That math does not sound quite right.
----- Original Message -----
From: Priscilla Oppenheimer <[EMAIL PROTECTED]>
To: Kevin L. Kultgen <[EMAIL PROTECTED]>; Tim O'Brien
<[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Friday, October 06, 2000 5:01 PM
Subject: Re: Ethernet Trivia
> Kevin,
>
> Great analysis.
>
> Does this help at all? Speed of light in twisted-pair cable is 177,000
> km/sec. So a bit occupies 177,000 divided by 10 million bits per second,
or
> 17.7 meters, in 10 Mbps Ethernet.
>
> 177,000 divided by 100 million bits per second is 1.77 meters for 100 Mbps
> Ethernet. (I'm sure you figured that one out already.)
>
> It would have to be a pretty long cable for the 100 Mbps versus 10 Mbps to
> make any difference!
>
> Priscilla
>
> At 10:12 AM 10/5/00, Kevin L. Kultgen wrote:
> >They would both start at the same time. The 100bT interface would be
> >placing bits on the wire faster than the 10bT interface and would
complete
> >placing bits on the wire in 1/10 the time. But those bits can't actually
> >move any faster through the copper medium. The copper isn't more
conductive
> >(it's still Cat 5(e)) and the speed of light hasn't increased. So the
bits
> >that are placed on the wire will move through the wire at exactly the
same
> >rate. If the bits for 10bT consume 5 meters of cable megth before the
NIC
> >moves the the next bit then a bit for 100bT will be 1/2 meter (.5 meters)
> >before the next bit is placed on the wire. This is just an example, I'm
not
> >sure of the exact lengths of the bits on the wire, but the point is that
the
> >bits can't move any faster because the speed of electricity through
copper
> >is fixed. The difference is that the 100bT card is placing bits on the
wire
> >10x faster than the 10bT card. And 1000bT (gigabit ethernet) places bits
on
> >the wire 100x faster than the 10bT card (or each bit would be .05 meters
(5
> >centimeters), given the above example).
> >
> >So, on 100bT the end of the packet (the whole packet) would arrive before
> >the 10bT would be done (in fact depending on the size of the packet 10bT
> >might still be sending the preamble or headers), but the start of the
> >packets (first bit of the preamble) would arrive at the same time.
> >
> >HTH,
> >
> >Thanx
> >
> >Kevin L. Kultgen
> >
> >Disclaimer: YMMV, the 5/.5/.05 meters are all fictional, I was told at
one
> >point how long a bit is on the wire but I forgot it. If I have anything
> >that needs clarification (or correction) then please feel free to add it
or
> >request it. This is helping me too, because I'm looking at taking the
> >CNX-Ethernet exam (http://www.mycnx2000.com, http://www.cnx2000.com).
> >
> >----- Original Message -----
> >From: "Tim O'Brien" <[EMAIL PROTECTED]>
> >To: "Kevin L. Kultgen" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
> ><[EMAIL PROTECTED]>
> >Sent: Thursday, October 05, 2000 5:49 AM
> >Subject: Re: Ethernet Trivia
> >
> >
> > > So if this were the case, and they both started at the same time and
used
> > > the same size frame/packet I would think that the 100Mbps interface
would
> > > get the packet onto the wire faster hence it would arrive sooner than
the
> > > 10Mbps interface which would probably still be putting the data on the
> >wire.
> > > Correct?
> > >
> > > Tim
> > >
> > > ----- Original Message -----
> > > From: "Kevin L. Kultgen" <[EMAIL PROTECTED]>
> > > Newsgroups: groupstudy.cisco
> > > To: <[EMAIL PROTECTED]>
> > > Sent: Wednesday, October 04, 2000 12:35 PM
> > > Subject: Re: Ethernet Trivia
> > >
> > >
> > > They would bith reach the destination at the same time (speed of
> >electricity
> > > through copper). The difference is in the rate at which the bits are
> >placed
> > > on the wire, the Fast Ethernet would be placing 20 bits of information
> > > (actually encoded as 24 bits) on the wire for every 2 bits that the
10bT
> > > would place on the wire. At least his is my understanding of 100bT vs
> > > 10bT..
> > >
> > > Anybody else have different(better?) interpretations?
> > >
> > > --
> > > Kevin L. Kultgen
> > >
> > >
> > > ""Frank"" <[EMAIL PROTECTED]> wrote in message
> > > 8rfksm$l2s$[EMAIL PROTECTED]">news:8rfksm$l2s$[EMAIL PROTECTED]...
> > > > Let's say we have a 10Mbps and 100Mbps interface. Both transmit the
> >same
> > > > sized
> > > > frame over the same type of media and over the same distance and
neither
> > > > experience
> > > > a collision. Which will get to the destination first?
> > > >
> > > >
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> ________________________
>
> Priscilla Oppenheimer
> http://www.priscilla.com
>
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