Actually the TIA/EIA 568-A standard breakdown is: Max Length - 100m, Horizontal
Cabling
- 90m, Telecommunications Closet Patch Cable - 6m, Work Area Patch Cable - 3m. Add it
all up and it equals 99m. Where did the last meter go? I'm told it compensates for
signal loss across RJ45 connections although I can't confirm. Here is a good site for
more information:
http://www.anixter.com/techlib/standard/cabling/d0502p08.htm
Watch that wrap.
Tom Lisa, Instructor, CCNA, CCAI
Community College of Southern Nevada
Cisco Regional Networking Academy
Priscilla Oppenheimer wrote:
> At 03:27 PM 1/23/01, Erik Mintz wrote:
> >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?
>
> A copper 100-Mbps full-duplex DTE-DTE link is still limited to 100 meters.
> Gigabit Ethernet has a 25-meter standard for use with STP, and work on a
> 100-meter segment for use with UTP is underway, last I heard.
>
> I think the 100 meter rule is based on attenuation. Note that the EIA/TIA
> also says you shouldn't have more than 100 meters for your horizontal
> cabling from a wiring closet to a workstation. (90 meters actually, plus a
> 10-meter patch cable.) I'm sure the rules are related to each other and are
> probably to avoid too much attenuation. I'm not a physical-layer person,
> though. Someone else can probably provide a more authoritative answer.
>
> Priscilla
>
> >-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.
> > > >
>
> ________________________
>
> Priscilla Oppenheimer
> http://www.priscilla.com
>
> _________________________________
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