ndt-users list created

[Rich Carlson <>]

Christian;

You are correct.  DataBytesOut *8/Duration will give you a good 
approximation.  Duration (capital D) is a web100 variable that gives the 
connection time of a socket.  duration (lower case d) is a derived value 
that comes from the sum of the 3 SndLimTimexxx variables.  These are in 
microseconds so the equation below would Mbps.

Rich

On 10/7/2010 6:34 PM, Christian Reimsbach wrote:
> Thanks!
>
> But if I understand correctly, then one should be able to calculate the
> throughput thanks to the following variables:
>
> (DataBytesIn | DataBytesOut) * 8 / Duration
>
> In my case download throughput would be: 30157608 [Bytes] * 8 / 10132874
> [?s] = 23.80 [?B/s]
>
> Can that be? In particular since according to tcp-kis.txt "Duration" is
> measured in second.
>
> Christian
>
> On Thu, 2010-10-07 at 17:37 -0400, Rich Carlson wrote:
> > Christian;
> >
> > The reported throughput values are not calculated or derived from the
> > web100 data.  These values are calculated using the measured test data.
> >    The server keeps a counter with the number of bytes sent/received and
> > it also calculates the time it spend sending/receiving data from the
> > client. The throughput values are then calculated as bytes/time.
> >
> > Rich
> >
> > On 10/7/2010 5:17 PM, Christian Reimsbach wrote:
> > >  Hi,
> > >
> > >  I am trying to understand how outbound and inbound throughput are being
> > >  calculated based on the WEB100 kernel variables.
> > >
> > >  I read Rich's answer to Lize saying that:
> > >
> > >  "The speeds reported in the Test Results section are the measured speed
> > >  achieved during this test. The values reported in the More Details
> > >  section are calculations of the maximum possible speed based on the
> > >  buffer size and RTT. [...] The NDT report calculates the max possible
> > >  speed by dividing the appropriate max buffer value (sender, receiver,
> > >  congestion control) by the average RTT. The theoretical limit is
> > >  calculated using the Mathis et.al. formula where speed is a function of
> > >  packet size, RTT, and packet loss."
> > >
> > >  I am still confused where in my case the 23.21Mb/s and 927kb/s (see
> > >  below) come from. Or does Rich's answer mean that the"speeds reported
> > >  in the Test Results section"  cannot be derived out of the WEB100 variable?
> > >
> > >  Thanks!
> > >
> > >  Christian
> > >
> > >
> > >
> > >  WEB100 Enabled Statistics:
> > >  Checking for Middleboxes . . . . . . . . . . . . . . . . . . Done.
> > >  Checking for firewalls . . . . . . . . . . . . . . . . . . . Done.
> > >  running 10s outbound test (client-to-server [C2S]) . . . . . 927.0kb/s
> > >  running 10s inbound test (server-to-client [S2C]) . . . . . . 23.21Mb/s
> > >
> > >  ------ Client System Details------
> > >  OS data: Name = Linux, Architecture = amd64, Version = 2.6.32-25-generic
> > >  Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0_20
> > >
> > >  ------ Web100 Detailed Analysis ------
> > >  Cable modem/DSL/T1 link found.
> > >  Link set to Full Duplex mode
> > >  Information: throughput is limited by other network traffic.
> > >  Good network cable(s) found
> > >  Normal duplex operation found.
> > >
> > >  Web100 reports the Round trip time = 21.57 ms; the Packet size = 1448
> > >  Bytes; and
> > >  69 packets retransmitted, 369 duplicate acks received, and 373 SACK
> > >  blocks received
> > >  The connection stalled 1 times due to packet loss
> > >  The connection was idle 0.23 seconds (2.3% of the time)
> > >  S2C throughput test: Packet queuing detected: 1.73%
> > >  This connection is network limited 99.6% 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: ON
> > >  RFC 1323 Window Scaling: ON; Scaling Factors - Server=7, Client=7
> > >
> > >  Server 'ndt.iupui.donar.measurement-lab.org' is not behind a firewall.
> > >  [Connection to the ephemeral port was successful]
> > >  Client is probably behind a firewall. [Connection to the ephemeral port
> > >  failed]
> > >  Information: Network Middlebox is modifying MSS variable
> > >  Server IP addresses are preserved End-to-End
> > >  Information: Network Address Translation (NAT) box is modifying the
> > >  Client's IP address
> > >  Server says [85.168.247.43], but Client says [192.168.0.10]
> > >
> > >  WEB100 Kernel Variables:
> > >  Client: localhost/127.0.0.1
> > >  CurMSS: 1448
> > >  X_Rcvbuf: 87380
> > >  X_Sndbuf: 926744
> > >  AckPktsIn: 1854
> > >  AckPktsOut: 0
> > >  BytesRetrans: 99912
> > >  CongAvoid: 1074
> > >  CongestionOverCount: 0
> > >  CongestionSignals: 6
> > >  CountRTT: 1486
> > >  CurCwnd: 33304
> > >  CurRTO: 232
> > >  CurRwinRcvd: 776192
> > >  CurRwinSent: 5888
> > >  CurSsthresh: 17376
> > >  DSACKDups: 2
> > >  DataBytesIn: 0
> > >  DataBytesOut: 30157608
> > >  DataPktsIn: 0
> > >  DataPktsOut: 20384
> > >  DupAcksIn: 369
> > >  ECNEnabled: 0
> > >  FastRetran: 5
> > >  MaxCwnd: 403992
> > >  MaxMSS: 1448
> > >  MaxRTO: 1263
> > >  MaxRTT: 485
> > >  MaxRwinRcvd: 776192
> > >  MaxRwinSent: 5888
> > >  MaxSsthresh: 201272
> > >  MinMSS: 1448
> > >  MinRTO: 209
> > >  MinRTT: 4
> > >  MinRwinRcvd: 5888
> > >  MinRwinSent: 5792
> > >  NagleEnabled: 1
> > >  OtherReductions: 10
> > >  PktsIn: 1854
> > >  PktsOut: 20384
> > >  PktsRetrans: 69
> > >  RcvWinScale: 7
> > >  SACKEnabled: 3
> > >  SACKsRcvd: 373
> > >  SendStall: 0
> > >  SlowStart: 391
> > >  SampleRTT: 26
> > >  SmoothedRTT: 29
> > >  SndWinScale: 7
> > >  SndLimTimeRwin: 0
> > >  SndLimTimeCwnd: 10087802
> > >  SndLimTimeSender: 40308
> > >  SndLimTransRwin: 0
> > >  SndLimTransCwnd: 29
> > >  SndLimTransSender: 29
> > >  SndLimBytesRwin: 0
> > >  SndLimBytesCwnd: 29560040
> > >  SndLimBytesSender: 597568
> > >  SubsequentTimeouts: 0
> > >  SumRTT: 32048
> > >  Timeouts: 1
> > >  TimestampsEnabled: 1
> > >  WinScaleRcvd: 7
> > >  WinScaleSent: 7
> > >  DupAcksOut: 0
> > >  StartTimeUsec: 694357
> > >  Duration: 10132874
> > >  c2sData: 2
> > >  c2sAck: 2
> > >  s2cData: 8
> > >  s2cAck: 4
> > >  half_duplex: 0
> > >  link: 100
> > >  congestion: 1
> > >  bad_cable: 0
> > >  mismatch: 0
> > >  spd: 23.82
> > >  bw: 29.86
> > >  loss: 0.000294349
> > >  avgrtt: 21.57
> > >  waitsec: 0.23
> > >  timesec: 10.00
> > >  order: 0.1990
> > >  rwintime: 0.0000
> > >  sendtime: 0.0040
> > >  cwndtime: 0.9960
> > >  rwin: 5.9219
> > >  swin: 7.0705
> > >  cwin: 3.0822
> > >  rttsec: 0.021567
> > >  Sndbuf: 926744
> > >  aspd: 0.00000
> > >  CWND-Limited: 769.73
> > >  minCWNDpeak: 1448
> > >  maxCWNDpeak: 403992
> > >  CWNDpeaks: 6
> > >
> > >  The theoretical network limit is 29.86 Mbps
> > >  The NDT server has a 452.0 KByte buffer which limits the throughput to
> > >  327.83 Mbps
> > >  Your PC/Workstation has a 758.0 KByte buffer which limits the throughput
> > >  to 274.58 Mbps
> > >  The network based flow control limits the throughput to 142.91 Mbps
> > >
> > >  Client Data reports link is 'T1', Client Acks report link is 'T1'
> > >  Server Data reports link is 'OC-48', Server Acks report link is 'T3'