NDT server has a 16384.0 KByte buffer which limits the throughput to 
54340.90 Mbps
Your PC/Workstation has a 65.0 KByte buffer which limits the throughput to 
107.87 Mbps
The network based flow control limits the throughput to 161.81 Mbps