Putting IP in perspective
nwfusion.com
By Thomas Nolle
Network World, 08/10/98
It's hard to look around the network
marketplace in 1998 and not see what
appears to be an IP revolution.
People who didn't know what networking was
five years ago have their own Web sites today,
and some experts are forecasting a future in
which Internet connectivity is as ubiquitous as
telephony. Maybe that will be
so, but we've got a long way to
go. U.S. public carrier revenue
is nearly $200 billion, and less
than $30 billion of the windfall
can be attributed in any way to
data services.
There's no question that data traffic will have an
impact on the public carrier infrastructure.
Often, the peak amount of bandwidth used by
data applications is 10 to 100 times the peak
bandwidth used in a voice call.
The current public network parcels bandwidth
out in fixed multiples of 64K bit/sec, and it
simply isn't efficient for bursty data traffic. As
we move into the 21st century, 80% of carrier
profits will come from non-voice services. More
data means more inefficiency, so we can expect
the public network to change.
But saying that IP will drive a revolution in
public infrastructure isn't the same as saying that
the public infrastructure will be based on IP. IP
can't reserve network resources to ensure
application performance is up to snuff. As such,
it isn't the ideal mechanism for carrying voice
traffic, H.320 video or other forms of
leased-line data. If optimum networks are the
goal, moving from a strategy that isn't optimal
for data to one that isn't optimal for voice is not
logical.
Time-division multiplexing (TDM) is going to be
replaced by a form of statistical multiplexing that
lets applications use bandwidth in a way that is
as bursty or as constant as necessary. But that
doesn't mean traditional telephony will go away.
The type of telephone switching that gives us
dial tones in our homes and offices isn't going to
pass away for decades, so switches and IP
routers will have to share the transport network
that replaces TDM.
We already know what that network will be:
ATM. Recent ATM announcements by
Williams, Sprint and Bell Atlantic show that the
facility-based carriers (which, after all, are
financial successes) believe ATM is the
multiservice architecture of the future.
This isn't to say that users will buy ATM
services or premises equipment. ATM will be
buried in the innards of public networks much
the way Synch-ronous Optical Network
(SONET) is buried now. It won't be a new kind
of service, but a way of making the telephone
services that are critical to users and service
providers today coexist with the data services
that will be critical to both in the future. IP has
won the race as the User-Network Interface
(UNI) for non-voice services in the future.
That's a worthy victory, but the fact that IP is
the best UNI doesn't make it the best
infrastructure.
The marriage of analog voice, IP data, ATM
transport and dense wave-division multiplexing
optics is going to be interesting and exciting, but
it will be difficult as the devil unless we accept
what's really going on. Accepting IP's limitations
as a network foundation doesn't diminish IP's
importance as the foundation of all new
profit-making applications. Trying to make IP
into something it isn't hurts IP and networking
for us all.
Nolle is president of
CIMI Corp., a
technology
assessment firm in
Voorhees, N.J. He
can be reached at
(609) 753-0004 or
tnolle@
cimicorp.com |
