I guess I'm wrong then. I thought that CSMA/CD was still running on
full-duplex Fast Ethernet links (even though it won't ever detect a
collision)
>>>Brian
>From: Priscilla Oppenheimer <[EMAIL PROTECTED]>
>Reply-To: Priscilla Oppenheimer <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: RE: EASY ?? FOR MOST OF YOU
>Date: Tue, 23 Jan 2001 15:05:49 -0800
>
>Full-duplex Fast Ethernet isn't CSMA/CD either. There are only two stations
>that can send and they each have their own private transmit pair and
>receive pair. So it's not really multiple access (MA). There's no need to
>sense the carrier to see if someone else is sending. There isn't anyone
>else. So it's not CS. There's no need to detect collisions since they can't
>happen and it's legal to be receiving while sending, so there's no CD
>either.
>
>Priscilla
>
>At 08:56 PM 1/23/01, Brian Lodwick wrote:
> >Well that depends, are you talking about Fast or Gigabit?
> >FastEthernet is always using CSMA/CD, but Gigabit has a specification to
> >better utilize full-duplex links which doesn't use CSMA/CD. Take a look
>at
> >802.3x. It sounds like you are talking about Fast Ethernet since you are
> >talking about copper, unless you are talking about 1000BASE-CX.
> >
> > >>>Brian
> >
> >
> > >From: "Erik Mintz" <[EMAIL PROTECTED]>
> > >Reply-To: "Erik Mintz" <[EMAIL PROTECTED]>
> > >To: "Priscilla Oppenheimer" <[EMAIL PROTECTED]>, "Brian
>Lodwick"
> > ><[EMAIL PROTECTED]>, <[EMAIL PROTECTED]>,
><[EMAIL PROTECTED]>
> > >Subject: RE: EASY ?? FOR MOST OF YOU
> > >Date: Tue, 23 Jan 2001 15:27:31 -0500
> > >
> > >I have a question regarding CSMA/CD vs full duplex. If the problems
> > >relating to distance are set due to the limitations of CSMA/CD,
> > >what are the limits when using full duplex? I have had several
>situations
> > >where I had to run fiber because of distance, but these
> > >where almost invariably full duplex uplinks or trunks. Can I go farther
> > >with copper if the link is full-duplex?
> > >
> > >-Erik
> > >
> > >-----Original Message-----
> > >From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
> > >Priscilla Oppenheimer
> > >Sent: Monday, January 22, 2001 7:16 PM
> > >To: Brian Lodwick; [EMAIL PROTECTED]; [EMAIL PROTECTED]
> > >Subject: Re: EASY ?? FOR MOST OF YOU
> > >
> > >
> > >At 09:20 PM 1/22/01, Brian Lodwick wrote:
> > > >BBBBBBBBBBBBBBBBBBBBBBBBBBBBB for
> > > >
> > > > >>>Brian
> > > >My additional question on top of this one is:
> > > >
> > > >If the maximum legal length was set to 1/10th the size to make
>regular
> > > >(10Mb/sec) increased by a factor of 10, what was done to further
>increase
> > > >100Mb/sec Ethernet by a factor of 10 to get Gigabit Ethernet?
> > >
> > >I like your plan to turn this into a non-easy question! The only
>experience
> > >I have with Gigabit Ethernet is in a fully-switched network where every
> > >port is full duplex, in which case CSMA/CD parameters are not an issue.
> > >However, shared, half-duplex Gigabit Ethernet is viable also.
> > >
> > >With shared 10 and 100-Mbps Ethernet, the minimum frame size is equal
>to
> > >the maximum round-trip propagation delay of the network. In other
>words,
> > >the minimum frame size is equal to the slotTime = 512 bits. Sticking to
> > >this rule would haver resulted in impracticably small networks for
>Gigabit
> > >Ethernet, however. The solution was a process called "carrier
>extension."
> > >
> > >According to Rich Seifert in his excellent book, "Gigabit Ethernet,"
>"The
> > >key change is that the slotTime and the minimum frame are no longer the
> > >same. The minimum frame is maintained at 512 bits (64 bytes, as in 10
>Mbps
> > >and 100 Mbps Ethernets), but the slotTime is set at 4096 bit-times (512
> > >bytes).
> > >
> > >Frames that are shorter than the slotTime are artificially extended by
> > >appending a carrier-extension field so that they are exactly one
>slotTime
> > >long. This extends the duration of the time that the station
>transmits....
> > >If a collision occurs during any time from the beginning of the frame
>to
> > >the end of the extension field, the MAC will jam, abort, and backoff."
> > >
> > >See the book for even more gory details! &;-)
> > >
> > >Priscilla
> > >
> > >
> > >
> > > > >>>Brian
> > > >
> > > >
> > > >attenuation is effected by 3 elements spreading, scattering, and
> > >absorption.
> > > >
> > > > >From: Alvarado Jesus <[EMAIL PROTECTED]>
> > > > >Reply-To: Alvarado Jesus <[EMAIL PROTECTED]>
> > > > >To: "'[EMAIL PROTECTED]'" <[EMAIL PROTECTED]>
> > > > >Subject: EASY ?? FOR MOST OF YOU
> > > > >Date: Mon, 22 Jan 2001 14:10:43 -0500
> > > > >
> > > > >The network span of a 100Base-T Network (205) meters is approx. 10
> > >times
> > > > >smaller than the network span of a 10Base-T network (2500) meters
> > >Because
> > > > >....
> > > > >
> > > > >A) , Higher speed data signals attenuate more quickly and so
>cannot be
> > > > >transmitted that far
> > > > >
> > > > >
> > > > >B) . Both Networks have minimum frame sizes of 64 bytes and the
> > >network
> > > > >spans must be tied directly to the minimum frame transmission time
>to
> > >avoid
> > > > >collisions.
> > > > >
> > > > >_________________________________
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> > >
> > >________________________
> > >
> > >Priscilla Oppenheimer
> > >http://www.priscilla.com
> > >
> > >_________________________________
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>
>________________________
>
>Priscilla Oppenheimer
>http://www.priscilla.com
>
>_________________________________
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