Internet Draft Jun Kyun Choi
Document: draft-choi-gsmp-optical-extension-00.txt Min Ho Kang
Expiration Date: December 2002 Gyu Myoung Lee
Jung Yul Choi
ICU
Young Wook Cha
ANU
Woo Seop Rhee
ETRI
June 2002
Extension of GSMP for optical burst switching
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
In this draft, we propose the extension of General Switch Management
Protocol (GSMP) for optical data burst switching control. This
document describes node architecture and reservation management using
GSMP interface for data burst switching in optical domain.
Particularly, we propose a reservation request message which is
extended to the existing GSMP protocol. It contains the information
about offset time and burst length to control data burst in optical
switch.
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.....................................................3
2. Switch control architecture......................................3
3. Reservation management for optical burst switching using GSMP v3.5
3.1. Reservation methods.........................................5
3.2. Reservation Request Message for optical burst switching.....5
4. Other considerations.............................................8
5. Security Considerations..........................................8
Appendix. Data burst switching in optical domain....................9
References.........................................................13
Acknowledgments....................................................13
Author's Addresses.................................................14
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1. Introduction
The General Switch Management Protocol (GSMP), which is a general-
purpose protocol to control a label switch, allows a controller to
establish, release, and reserve connections across the switch [1]. It
also provides several capabilities for connection management,
reservation management, management, status and event management, and
configuration so as to satisfy the requested capabilities and control
the switch. The evolution form of GSMP has been studied to apply in
optical domain as well as in electric domain [2]. The existing GSMP
SHOUD be extended to support of optical, SONET/SDH, and IP packet,
TDM data. The GSMP controller is connected with OXC and needs to be
extended to establish a connection in optical domain.
Recently, data burst switching technology has been emerging to
utilize resources and transport data more efficiently than the
existing circuit switching [3]-[6]. Such a data burst switching is
recognized an alternative switching technology due to the limitation
of optical devices before evolving into optical packet switching.
This draft intends to describe the required elements and updates to
GSMP for high-speed data burst switching. It requires a new
reservation scheme for a connection in a switch fabric in real time.
In optical domain, there are several types of method to establish a
connection before switching data burst [3]-[6]. However we consider
the general method which can allow any types of burst switching
technology. For doing so, in this draft, we consider a reservation
mechanism in the GSMP and requested updates on the message. A switch
controller on a node to provide the required functions for switching
data burst is illustrated. Finally we briefly refer to the required
elements to be expanded in optical domain.
2. Switch control architecture
Figure 1 illustrates a node architecture that is capable of high-
speed data burst switching based on GSMP interface. This node
constitutes optical switching elements that enable data burst
switching in real time and control plane that has signaling protocol
part and data burst switching controller part. Between two blocks,
GSMP master and slave controller perform all required switching
functions for making it possible to switching data burst in real time.
The detailed description of each block is following.
The key functions of data burst switching controller are as follows.
The ingress node assembles IP packets into bursts. When the burst is
at the head of the burst queue, this controller determines the offset
time value to be used for this burst and launch a control packet that
contains information about this offset time, the length of the burst,
and routing information [7]. It also transmits the control
information to the GSMP controller in control plane.
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GMPLS Signaling protocol, such as CR-LDP and RSVP-TE, which supports
optical switching is used in control plane. This signaling protocol
MUST setup optical label switched path (LSP) before data transmission
and release resources.
We use the GSMP interface for real-time optical switch control. In
this interface which is composed of master and slave, the controller
(e.g., GSMP Master) issues the reservation request message to the
optical switch (e.g., GSMP Slave). The switch replies with a response
message indicating either a successful result or a failure. We use
the existing GSMP protocol procedure but a particular message MUST be
extended to include the required information for data burst switching
in optical switching element. Data burst switching unit in optical
switching element executes the control commands received by GSMP
interface.
+------------------------------+
| Control plane |
| +------------+ |
| | Signaling | |
----------->| | Protocol | |----------->
| +------------+ |
| +--------------------------+ |
----------->| | Data Burst | |----------->
| | Switching Controller | |
| +--------------------------+ |
| +--------------------------+ |
| | GSMP Master | |
| +--------------------------+ |
+---------------------^--------+
| GSMP |
| Message |
| |
+--------V---------------------+
| +--------------------------+ |
| | GSMP Slave | |
| +--------------------------+ |
| +--------------------------+ |
| | Data Burst Switching Unit| |
| +--------------------------+ |
| --- --- |
---------->| \ / |---------->
| \ / |
---------->| \ |---------->
| / \ |
---------->| / \ |---------->
| --- --- |
+------------------------------+
Optical Switching Element
Figure 1. Node architecture for burst switching using GSMP interface
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3. Reservation management for optical burst switching using GSMP v3
3.1. Reservation methods
Optical data burst switching can be implemented by reserving
bandwidth when a connection request is arrived at an ingress node.
During reservation process in intermediate nodes each GSMP switch
controller should control bandwidth reservation management for the
connection. There are several reservation schemes for data burst
switching in real time [3]-[6]. They differ from the way of
indicating the end of a burst and the allocation time of a WDM
channel start. However, a common feature is that bandwidth for data
burst is reserved using a one-way reservation process and a burst can
cut through intermediate nodes.
In the existing fast circuit switching for data burst, when an
intermediate node receives a connection request message, GSMP
controller makes use of a reservation management for reserving a
bandwidth for the connection. The existing defined reservation
message can be applied for reserving and establishing a connection in
this case. After sending the whole data burst the following
connection release message is sent to the destination node to release
the reserve bandwidth and disconnect the connection. The whole
process of reservation management and control follows that defined in
GSMP v3 [1].
The above data burst switching based on the fast circuit switching
reserves the whole bandwidth from the time that receives a connection
request message and to the time that receives a connection release
message. Therefore it wastes the bandwidth excessively. A new data
burst switching technology that overcomes the shortcoming has been
proposed and studied [3]-[5]. In this scheme, information about the
start time for bandwidth reservation the exact duration of data burst
is delivered in control packet. A node that receives such a control
packet reserves resource to establish and release a connection more
delicate duration using GSMP control mechanism. Since the control
packet already contains the duration of data burst, an explicit
release message does not required.
Even though several switching options for data burst, we consider a
general reservation scheme which allows all kinds of switching
techniques.
3.2. Reservation Request Message for optical burst switching
In this section we define a required elements and updates to the
existing GSMP and propose an extended Reservation Request message in
order to enable such a optical data burst switching.
The Reservation Request message creates a Reservation in the
switch and reserves switch resources for a connection that may
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later be established using an Add Branch message [1]. In optical data
burst switching, the Reservation Request Message is:
Message Type = 70
It uses the same message type as the existing message. The
Reservation Request message has the following format for the
request message:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Version | Message Type | Result | Code |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Partition ID | Transaction Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|I| SubMessage Number | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Port Session Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reservation ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Input Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Input Service Selector |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Output Port |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Output Service Selector |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|IQS|OQS|P|x|N|O| Adaptation Method |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x|S|M|B| |
+-+-+-+-+ Input Label |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|x|S|M|R| |
+-+-+-+-+ Output Label |
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When the value of either IQS or OQS is set to 0b10 then the
following Traffic Parameters Block is appended to the above
message:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Input TC Flags |x x x x x x x x x x x x x x x x x x x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Input Traffic Parameters Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Output TC Flags|x x x x x x x x x x x x x x x x x x x x x x x x|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
~ Output Traffic Parameters Block ~
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note: Field and Parameters will not be explained in this draft.
Please refer to GSMP v3 [1] for details.
We define the new service to support optical data burst switching.
This service includes the following definitions.
Service Identifier
The new reference number which is used to identify optical data
burst switching in GSMP messages MUST be defined.
Example: Optical Burst Switching - Service ID : XXXX
Service Characteristics
- see Appendix.
Traffic Parameters
- Offset Time (T)
- Burst Length (L)
QoS Parameters
- TBD.
Traffic Controls
- TBD.
Format and encoding of the Traffic Parameters is:
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0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Offset Time (T) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Burst Length (L) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Offset Time (T)
This field is the time between each burst and its control
packet.
Burst Length (L)
This field is the time duration of data burst
4. Other considerations
This draft focus on reservation procedures to control data burst
switching element. To support data burst switching control, the
switching element is controlled and managed by GSMP protocol without
other control protocol. This mechanism allows GSMP controller of IPы
based control plane to direct control optical switching elements.
Several concepts for optical switching such as optical labels and
service and resource abstractions SHOULD be extended to GSMP [2]. We
are studying about these issues.
5. Security Considerations
This document does not have any security concerns. The security
requirements using this document are described in the referenced
documents.
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Appendix. Data burst switching in optical domain
1. Definition and features of optical burst switching
Data burst switching in optical domain is called as an optical burst
switching (OBS). Burst switching, as opposed to circuit or packet
switching, implies that the network is capable of switching variable
length of data. Basically, the core idea of optical burst switching
is to use no buffers inside the network and to switch variable length
of bursts on the flying using a reservation mechanism. Intermediate
nodes are only configured for a short period of time, just enough to
pass data burst, and are available to switch other data bursts
immediately after. In present day, packet switching in optical domain
has severe limitations on optical devices, such as the lack of
optical memory, difficulty of synchronization and packet header
processing. Therefore, no buffering in a node is the main advantage
of optical burst switching to implement.
Compared with packet switching and circuit switching, optical burst
switching has the following differences [4]; A data burst has an
intermediate granularity. Bandwidth is reserved in one-way process
that a burst can be sent without an acknowledgement for a successful
reservation. A burst passes through intermediate nodes without being
buffered. Optical burst switching, compared to optical circuit
switching based on wavelength routing, can achieve better bandwidth
utilization because it allows statistical sharing of each wavelength
among flows of bursts that may otherwise consume several wavelength.
In OBS, a data burst will have a shorter end-to-end latency since the
offset time used is often much smaller than the needed time to set up
a path in wavelength-routed networks. On the other hand, optical
burst switching has lower control overhead compared to optical packet
switching because the burst size can be variable and usually longer
than packet size. Moreover, a control packet and its corresponding
data burst can be loosely coupled in both space (by using out of band
signaling) and time (timing gap between control packet and data
burst) than a header and its payload in optical packet switching.
Therefore, the requirements for processing control packets and
synchronizing between data bursts can be less strict than those for
processing packet headers and synchronizing between packets.
2. Types of optical burst switching technology
Various types of optical burst switching technology have been
proposed and they are distinguished by the way of indicating the end
of a burst and the allocation time of a WDM channel start [3]-[6].
That is, how to open a connection and how to close the connection are
the key features of them. A common feature is that bandwidth is
reserved at the burst level using a one-way reservation process and a
burst can cut through intermediate nodes.
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We briefly introduce three representative data burst switching
technologies and consider implementing aspect.
First, burst switching based on "tell-and-go (TAG)" is similar to
fast circuit switching not requiring acknowledgement [3]-[4]. This
switching scheme is also called as just-in-time (JIT) [6]. A source
node first sends a control packet (or signaling message) just ahead
of the data burst in order to reserve bandwidth for a requested
connection. Then a corresponding data burst is transmitted without
waiting for the acknowledgement that bandwidth has been successfully
reserved for the connection. This scheme eliminates the round-trip
waiting time before the information is transmitted. The switching
fabric in the switches is configured for the incoming data burst as
soon as the first signaling message announcing the data burst is
received. Finally the source node sends a release message to
explicitly release the reserved bandwidth. The operational mechanism
is illustrated in Figure 2 [6].
A B C D
setup
<----->
|\ |
| \ |
| \ switch |
| \ configured|
| | |
|------++ | |
|\ ||\ | |
| \ || \ | | |
| \ || \ V | V
| \| +------+-- processing
| \ ++-----+-- delay
| \ || | ^
| \|| | |
| \ Data \ |
| \ burst \ |
|\ \ \ |
| \ ||\ |
| \ || \ |
| ++ \ |
| \ |\ |
| \ || \ |
| \|| \ |
| <---> ++ |
| release \ |
| \ |
| |
A; source node, B,C; intermediate node, D; destination node
Figure 2. Optical burst switching base on JIT
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Let us brief touch a function of a scheduler in an OBS node. The
scheduler needs to keep state information for each data burst
traversing it in order to configure the switching fabric to route the
data burst [6]. This switching scheme requires a single on/off bit
for each switching fabric involved in routing a particular data
burst; on implies the switching element is busy routing a data burst,
off implies the switching element is free to route a new data burst.
For implementing the JIT, the signaling protocol functions and
signaling messages are defined in [6]. Basic functions of signaling
protocol are session declaration, path setup, data transmission,
state maintenance, and path release. The basic message types are
session declaration, setup, setup_ack, declaration_ack, connect,
session release, release, keepalive, and failure.
Second, in in-band-terminator based burst switching, control
information for establishing a connection is sent as either in-band
control or out-of-band control, followed by a burst which contains an
in-band-terminator (IBT) to indicate the end of the burst [3]-[4].
Bandwidth is reserved as soon as the control information is processed,
and released as soon as the IBT is detected. A challenge of
implementing IBT-based burst switching in optical networks is to
optically recognize the IBT, which requires optical processing.
Finally, in reserved-a-fixed-duration (RFD) based on burst switching,
a control packet is sent first to reserve bandwidth, followed by data
after an offset time [3]-[6]. The bandwidth is reserved for a
duration specified by the control packet. With offset time and data
burst duration information to predict the star time and end time of
the data burst this scheme can utilize resource more efficiently than
the above switching schemes. Because this scheme reserves the
resource for the connection for requested data burst just enough time
for transmitting the data burst. Therefore, it is also called a just-
enough-time (JET) burst switching. As such, this scheme does not need
any release or termination mechanism. By choosing the offset time
among the data bursts with different services quality of service can
be provided and the probability of successful transmission of the
burst through the network [3]. The two representative features are
delayed reservation which reserves the bandwidth on each link just
for the data burst duration after offset time and delay of the
arrival of the data burst which reduces blocking probability. However,
one drawback of this switching is implementation complexity.
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A B C D
setup
<----->
|\ |
| \ |
| \ switch |
| \ configured|
| | |
| | | |
|\ | \ | |
| \ ++ \ | | |
| \ || \ V | V
| \| |------+-- processing
| \ |------+-- delay
| \ ++ | ^
|\ \|| | |
| \ Data \ |
| \ burst \ |
| \ \ |
| ||\ |
| ++ \ |
| \ |
| |\ |
| || \ |
| ++ \ |
| |
| |
A; source node, B,C; intermediate node, D; destination node
Figure 3. Optical burst switching base on JET
3. Implementing consideration of optical burst switching
In Optical burst switching a switch fabric should operate and
reconfigure in nanoseconds, and hence can support of the dynamic data
burst transmission. Requirements of optical switching device for
implement OBS are following; fast reconfigurability, low-loss and
negligible polarization effects, wavelength independence, transfer of
individual wavelengths or wavelength bundles, simple to manufacture,
competitive const, and so on [8]. The switching device technology
needs to be complemented by a switch fabric architecture that
combines the individual optical switching device technology and
delivers the capabilities of OBS. The burst switching capable switch
fabric should scale to several hundreds of ports and intelligent
scheduling algorithms are needed to control the reconfiguration of
switching elements.
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References
[1] Avri Doria., et al. "General Switch Management Protocol V3",
Internet-Draft draft-ietf-gsmp-11, work in progress, December
2001.
[2] Georg Kullgren, et al. "Requirements for adding optical support
to GSMPv3", Internet-Draft draft-ietf-gsmp-reqs-01, work in
progress, February 2002.
[3] C. Qiao, M. Yoo, "Choice, and Feature and Issues in Optical
Burst Switching", Optical Net. Mag., vol.1, No.2, Apr.2000,
pp.36-44.
[4] C. Qiao, "Labeled Optical Burst Switching for IP over WDM
Integration", IEEE Comm. Mag., Sept. 2000, pp.104~114.
[5] Yijun Xiong, Marc Vandenhoute, Hakki C. Cankaya, "Control
Architecture in Optical Burst-Switched WDM Networks", IEEE JSAC,
Vol.18, No.10, Oct. 2000.
[6] 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., Fab. 2002.
[7] Sanjeev Verma, et al. "Optical burst switching: a viable
solution for terabit IP backbone", IEEE network, pp. 48-53,
Nov/Dec 2000.
[8] Albert Leon-Garcia, "Photonic Burst Switching", whitepaper,
Accelight networks, March 2001.
Acknowledgments
This work was supported in part by the Korean Science and Engineering
Foundation (KOSEF) through OIRC project.
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Author's Addresses
Jun Kyun Choi
Information and Communications University (ICU)
58-4 Hwa Ahm Dong, Yuseong, Daejeon
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, Yuseong, Daejeon
Korea 305-732
Phone: +82-42-866-6136
Email: mhkang@icu.ac.kr
Gyu Myoung Lee
Information and Communications University (ICU)
58-4 Hwa Ahm Dong, Yuseong, Daejeon
Korea 305-732
Phone: +82-42-866-6231
Email: gmlee@icu.ac.kr
Jung Yul Choi
Information and Communications University (ICU)
58-4 Hwa Ahm Dong, Yuseong, Daejeon
Korea 305-732
Phone: +82-42-866-6208
Email: passjay@icu.ac.kr
Young Wook Cha
Andong National University (ANU)
388 Song-chon Dong, Andong, Kyungsangbuk-do
Korea 760-749
Phone: +82-54-820-5714
Email: ywcha@andong.ac.kr
Woo Seop Rhee
Electronics and Telecommunications Research Institute (ETRI)
161 Kajeong, Youseong, Daejeon
Korea 305-350
Phone: +82-42-860-5324
Email: wsrhee@etri.re.kr
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Document: draft-choi-gsmp-optical-extension-00.txt
Expiration Date: December 2002
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