Actually 101 times.
""Brian Lodwick"" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> 3) Why is the ATM frame size 53 bytes?
>
> I bet if we counted how many times this question was asked it would be
near
> 100.
>
> Well if telecom guys would've gotten their way and the size was set for
> telecom to prevent delay and jitter it would've been smaller than 32
bytes.
> What I have read is that it was a compromise between the data side (wanted
> atleast 128 bytes)and the telecom side (wanted less than 32 bytes or it
> would need echo suppressors) which I'm sure made everyone evenly upset.
>
> >>>Brian
>
> >From: "David L. Blair" <[EMAIL PROTECTED]>
> >Reply-To: "David L. Blair" <[EMAIL PROTECTED]>
> >To: [EMAIL PROTECTED]
> >Subject: Re: why there is an ethernet frame size limitation
> >Date: Wed, 24 Jan 2001 14:28:31 -0500
> >
> >I know the reason for two of three.
> >
> >1) Why is the Ethernet minimum frame size of 64 bytes?
> >
> >Ethernet timing is based upon "bit time" the time a bit takes to travel
> >the
> >distance of an maximum Ethernet segment length 100m or 328 ft. The
> >minimum
> >frame size 64 bytes equals 512 bits or 512 bit times to travel the wire.
> >This has to do with a host on one end of the wire listening to use the
wire
> >and another host on the opposite end transmitting. Note: This does not
> >include the Preamble.
> >
> >2) Why is the Ethernet maximum frame size of 1518 bytes(not 1526)?
> >
> >I guess for a similar reason. Remember most Ethernet implementations are
> >share media. So everyone host is contending for access to the wire.
That
> >is why Ethernet is contention based and Token Ring & FDDI are
> >deterministic.
> >A packet to large would actually allow less hosts per segment to transmit
> >their data in a timely fashion.
> >
> >3) Why is the ATM frame size 53 bytes?
> >
> >I do know exactly why 53 bytes was picked. I do know why a small frame
> >size
> >was picked. A ATM packet has two parts: Address and Payload. The
Address
> >is 5 bytes long and the Payload is 48 bytes longs. ATM was designed as a
> >Multi-service access medium, i.e. to handle Data, Voice, and Multimedia
> >content. The "Holy Grail" of voice transmission is delay and jitter.
When
> >the Delay in voice transmission is more than 250ms, humans start talking
> >before the other person has finished. Resulting in a garbled conversion.
> >It takes less time to fill small frames with data. All the frames are
the
> >same size so the transmission time, for a given network, is constant.
> >QoS,
> >Quality of Service, features are implemented in ATM to guarantee delivery
> >of
> >time sensitive frames like voice.
> >
> >
> >I hoe this helps. A good Ethernet book with some ATM and FDDI
information
> >is Switched, Fast, and Gigabit Ethernet ISBN: 1-57870-073-6
> >
> >-dlb
> >
> >
> >"azhar mumtaz" <[EMAIL PROTECTED]> wrote in message
> >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > Hello Guys:
> > > What i want to know is why there is a limit that ethernet frame size
> >cannot be
> > > less than 64 bytes and more than 1526 bytes. I know that this is how
> >ethernet
> > > should be understand but whats the logic behind it. Similarly why we
are
> > > limiting cell size of ATM to 53 bytes.
> > > Regards
> > > Azhar Soomro
> > >
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