Nice article about IP switching with ASND reference.
nwfusion.com
Vendors are starting to incorporate SS7
capabilities into remote access platforms.
Ascend Communications recently announced a
gateway module that enables its carrier-class
MAX TNT WAN access switches to
communicate with the SS7 net. Service
providers can deploy the Ascend switches to
divert data traffic away from voice switches.
Such products aren't available yet, however.
"IP equipment still lacks a lot of the features
and functions of circuit switches, such as the
ability to put a call on hold, or do call
forwarding, credit card calling or 800
numbers," says Michael Day, senior director of
network evolution planning for Alcatel
Network Systems in Richardson, Texas. "It
will take some time to get a full set of voice
features into IP equipment."
IP equipment also lacks the large-scale
directory databases that run on parallel
computers. And, of course, public IP networks
need to have QoS levels before they can scale
to replace the PSTN.
An emerging class of high-speed IP switches
can read the beginning and end of packets at
line speeds, a capability that will go a long
way toward enabling QoS in IP environments.
Marlborough, Mass.-based Nexabit Networks
is breaking new ground with a product that
offers multiterabit switching capacity in a
single chassis. The NX64000 routing switch
can forward 6.4 terabits per second and will
support up to 64 OC-48 (2.4G bit/sec)
connections or 16 OC-192 (9.6G bit/sec) links.
Nexabit built in eight QoS queues per interface
so the switch can handle voice and other
time-sensitive traffic.
NX64000 is now in beta testing, with
commercial release scheduled for October.
Juniper Networks, based in Mountain View,
Calif., plans to deliver a similar product before
year-end.
Reliability issues also have to be addressed.
Telephone networks are developed to meet a
"five nines" standard of minimum reliability,
meaning that the network has to be up
99.999% of the time. The telephone networks
achieve this in part through the use of
special-purpose, rather static equipment -
such as telephones - at the end points.
Data networks, on the other hand, have
traditionally traded a certain amount of
reliability for added flexibility. Users interface
with them through general-purpose PCs that
are constantly changing.
"How many people haven't rebooted their
desktops this year?" asks John Hart, chief
technology officer at 3Com in Santa Clara,
Calif. "It doesn't help to get the network to
99.999% reliability if the desktops are less
reliable."
IP improvements wanted
Similarly, the network is only as fast as its
slowest component. The ability to provision
end-to-end QoS is at the top of the list of
things IP still needs, and variable QoS on the
Internet is still at least a couple of years
away. Some service providers are
approximating it by using private network
segments to avoid congested areas on the
public Internet. However, such transmissions
don't get the full economic benefit of using the
public backbone.
Some say a lot of the latency and QoS issues
can be mitigated by throwing bandwidth at
them. "Then you don't have to resort to IPv6
and Resource Reservation Protocol and the
like," Level 3's Vidal says.
Others insist these problems are best
addressed by managing bandwidth.
"Over-provisioning can work in the campus
environment because bandwidth is so cheap
there," says Lucent's Schriftgieffer. "But in the
WAN, the management approach is going to
win. We have to use ATM to do QoS right now,
but in the long run ATM will probably
disappear."
Vendors and service providers also want to
see more standards so more of their
equipment interoperates. Wish lists include
standardized IP-to-ATM transfers,
cross-checking between policy servers and
standardized billing methods.
Essential standards work is being done by the
Internet Engineering Task Force's
Differentiated Services Working Group. The
committee is working on standard methods for
providing different classes of service across
the public Internet.
One is a mechanism for using the Lightweight
Directory Access Protocol to map user profiles
to different services. This would enable edge
devices to play the role of ticket agents,
identifying various types of users and data and
relegating them to first-class, coach, steerage
or the like.
Industry experts expect different-
iated services to be offered first on "private
Internets" within a single service provider's
infrastructure. Then two service providers will
enter into bilateral signaling agreements that
will enable differentiated services to be
offered across their networks. Gradually, more
providers will join in, and eventually the entire
public Internet will be included.
"It's as if the Internet is a biological
organism," Bay's Hawe says. "It has no
long-term strategy and moves in tactical steps
instead of according to some master plan."
No turning back
Maybe so, but one thing is clear: The IP
convergence train has left the station. Some
of the passengers are wildly enthusiastic
about the journey, and others are being
dragged along kicking and screaming as they
enumerate IP's many flaws. But whatever its
shortcomings, IP is a done deal - it's the
standard that got adopted, period. It has so
much momentum and development action
there is nothing else on the horizon.
Network managers won't be disconnecting
from the traditional voice network over the
next couple of years. Local IP networks have
to connect to the telco infrastructure in a
seamless fashion so enterprises don't have to
buy separate equipment and employees don't
have to punch in a lot of numbers just to tell
the network who they are and who they're
calling.
But you will gradually see more applications
that handle multimedia converge onto IP
networks. Enterprises will start with functions
such as customer service that offer an
immediate payoff. Conver-gence will spread
from there as new applications are developed.
Eventually, it will move from the intranet to
the extranet and on to the public network.
When will this last stage of the transition
begin? Estimates vary widely, but it will
certainly be before the first decade of the 21st
century closes, and very possibly as soon as
five or six years from now.
"Major industry participants are investing in
and rolling out products, and ISPs and telcos
are rolling out services to create a market,"
says Neville O'Reilly, director of enterprise
consulting for TeleChoice, a consultancy in
North Brunswick, N.J. "We have to have the
whole system in place, so it's still a
cart-before-the-horse problem. But we're
reaching the point where we can start putting
solutions together."
IP lets general-purpose and special-purpose
machines talk together in a way that wasn't
possible before. Right now, we have a
specialized network sitting between those
machines. That network does what it was
designed to do - voice - very well. But we need
a general-purpose network now because the
key application isn't voice anymore.
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