Internet DRAFT - draft-choi-burst-control
draft-choi-burst-control
CCAMP Working Group Internet Draft Jun Kyun Choi
Document: draft-choi-burst-control-00.txt Min Ho Kang
Expiration Date: December 2003 Jung Yul Choi
ICU
Tae-Gon Noh
Kyoo Ryon Hahm
Samsung AIT
June 2003
Requirements of Burst-Level Control in Optical Networks
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC-2026.
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Abstract
This draft presents the requirements of burst-level control in order
to improve channel efficiency in optical networks. By processing and
control the finer granularity of burst data, the network can improve
its utilization than the present circuit switching based optical
networks. Implementation issues of transmission and switching for
data burst are took into consideration.
Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119.
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Table of Contents
1. Introduction.....................................................2
2. Needs of burst-level control.....................................3
3. Consideration Issues for burst-level control.....................4
4. Enabling technologies for burst-level control....................5
4.1 Classification of data burst switching..........................5
4.2 Switch control for data burst switching.........................5
4.3 Signaling control for data burst switching......................6
4.3.1 Label for identifying data burst..............................6
4.3.2 Signaling messages for data burst switching...................6
5. Conclusion.......................................................7
6. Security Considerations..........................................7
References..........................................................7
Acknowledgement.....................................................8
Author's Addresses..................................................8
Full Copyright Statement............................................9
1. Introduction
Through the emergence of wavelength division multiplexing (WDM)
technology, optical networks could provide the explosively increasing
transmission capacity. It enables several Terabit/sec transmission
capacity in a single fiber which contains several tens or hundreds of
wavelength with multiplexing [1]. Nevertheless of the huge
transmission capacity of fibers, the transmission efficiency comes to
decrease due to diverse applications traffic from access networks and
resulting bursty characteristics of Internet traffic in a backbone
network. Therefore, the needs for new efficient transmission and
switching technology for bursty Internet traffic efficiently and
accommodation of many subscribers are required.
First of all, we will discuss the main research streams for pursuing
implementation of optical networks. First, wavelength routing
functions to establish a lightpath which is an all-optical data path
along which data does not need to go through any O/E/O conversion
before data can be sent [2]. Such lightpaths can provide a high-speed,
high-bandwidth pipe that is transparent to bit rate and coding format.
Some end users will require one or more lightpaths only for a
relatively short period (e.g. from minutes to weeks). WDM layer MAY
need to establish and tear down wavelength-routed lightpahts
dynamically. One of the limitations of wavelength routing is that is
inefficient for Internet traffic which is self-similar (or bursty at
all time scales). Due to bursty traffic, the bandwidth utilization of
a lightpath is very poor. Even though lightpaths are established
dynamically, the set-up time of a lightpath based on two-way
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reservation may be too long for a burst which contains small size of
data given the high transmission rate.
Second, optical packet switching, which processes data traffic in all
optical domain, is recognized as an ultimate solution for
transmission and switching technology in optical networks [3].
However, the doubt of possibility of implementation of optical packet
switching raises due to lack of optical buffer, difficulty of header
processing, and synchronization in optical domain.
Because of the above mentioned inefficiency of the present switching
technology and difficulty in implementation of future switching
technology, we need a new transmission and switching technology as an
implementable intermediate solution. Burst-level control is an
emerging technology to provide finer granularity as optical packet
switching and alleviate difficulty of implementation [5-9]. Burst-
level control means that a network deals with burst data for
transmission and switching in order to improve network utilization.
It makes it possible interleaving several data burst into a single
link. This draft introduces the requirements of transmission and
switching per data burst in order to improve channel efficiency in
bursty Internet traffic environment. Burst-level processing will be
specified with the advantages, the operational mechanisms of it as
well as in the aspect of switch control and signaling control.
2. Needs of burst-level control
The circuit switching based wavelength routing is recognized to be
not suitable for the present Internet where traffic characteristic is
bursty and self-similar. Thus, even though transmission capacity is
increased with WDM technology, the Internet can not process the huge
burst traffic at an instant. Therefore, a new transmission and
switching technology is required to deal with the bursty Internet
traffic.
To deliver bursty data traffic efficiently means to increase channel
efficiency. So far, researches on improvement of channel efficiency
have been progressed in time domain and frequency domain [1,3,5-9].
In frequency domain, wavelength division multiplexing is one of the
main results [1]. In time domain, optical packet switching, which
processes data packet and delivers them in all optical domain, is the
key issue for pursuing the ultimate solution for optical internet [3].
However, due to the limitation of optical technology such as optical
buffer and header processing, optical packet switching is recognized
as a future technology. The fast circuit switching has been studied
to overcome the overhead of connection establishment and release of
the legacy circuit switching based on three-way-handshaking [4]. In
fast circuit switching, connection setup (or tear down) takes place
when the start (or end) of a burst is detected by sending a control
signal, and is fast since routing has already been done. Even though
it tries to increase channel efficiency by reducing connection
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establishment overhead by one-way reservation without receiving
connection setup acknowledgment, its efficiency decreases when it
delivers short burst traffic.
As a solution of the above problems in the present Internet, a new
transmission and switching technology suitable for bursty Internet
traffic is required. For the purpose, optical burst transmission and
switching was suggested and they have been studied [5-9]. The main
feature of optical burst switching is the elimination of the round-
trip waiting time before data burst is transmitted: the switching
fabric inside the switches are configured for the incoming data burst
as soon as the first control packet announcing the burst is received.
Since the switching fabric already has been configured before data
burst comes in the switch, the data burst will cut through the switch,
even without buffering themselves. Another feature of optical burst
switching is to transmit and switch per each data burst, contrary to
circuit switching which establishes a full connection for data
transmission. Once a connection has established in circuit switching,
it is not possible to interleave other data into the connection even
if empty space in the connection. However, in optical burst switching,
other data burst can be inserted into empty space among different
data burst in a link.
By applying burst-level control, we can get the following advantages.
- Multiplexing of data burst in a link
- Dynamic provisioning for data burst
- Short transmission delay owing to one-way reservation
- Improvement of link utilization
3. Consideration Issues for burst-level control
The following items should be taken into account for implementation
of transmission and switching per data burst.
- One-way-reservation for fast transmission.
- Multiplexing of data burst in a link
- Switch control mechanisms for setting the switch fabric to switch
and transmit short bursty data traffic.
- Signaling mechanisms to support dynamic provisioning for short
data burst.
- Route reuse scheme to use the existing established path not for
calculate and setup new path for burst data.
- Definition of new label to identify data burst.
- Definition of service model to support data burst.
Based on the above mentioned issues, the burst-level control will be
developed to support burst data in all optical domain. First of all,
a new label which identifies data burst SHOULD be defined. Switch
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control and signaling mechanism also SHOULD be developed to support
data burst and systems with the burst-specific characteristics.
4. Enabling technologies for burst-level control
In chapter 4, classification of data burst switching according to the
reservation time and types which should be supported are presented.
Switch control to support them and signaling protocol to support end
to end burst data transmission and switching will be discussed.
4.1 Classification of data burst switching
Data burst switching can be categorized as the following types based
on the beginning and releasing time of resource reservation for data
burst transmission. According to how soon before the burst arrival
and how soon after its departure, the switching elements are made
available to route other data bursts.
Explicit setup - Explicit release;
After a switch receive the setup request for data burst the switch
fabric is configured for the incoming data burst immediately and
remains in that configuration until a release request arrives.
Explicit setup - Implicit release;
The setup request contains information about the length of the data
burst so that a release request is not needed to indicate the end of
the data burst.
Implicit setup - Explicit release;
The start of data burst is estimated based on information contained
in a setup request while a release request notifies the switching
resource to be released.
Implicit setup - Implicit release;
Both the start and end time of data burst are predicted based on
information contained in a setup request.
In the above four types, when we estimate the start and end of the
burst tightly with implicit notifications, there is smaller overhead
of keeping the switching resources configured and lower blocking
probability in the network. However, there is a tradeoff between
utilization and complexity of control.
4.2 Switch control for data burst switching
Optical switch is required to establish and release a connection for
data burst in order to transmit data burst fast without optical-
electrical-optical conversion. For the purpose, General Switch
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Management Protocol (GSMP) working group (WG) is working on
standardization about switch control for optical switching per data
burst as well as wavelength and fiber [10-11]. The work uses the
Reservation Request message in order to reserve switching resource
for data burst efficiently. According to different reservation
mechanisms for data burst transmission mentioned in section 4.1, the
switch controller tries to reserve the resource for the transmission
with the message. That is, by setting the start time and burst length
information contained in the message appropriately, resource on the
switch is reserved and activated for the enough bandwidth. The other
related to switch control follows GSMP WG documents [10-11].
4.3 Signaling control for data burst switching
Since the length of data burst is assumed to be short, one-way-
reservation scheme is recommended to reserve resource for data burst
under the assumption that the out-of-band control channel is reliable
to deliver control message without transmission error or blocking.
The setup request to reserve resource for data burst is delivered
from an ingress node to an egress node. The intermediate nodes, which
receive the setup request, reserve the switching resource according
to information contained the request for data burst without sending
back acknowledge about the setup request. At this time, the switch
controller configures the switch element for the data burst switching
as well as reserves the switching resource. If there is inefficient
resource and no available output port the controller sends the
failure of the setup request to the ingress node.
Generalized Multi-Protocol Label Switching (GMPLS) signaling protocol,
such as RSVP-TE or CR-LDP, can be used as a signaling protocol to
transmit and switch data burst with some modification or extension.
GMPLS supports multiple types of switching: Packet, Layer-2, TDM,
Lambda, and Fiber level switch capable [12-13]. For delivery of data
burst, GMPLS SHOULD support optical burst switch capable interface.
Since the existing signaling protocols use two-way reservation for
establishing label switched path (LSP), the protocols SHOULD be
modified to support one-way reservation for data burst. A new
identifier is required to identify data burst as a new switching unit
in the signal protocol. For the purpose, "Label for optical burst"
SHOULD be defined to identify data burst. The label is used to
identify data burst of which granularity is coarser than packet (PSC)
and finer than wavelength (LSC).
4.3.1 Label for identifying data burst
This label is used to identify data burst. The format and its
semantic is TBD.
4.3.2 Signaling messages for data burst switching
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Signaling messages are used to establish a connection for data burst
in one-way reservation mechanism, not like the existing signaling
mechanisms which is based on two-way reservation. Therefore, the
existing signaling mechanisms SHOULD be modified to fast transmit and
switch data burst. The candidate protocols are CR-LDP and RSVP-TE.
The format and semantic of signaling message is TBD.
5. Conclusion
This draft specifies the requirements and basic technology for burst-
level control in order to improvement channel efficiency in optical
networks. For achieving higher utilization of channel, data burst
with a finer granularity SHOULD be processed in all optical domain.
Burst-level control can be implemented with GSMP for switch control
and GMPLS for signaling protocol with some modification and extension.
6. Security Considerations
This document does not have any security concerns. The security
requirements using this document are described in the referenced
documents.
References
[1] C.A. Bracket, "Dense Wavelength Division Multiplexing Networks,
Principles and Applications", IEEE JSAC, August, 1990.
[2] Zang, H., Jue, J. P., Mukherjee, B., "A Review of routing and
wavelength assignment approaches for wavelength routed optical WDM
networks", Optical Networks Magazine, 2000
[3] D. J. Blumenthal, et. at., "Photonic packet switches:
Architectures and experimental implementations", Proceedings of the
IEEE, Nov., 1994
[4] Christer, B., Markus, H., Per, L., Lars, R., Peter, S., "Fast
Circuit Switching for the Next Generation of High Performance
Networks", JSAC, 1996
[5] C. Qiao, M. Yoo, "Choice, and Feature and Issues in Optical Burst
Switching", Optical Net. Mag., vol.1, No.2, April 2000, pp.36-44.
[6] C. Qiao, M. Yoo, "Optical Burst Switching (OBS) - a new paradigm
for an optical Internet", Journal of High Speed Networks, 1999
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[7] J. Turner, "Terabit burst switcing", Journal of High Speed
Networks, 1999
[8] Ilia Baldine, George N. Rouskas, Harry G. Perros, Dan Stevension,
"JumpStart: A Just-in-time Signaling Architecture for WDM Burst-
Switching Networks", IEEE Comm. Mag., Feb. 2002.
[9] Illia Baldine, et. al., "JumpStart: A Just-in-Time Signaling
Architecture for WDM Burst-Switched Networks", IEEE Comm. Mag., Feb.,
2002
[10] Doria, A, "GSMPv3 Base Specification", draft-ieft-gsmp-v3-base-
spec-02.txt, June 2003.
[11] Junkyun Choi, JungYul Choi, et. al., "General Switch Management
Protocol (GSMP) v3 for Optical Support", draft-ietf-gsmp-optical-
02.txt (work in progress), June 2003.
[12] Mannie, E., et. al., "Generalized Multi-Protocol Label Switching
(GMPLS) Architecture", draft-ietf-ccamp-gmpls-architecture-03.txt
(work in progress), August 2002.
[13] Ashwood-Smith, D., et. al., "Generalized MPLS - Signaling
Functional Description", RFC3471, Jan. 2003.
Acknowledgement
This work was supported in part by the Korean Science and Engineering
Foundation (KOSEF) through OIRC project
Author's Addresses
Jun Kyun Choi
Information and Communications University (ICU)
58-4 Hwa Ahm Dong, Yusong, Daejon
Korea 305-732
Phone: +82-42-866-6122
Email: jkchoi@icu.ac.kr
Min Ho Kang
Information and Communications University (ICU)
58-4 Hwa Ahm Dong, Yusong, Daejon
Korea 305-732
Phone: +82-42-866-6136
Email: mhkang@icu.ac.kr
Jung Yul Choi
Information and Communications University (ICU)
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58-4 Hwa Ahm Dong, Yusong, Daejon
Korea 305-732
Phone: +82-42-866-6208
Email: passjay@icu.ac.kr
Tae-Gon Noh
Samsung Advanced Institute of Technology
P.O. Box 111, Suwon, Kyoungki
Korea, 440-600
Phone: +82-31-280-9621
Email: tgnoh@samsung.com
Kyoo Ryon Hahm
Samsung Advanced Institute of Technology
P.O. Box 111, Suwon, Kyoungki
Korea, 440-600
Phone: +82-31-280-9549
Email: ryonhahm@samsung.com
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