Multi-threaded copy / download tools?

[deanwebb]

If I had a kb for every time it was mixed up with KB, I'd have a KB.

[packetherder]

Wintermute I used the same website:

Bandwidth-delay Product and buffer size

BDP (100 Mbit/sec, 340.0 ms) = 4.25 MByte
required tcp buffer to reach 100 Mbps with RTT of 340.0 ms >= 4150.4 KByte
maximum throughput with a TCP window of 64 KByte and RTT of 340.0 ms <= 1.54 Mbit/sec.

so, 1540000 bit /8 = 192.5kbyte/s total bit rate.
Add on VPN headers, the odd packet loss (as some packets do get lost), as well as TCP / FTP headers I expect this is why I'm getting around 180k, roughly.

Although I have seen single connections sometimes getting quite high throughput yesterday, 400k.

What's the deciding factors to go above 64k window size? I'm going to install wireshark and see what is going on.

afaik, XP doesn't initiate window scaling by default, and from what I've read, neither does Win7 in some configurations (e.g. "Public" networks). There are registry hacks you can do for both to enable though. I've run into this exact issue with a long-fat connection where $stupidapp didn't do connection parallelization or window scaling. Easiest way to confirm is to see what's happening in wireshark but the math certainly seems to suggest that's the case.

[NetworkGroover]

I always get confused with k K b B. I've looked it up so many times. Still confuses me about which way round it goes. 

The "k" is always lower case, AFAIK.

b is lower case, and "smaller" than B, as bits are smaller than Bytes.

m is lower case, and "smaller" than M, as milli is smaller than Mega - so for us in the networking world... I don't think you'll see a lower case m too much.

[SimonV]

m is lower case, and "smaller" than M, as milli is smaller than Mega - so for us in the networking world... I don't think you'll see a lower case m too much.

My ping command shows it all the time 

[Reggle]

My ping command shows it all the time 

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Reply from 8.8.8.8: bytes=32 time=7Ms TTL=3