May 23, 2003
"GMPLS Signaling Protocol Interoperability
Test in Multilayer Network"
- Establishing a Global Standard
for the Next-generation
Photonic Network
TOKYO, May 20, 2003 - NTT, NEC Corporation, Fujitsu Laboratories
Ltd., The Furukawa Electric Co., Ltd., and Mitsubishi Electric
Corporation are pleased to announce the successful conclusion
to the world first GMPLS*1 signaling*2 interoperability
test using a multilayer network consisting of packet, TDM*3,
wavelength, and fiber layers. Given the quality requirements
set by the application or traffic state, it is possible
to select the optimal communication path from among all
possible paths that can be established on the multilayer
network.
The results of this experiment were reported on May 22, 2003 in the Workshop
held in Kagoshima University organized by the Technical Group on the Photonic-Network-based
Internet and the Technical Group of Photonic Switching in the Institute of
Electronics, Information, and Communication Engineers of Japan.
Background and achievements
GMPLS enables unified control management of the network
layers. In the conventional network, each layer network
is constructed independently. Conventional technology
demands that each is independently controlled by operators specializing
in that layer. For example, in conventional electrical
or optical cross-connects,
the network operator uses a terminal of a centralized control device. This
device issues instructions to control cross-connect equipment and hence
the setup of TDM or wavelength paths. If the cross-connect
equipment supports
GMPLS
control, then a path is set up by exchanging control packets between these
control devices as well as MPLS routers. Therefore, a network operator
who has MPLS expertise can manage cross-connects. However,
current equipment
that supports GMPLS control simply offers a unified
management approach. Each layer
network must still be managed separately as before. It is impossible to
handle all layers in the whole network systematically,
such as if one side using
TDM routing and the other side uses wavelength routing.
To avoid this problem, control software programs for
setting up and releasing paths in the multilayer network
were newly developed and installed in the
network control devices of each company. The fact that these control devices
can be
mutually interconnected is a key factor in the success of the interoperability
test that examined path setup of multilayer signaling: a world first. These
control devices exchange signals based on the protocol RSVP-TE*4, extended
to GMPLS, to set up and release multilayer paths on the multilayer network.
The test setup is shown in Fig. 1. It was designed to replicate a multilayer
network with various kinds of network equipment including packet routers,
electrical connections, optical cross-connects, and optical switches
for fiber port switching. It provides control functionality for both packet
and
TDM
paths using control devices 1 and 2. Control device 1 can freely set
the packet path of route A and the TDM path of route B. Control device
2 on Route
A has
path control functions for both packet and wavelength paths. Control
devices 2 to 6 are for optical cross-connect control, which sets up the
wavelength paths. They newly set up a wavelength path for the packet path
from devices
1 to
7. Thus, the setup and release of a multilayer path can be performed
by
exchanging a control signal among all the control devices handling a particular
layer.
Given the quality requirements set by the application or traffic state,
it is possible to select the optimal communication path from among all
possible paths that can be established on the multilayer network.
GMPLS allows network operations to be unified. Significant reductions
in network operation costs can be expected because the most economic
path can
be selected by configuring the optimal configuration of network resource
from among all layers of the network. In addition, novel network services
can be
created, such as a wavelength-dedicated line that changes wavelength
path connection points according to user demand. For this reason, GMPLS
has
been attracting attention as the base technology of the next-generation
broadband
IP network. GMPLS is being actively discussed and advanced in international
standardization organizations, such as IETF (Internet Engineering Task
Force), OIF (Optical Internetworking Forum), and ITU (International Telecommunication
Union).
Future plans
This interoperability test was carried out by the Photonic
Internet Lab (PIL). Further interoperability tests
with several global companies are planned.
Glossary
*1 GMPLS (Generalized Multi-Protocol Label Switching):
GMPLS is a protocol that establishes generalized MPLS in all layers of the
IP network. The basic MPLS is a control mechanism that attaches fixed-length
labels to IP packets. The basic functions of GMPLS were released as a Proposed
Standard in February 2003, with registration number RFC 3471-3473. To make
it complete and a truly practical protocol, world-wide efforts are needed
to finalize the remaining details and develop protocol code that can be directly
installed in network equipment
.*2 Signaling:
An exchange of signals between network equipment control
devices, such as routers and optical cross-connects to
set up and release paths. The format of the control
signal and the procedure for exchanging control packets are defined in the
signaling protocol.
*3 TDM (Time Division Multiplexing):
Transmission technology using time division multiplexing. Many TDM networks
use SDH/SONET [?].
*4 RSVP-TE (Resource ReSerVation Protocol with Traffic
Extensions)
A signaling protocol. An extension of RSVP (a bandwidth reservation protocol)
for MPLS.
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