[svlug] help transfering data over 1394 cable

[Daniel Gimpelevich]

On Tue, 06 May 2008 20:23:13 -0700, Christian Einfeldt wrote:

> I do have a crossover cable that I am going to be taking back to the office,
> in the event that I have just a massive transfer that I want to do.  It is
> my understanding that a crossover cable will be faster than a switch.

No, the switch is faster than a crossover cable. Data may only travel on a
crossover cable in one direction at a time ("Half Duplex"), whereas it may
travel in both directions at once through a switch ("Full Duplex"). Each
TCP packet sent in one direction must be acknowledged in the other.
Consequently, after a packet is sent over a half-duplex pipe, there is a
slight wait while the direction is briefly reversed, during which no other
simultaneous packets may be sent. Therefore, any process trying to access
the Internet in any way, such as the background apt update that Ubuntu
does, will severely disrupt half-duplex communication to another local
machine. Of course, this specific example is assuming that the machine is
somehow connected to the Internet and the crossover cable at the same
time, but the general principle applies regardless of that.