ndt-users list created

[Mark <>]

I'm having some issues with NDT making some silly conclusions based on what
looks to be accurate speed tests.  The only information I've been able to find
about running NDT on a VM was back in 2007 under vmware:
https://lists.internet2.edu/sympa/arc/ndt-users/2007-10/msg00000.html

I've tried turning off TCP segmentation offloading (ethtool -K eth0 tso off)
on the Dom0 with no luck.

Running NDT under a Xen HVM seems to fix the problem, however network i/o
under HVM is too slow.  I just wanted to confirm that the problem was related
to running paravirtualized.

All of the following versions report ~940Mb/s network speed (expected), but
report 10Mb/s link somewhere in the path.  Some versions have additional
errors (like "protocol error!"), but from what I've gathered from other posts
here, that's a common problem and unrelated to this issue.

ndt-3.0.20
ndt-3.0.7
ndt-3.4.1
ndt-3.4.4a
ndt-3.5.14
ndt-3.5.9
ndt-3.6.2b
ndt-3.6.3
ndt-3.6.4

Output below.



TCP/Web100 Network Diagnostic Tool v5.5.1
click START to begin
Connected to: web100pvm  --  Using IPv4 address
Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client-to-server [C2S]) . . . . . 940.29Mb/s
running 10s inbound test (server-to-client [S2C]) . . . . . . 935.95Mb/s
The slowest link in the end-to-end path is a 10 Mbps Ethernet subnet
Information: Other network traffic is congesting the link

click START to re-test


WEB100 Enabled Statistics:
Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client-to-server [C2S]) . . . . . 940.29Mb/s
running 10s inbound test (server-to-client [S2C]) . . . . . . 935.95Mb/s

        ------  Client System Details  ------
OS data: Name = Linux, Architecture = i386, Version = 2.6.26-2-686-bigmem
Java data: Vendor = Sun Microsystems Inc., Version = 1.6.0_22

        ------  Web100 Detailed Analysis  ------
10 Mbps Ethernet 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 = 14.59 msec; the Packet size = 1448 Bytes;
and 
No packet loss was observed.
C2S throughput test: Packet queuing detected: 0.17%
S2C throughput test: Packet queuing detected: 1.32%
This connection is network limited 99.52% 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

Server 'web100pvm' 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
Client IP addresses are preserved End-to-End


WEB100 Kernel Variables:
Client: localhost/127.0.0.1
CurMSS: 1448
X_Rcvbuf: 33554432
X_Sndbuf: 33554432
AckPktsIn: 164492
AckPktsOut: 0
BytesRetrans: 0
CongAvoid: 0
CongestionOverCount: 0
CongestionSignals: 6
CountRTT: 164493
CurCwnd: 1854888
CurRTO: 216
CurRwinRcvd: 2549760
CurRwinSent: 6144
CurSsthresh: 1297408
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 1200904560
DataPktsIn: 0
DataPktsOut: 811422
DupAcksIn: 0
ECNEnabled: 0
FastRetran: 0
MaxCwnd: 1854888
MaxMSS: 1448
MaxRTO: 220
MaxRTT: 24
MaxRwinRcvd: 2549760
MaxRwinSent: 6144
MaxSsthresh: 1297408
MinMSS: 1448
MinRTO: 204
MinRTT: 0
MinRwinRcvd: 5888
MinRwinSent: 5792
NagleEnabled: 1
OtherReductions: 1
PktsIn: 164492
PktsOut: 811422
PktsRetrans: 0
RcvWinScale: 9
SACKEnabled: 3
SACKsRcvd: 0
SendStall: 6
SlowStart: 0
SampleRTT: 16
SmoothedRTT: 16
SndWinScale: 6
SndLimTimeRwin: 8000
SndLimTimeCwnd: 10020000
SndLimTimeSender: 40000
SndLimTransRwin: 3
SndLimTransCwnd: 5
SndLimTransSender: 2
SndLimBytesRwin: 1055240
SndLimBytesCwnd: 1199849320
SndLimBytesSender: 0
SubsequentTimeouts: 0
SumRTT: 2399744
Timeouts: 0
TimestampsEnabled: 1
WinScaleRcvd: 6
WinScaleSent: 9
DupAcksOut: 0
StartTimeUsec: 128800
Duration: 10068000
c2sData: 3
c2sAck: 3
s2cData: 3
s2cAck: 4
half_duplex: 0
link: 0
congestion: 1
bad_cable: 0
mismatch: 0
spd: 954.23
bw: 278.48
loss: 0.000007394
avgrtt: 14.59
waitsec: 0.00
timesec: 10.00
order: 0.0000
rwintime: 0.0008
sendtime: 0.0040
cwndtime: 0.9952
rwin: 19.4531
swin: 256.0000
cwin: 14.1517
rttsec: 0.014589
Sndbuf: 33554432
aspd: 0.00000
CWND-Limited: 48639.78

The theoretical network limit is 278.48 Mbps
The NDT server has a 16384.0 KByte buffer which limits the throughput to
17547.46 Mbps
Your PC/Workstation has a 2490.0 KByte buffer which limits the throughput to
1333.40 Mbps
The network based flow control limits the throughput to 970.02 Mbps

Client Data reports link is 'Ethernet', Client Acks report link is 'Ethernet'
Server Data reports link is 'Ethernet', Server Acks report link is 'T3'