re: lambda classes, optical routing, WaRP
Dave,
I'm not sure where the discussion with AHhaha started (maybe you can point me to the message) concerning classful lambdas. From what I was able to pick up in your dialog it sounded a lot like Monterey Networks' (acquired by CSCO last year) WaRP, which stands for Wavelength Routing Protocol.
WaRP works by forwarding (mapping) IP flows to wavelengths which are associated with router ports (routes), according to destination, and conceivably also class of service (CoS), and other criteria. This is grossly oversimplified, granted, but that's the gist of it. [See the article below for a better description.]
WaRP has been likened to MPLS/labeled (or tagged) flows, and ATM/Virtual Circuits and Paths, which are Layer 2 functions. I'd suggest the following reading from Lightwave Magazine as a good introduction to WaRP (which serves as an instructive read for other vendors' approaches, too), although I can't vouch that things haven't changed ( presumably for the better) since their being acquired by CSCO. The article which follows also serves as a good review of the other lebacy approaches which now exist as the underpinnings of today's network, which WaRP and other optical cross-connects will eventually supplant.
lw.pennwellnet.com
I would suggest going to the url for the illustrations and graphics. I've copied the text portion below for posterity. Enjoy.
FAC.
===========
Laying the foundation of the optical Internet
Article Date: February, 1999
An optimal optical networking architecture must integrate
intelligence within the network, rather than lay it on top.
John C. Adler and Stevan Plote, Monterey Networks Inc.
The realization of the optical Internet requires great leaps
in network scalability, latency, and survivability. The
abundance of bandwidth afforded by dense
wavelength-division multiplexing (DWDM) creates only a set
of point-to-point optical pipes. Internetworking gigabit
switch/routers around these pipes using Synchronous
Optical Network/Synchronous Digital Hierarchy (SONET/
SDH) network elements is not feasible given that with
OC-48c/192c Internet protocol (IP) routing, no
time-division multiplexing (TDM) is necessary. Introducing
Asynchronous Transfer Mode (ATM) switches or terabit
routers as intermediaries where there are one or more
OC-48c flows between backbone routers misapplies
grooming devices for wavelength forwarding, while
simultaneously increasing latency and requiring seconds and
even minutes for restoration versus the 50 msec previously
provided by SONET.
A new architecture, based on a device we will call the
wavelength router, would achieve all three objectives by
introducing "native" intelligence into the optical network. It
would directly connect gigabit switch/routers across
network-wide wavelength routes restorable in 50 msec
without a SONET ring`s bandwidth penalty. By solving the
wavelength junction connectivity problem, the wavelength
router would go beyond the optical crossconnect to lay the
foundation for the long-haul optical Internet core and
enable the broad deployment of multi-gigabit services for
wholesale, retail, and on-the-spot bandwidth markets.
Need for intelligence
As the amount of data carried by the Internet backbone
has grown exponentially, and as voice and data traffic have
begun to unite on the emerging optical Internet, network
architects have recognized three significant challenges:
making the network grow to meet demand (scalability)
keeping the added demand from causing excessive network
queuing delays (latency)
protecting against and recovering quickly from failures
(survivability or restoration).
It is generally recognized that to deal with a growth rate of
1000% per year, the Internet must be scaled through the
effective interconnection of the new generation of gigabit
switches/routers. Adequate scaling of long-haul backbones
will also involve optical transmission technologies like
DWDM.
But as DWDM vendors continue to topple barriers to the
number of wavelengths a fiber strand can carry, managing
the abundant bandwidth DWDM affords is a growing
challenge. Today, wavelength provisioning and traffic
assignment is a largely manual process. Assignment of
SONET systems to wavelengths is done through physical
cabling, which offers little flexibility.
In contrast to the intelligent IP routing infrastructure in
place today, the optical infrastructure thus far has emerged
as a set of point-to-point pipes that does not incorporate
the intelligence needed to scale and self-restore. So long
as this situation remains, the emerging fiber-rich bandwidth
brokers will be able to sell optical bandwidth only in the
form of dark fiber or unmanaged wavelength bundles. And
large Internet service providers hoping to offer ubiquitous
multi-megabit IP-based network services over the optical
infrastructure will be hard-pressed to scale their services
without a far greater level of intelligence integrated into
the optical network.
Two strategies are under consideration to achieve the
objectives of network scalability, survivability, and reduced
latency. These involve deploying intermediate network
elements--either SONET add/drop multiplexers and
crossconnects or ATM switches and virtual path
crossconnects--between the gigabit switch/router and the
point-to-point optical pipes. These solutions have
drawbacks. But in each cases, intelligence is built on top of
the optical network rather than integrated into it, making
them ineffective as the network scales.
In contrast, the wavelength router architecture would
integrate wavelength-routing intelligence--including
network-wide wavelength provisioning and failed-route
restoration capability--directly into the long-haul optical
core. Wavelength routes between gigabit switch/routers
would be rapidly restored without the use of intermediary
devices. Wavelength routers would actually remove a layer
of complexity from the network; along with gigabit
switch/routers and the DWDM terminals, they would be the
only network elements needed to build the optical Internet
core.
Solution 1: SONET ADMs and crossconnects
Over the past decade SONET has become the transport
medium of choice for service providers and has matured
into a stable technology familiar to installation,
maintenance, and operations personnel. Its ring
architecture provides rapid (50-msec) restoration, easy
access to lower-bandwidth circuits at intermediate network
points, and circuit visibility.
But SONET`s main value has been its TDM capability, a
technique in which information from multiple sources can be
allocated bandwidth on a single wire based on a time-slot
assignment. While TDM was a critical function in voice and
leased-line networks where there are large numbers of
lower-speed interfaces, it becomes superfluous when
gigabit switch/routers are able to groom packets at the
OC-48c and OC-192c levels.
Furthermore, the SONET ring architecture requires
extensive use of repetitive equipment--and in the most
common SONET implementations, service providers
frequently double the number of SONET devices to extend
full physical-line protection to all traffic. While SONET
elements were once the consolidation point for many
lower-speed circuits, accelerated network growth has
positioned them as rapidly multiplying transmission elements
that are difficult to manage and costly to deploy.
Solution 2:
ATM switches, virtual-path crossconnects
ATM has been widely accepted as a means to effectively
engineer Internet traffic by establishing connections or
virtual paths between routers. The ATM virtual paths make
router networks easier to construct by giving the routers
the appearance of being just a hop apart, where in reality
the virtual path may traverse many intermediate ATM
switches. The characteristics of each such virtual path can
be controlled through ATM`s quality-of-service constructs,
thereby optimizing the sharing of bandwidth. Furthermore,
the physical routes that the virtual paths traverse can be
tracked for performance-monitoring and traffic-engineering
purposes. Additionally, ATM`s automated connection
recovery establishes a stable link infrastructure between
switches, presenting the routers with restorable circuits.
All this is about to change. As IP network cores continue to
scale--as traffic between pairs of backbone routers reach
just a single OC-48c/OC-192c volume--ATM`s virtual path
becomes equivalent to a wavelength (see Fig. 1). So while
the benefits of ATM`s fine virtual-path granularity,
including quality of service, make it eminently suitable for
access use, it becomes irrelevant in the optical core, where
the appropriate switching granularity is the wavelength.
Finally, the effective management of these huge numbers
of virtual paths depends on the widespread introduction of
Private Network to Network Interface (PNNI), ATM`s
dynamic virtual-path provisioning and restoration protocol.
Even then, PNNI`s restoration times will be seconds or
minutes, far inferior to the 50-msec benchmark set by the
SONET ring. As a result, ATM switches and crossconnects
offer no compelling value for inclusion as intermediaries in
the optical Internet core.
Solution 3: Wavelength router architecture
The wavelength router aims to integrate intelligence
directly into the optical network without introducing
intermediate devices. In addition to many other benefits,
this approach dramatically shortens the provisioning and
restoration times that characterize non-native solutions.
The wavelength router interconnects backbone gigabit
switches/routers directly through optical routes. With
intermediate SONET and ATM eliminated, only the
wavelength router and the gigabit switch/router are needed
in the long-haul optical infrastructure with the DWDM
terminals. The architectural division of labor between the
two routers is straightforward and highly efficient. The
gigabit router grooms packets from DS-1 (1.544 Mbits/sec),
DS-3 (44.736 Mbits/sec), OC-3 (155 Mbits/sec), and OC-12
(622 Mbits/sec) flows to OC-48c or OC-192c streams. The
wavelength router maps these streams to wavelengths,
which replace ATM virtual paths for end-to-end transport
across the network. As traffic increases, additional
wavelengths are provisioned between appropriate router
pairs performing traditional IP routing, tag switching, or
MPLS (multi protocol label switching) (see Fig. 2).
Central to the wavelength router architecture is a
distributed Wavelength Routing Protocol (WaRP), which
provisions transcontinental virtual wavelength paths in
seconds across many hops, restores them within 50 msec
following physical failure, and prioritizes their restoration.
Figure 3 shows a simulated use of WaRP on a realistic
national backbone with restoration times ranging from 24 to
48 msec and with significant bandwidth savings over
comparable ring topologies. WaRP is based on open routing
protocols and standards established in packet and cell
networks and is optimized to provide ultra-fast provisioning
and restoration without the bandwidth penalties of SONET
rings.
Role of the optical crossconnect
The advent of DWDM, and the resulting creation of huge
numbers of wavelength-level junctions between traffic
sources and destinations, has engendered a connectivity
problem that, to date, has been handled via a cumbersome
manual process. The optical crossconnect can solve the
wavelength junction connectivity problem, but it alone
cannot provide the needed intelligence to route and rapidly
restore wavelengths end-to-end across the network.
This intelligence is best added through integral native
wavelength-routing capability. Given that the wavelength
router requires a switching core, which may be optical,
electronic, or a hybrid, an optical crossconnect can serve
as a key subsystem--the switching core--within the
wavelength router, making advances in optical switching
technologies highly synergistic with the wavelength router.
Architects of the intelligent optical Internet
The intelligent optical Internet will be built by Internet
backbone providers and bandwidth providers or "brokers." IP
backbone providers can flexibly aggregate gigabit
switches/routers at IP terabit points of presence (PoPs)
using wavelength routers while simultaneously
interconnecting these "tera-PoPs" with optical bandwidth
services available internally or through wholesale carriers.
Bandwidth service providers can deploy wavelength routers
at their backbone sites to optimize backbone bandwidth use
and restore links upon failure. Regardless of traffic type,
the wavelength router connects to OC-48 and OC-192
sources such as gigabit switches/ routers, ATM switches,
and the installed base of SONET terminals that aggregate
lower-speed voice, IP, and ATM leased-line traffic. It also
connects to other wavelength routers to create the optical
foundation that allows flexible assignment and end-to-end
restoration of the wavelength paths. No longer dependent
on the reliability and restoration capabilities of their
facilities providers, Internet engineers can manage their
physical infrastructure and optimize the technology for
Internet network designs and architectures.
Bandwidth brokers can transition from today`s dark fiber
sales and leapfrog wavelength services to create new
bandwidth denominations--differentiated OC-48/192
wholesale, retail, and on-the-spot markets for ubiquitous
multigigabit bandwidth. The wavelength router provides an
integrated platform for building and controlling large
transmission infrastructures for both long-distance and local
providers. It gives service providers the flexibility to quickly
adapt to the fast-changing requirements of the
transmission infrastructure and meet the growing demand
for multigigabit services to build new private and public
networks. q
John C. Adler is director of product management and
Stevan Plote is senior product manager at Monterey
Networks, Inc. (Richardson, TX), www.montereynets.com
Click here to enlarge image
Fig. 2.
With
OC-48c/192c
gigabit
router-to-router
connections,
the
wavelength
routers
create an
intelligent,
highly
scalable
optical
networking
core that
enables
end-to-end
wavelength
virtual
paths to
be
provisioned
and restored rapidly without the bandwidth penalties of
SONET rings and with near "glass" latencies.
Click here to enlarge image
Fig. 1.
With
OC-48c/192c
router-to-router
connections,
ATM
virtual
paths
become
equivalent
to a
wavelength and ATM loses much of its value in the optical
core, causing difficulty in justifying its introduction as an
intermediate layer between the routers and the optical
core. Furthermore, these connections add latency and
lengthen restoration times.
Click here to enlarge image
Fig. 3.
Simulations
have
shown the
effectiveness
of the
Wavelength
Routing
Protocol
(WaRP).
The
simulated
network
(a)
comprised
39 major
WDM
junctions,
hundreds
of
wavelengths
per
junction,
and hundreds of virtual paths end-to-end across the
network. WaRP restoration times (b) ranged from 24 to 48
msec for long routes and lower for shorter routes while
yielding significant bandwidth savings over comparable ring
topologies.
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