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Re: [LUG] Network speeds



On 2004.10.20 06:38 alan wrote:
On 2004.10.20 02:03 Mark Mitchell wrote:
Dear List,

I'm having a slight problem with my home "network" and I'm not sure
where to start looking for a solution.

The problem is I'm not getting anything like the speeds I should be.
Basically I've got two computers connected via a Netgear 10/100M
Ethernet Switch. One computer is running Mandrake 10 and the other
OpenBSD 3.5. File transfers with sftp are reporting speeds of around
"100KB/s" - I'm not sure if this is Bytes or Bits, but either way it's
a fraction of the 100 Mbits/s I should get.



Hi,




100 Kilobyte per second (KB/s)  = 100000 Bytes per second
100Mbps = 100000000 bits per second

Its best not to confuse bits and bytes in networking, but multiply 100000 ( 100KB/s) by 8 to get an approximate figure in bits per second
= 800000


To get the best transfer speed, you need both cards to be using simplex rather than duplex, because duplex means both incoming and outgoing data share the same priority. With simplex, only one direction of data travel can happen at once, so the full "pipe" can be used. It looks to me from your data, that one card is simplex and one is duplex. Google around to find out how to get them both onto the same type. (duplex is more useful , as it allows failed packets to be reported and resent, without greatly interupting the transfer , QoS (quality of service) etc.

I think

alan

I checked out full duplex, and heoretically you should be able to get 200Mbps from a full duplex system, but thats still only 100Mbps in each direction.
You have also to make sure that the switch is set to 100Mbps, both NICs are set to 100Mbps and all 3 are set to either Full Duplex or not.
Any 1 being set differently will slow the whole thing down. You will realistically only get around 70% of the 100Mbps available anyway, due to the network overheads, which should still equate to around 7MB (mega bytes) per second.


alan

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