ndt-users list created

[Maurice Volaski <>]

Since web100 kernel patches aren't stable enough to run on a system 
doing other stuff, I've put together a (Gentoo) Linux guest OS on 
VMWare, which is hosted by (Gentoo) Linux.

The underlying NICs are motherboard-attached Broadcom 5704 and uses 
the tg3 driver and it's attached to a Cisco 6509 at gigabit. The 
guest OS is in its own VLAN on the switch.

I've been having weird results with my Mac sometimes testing as if it 
had a duplex mismatch. I don't know what's causing that. But when it 
does work (another odd thing is that it sometimes works, sometimes 
not), NDT insists I have just a 10 Mb connection, even though it's 
gigabit and it's testing at half its full throughput. Could this have 
something to do with the vmxnet driver that handles the Ethernet in 
guest OS?



WEB100 Enabled Statistics:
Checking for Middleboxes . . . . . . . . . . . . . . . . . .  Done
checking for firewalls . . . . . . . . . . . . . . . . . . .  Done
running 10s outbound test (client-to-server [C2S]) . . . . . 470.75Mb/s
running 10s inbound test (server-to-client [S2C]) . . . . . . 402.88Mb/s

        ------  Client System Details  ------
OS data: Name = Mac OS X, Architecture = i386, Version = 10.4.10
Java data: Vendor = Apple Computer, Inc., Version = 1.5.0_07

        ------  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 = 0.52 msec; the Packet size = 
1448 Bytes; and
No packet loss - but packets arrived out-of-order 1.32% of the time
C2S throughput test: Packet queuing detected: 0.01%
S2C throughput test: Packet queuing detected: 1.06%
This connection is sender limited 99.37% 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: OFF

Server 'gordonmacone.aecom.yu.edu' is not behind a firewall. 
[Connection to the ephemeral port was successful]
Client is not behind a firewall. [Connection to the ephemeral port 
was successful]
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
X_Rcvbuf: 212992
X_Sndbuf: 212992
AckPktsIn: 74991
AckPktsOut: 0
BytesRetrans: 0
CongAvoid: 0
CongestionOverCount: 0
CongestionSignals: 0
CountRTT: 71950
CurCwnd: 112944
CurMSS: 1448
CurRTO: 204
CurRwinRcvd: 65535
CurRwinSent: 5792
CurSsthresh: 2147483647
DSACKDups: 0
DataBytesIn: 0
DataBytesOut: 520605184
DataPktsIn: 0
DataPktsOut: 359792
DupAcksIn: 987
ECNEnabled: 0
FastRetran: 0
MaxCwnd: 112944
MaxMSS: 1448
MaxRTO: 204
MaxRTT: 8
MaxRwinRcvd: 65535
MaxRwinSent: 5792
MaxSsthresh: 0
MinMSS: 1448
MinRTO: 204
MinRTT: 0
MinRwinRcvd: 44432
MinRwinSent: 5792
NagleEnabled: 1
OtherReductions: 0
PktsIn: 74991
PktsOut: 359792
PktsRetrans: 0
RcvWinScale: 4
SACKEnabled: 3
SACKsRcvd: 0
SendStall: 0
SlowStart: 0
SampleRTT: 0
SmoothedRTT: 4
SndWinScale: 0
SndLimTimeRwin: 52007
SndLimTimeCwnd: 12002
SndLimTimeSender: 10025141
SndLimTransRwin: 409
SndLimTransCwnd: 44
SndLimTransSender: 437
SndLimBytesRwin: 4414840
SndLimBytesCwnd: 667480
SndLimBytesSender: 515522864
SubsequentTimeouts: 0
SumRTT: 37460
Timeouts: 0
TimestampsEnabled: 1
WinScaleRcvd: 0
WinScaleSent: 4
DupAcksOut: 0
StartTimeUsec: 695584
Duration: 10089150
c2sData: 3
c2sAck: 6
s2cData: 3
s2cAck: 4
half_duplex: 0
link: 100
congestion: 0
bad_cable: 0
mismatch: 0
spd: 412.80
bw: 21218.84
loss: 0.000001000
avgrtt: 0.52
waitsec: 0.00
timesec: 10.00
order: 0.0132
rwintime: 0.0052
sendtime: 0.9937
cwndtime: 0.0012
rwin: 0.5000
swin: 1.6250
cwin: 0.8617
rttsec: 0.000521
Sndbuf: 212992
aspd: 0.00000
CWND-Limited: 184.18

The theoretical network limit is 21218.84 Mbps
The NDT server has a 104.0 KByte buffer which limits the throughput 
to 3119.00 Mbps
Your PC/Workstation has a 63.0 KByte buffer which limits the 
throughput to 959.69 Mbps
The network based flow control limits the throughput to 1653.93 Mbps

Client Data reports link is 'Ethernet', Client Acks report link is 'OC-12'
Server Data reports link is 'Ethernet', Server Acks report link is 'T3'
--

Maurice Volaski, 

Computing Support, Rose F. Kennedy Center
Albert Einstein College of Medicine of Yeshiva University