Here is a posting from the Ciena thread made before the news of Tellabs acquiring Ciena. It is very technical but I get the feeling it is an important analysis of the things Tellabs is into. I hope some of the experts in this thread could give their opinions and explanations in laymen's language as just what this means and how it pertains to Tellabs.
Talk : Communications : Ciena IPO
To: Peppe (2226 )
From: pat mudge Thursday, May 28 1998 9:26PM ET
Reply # of 2292
pubs.cmpnet.com
<<<
Posted: 11:45 p.m. EST, 4/24/98
Pact could transform Internet backbone
By Loring Wirbel
LINTHICUM, Md. - While industry attention
has focused on the recent joint development pact
between Ciena Corp. and Cisco Systems Inc., a
little-noticed second agreement between the two
companies may have been an industry milestone.
Ciena and Cisco united with AT&T, Bellcore,
Hewlett-Packard Co., Sprint Inc., WorldCom
Inc., and Qwest Communications International Inc.
to form the Optical Internetworking Forum.
The agreement may be the first step toward
altering the architecture and ownership of the
Internet backbone, may preface the end of the
router as we know it, and may lessen the
importance of the Synchronous Optical Network
(Sonet) protocol and asynchronous transfer mode
in the network infrastructure.
The more obvious agreement was significant
enough. Cisco (San Jose, Calif.) and Ciena
(Linthicum) will collaborate to interface Cisco's
GSR 12000 gigabit switch/router with Ciena's
metropolitan and long-haul dense
wavelength-division multiplexing (DWDM)
systems. The move will give Cisco's GSR boxes
direct access to the growing number of backbones
- both metropolitan-area and long-haul - that
are implemented using Ciena's DWDM physical
layer.
DWDM optical fiber links are increasingly being
used as an upgrade to 2.5 Gbit/second OC-48
Sonet links, since the upgrade is much less
expensive than moving to OC-192 (10-Gbit)
Sonet at the same capacity. While Sonet uses
time-division multiplexing (TDM) to create virtual
channels over an optical fiber, DWDM uses
wavelength division - the separation of the light
signal into its component colors - to create
separate physical channels. The technique
multiplies the capacity of an optical fiber by the
number of wavelengths separated out in the
DWDM multiplexer.
It appears that DWDM will not only slow the
deployment of OC-192 but will also speed the
wholesale conversion of the Internet backbone
from cable to optical fiber. That, in turn, threatens
to wrest the Internet long-haul business out of the
hands of MCI and other traditional carriers and to
hand it over to a new category of smaller carriers
that have been quicker to adopt DWDM.
But before such a revolution can take place, a
number of issues have to be worked out. One is
the connection between existing enterprise
backbones - typically based on gigabit
switch/router equipment - and the new DWDM
links. Another is an efficient way of transporting the
ubiquitous Internet Protocol (IP) over the DWDM
physical layer.
A new batch of routers
The first issue has led to industry buzz over a
generation of "terarouter"startups, such as Juniper
Networks Inc. and Avici Systems Inc. Only two
weeks ago, Northern Telecom Inc. made a
minority investment in Avici, and Juniper already
has investments from multiple OEMs and carriers.
Cisco's efforts to link its DWDM futures with
Ciena could be read as an attempt to head off the
growing interest in the terarouter companies. But at
a deeper level, the collaboration suggests that the
new breed of ultra-fast backbone routers may be
different in aspects other than raw speed.
If DWDM is adopted as a common physical-layer
networking scheme, router and switch developers
may well look at improving data throughput by
collapsing one or more of the seven layers of the
Open Systems Interconnect protocol stack. Cisco
and other OEMs already are working on
IP-over-Sonet implementations that would remove
ATM as a transport layer between the Internet
Protocol and the Synchronous Optical Network.
But OIF members also could look at removing a
Sonet payload envelope from the encapsulated
data, carrying IP or ATM packets directly on
DWDM optical layers, treated as logical layers in
the network.
"Depending on the architecture, Sonet layers may
not be necessary," said Denny Bilter, director of
marketing at Ciena. "Sonet is a TDM layer
designed primarily for voice, not data."
That does not mean Cisco's work on
IP-over-Sonet, carried out in part through its
acquisition of Canadian chip-set specialist
Skystone Inc., becomes obsolete, said Graeme
Fraser, vice president of engineering and general
manager of Cisco's Internet service provider
business unit. Fraser predicted that Internet
backbones will be built on systems that provision
wavelengths at the optical layer, whereas systems
that mediate access from enterprise networks to
local carriers will continue to function with
traditional internetworking layers preserved.
"We don't see Sonet going away anytime soon,"
Fraser said. "What is going on in the next
generation of routers and switches is not the
removal of layers in the OSI stack but the
collapsing of functions of multiple layers into single
systems, simplifying the stack in some instances."
Seeking a standard
Vital to that process is the standardization of the
DWDM world, in much the way that the ATM
Forum and its open standards proved vital in the
ATM universe. And that is the thrust of the
second, less noticed agreement between Ciena and
Cisco.
The two companies are hoping the Optical
Internetworking Forum will be DWDM's version
of the ATM Forum. Bilter pointed out that a few
large DWDM companies, such as Lucent
Technologies and Nortel, were conspicuous by
their absence from the founding group, but he
added that OIF is open to any company in the
DWDM, router or optical interconnect markets.
Cisco and Ciena see OIF playing a revolutionary
role, not only in increasing awareness of DWDM
but in steering DWDM architectures away from
the telephony model of virtual circuits and toward a
model that takes into account data-centric
topologies for establishing broadband connections.
Analogously, ATM Forum steered ATM
advocates away from a singular focus on
Broadband ISDN and toward a more
LAN-oriented model with such functions as ATM
Adaptation Layer 5 and LAN emulation software.
The ability of OIF to integrate the viewpoints of
both the telco and LAN camps will be vital to such
tasks as collapsing the OSI stack or removing the
Sonet protocol without giving up the functionality
for which the telcos have always relied on Sonet.
Cisco's Fraser said OIF will differ from such
DWDM projects as those of the International
Telecommunications Union (ITU) and American
National Standards Institute (ANSI) because data
companies' views will be weighed equally with
those of telephone equipment manufacturers and
carriers. Telephony advocates, he said, simply
assume that DWDM will replace a variety of Sonet
and ATM functions in establishing switched virtual
circuits based on wavelength. They ignore the
contention of networking OEMs and Internet
service providers that end-to-end circuit
establishment, whether based on ATM or on
DWDM, is not always a preferred situation in the
connectionless world of the Internet protocol.
"For example, where is protection provided? The
Bellheads would assume that it takes place based
on wavelengths or optical paths. The data people
would say that it might make sense to provide
protection at the network layer, using IP route
protocols instead of physical-layer
protection,"Fraser said. "We don't want to
promote only the data view of DWDM within the
forum; we want to have data and telephony
representatives have an open discussion."
In theory, OIF could take many standardization
functions off the hands of ITU or ANSI, at least in
terms of creating "fast-track"drafts that are passed
to the official bodies. But Fraser said he wants to
avoid the problems the ATM Forum experienced
in promoting standards that became overly
complicated as features were added to satisfy both
the telephony and IP camps.
Many of Cisco's and Ciena's direct competitors
are expected to join OIF, and Fraser said he has
been bombarded with phone and e-mail messages
seeking more information on the forum prior to its
first meeting May 6th at NetWorld+Interop.
Despite the founders' enthusiasm, the OIF isn't the
first industry consortium for DWDM. The National
Security Agency (NSA) and Naval Research Labs
(NRL), working with AT&T and several regional
Bell operating companies, formed Project Monet
(Multiwavelength Optical Network) two years ago
to define DWDM architectures for such telephony
equipment as optical add-drop muxers, optical
cross-connects and optical routers. Two weeks
ago, Monet hit a milestone when the Defense
Advanced Research Projects Agency awarded a
contract to DWDM startup Tellium Inc. (Edison,
N.J.) for a unidirectional ring linking several
intelligence agencies in Washington.
Tellium, a spinoff of Bellcore funded by Ortel
Corp. and Science Applications International
Corp., is receiving $2.5 million from Darpa to build
a unidirectional path-switched ring, based on the
Tellium Aurora architecture, among the Defense
Intelligence Agency, Defense Information Systems
Agency and Darpa. The path-switched ring will
augment an existing Monet testbed linking the
NSA, the NRL, Lucent and Bellcore.
Monet and OIF appear to be in agreement on
some key issues. Richard Barcus, vice president of
marketing and product management at Tellium,
agreed with the concept of collapsing optical and
logical layers for different network purposes. He
said the factor that sold Darpa on the
MetroExpress32 WDM transport equipment and
Aurora cross-connect equipment was the ability to
provide "Sonet-like" services at an optical layer.
Barcus said that Tellium already has been in
discussions with Cisco on a number of fronts,
including OIF's structure, and that the company is
interested in joining the forum. The goals of the
organization seem complementary to those of
Monet and the official standards bodies, he said.
An obvious adjunct to collapsing protocol layers is
to integrate the equipment that supports them. A
single box providing switch/router services for
incoming Gbit connections and DWDM
multiplexer services for connection to optical fiber
seems very much on the horizon.
In fact, if DWDM succeeds in taking over the
metro and long-line links that constitute the heart of
the Internet, such integrated boxes would naturally
displace existing routers.
Nevertheless, Cisco and Ciena will limit their own
collaborative projects for the time being to
interfaces between GSR and the Ciena
multiplexers. Fraser said that the number of
channels for DWDM systems is changing so fast
- with Lucent Bell Labs, for instance, claiming
systems with 100 channels of 10-Gbit/s capacity
each, for aggregate capacity of multiple terabits per
second - that it would be premature to integrate
DWDM interfaces directly inside a router.
Such a system may make more sense in a few
years, he said, once a given density of DWDM
channels becomes a de facto standard.
The next few months should nonetheless prove
interesting as the router and DWDM worlds are
brought together, particularly since many
terarouters are expected to debut from aggressive
startups at the NetWorld+Interop and Supercomm
shows.>>>> |
