[rescue] RE: CSMA vs. CDMA Carrier Sense vs. Carrier Detect)

Ken Hansen rescue at sunhelp.org
Tue Jun 26 16:19:29 CDT 2001

My bad cellphones are like ethernet cards though unique address, and disposable.

On to your points - I hadn't considered full-duplex, see subject line for CSMA vs. CDMA mix-up.

I don't want my keyboard, mouse, scanner, video cam all in the same "collision domain" - the no QoS is a *huge* problem, IMHO for the applications proposed.

-----Original Message-----

Message: 6
From: James Fogg <jfogg at vicinity.com>
Organization: Vicinity Corporation
To: rescue at sunhelp.org
Subject: Re: [rescue] RE: Time division and collision domains!
Date: Tue, 26 Jun 2001 14:45:13 -0400
Reply-To: rescue at sunhelp.org

On Tue, 26 Jun 2001, THOU SPAKE:
>> You can not get 10 Mb/s through a 10 Mb/s ethernet port - period. 

Yeah, you almost can. TCP's send/ack is a limiting factor, and the required
wait-times between packets is another factor. Up the MTU to a higher number,
switch to a UDP protocol and stream packets and you can very close to 10Mbs.

>>Even crossover connections are less than 10 Mb/s. 

Not if you set both interfaces for full duplex (not supported by many 10mbit
cards, well supported at 100mbs).

>> When an Ethernet device has a packet to send, it does,

Ummm... no it doesn't. Find a website that describes CSMA.

>>and if there was already another device using the Ethernet "backbone", the
device attempting to communicate will not only clobber the packet that was
being sent (I think), but the attempting device will wait a random period of
time and then attempt again. This is collison detect. >  

Ahh, no, this is collision avoidance. Well understood by WAN protocols, like

>> I suspect USB uses some sort of sync signal, and
devices consume time slices. >  

If you like Nazi lan protocols, try Token Ring or FDDI- even better than time

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