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To: Mark Ambrose who wrote (9784)10/24/1997 5:22:00 PM
From: Mark Ambrose  Respond to of 77400
 
"Cisco Systems could not muster up the equipment."
From NETWORK COMPUTING ONLINE (The Technology Solution Center)
Here's the URL: techweb.cmp.com
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Wide Area Systems & Services

FEATURE

Hardcore ATM Switches for the WAN

By David Willis All enterprise networks have
something in common: Growth, with a capital G.
Wild, organic growth that makes you wonder if
you're managing the network or if it's managing
you. Although new campus technologies spit out
data streams at alarming rates, the old stuff still
demands reliable plumbing. How can you
deliver the network capacity to sustain growth,
without losing stability and blowing the budget?

Carriers have learned that the best way to attack skyrocketing network costs
is to reduce the number of networks they support, and they're using ATM as
the mechanism to do it. Multiservice switches take on multiple personalities,
exposing varied interfaces to end equipment over a single infrastructure. Like
the carriers, larger enterprise managers can consolidate legacy networks into
a common core, while providing new service features that are going to be
required at the campus, or even desktop, level in the near future.

It's important to understand where these switches fit in the enterprise
network, since they fall into a completely different category from ATM
campus and LAN switching products. Instead of consolidating data traffic
over a high-speed switching infrastructure where bandwidth is essentially free,
they provide consolidated trunking for a variety of WAN interface and
protocol types.

To view the Report card.
Thus, trunk speeds generally achieve a DS-3 (44.736
Mbps) level. Carrier services at higher rates are often too
expensive, and ATM inverse multiplexing over T1 circuits is
only now being standardized to provide more affordable links. It's also
important to note that falling T3 circuit tariffs are making T3 more viable for
the enterprise. In some areas, T3 costs have dropped to only three to four
times the current cost of T1 service.

We asked the major enterprise WAN switch manufacturers to submit their
multiservice switches for a hands-on test. To qualify for the test, the switches
had to support ATM, frame relay and circuit emulation, and have some
provision for handling voice traffic. Cascade Communications Corp. opted
out, citing its carrier-only focus; Newbridge Networks did not have strong
voice support (such as compression, echo cancellation and bandwidth
optimization) available; Alcatel Data Networks and
Cisco Systems could not muster up the equipment. <===================

This left us with three switches that have
the right mix of multiservice capabilities for
the enterprise WAN, backed by vendors
with the cojones to offer them up for a
public performance test: General
DataComm's APEX MAC, IBM Corp.'s
2220 Nways BroadBand Switch Model
500 and Northern Telecom's Magellan
Passport 160.

Unlike other performance tests, ours was
not an attempt to "break" the switches by
mindlessly blasting them with cells. Just as
you wouldn't buy a car based on the
temperature at which the engine liquifies, sending unrealistic traffic levels over
switch ports doesn't tell you much about how the switch behaves in the real
world. Instead, our test involved sending a mix of traffic types at reasonable
levels while measuring loss, delay, circuit quality and reliability (see "How We
Tested," page 58).

Of course, there is much more to these switches than just performance. When
you put all your traffic over a single infrastructure, your network management
system (NMS) had better be top-notch. The switches must support standard
interfaces to your existing equipment, so you're not forced to invest in new
edge gear. They must also supply a cost-effective migration path when your
needs grow beyond current capacity. To offer any hope of interoperability,
they must support the rapidly evolving set of ATM standards now being
ratified by the ITU Telecommunication Standardization Sector (ITU-T) and
the ATM Forum.

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