Internet Draft Dan Guo, Jibin Zhan,
draft-guo-optical-aps-00.txt Wenjing Chu, Hui Zhang
July 2001 (Turin Networks)
Nasir Ghani, James Fu,
Zhensheng Zhang
(Sorrento Networks)
Dimitrios Pendarakis
(Tellium)
Expiration Date: Jan 2002 Sudheer Dharanikota
(Nayna Networks)
Optical Automatic Protection Switching Protocol (O-APS)
<draft-guo-optical-aps-00.txt>
Status of this Memo
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provisions of Section 10 of RFC2026.
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1. Abstract
We describe an optical automatic protection switching protocol (O-APS)
for optical rings. Specifically, the O-APS protocol is an IP-based
light-weight protocol which exploits the characteristics of rings and
initially supports the optical ring protection on the Optical Channel
(OCh) level. The O-APS protocol can also be used for mesh networks,
when we view two diverse lightpaths for 1+1 or 1:1 mesh protection as
a logical Optical Channel Dedicated Protection Ring. Functionally the
O-APS protocol can be viewed as an optical version of the ubiquitous
SONET APS (Automatic Protection Switching) protocol using K1/K2 bytes.
The O-APS protocol performs only protection signaling, independent of
fault detection and lightpath provisioning mechanisms. The operational
model for O-APS is made compatible with SONET APS protocol, due to the
wide-spread adoption of SONET APS in many operators' networks.
2. Conventions used in this document
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.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 1]
3. Introduction
With rapid development of optical add-drop multiplexer (O-ADM) and
optical cross-connect (OXC) technologies, optical ring networks emerge
as a natural migration choice for operators with existing SONET/SDH
networks. Optical rings are of importance due to the large installed
base of fiber rings and the extensive OAM&P experience on SONET/SDH
rings. In [GHANI], we have provided a generic architectural framework
for optical rings.
One important feature for dynamic optical rings is their ability to
provide fast protection and restoration functionality. Various optical
ring protection schemes have been specified in [GR-2979]. Given the
stringent protection and restoration requirements, there is a strong
need for developing a lightweight O-APS protocol, functionally viewed
as an optical equivalent of the ubiquitous SONET/SDH APS (Automatic
Protection Switching) protocol using K1/K2 bytes. The O-APS protocol
is an IP-based protocol and exploits the characteristics of rings to
support optical ring protection on OCh level initially and on OMS level
in a future revision. It should be noted that the O-APS protocol per-
forms only protection signaling upon fault events and not setup pro-
visioning or fault detection. This protocol can be considered as an
orthogonal addition to the GMPLS protocols suite to achieve fast
protection signaling.
Overall, the O-APS protocol is a specialized automatic protection
switching protocol designed for optical rings and adopts an operational
model similar to that of SONET/SDH. Note that two diverse lightpaths for
1+1 or 1:1 mesh protection can be viewed as a logical Optical Channel
Dedicated Protection Ring (OCh DPRing). Due to this shared characteristic
between path level 1+1 or 1:1 mesh protection schemes and the OCh DPRing
protection scheme, the O-APS protocol can also be used for mesh networks.
This draft first describes the motivation for introducing the O-APS
protocol. We then shift the focus to the requirements (including
architectural, functional, and operational requirements) of the O-APS
protocol. Subsequently, the O-APS protocol engine and particularly the
related O-APS message formats are also briefly specified.
4. Motivation for the O-APS Protocol
This section describes the motivations for developing an O-APS protocol.
4.1 Support for Unique Protection Features of Optical Networks
The unique protection features of optical rings are specified in the
ITU-T G841 and Telcordia GR-2979 documents. To operators, a major
attraction of optical rings is their inherent ability to provide fast
protection and restoration. Expectedly, operators will likely demand
stringent "SONET/SDH-like" protection performance for related optical
rings. To date, however, an optical protection switching protocol for
optical rings has not been defined. The unique protection switching
features and requirements for optical rings warrant a specialized
lightweight O-APS protocol.
Additionally, because two diverse lightpaths in mesh networks can form
a logical Optical Dedicated Protection Ring (OCh-DPRing), the O-APS
protocl designed for optical rings can also be used to support path
level 1+1 or 1:1 mesh protection schemes.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 2]
4.2 Interoperability at Optical Ring Level
Given the large number of equipment vendors building optical rings,
there is a strong need for multi-vendor interoperability at the optical
ring level. Here the O-APS protocol definition will increase interoper-
ability amongst equipment from different vendors.
4.3 Enabling Efficient Operational Control
Functionally, the O-APS protocol can be viewed as an optical equivalent
of the field-proven SONET/SDH APS protocol. Operators have accumulated
significant OAM&P experience with SONET/SDH APS. We choose to adopt an
operational model for O-APS similar to that of SONET/SDH APS. Addition-
ally, O-APS will facilitate network management required for efficient
operational control of optical ring networks.
4.4 Performance Consideration
The performance benchmark for protection switching that is commonly cited
is protection switching within a 50 ms time window (as derived from SONET/
SDH). Admittedly this is a challenging task for optical network designers.
In order to miminize overhead, the O-APS protocol is purposely built for
optical rings with no dependence on GMPLS. It only performs protection
signaling upon fault events and not any setup provisioning. Furthermore,
it is independent of the exact fault detection module, as this is closely
related to the underlying specific technology.
5. O-APS Requirements
This section describes the protocol requirements for O-APS, including
architectural, functional and operational requirements. As expected,
various technology-specific design issues are intentionally left open in
order to permit proprietary value-added implementation.
5.1 Overview of Optical Rings
An optical ring is defined as a two or four fiber ring on which all of
nodes are either dynamic OADM or OXC nodes. These network elements can
utilize all-optical (i.e., transparent) or opto-electronic (i.e., opaque)
designs (see [GHANI]). Optical ring protection switching schemes have
been specified in various standards documents (e.g., ITU-T G.841 and
Telcordia Generic Requirement documents GR 2979, GR 2918). The various
possible optical rings are listed as follows:
- Optical Channel Dedicated Protection Ring (OCh-DPRing). Dedicated
protection can also be provided through single optical Channel (1+1)
Sub-network Connection Protection (OCh-SNCP). Note that two diverse
lightpaths provisioned in mesh networks can be viewed as a logical
Optical Dedicated Protection Ring (OCh-DPRing) (see [PAPAD]).
- Optical Channel Shared Protection Ring (OCh-SPRing) or O-BPSR (Optical
Bi-directional Path Switched Ring) exist in two flavors, 2-Fiber
O-BPSR (O-BPSR/2) and 4-Fiber O-BPSR (O-BPSR/4). Additionally, there
are two switching strategies, ring switching (2- and 4-Fiber) and span
switching (4-Fiber only).
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 3]
- Optical Multiplex-Section Dedicated Protection Ring (OMS-DPRing) or
Optical Unidirectional Line Switched Ring (O-ULSR).
- Optical Multiplex-Section Shared Protection Ring (OMS-SPRing) or
Optical Bi-directional Line Switched Ring(O-BLSR ) exists in 2
variants, namely 2 Fiber O-BLSR (O-BLSR/2) and 4-Fiber O-BLSR (O-
BLSR/4). Additionally, there are two switching strategies here, ring
switching and span switching.
Furthermore, related equivalence between linear (mesh networks) and ring
protection schemes is presented in the following table:
Linear Protection Ring Protection
--------------------------------------------------------------------
Dedicated Line Protection (1+1, 1:1) OMS-DPRing
Shared Line Protection (1:N) OMS-SPRing
Dedicated Path Protection (1+1, 1:1) OCh-DPRing
Shared Path Protection (1:N) OCh-SPRing
For more details on optical ring protection switching schemes, refer to
[GR 2979] and [GHANI].
5.2 O-APS Functional Requirements
The O-APS protocol will support the protection and restoration features
outlined above. In this draft, we limit the scope to ring protection at the
optical channel (OCh) level, but will expand the scope to include support at
the OMS level in future revisions. The ring protection at the OCh level
provides an efficient support for path-level 1+1 and 1:1 mesh protection
schemes through logical rings (or ring emulations). For detailed discussions
regarding ring emulations of mesh networks, see [PAPAD].
For optical rings, three types of traffic are considered:
- Normal traffic carried on working channel and protected by O-APS;
- Extra traffic, carried on protection channel and preemptible;
- Non-preemptible Unprotected Traffic (NUT).
5.3 O-APS Architectural Requirements
There are several possibilities that can be taken into account when
designing the O-APS protocol. For example, it can be frame-based and built
on top of the data link layer, or packet-based and built on top of IP.
Each of these approaches has its advantages and disadvantages. In this
draft, we use a packet-based approach, i.e., the O-APS protocol is directly
layered on top of raw IP (instead of TCP or UDP). The protocol number for
O-APS is to be assigned.
Furthermore, it is assumed that O-APS packets are transported on control
channels, through the optical supervision channels (OSC). (Although in-band
signaling through digital wrapper overheads is another choice, this is left
for future study). It should be noted that when using OSC for transporting
O-APS packets, O-APS packets must be assigned the highest priority for
expedited processing.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 4]
Additionally, the O-APS protocol must provide a fast dedicated "hello"
mechanism for optical rings. This "hello" mechanism is for inter-node keep-
alive messaging purpose, enabling the rapid detection of control channel
failures. Functionally, this is similar to non-alarm K1/K2 byte fields in
the SONET/SDH APS protocol and the "hello" message defined in the Link
Management Protocol (LMP) (see [LMP]).
Finally, note that due to reliability considerations, the O-APS protocol
also introduces retransmission mechanism. Specifically, after an O-APS
message is sent, it is also added into a re-transmission queue associated
with a timer. Since the protocol is IP-based, a fast re-transmission
mechanism is required. For example, an O-APS message can be lost when
transported over the control channel. Therefore, under normal operation,
an O-APS message will be acknowledged via another O-APS message. The exact
message exchange mechanisms (including retransmission, acknowledgement, and
time-out) are intricately associated with the details of the finite-state
machine (FSM) of the protocol engine.
5.4 Protection Switching Performance Requirements
The O-APS protocol needs to achieve reliability, recovery and restoration
performance levels that are comparable to those of the traditional SONET/SDH
APS protocol.
1) Switch time. In an optical ring with no extra traffic and all nodes in
the idle state (i.e., no detected failures, no active automatic. or
external commands), the ring and span switching completion time for a
failure on a single span shall be less than 50 ms. On rings under all
other conditions, the switching completion time can exceed 50 ms in order
to allow time for removing extra traffic, or for negotiating co-existed
O-APS requests.
Note that the protection switching completion time excludes the fault
detection time necessary to initiate the protection switching.
2) Extent of protection. O-APS protection shall restore all normal traffic
(i.e., excluding extra traffic and NUT) which has been interrupted due
to failure of a link connection and that has been designated as forming
part of an optical ring protection scheme.
5.5 O-APS Operational Requirements
The O-APS protocol adopts an operational model similar to that of SONET/
SDH APS. This will assist the migration to optical rings, owing to the
wide-spread adoption of SONET APS. The O-APS protocol should also allow
operators to set up switch initiation criteria. The following initiation
features shall be supported:
- Signal Failure (SF);
- Signal Degrade (SD);
- Reverse Request;
- Wait-To-Restore.
The operational modes for O-APS are the following:
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 5]
- Revertive/non-revertive modes: Revertive mode shall be provided. In
this mode, when protection is no longer requested (i.e., the failed
working section is no longer in SD or SF condition) and assuming that
no other requesting sections exist, a local wait-to-restore state
shall be activated.
A switch shall only revert to the working channels and not to a
different set of protection channels.
- Operator-control. The following externally initiated commands shall
be supported: 1) Lockout, 2) Forced Switch, and 3) Manual Switch.
Note that the O-APS protocol can work with a centralized provisioning
solution since it is decoupled from GMPLS. This feature is useful
because some operators may want to deploy GMPLS-based control plane at
later time.
Despite the above-mentioned similarities, O-APS and SONET/SDH APS are
distinctly different. In particular, SONET/SDH APS is designed for TDM
networks whereas O-APS is intended for optical WDM rings. SONET/SDH APS
is performed via in-band signaling whereas O-APS is designed to be IP-
based. Fundamentally, these two protocols support different protection
switching mechanisms.
6. O-APS Protocol Engine
6.1 Architecture
The overall O-APS protocol interworking architecture is described in
the following diagram:
+--------------------+ +-------------------+
| O-APS Protocol | | Resource/TE |
| Engine |<------------> | Manager |
+--------------------+ +-------------------+
^ ^
| |
v v
+--------------------+ +-------------------+
| Control Channel | | Performance |
| Device Driver | | Monitor (PM)/ |
| | | Fault manager |
+--------------------+ +-------------------+
Fig 1. O-APS Interworking Diagram
The O-APS protocol engine works very closely with resource/traffic
engineering (TE) manager. The latter entity maintains all information
regarding the ring map and the protection groups provisioned at a node.
Meanwhile, the performance monitor and fault manager monitors the light-
paths at a node and triggers fault events towards the resource/TE manager.
O-APS events can be triggered locally and relayed to the O-APS protocol
engine.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 6]
When a new protection group is provisioned or a protection group under-
goes any change in status (i.e., during faults, forced deletions, or
modifications regarding protection path and working path), the resource/
TE manager notifies the O-APS protocol engine. Note that O-APS messages
can be sent to and received from other nodes via the control channel.
6.2 O-APS Protocol Description
The O-APS protocol engine has a related finite state machine (FSM) that
coordinates the O-APS event-handling and state transition. It is possible
to devise separate FSMs for different optical ring protection switching
schemes (e.g., there would be one FSM for OCh DPRing and another FSM for
OCh SPRing). This strategy is both effective and necessary, due to the
unique features of each optical ring protection scheme.
For each protection scheme, there are various specific O-APS events. Due
to their complexity, we will leave those for a future revision of this
draft. Note that it is possible to devise different ways to represent
the internal states and thus different FSM entities for the same protocol.
This aspect leads us to act cautiously on standardizing the O-APS events,
states, and FSMs. As an example, in this draft, we list the following
events and states for OCh-DPRing:
OAPS_CONNECTION_FAIL: Primary-connection fails;
OAPS_CONNECTION_TEAR: Protection group is torn down;
OAPS_BRIDGE_REQUEST: Bridge-request for this protection group;
OAPS_BRIDGE_INDICATION: Bridge-indication for this protection group;
OAPS_SWITCH_CONFIRM: Switch-confirm for this protection group;
OAPS_BRIDGE: Inform OXC to "bridge" at source node;
OAPS_SWITCH: Inform OXC to "switch" at sink node;
OAPS_TIME_OUT: Timer expiration
OAPS_ERROR: Invalid event
OCh-DPRing handles each protection group independently. A protection
group consists of a primary (working) path and a secondary (protection)
path. Note that here the terms "bridge" and "switch", commonly used in
SONET/SDH APS terminology, have different meanings. Specifically, "bridge"
refers to conducting protection switching at the source node of a uni-
directional path and "switch" refers to conducting protection switching
at the sink node of a uni-directional path.
OCh-DPRing will have 6 major FSM states, each of which could have further
sub-states:
OAPS_PG_INIT: Protection group is in idle state
OAPS_PG_BRIDGE_INITIATED: Protection group is in bridge-initiated state;
OAPS_PG_BRIDGED: Protection group is in bridged state;
OAPS_PG_SWITCHED: Protection group is in switched state;
OAPS_PG_BRIDGED_SWITCHED: Protection group is in bridged/switched state;
OAPS_PG_FAIL, Protection group is in failure state.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 7]
To illustrate the behavior of O-APS for OCh-DPRing, a potential interaction
between an O-APS protocol engine and a resource manager is described:
1. When a new protection group is provisioned, the resource manager
informs the O-APS protocol engine which sets up an internal "control"
block with a state "OAPS_PG_INIT";
2. When a fiber span of a working connection fails, an "OAPS_CONNECTION_
FAIL" event will be detected at the sink node (say node A). Here, a
"BRIDGE-REQUEST" event is generated, packaged into an O-APS message,
and sent via the control channel to the source node (say node B) of
this connection. Subsequently, the state is transited to "OAPS_PG_BRIDGE
_INITIATED" for this protection group.
As in SONET APS, actually two messages are sent around the ring, one
east bound and the other west bound. The event types (and additional
information) are coded into K1/K2 bytes of an O-APS message (see
section 7);
3. Upon receiving a "BRIDGE-REQUEST" event, the source node (node B) will
conduct protection switching and transition to "OAPS_PG_BRIDGED" state.
Subsequently, node B triggers an "OAPS_BRIDGE_INDICATION" event and an
O-APS message towards node A.
4. Upon receiving "OAPS_BRIDGE_INDICATION", node A will send an event
"OAPS_SWITCH" to tell the local OXC to perform protection switching.
The above description handles only "half" of protection switching, since a
connection is bi-directional. It also does not consider any message re-
transmission and time-out mechanisms. The complete details of the FSM will
be relegated to a future revision of this draft.
7. O-APS Packet Specification
In this section, the O-APS protocol message format is described. The O-APS
messages are encapsulated in IP packets and use an encoding scheme similar
to that of SONET APS. Specifically, each O-APS message consists of a message
header and message body, as detailed subsequently.
7.1 O-APS Packet Header
Each O-APS message carries the following header:
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 Number |O-APS Msg Type | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message sequences |
+---------------------------------------------------------------+
Currently, there are five types of O-APS protection messages.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 8]
O-APS Msg Type Value
----------------------------
HELLO 1
OCh-DPRing 2
OCh-SPRing 3
OMS-DPRing 4
OMS-SPRing 5
7.2 O-APS Message Body
Each O-APS event is encoded into an O-APS message. An O-APS message should
contain a protection group identifier (PG ID) to uniquely identify a
protection group. A PG ID consists of the source ID, the destination ID
and the connection ID (assigned when a connection is provisioned).
In addition to the protection group ID, an O-APS message should contain
K1/K2 code to represent specific network events and protection switching
actions. Similar to SONET APS, these codes are split into two parts, termed
K1 and K2, respectively. Both of these codes are two bytes each and defined
as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source ID |
+---------------------------------------------------------------+
| Destination ID |
+---------------------------------------------------------------+
| Connection ID |
+---------------------------------------------------------------+
| K1 | K2 |
+---------------------------------------------------------------+
K1 and K2 Bytes
K1 byte Value
-----------------------------------------------------
K1_OAPS_CONNECTION_FAIL 0xD000
K1_OAPS_BRIDGE_REQUEST 0x7000
K1_OAPS_SWITCH_REQUEST 0xF000
K1_OAPS_CONNECTION_UP 0x9000
K1_OAPS_CONNECTION_DELETE 0xA000
K1_OAPS_BRIDGE_INDICATION 0x6000
K1_OAPS_SWITCH_CONFIRM 0x4000
K1_OAPS_SWITCH_OK 0x5000
K2 byte Value
------------------------------------------------------
K2_LONG 1st bit =1
K2_SHORT 1st bit =0.
Here, "short" side is used to denote the "working" lightpath while the
"long" side is used to denote the "protection" lightpath. We use the
last bit of K2 byte to indicate whether the sender of this O-APS message
is the source node of the protection group:
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 9]
- 8th bit of K2=0: sender is the source node of a protection group;
- 8th bit of K2=1: sender is the destination node of a protection group.
This bit is termed as "direction" bit. Meanwhile, the actual K2 byte is
coded as follows:
K2 byte value
------------------------------------------------------
K2_LONG and as Source node 0x8000;
K2_LONG and as Destination node: 0x8001;
K2_SHORT and as Source node: 0x0000;
K2_LONG and as Destination node: 0x0001.
Additional K1/K2 codes can be defined in a future revision. Note that
SONET/SDH K1/K2 codes can also be mapped into these O-APS K1/K2 fields.
8. Fault Detection
Fault detection mechanisms are independent of the protection and
restoration protocol. There will be information exchange between the
fault detection module and the O-APS protocol engine (as illustrated
in Fig 1).
The O-APS protocol will interwork with the emerging LMP protocol [LMP].
LMP provides generic fault correlation and notification functionalities
that are independent of the actual fault detection schemes. Recent
proposals for new WDM related considerations within the LMP framework
[LMP-WDM] will help improve its scalability and fault notification
timings in optical ring networks. Switching triggers and mapping of LMP
notifications to O-APS need to be defined, and this work is left for
further investigation.
9. Security Considerations
Security considerations are for future study. Overall, it poses the
same security requirements as those present in the SONET APS.
10 Acknowledgements
We would like to thank D. Papadimitriou of Alcatel at Belgium for
helpful discussions and feedbacks during the course of writing this
draft.
11. References
[GR-2979] "Common Generic Requirements for Optical Add-Drop Multiplexers
(OADMs) and Optical Terminal Multiplexers (OTMs), GR-2979-Core, Telcordia
Generic Requirement Documents.
[ANSI-T1.105] "Synchronous Optical Network (SONET): Basic Description
Including Multiplex Structure, Rates, and Formats," ANSI T1.105, 2000.
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 10]
[CVIJETIC1] M. Cvijetic, T. Shiragaki, "Standardization of OCh Shared
Protection Ring and Its Open Issue List," T1X1 Forum, T1X1.5/99-255R1,
October 1999.
[GHANI] N. Ghani, et al, "Architectural Framework for Automatic Protection
Provisioning In Dynamic Optical Rings", draft-ghani-optical-rings-01.txt,
Internet Drafts, March 2001.
[GMPLS-ARCH] E. Mannie, et al., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", Internet Draft, Work in progress,
draft-many-gmpls-architecture-00.txt, February 2001.
[GMPLS-G709] A. Bellato, et al., "Generalized MPLS Signalling
Extensions for G.709 Optical Transport Networks", Internet Draft,
Work in progress, draft-fontana-ccamp-gmpls-g709-00.txt, June 2001.
[GMPLS-RSVP] P. Ashwood-Smith, et al., "Generalized MPLS Signaling
- RSVP-TE Extensions", Internet Draft, Work in progress, draft-ietf-
mpls-generalized-rsvp-te-03.txt, May 2001.
[GMPLS-SIG] P. Ashwood-Smith, et al., "Generalized MPLS - Signaling
Functional Description", Internet Draft, Work in progress, draft-ietf-
mpls-generalized-signaling-04.txt, May 2001.
[LMP-WDM] A. Fredette, et al, "Link Management Protocol (LMP) for WDM
Transmission Systems," Internet Draft, draft-fredette-lmp-wdm-01.txt,
March 2001.
[LMP] J. Lang, et al, "Link Management Protocol (LMP)," Internet
Draft, Work in progress, draft-ietf-mpls-lmp-02.txt, March 2001.
[PAPAD] D. Papadimitriou, "Optical Rings and Hybrid Mesh-Ring Optical
Networks", draft-papadimitriou-optical-rings-01.txt, Internet Drafts,
Work in progress, May 2001.
12. Author's Addresses
Dan Guo, Jibin Zhan, Wenjing Chu, Hui Zhang
Turin Networks, Inc.
1415 N. McDowell Blvd, Petaluma, CA 95454
Phone: +1 707-665-4357
Email: {dguo,jzhan,wchu,hzhang}@turinnetworks.com
Nasir Ghani, James Fu, Zhensheng Zhang
Sorrento Networks, Inc.
9990 Mesa Rim Road, San Diego, CA 92121
Email: {nghani,jfu,zzhang}@sorrentonet.com
Dimitrios Pendarakis
Tellium Optical System
2 Crescent Place, Oceanport, NJ 07757-0901
Email: DPendarakis@tellium.com
Sudheer Dharanikota
Nayna Networks, Inc.
157 Topaz Street, Milpitas, CA 95035, USA
Email: sudheer@nayna.com
Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 11]
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Internet Draft D. Guo et al, draft-guo-optical-aps-00.txt [Page 12]