Politics is the art of compromise, which in and of itself is not necessarily
a Bad Thing.
I would venture the opinion that both 32 and 64 are poor choices in this
more modern age. What was suitable or viable 10-15 years ago is no longer
so. Data folks are now seriously discussing MTU's in the multiple K range.
Which makes the voice folks nervous, because voice still performs better
with smaller packets. This BTW has serious implications on the Internet, as
more people and companies increase their use of the internet as their own
transport mechanism , using VPN's.
Howard?
-------------
Chuck
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] On Behalf Of SI
cable news
Sent: Sunday, November 26, 2000 10:15 AM
To: [EMAIL PROTECTED]
Subject: Re: Why 53-bytes for a cell & AL GORE
The agreement for a 53 byte cell is the worst mistake made by politicians,
it should be a 2^X for acceptable optimized and efficient transportation
Either 32 or 64 was acceptable
This is a classic example of politicians intervening in standards committee.
Prasad
""Rahul Kachalia"" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Hi All,
>
> There were several different reasons for choosing such smaller size of
> payload carrier some of them as follows :
>
> Why such a small-sized packet for ATM? Why not larger than 48 bytes in the
> payload (48 bytes is very, very small)? The answer to that is simple. ATM
> and the inventors of ATM targeted the single challenge-to reduce delay in
> the network. If we have large packets they take a long time to
assemble.For
> instance, we know that a DS0, Plain Old Telephony service is running at
> 64,000 bits per second. If you take that 64,000 bits per second and divide
> it by 8000, which is an 1/8000 of a second, you end up with 8 bits every
> 1/8000 of a second.
> That's very repeatable; its going to be the same in any country. If we
> know we're getting 8 bits, or 1 byte every 1/8000 of a second, we know
that
> filling up a packet is going to take a measurable amount of time (1 byte
> every 125 microseconds). If we make the packet long, it's going to take a
> long time to fill it up. This is called cell assembly delay. In order to
> maintain delay constraints that were targeted towards ATM, they decided to
> make these packets very, very small. It would have been better for file
> transfer for data application to have a longer packet, but they erred on
the
> side of voice-to maintain a Quality of Service for voice in a packet
> network, similar to today's TDM networks. That's why it was so small. It's
> all about that cell assembly delay.
> Voice and video applications are sensitive to delay, especially when it's
> interactive. When you're talking to someone on the phone, and they're
> talking back at you, this is where delay becomes very important. We have a
> test that we often do for this kind of thing: if I were to say "one," and
> then you were to say "two," and I were to say "three," and we were to go
> back and forth as quickly as possible, we would be able to understand
> exactly how much delay exists in this interactive conversation. It's a
great
> test for delay.
> For non-interactive, for instance, when I'm just speaking to you, and
> there's no real interaction with me, delay isn't as important. Perhaps we
> could have gotten away with longer packets for this type of application.
ATM
> elected to default to the best performance for interactive voice.
>
> hope this helps everyone...
>
> regards
> rahul.
>
>
>
>
> --------------------------------------------------------------------------
--
> ----
> (c) 1984-2000 TRA. All Rights Reserved.
> ----- Original Message -----
> From: "Circusnuts" <[EMAIL PROTECTED]>
> To: "themitmo" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> Sent: Saturday, October 21, 2000 4:29 AM
> Subject: Re: Why 53-bytes for a cell & AL GORE
>
>
> > Al Gore thought up the 53-byte cell after he invented the Internet :-)
> >
> > Honestly- the best ATM books I've read (that were readable & not a bunch
> of
> > algorithms) were Global Knowledge's beginner series. They explain
> > international agreements between cell sizes, echo, QOS, etc., etc.,.
The
> > best ATM working explanation I've ever read, is Chapter 7 in the CCNA
WAN
> > Quick Start book (& I usually don't like Cisco Press :-)
> >
> > Good Luck !!!
> > Phil
> >
> > ----- Original Message -----
> > From: "themitmo" <[EMAIL PROTECTED]>
> > To: "Andy Xing" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> > Sent: Friday, October 20, 2000 8:08 AM
> > Subject: Re: Why 53-bytes for a cell?
> >
> >
> > > Because back when they were creating an ATM standard
> > > from stratch it had to be some number. I believe there
> > > were two factions (US vs. European) on what size the
> > > payload area should be. 48 bytes turned out to be the
> > > compromise between speed and size.
> > >
> > > --- Andy Xing <[EMAIL PROTECTED]> wrote:
> > > > Thanks
> > > >
> > > >
> > > > _________________________________
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