Cell Relay Archive

[albert.e.manfredi@boeing.com]

In article <70pjti$mgr$1@debris.uits.indiana.edu>,
  Anouch Gharagozlou <anoush@club-internet.fr> wrote:
> Hi everybody,
>
> It seems that many telecom providers are willing to offer IP services
> directly over Sonet or SDH by-passing ATM levels.
>
> They say Quality Of Services guaranty may not be a problem with the huge
> amount of bandwidth provided.
>
> This may be a frequently asked question by now. What do you think about
> this technology?
> Is that mean the death of ATM after so many promises it gave ?
> What are the pros/cons ?
>
> Can anyone direct me to more litterature on this subject ?

Check out the Trillium web site. They have a paper on this subject.

IP over SONET has always made a lot of sense to me, since SONET provides the
simple pipe that dedicated phone lines now provide between IP routers (with
more bandwidth). IP over ATM makes little to no sense, if there are options.
And now, there are options. (Used to be that the fastest LAN was FDDI, so IP
over ATM for something greater than 100 Mb/s was the only choice. Not true
anymore.)

Why should IP care about ATM's QoS finery? How many IP applications request
any sort of QoS anyway?

Maybe eventually IP applications will demand QoS, and maybe then the tradeoff
will be how well IP QoS-sensitive apps operate over RSVP+QoS routing vs IP
over ATM.

It is, in my opinion, services such as high quality voice, high quality
videoconferencing and high quality video on demand that drive the need for
QoS. If IP does not provide QoS, then ATM's raison d'etre will be obvious. If
IP does introduce QoS, then it will be a competition for who does it better.

Betting on a permanent state of huge excesses of backbone bandwidth, as a way
out of having to worry about QoS, is, I do believe, just wishing away the hard
part.

Bert
manfredi@arl.bna.boeing.com

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