"Tellium, Ciena eye hybrid switches for optical transport"
Hi Tim,
Re: I saw the Tellium product at OFC this year and was fairly impressed. They drew a lot of attention from competitors and had partnered, at the show, with Avici
I'm curious as to what you've heard about AVCI's ability to interface and interoperate with CSCO's IOS and JNPR's JunOS. I've heard there are some problems with AVCI's implementation of BGP-4. Any comments welcomed.
We're finally getting some reportage out of the Opticon 2000 conference, here's something from Loring Wirbel at EETimes:
eetimes.com
Tellium, Ciena eye hybrid switches for optical
transport
By Loring Wirbel
EE Times
(08/11/00, 12:18 p.m. EST)
BURLINGAME, Calif. — Tellium Inc. and Ciena Corp. revealed details of their
upcoming hybrid optical/electronic telecom switches at the Opticon conference last
week. Both were on a crusade at the show to convince analysts that the all-optical
networks touted by some startups are neither optimal for service transport nor
possible, given the state of optical switching components.
True all-optical switching will not be required until systems hit 20-terabit/second data
rates, said Tellium chief technical officer Krisha Bala. In the meantime, Bala and
Ciena chief technical officer Steve Alexander agreed that the broadband switching
architectures that matter will combine elements of medium-density photonic switching
and electronic control of wavelength management. In upcoming systems, both
companies will use electronic control points as mediating switch fabrics to manage
medium-density optical fabrics.
"It is so important that vendors right now define their terms when they speak of
transparent optical networking," Bala said. "Photonic switching of reasonable density
can play a role in systems today, but a true all-optical switching system is not
deployable today and will not be until further component development makes it
feasible and the speed of the core network makes it necessary."
The companies have good reason to wish to clear the air. Investors have wildly
escalated the price of recent public stocks in the optical domain — such as that of
Corvis Inc. — where companies bandy about the term "all-optical networking" while
refusing to reveal where optoelectronic conversions take place. But in speech after
speech at Opticon, developers warned that intelligent control of optical packet
switching requires the development of optical memories, optical clock/data recovery
circuits, optical header analyzers and other devices to transform the current analog
control of wavelengths into true digital all-optical networks.
Tellium (Oceanport, N.J.) will add to its Aurora line of optical cross-connect products,
in which electronic switch fabrics are used to control wavelength path assignment,
with a new family called Aurora Full-Spectrum. The switch product line will integrate
true photonic switching fabrics, based on three-dimensional gimbal-based
micromirrors, with an electronic switching fabric to control light paths.
Bala said the aim of the new product line is to allow broadband switch architectures to
support OC-768 (40-Gbit/second) signals at wire speed, while sending only those
packet flows requiring a true optoelectronic conversion to the secondary electronic
switching fabric.
Significant break
Tellium, which grew out of Bellcore/Telcordia's work in the Project Monet
(Multiwavelength Optical Networks) optical switching experiments, does not have a
particular legacy environment to support other than existing users of the Aurora
cross-connect. Vice president of marketing Grace Carr said the concept of a two-tiered
optical/optoelectronic switching fabric was a significant enough break from the past to
justify debuting Full-Spectrum as a new product line in early 2001.
Ciena (Linthicum, Md.) came to similar conclusions based on different motivations.
The company moved from passive dense wave-division multiplexing (DWDM)
systems to active optical switching when it made simultaneous acquisitions of
cross-connect developer LightEra Corp. and Sonet specialist Omnia Communications
Inc.
CTO Alexander said that Ciena's interest in Omnia did not come from Omnia's
presence in traditional Sonet add-drop architectures but from its work on a 622-Mbit/s
asynchronous-transfer-mode switching fabric. Unfortunately, the Omnia window of
opportunity "passed Ciena by," Alexander said, and Omnia developers were
redeployed to LightEra teams working on different speed interfaces for the switch that
became known as CoreDirector.
In contrast to Omnia, the LightEra project gained immediate success as a core switch
for highly dense long-haul applications. The company extended CoreDirector to
smaller central offices in metropolitan and regional rings, unveiling the CoreDirector
CI switch at the Supercomm show in June.
Alexander said that a factor as important as the hardware was the LightWorks
dynamic service provisioning environment that Ciena launched for CoreDirector, which
allows efficient real-time assignment of services to wavelengths.
Intelligent control of that process virtually requires some electronic-domain control of
wavelength assignment for the present, Alexander said. LightWorks also makes it
easier for Ciena to link topological meshes, which will be the logical architecture for
most core broadband fiber networks for the foreseeable future, with the physical rings
that are becoming more predominant in metro and regional networks, Alexander said.
In an Opticon panel, Alexander agreed with several points raised by Cisco Systems
Inc. product manager John Adler, who said that moving to an all-optical "transparent"
network would remove any possibility of monitoring optical transmission for
operations, administration, maintenance and provisioning problems. Alexander said
that many analysts today do not grasp the difficulty of moving from analog DWDM
wavelength assignment to an all-digital photonic switching system based on true
optical packets.
Conversion requirement
"Distance is not the issue as much as connectivity, which turned out to be a key
problem in Monet and other early experiments," Alexander said. "Today, you need
wavelength-selectable switches and wavelength converters in order to scale to
thousands or tens of thousands of connections, and that requires an optoelectronic
conversion."
Alexander described a three-tiered model for optical transmission equipment to link to
terabit routers, using a space-domain optical cross-connect at the top layer, a
frequency-domain cross-connect in the middle and an underlying electronic fabric for
control of packets. Alexander said that the general rule of thumb should be, "if you
have to touch bits, you need to go electronic."
Bala said that Tellium is applying this kind of philosophy to the new Full-Spectrum
switch. If all-optical systems try to handle OC-768 links carrying a mix of services, "the
devil is in the demuxing."
Tellium began with a strategy of retaining electronic-domain switching for traffic
grooming and mux/demuxing, and using optical-layer speed advantages only where
signal regeneration clearly was not necessary. Creating intermediate nodes to handle
regeneration will give carriers a best-of-both-worlds approach where optical
transparency is used for transmission speed and bit transparency, while hybrid
opaque conversion to electronic signals intelligently controls wavelengths. |
