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[SOLVED] Need help with computer to computer LAN connection speed - Page 2

post #11 of 13
Quote:
Originally Posted by hks85 View Post

:::EDIT:::
/10 just seems to work on ethernet but as you will read below the math doesn't seem to work out just right
:::/EDIT:::
It's /10 because of overhead data. For example, every TCP packet has something like 20Bytes for the header. The header contains, addresses, port numbers, sequence numbers etc. most packets dont have a length greater than 1500 Bytes though usually they are far less. If your router/switch and Nics support Jumbo Frames you can raise this number from 1.5KB to the standard 8K and i think up to 15K. You can get a nice Intel Gbit PCI-e NIC with jumbo support for $18.
I just did a SAMBA file transfer without Jumbo Frames turned on and did a packet capture with Wireshark. I get an average of about 12 TCP packets for every SMB packet. The SMB transfer goes something like this,
about 12 TCP packets of 1514 Bytes in length (this is the data portion)
1 TCP 54 Byte TCP Acknowledgement packet
1 SMB 117Byte packet about every 2 cycles (12 TCP, 1 TCP, 12TCP, 1 TCP, 1 SMB)
pulling the 1514 byte packets further apart, we see that they
-start with an Ethernet (14 Bytes of addressing)
-IPV4 Header (20 Bytes)
-TCP Protocol (20 Bytes)
-Data (1460 Bytes)
14+20+20 = 54 Bytes of overhead / 1460 Data = 3.7% loss
then look at the loss related to the acknowledgement TCP and the SMB packets we get,
1416x12 = ~17K
54+(117/2) = 112
112/17K = <1%
this is interesting because the only real loss is about 3.7%. I guess the rest of it comes from latency and I/O lag. I dont know...

Right ON! very informative!
post #12 of 13
Quote:
Originally Posted by FuzzyPants View Post

why did you divide by ten? that would be 10 megabytes per second which is incorrect. it is 10 MegaBITS per second
He clearly stated 10 MB/sec. Bytes.
10 mbit on LAN would be pathetic, 10/100 NICs have been around for 10+ years.
Quote:
Originally Posted by hks85 View Post

I guess the rest of it comes from latency and I/O lag. I dont know...
I'm thinking something else.

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post #13 of 13
Thread Starter 
OK Finally solved the problem.It was the Ethernet cable.The old cable was CAT5.E but the connection was only 2 pair. I bought a new 4 pair CAT5.E 2mt patch cable from a local computer store.After connecting it the the adapters set the LAN to 1 Gbps under auto negotiation.

Here's my transfer speed.I think my 7200 rpm seagate is the bottleneck..

THANKS FOR ALL THE HELP GUYS


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Edited by DEADMASK - 3/9/12 at 6:01am
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Overclock.net › Forums › Software, Programming and Coding › Networking & Security › [SOLVED] Need help with computer to computer LAN connection speed