draft-ietf-ccamp-sdhsonet-control-04.txt   draft-ietf-ccamp-sdhsonet-control-05.txt 
Network Working Group G. Bernstein (Grotto Networking) Network Working Group G. Bernstein (Grotto Networking)
Internet Draft E. Mannie (InterAir Link) Internet Draft E. Mannie (InterAir Link)
Category: Informational V. Sharma (Metanoia, Inc.) Category: Informational V. Sharma (Metanoia, Inc.)
E. Gray (Marconi Communications) E. Gray (Marconi Communications)
Expires March 30, 2005 September 2004 Expires August 2005 February 2005
Framework for GMPLS-based Control of SDH/SONET Networks Framework for GMPLS-based Control of SDH/SONET Networks
<draft-ietf-ccamp-sdhsonet-control-04.txt> <draft-ietf-ccamp-sdhsonet-control-05.txt>
Status of this Memo Status of this Memo
This document is an Internet-Draft and is subject to all provisions This document is an Internet-Draft and is subject to all provisions
of section 3 of RFC 3667 [1]. By submitting this Internet-Draft, of section 3 of RFC 3667 [1] and Section 6 of RFC 3668 [2].
each author represents that any applicable patent or other IPR
claims of which he or she is aware have been or will be disclosed, By submitting this Internet-Draft, each author represents that any
and any of which he or she becomes aware of will be disclosed, in applicable patent or other IPR claims of which he or she is aware
accordance with RFC 3668 [2]. have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as reference at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
GMPLS consists of a suite of protocol extensions to MPLS to make Generalized MPLS (GMPLS) is a suite of protocol extensions to MPLS
these protocols more generally applicable, to include - for example (Multi-Protocol Label Switching) to make it generally applicable, to
- control of non-packet based switching, and particularly, optical include - for example - control of non packet-based switching, and
switching. One area of prime consideration is to use Generalized particularly, optical switching. One consideration is to use GMPLS
MPLS (GMPLS) protocols in upgrading the control plane of optical protocols to upgrade the control plane of optical transport networks.
transport networks. This document illustrates this process by This document illustrates this process by describing those extensions
describing those extensions to GMPLS protocols that are directed to GMPLS protocols that are aimed at controlling Synchronous Digital
towards controlling SDH/SONET networks. SDH/SONET networks make Hierarchy (SDH) or Synchronous Optical Networking (SONET) networks.
very good examples of this process since they possess a rich SDH/SONET networks make good examples of this process for a variety
multiplex structure, a variety of protection/restoration options, of reasons. This document high-lights extensions to GMPLS-related
are well defined, and are widely deployed. The document discusses routing protocols to disseminate information needed in transport path
extensions to GMPLS routing protocols to disseminate information computation and network operations, together with (G)MPLS protocol
needed in transport path computation and network operations, extensions required for the provisioning of transport circuits. New
together with the extensions to GMPLS label distribution protocols capabilities that an GMPLS control plane would bring to SDH/SONET
needed for the provisioning of transport circuits. New capabilities networks, such as new restoration methods and multi-layer circuit
that an GMPLS control plane would bring to SDH/SONET networks, such establishment, are also discussed.
as new restoration methods and multi-layer circuit establishment,
are also discussed.
Internet Draft Expires March 2005 Page 1
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
1. Introduction.................................................3 1. Introduction ................................................3
1.1. MPLS Overview..............................................3 1.1. MPLS Overview .............................................3
1.2. SDH/SONET Overview.........................................4 1.2. SDH/SONET Overview ........................................4
1.3. The Current State of Circuit Establishment in SDH/SONET 1.3. The Current State of Circuit Establishment in SDH/SONET
Networks...................................................7 Networks ..................................................7
1.3.1. Administrative Tasks...................................7 1.3.1. Administrative Tasks ..................................7
1.3.2. Manual Operations......................................7 1.3.2. Manual Operations .....................................7
1.3.3. Planning Tool Operation................................7 1.3.3. Planning Tool Operation ...............................7
1.3.4. Circuit Provisioning...................................8 1.3.4. Circuit Provisioning ..................................8
1.4. Centralized Approach versus Distributed Approach...........8 1.4. Centralized Approach versus Distributed Approach ..........8
1.4.1. Topology Discovery and Resource Dissemination..........9 1.4.1. Topology Discovery and Resource Dissemination .........9
1.4.2. Path Computation (Route Determination).................9 1.4.2. Path Computation (Route Determination).................9
1.4.3. Connection Establishment (Provisioning)...............10 1.4.3. Connection Establishment (Provisioning)...............10
1.5. Why SDH/SONET will not Disappear Tomorrow.................11 1.5. Why SDH/SONET will not Disappear Tomorrow ................11
2. GMPLS Applied to SDH/SONET..................................12 2. GMPLS Applied to SDH/SONET .................................12
2.1. Controlling the SDH/SONET Multiplex.......................12 2.1. Controlling the SDH/SONET Multiplex ......................12
2.2. SDH/SONET LSR and LSP Terminology.........................13 2.2. SDH/SONET LSR and LSP Terminology ........................13
3. Decomposition of the GMPLS Circuit-Switching Problem Space..13 3. Decomposition of the GMPLS Circuit-Switching Problem Space .13
4. GMPLS Routing for SDH/SONET.................................14 4. GMPLS Routing for SDH/SONET ................................14
4.1. Switching Capabilities....................................15 4.1. Switching Capabilities ...................................15
4.1.1. Switching Granularity.................................15 4.1.1. Switching Granularity ................................15
4.1.2. Signal Concatenation Capabilities.....................16 4.1.2. Signal Concatenation Capabilities ....................16
4.1.3. SDH/SONET Transparency................................17 4.1.3. SDH/SONET Transparency ...............................17
4.2. Protection................................................18 4.2. Protection ...............................................18
4.3. Available Capacity Advertisement..........................21 4.3. Available Capacity Advertisement .........................21
4.4. Path Computation..........................................22 4.4. Path Computation .........................................22
5. LSP Provisioning/Signaling for SDH/SONET....................22 5. LSP Provisioning/Signaling for SDH/SONET ...................22
5.1. What do we Label in SDH/SONET? Frames or Circuits?........23 5.1. What do we Label in SDH/SONET? Frames or Circuits?........23
5.2. Label Structure in SDH/SONET..............................24 5.2. Label Structure in SDH/SONET .............................24
5.3. Signaling Elements........................................24 5.3. Signaling Elements .......................................24
6. Summary and Conclusions.....................................26 6. Summary and Conclusions ....................................26
7. Security Considerations.....................................27 7. Security Considerations ....................................27
8. Acknowledgments.............................................27 8. Acknowledgments ............................................27
9. Author's Addresses..........................................27 9. Author's Addresses .........................................27
10. References..................................................28 10. References .................................................28
10.1. Normative References....................................28 10.1. Normative References ...................................28
10.2. Informative References..................................28 10.2. Informative References .................................28
11. Intellectual Property Statement.............................29 11. Intellectual Property Statement ............................29
12. Disclaimer of Validity......................................30 12. Disclaimer .................................................30
13. Copyright Statement.........................................30 13. Copyright Statement ........................................30
14. Acknowledgement..............................................30 14. IANA Considerations .........................................30
15. Acronyms ....................................................30
Internet Draft Expires March 2005 Page 2 16. Acknowledgement .............................................31
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
1. Introduction 1. Introduction
The CCAMP Working Group of the IETF has the goal of extending MPLS The CCAMP Working Group of the IETF has the goal of extending MPLS
[3] protocols to support multiple network layers and new services. [3] protocols to support multiple network layers and new services.
This extended MPLS, which was initially known as Multi-Protocol This extended MPLS, which was initially known as Multi-Protocol
Lambda Switching, is now better referred to as Generalized MPLS (or Lambda Switching, is now better referred to as Generalized MPLS (or
GMPLS). GMPLS).
The GMPLS effort is, in effect, extending IP/MPLS technology to The GMPLS effort is, in effect, extending IP/MPLS technology to
skipping to change at line 148 skipping to change at line 143
1.1. MPLS Overview 1.1. MPLS Overview
A major advantage of the MPLS architecture [3] for use as a general A major advantage of the MPLS architecture [3] for use as a general
network control plane is its clear separation between the forwarding network control plane is its clear separation between the forwarding
(or data) plane, the signaling (or connection control) plane, and (or data) plane, the signaling (or connection control) plane, and
the routing (or topology discovery/resource status) plane. This the routing (or topology discovery/resource status) plane. This
allows the work on MPLS extensions to focus on the forwarding and allows the work on MPLS extensions to focus on the forwarding and
signaling planes, while allowing well-known IP routing protocols to signaling planes, while allowing well-known IP routing protocols to
be reused in the routing plane. This clear separation also allows be reused in the routing plane. This clear separation also allows
for MPLS to be used to control networks that do not have a packet- for MPLS to be used to control networks that do not have a
based forwarding plane. packet-based forwarding plane.
An MPLS network consists of MPLS nodes called Label Switch Routers An MPLS network consists of MPLS nodes called Label Switch Routers
(LSRs) connected via circuits called Label Switched Paths (LSPs). An (LSRs) connected via circuits called Label Switched Paths (LSPs). An
LSP is unidirectional and could be of several different types such LSP is unidirectional and could be of several different types such
as point-to-point, point-to-multipoint, and multipoint-to-point. as point-to-point, point-to-multipoint, and multipoint-to-point.
Internet Draft Expires March 2005 Page 3
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
Border LSRs in an MPLS network act either as ingress or egress LSRs Border LSRs in an MPLS network act either as ingress or egress LSRs
depending on the direction of the traffic being forwarded. depending on the direction of the traffic being forwarded.
Each LSP is associated with a Fowarding Equivalence Class (FEC), Each LSP is associated with a Fowarding Equivalence Class (FEC),
which may be thought of as a set of packets that receive identical which may be thought of as a set of packets that receive identical
forwarding treatment at an LSR. The simplest example of an FEC might forwarding treatment at an LSR. The simplest example of an FEC might
be the set of destination addresses lying in a given address range. be the set of destination addresses lying in a given address range.
All packets that have a destination address lying within this All packets that have a destination address lying within this
address range are forwarded identically at each LSR configured with address range are forwarded identically at each LSR configured with
that FEC. that FEC.
skipping to change at line 211 skipping to change at line 203
There are currently two different multiplexing technologies in use There are currently two different multiplexing technologies in use
in optical networks: wavelength division multiplexing (WDM) and time in optical networks: wavelength division multiplexing (WDM) and time
division multiplexing (TDM). This work focuses on TDM technology. division multiplexing (TDM). This work focuses on TDM technology.
SDH and SONET are two TDM standards widely used by operators to SDH and SONET are two TDM standards widely used by operators to
transport and multiplex different tributary signals over optical transport and multiplex different tributary signals over optical
links, thus creating a multiplexing structure, which we call the links, thus creating a multiplexing structure, which we call the
SDH/SONET multiplex. SDH/SONET multiplex.
Internet Draft Expires March 2005 Page 4
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
ITU-T (G.707) [4] includes both the European ETSI SDH hierarchy and ITU-T (G.707) [4] includes both the European ETSI SDH hierarchy and
the USA ANSI SONET hierarchy [5]. The ETSI SDH and SONET standards the USA ANSI SONET hierarchy [5]. The ETSI SDH and SONET standards
regarding frame structures and higher-order multiplexing are the regarding frame structures and higher-order multiplexing are the
same. There are some regional differences in terminology, on the use same. There are some regional differences in terminology, on the use
of some overhead bytes, and lower-order multiplexing. Interworking of some overhead bytes, and lower-order multiplexing. Interworking
between the two lower-order hierarchies is possible using gateways. between the two lower-order hierarchies is possible using gateways.
The fundamental signal in SDH is the STM-1 that operates at a rate The fundamental signal in SDH is the STM-1 that operates at a rate
of about 155 Mbps, while the fundamental signal in SONET is the STS- of about 155 Mbps, while the fundamental signal in SONET is the STS-
1 that operates at a rate of about 51 Mbps. These two signals are 1 that operates at a rate of about 51 Mbps. These two signals are
made of contiguous frames that consist of transport overhead made of contiguous frames that consist of transport overhead
(header) and payload. To solve synchronization issues, the actual (header) and payload. To solve synchronization issues, the actual
data is not transported directly in the payload but rather in data is not transported directly in the payload but rather in
another internal frame that is allowed to float over two successive another internal frame that is allowed to float over two successive
SDH/SONET payloads. This internal frame is named a Virtual Container SDH/SONET payloads. This internal frame is named a Virtual Container
(VC) in SDH and a Synchronous Payload Envelope (SPE) in SONET. (VC) in SDH and a SONET Payload Envelope (SPE) in SONET.
The SDH/SONET architecture identifies three different layers, each The SDH/SONET architecture identifies three different layers, each
of which corresponds to one level of communication between SDH/SONET of which corresponds to one level of communication between SDH/SONET
equipment. These are, starting with the lowest, the regenerator equipment. These are, starting with the lowest, the regenerator
section/section layer, the multiplex section/line layer, and (at the section/section layer, the multiplex section/line layer, and (at the
top) the path layer. Each of these layers in turn has its own top) the path layer. Each of these layers in turn has its own
overhead (header). The transport overhead of a SDH/SONET frame is overhead (header). The transport overhead of a SDH/SONET frame is
mainly sub-divided in two parts that contain the regenerator mainly sub-divided in two parts that contain the regenerator
section/section overhead and the multiplex section/line overhead. In section/section overhead and the multiplex section/line overhead. In
addition, a pointer (in the form of the H1, H2 and H3 bytes) addition, a pointer (in the form of the H1, H2 and H3 bytes)
skipping to change at line 267 skipping to change at line 256
does not fill a time slot completely, and the mapping rules define does not fill a time slot completely, and the mapping rules define
precisely how to fill it. precisely how to fill it.
What is important for the GMPLS-based control of SDH/SONET circuits What is important for the GMPLS-based control of SDH/SONET circuits
is to identify the elements that can be switched from an input is to identify the elements that can be switched from an input
multiplex on one interface to an output multiplex on another multiplex on one interface to an output multiplex on another
interface. The only elements that can be switched are those that can interface. The only elements that can be switched are those that can
be re-aligned via a pointer, i.e. a VC-x in the case of SDH and a be re-aligned via a pointer, i.e. a VC-x in the case of SDH and a
SPE in the case of SONET. SPE in the case of SONET.
Internet Draft Expires March 2005 Page 5
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
xN x1 xN x1
STM-N<----AUG<----AU-4<--VC4<------------------------------C-4 E4 STM-N<----AUG<----AU-4<--VC4<------------------------------C-4 E4
^ ^ ^ ^
Ix3 Ix3 Ix3 Ix3
I I x1 I I x1
I -----TUG-3<----TU-3<---VC-3<---I I -----TUG-3<----TU-3<---VC-3<---I
I ^ C-3 DS3/E3 I ^ C-3 DS3/E3
STM-0<------------AU-3<---VC-3<-- I ---------------------I STM-0<------------AU-3<---VC-3<-- I ---------------------I
^ I ^ I
Ix7 Ix7 Ix7 Ix7
skipping to change at line 319 skipping to change at line 305
byte interleaving. The VCs/SPEs in the N interleaved frames are byte interleaving. The VCs/SPEs in the N interleaved frames are
independent and float according to their own clocking. To transport independent and float according to their own clocking. To transport
tributary signals in excess of the basic STM-1/STS-1 signal rates, tributary signals in excess of the basic STM-1/STS-1 signal rates,
the VCs/SPEs can be concatenated, i.e., glued together. In this case the VCs/SPEs can be concatenated, i.e., glued together. In this case
their relationship with respect to each other is fixed in time and their relationship with respect to each other is fixed in time and
hence this relieves, when possible, an end system of any inverse hence this relieves, when possible, an end system of any inverse
multiplexing bonding processes. Different types of concatenations multiplexing bonding processes. Different types of concatenations
are defined in SDH/SONET. are defined in SDH/SONET.
Internet Draft Expires March 2005 Page 6
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
For example, standard SONET concatenation allows the concatenation For example, standard SONET concatenation allows the concatenation
of M x STS-1 signals within an STS-N signal with M <= N, and M = 3, of M x STS-1 signals within an STS-N signal with M <= N, and M = 3,
12, 48, 192,...). The SPEs of these M x STS-1s can be concatenated 12, 48, 192,...). The SPEs of these M x STS-1s can be concatenated
to form an STS-Mc. The STS-Mc notation is short hand for describing to form an STS-Mc. The STS-Mc notation is short hand for describing
an STS-M signal whose SPEs have been concatenated. an STS-M signal whose SPEs have been concatenated.
1.3. The Current State of Circuit Establishment in SDH/SONET Networks 1.3. The Current State of Circuit Establishment in SDH/SONET Networks
In present day SDH and SONET networks, the networks are primarily In present day SDH and SONET networks, the networks are primarily
statically configured. When a client of an operator requests a statically configured. When a client of an operator requests a
skipping to change at line 372 skipping to change at line 355
This first-time connection time is frequently accounted for in the This first-time connection time is frequently accounted for in the
overall establishment time. overall establishment time.
1.3.3. Planning Tool Operation 1.3.3. Planning Tool Operation
Another portion of the time is consumed by planning tools that run Another portion of the time is consumed by planning tools that run
simulations using heuristic algorithms to find an optimized simulations using heuristic algorithms to find an optimized
placement for the required circuits. These planning tools can placement for the required circuits. These planning tools can
require a significant running time, sometimes on the order of days. require a significant running time, sometimes on the order of days.
Internet Draft Expires March 2005 Page 7
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
These simulations are, in general, executed for a set of demands for These simulations are, in general, executed for a set of demands for
circuits, i.e., a batch mode, to improve the optimality of network circuits, i.e., a batch mode, to improve the optimality of network
resource usage and other parameters. Today, we do not really have a resource usage and other parameters. Today, we do not really have a
means to reduce this simulation time. On the contrary, to support means to reduce this simulation time. On the contrary, to support
fast, on-line, circuit establishment, this phase may be invoked more fast, on-line, circuit establishment, this phase may be invoked more
frequently, i.e., we will not "batch up" as many connection frequently, i.e., we will not "batch up" as many connection
requests before we plan out the corresponding circuits. This means requests before we plan out the corresponding circuits. This means
that the network may need to be re-optimized periodically, implying that the network may need to be re-optimized periodically, implying
that the signaling should support re-optimization with minimum that the signaling should support re-optimization with minimum
impact to existing services. impact to existing services.
skipping to change at line 427 skipping to change at line 407
approach has its merits. The application of GMPLS to SDH/SONET approach has its merits. The application of GMPLS to SDH/SONET
networks does not preclude either model, although GMPLS is itself a networks does not preclude either model, although GMPLS is itself a
distributed technology. distributed technology.
The basic tradeoff between the centralized and distributed The basic tradeoff between the centralized and distributed
approaches is that of complexity of the network elements versus that approaches is that of complexity of the network elements versus that
of the network management system (NMS). Since adding functionality of the network management system (NMS). Since adding functionality
to existing SDH/SONET network elements may not be possible, a to existing SDH/SONET network elements may not be possible, a
centralized approach may be needed in some cases. The main issue centralized approach may be needed in some cases. The main issue
facing centralized control via an NMS is one of scalability. For facing centralized control via an NMS is one of scalability. For
Internet Draft Expires March 2005 Page 8
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
instance, this approach may be limited in the number of network instance, this approach may be limited in the number of network
elements that can be managed (e.g., one thousand). It is, therefore, elements that can be managed (e.g., one thousand). It is, therefore,
quite common for operators to deploy several NMS in parallel at quite common for operators to deploy several NMS in parallel at
the Network Management Layer, each managing a different zone. In the Network Management Layer, each managing a different zone. In
that case, however, a Service Management Layer must be built on the that case, however, a Service Management Layer must be built on the
top of several individual NMS to take care of end-to-end on-demand top of several individual NMS to take care of end-to-end on-demand
services. On the other hand, in a complex and/or dense network, services. On the other hand, in a complex and/or dense network,
restoration could be faster with a distributed approach than with a restoration could be faster with a distributed approach than with a
centralized approach. centralized approach.
skipping to change at line 452 skipping to change at line 428
are handled via the centralized and distributed approaches: are handled via the centralized and distributed approaches:
1.4.1. Topology Discovery and Resource Dissemination 1.4.1. Topology Discovery and Resource Dissemination
Currently an NMS maintains a consistent view of all the networking Currently an NMS maintains a consistent view of all the networking
layers under its purview. This can include the physical topology, layers under its purview. This can include the physical topology,
such as information about fibers and ducts. Since most of this such as information about fibers and ducts. Since most of this
information is entered manually, it remains error prone. information is entered manually, it remains error prone.
A link state GMPLS routing protocol, on the other hand, could A link state GMPLS routing protocol, on the other hand, could
perform automatic topology discovery and dissemination the topology perform automatic topology discovery and disseminate the topology
as well as resource status. This information would be available to as well as resource status. This information would be available to
all nodes in the network, and hence also the NMS. Hence one can all nodes in the network, and hence also the NMS. Hence one can
look at a continuum of functionality between manually provisioned look at a continuum of functionality between manually provisioned
topology information (of which there will always be some) and fully topology information (of which there will always be some) and fully
automated discovery and dissemination as in a link state protocol. automated discovery and dissemination as in a link state protocol.
Note that, unlike the IP datagram case, a link state routing Note that, unlike the IP datagram case, a link state routing
protocol applied to the SDH/SONET network does not have any service protocol applied to the SDH/SONET network does not have any service
impacting implications. This is because in the SDH/SONET case, the impacting implications. This is because in the SDH/SONET case, the
circuit is source-routed (so there can be no loops), and no traffic circuit is source-routed (so there can be no loops), and no traffic
is transmitted until a circuit has been established, and an is transmitted until a circuit has been established, and an
skipping to change at line 484 skipping to change at line 460
diversity or new optimization algorithms can be introduced with a diversity or new optimization algorithms can be introduced with a
simple NMS software upgrade. On the other hand, updating switches simple NMS software upgrade. On the other hand, updating switches
with new path computation software is a more complicated task. In with new path computation software is a more complicated task. In
addition, many of the algorithms can be fairly computationally addition, many of the algorithms can be fairly computationally
intensive and may be completely unsuitable for the embedded intensive and may be completely unsuitable for the embedded
processing environment available on most switches. In restoration processing environment available on most switches. In restoration
scenarios, the ability to perform a reasonably sophisticated level scenarios, the ability to perform a reasonably sophisticated level
of path computation on the network element can be particularly of path computation on the network element can be particularly
useful for restoring traffic during major network faults. useful for restoring traffic during major network faults.
Internet Draft Expires March 2005 Page 9
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
1.4.3. Connection Establishment (Provisioning) 1.4.3. Connection Establishment (Provisioning)
The actual setting up of circuits, i.e., a coupled collection of The actual setting up of circuits, i.e., a coupled collection of
cross connects across a network, can be done either via the NMS cross connects across a network, can be done either via the NMS
setting up individual cross connects or via a "soft permanent LSP" setting up individual cross connects or via a "soft permanent LSP"
(SPLSP) type approach. In the SPLSP approach, the NMS may just kick (SPLSP) type approach. In the SPLSP approach, the NMS may just kick
off the connection at the "ingress" switch with GMPLS signaling off the connection at the "ingress" switch with GMPLS signaling
setting up the connection from that point onward. Connection setting up the connection from that point onward. Connection
establishment is the trickiest part to distribute, however, since establishment is the trickiest part to distribute, however, since
errors in the connection setup/tear down process are service errors in the connection setup/tear down process are service
skipping to change at line 522 skipping to change at line 495
Distributed load Bottleneck: #requests and Distributed load Bottleneck: #requests and
actions to/from NMS actions to/from NMS
Individual local routing Centralized routing decision, Individual local routing Centralized routing decision,
decision can be done per block of decision can be done per block of
requests requests
Routing scalable as for the Assumes a few big Routing scalable as for the Assumes a few big
Internet administrative domains Internet administrative domains
Complex to change routing Very easy local upgrade (non- Complex to change routing Very easy local upgrade (non
protocol/algorithm intrusive) protocol/algorithm intrusive)
Requires enhanced routing Better consistency Requires enhanced routing Better consistency
protocol (traffic protocol (traffic
engineering) engineering)
Ideal for inter-domain Not inter-domain friendly Ideal for inter-domain Not inter-domain friendly
Suitable for very dynamic For less dynamic demands Suitable for very dynamic For less dynamic demands
demands (longer lived) demands (longer lived)
Probably faster to restore, Probably slower to restore,but Probably faster to restore, Probably slower to restore,but
but more difficult to have could effect reliable but more difficult to have could effect reliable
reliable restoration. restoration. reliable restoration. restoration.
Internet Draft Expires March 2005 Page 10
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
High scalability Limited scalability: #nodes, High scalability Limited scalability: #nodes,
(hierarchical) links, circuits, messages (hierarchical) links, circuits, messages
Planning (optimization) Planning is a background Planning (optimization) Planning is a background
harder to achieve centralized activity harder to achieve centralized activity
Easier future integration Easier future integration
with other control plane with other control plane
layers layers
skipping to change at line 594 skipping to change at line 564
fairly fine granularity and that provides a very cheap and simple fairly fine granularity and that provides a very cheap and simple
physical separation of the transported traffic between circuits, physical separation of the transported traffic between circuits,
i.e., QoS. Moreover, even IP datagrams cannot be transported i.e., QoS. Moreover, even IP datagrams cannot be transported
directly over a wavelength. A framing or encapsulation is always directly over a wavelength. A framing or encapsulation is always
required to delimit IP datagrams. The Total Length field of an IP required to delimit IP datagrams. The Total Length field of an IP
header cannot be trusted to find the start of a new datagram, since header cannot be trusted to find the start of a new datagram, since
it could be corrupted and would result in a loss of synchronization. it could be corrupted and would result in a loss of synchronization.
The typical framing used today for IP over DWDM is defined in The typical framing used today for IP over DWDM is defined in
RFC1619/RFC2615 and known as POS (Packet Over SDH/SONET), i.e., IP RFC1619/RFC2615 and known as POS (Packet Over SDH/SONET), i.e., IP
over PPP (in HDLC-like format) over SDH/SONET. SDH and SONET are over PPP (in HDLC-like format) over SDH/SONET. SDH and SONET are
Internet Draft Expires March 2005 Page 11
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
actually efficient encapsulations for IP. For instance, with an actually efficient encapsulations for IP. For instance, with an
average IP datagram length of 350 octets, an IP over GBE average IP datagram length of 350 octets, an IP over GBE
encapsulation using an 8B/10B encoding results in 28% overhead, an encapsulation using an 8B/10B encoding results in 28% overhead, an
IP/ATM/SDH encapsulation results in 22% overhead and an IP/PPP/SDH IP/ATM/SDH encapsulation results in 22% overhead and an IP/PPP/SDH
encapsulation results in only 6% overhead. encapsulation results in only 6% overhead.
Any encapsulation of IP over WDM should, in the data plane, at least Any encapsulation of IP over WDM should, in the data plane, at least
provide error monitoring capabilities (to detect signal provide error monitoring capabilities (to detect signal
degradation); error correction capabilities, such as FEC (Forward degradation); error correction capabilities, such as FEC (Forward
Error Correction) that are particularly needed for ultra long haul Error Correction) that are particularly needed for ultra long haul
transmission; sufficient timing information, to allow robust transmission; sufficient timing information, to allow robust
synchronization (that is, to detect the beginning of a packet). In synchronization (that is, to detect the beginning of a packet). In
the case where associated signaling is used (that is the control and the case where associated signaling is used (that is the control and
data plane topologies are congruent) the encapsulation should also data plane topologies are congruent) the encapsulation should also
provide the capacity to transport signaling, routing and management provide the capacity to transport signaling, routing and management
messages, in order to control the optical switches. Rather SDH and messages, in order to control the optical switches. Rather SDH and
SONET cover all these aspects natively, except FEC, which tends to SONET cover all these aspects natively, except FEC, which tends to
be supported in a proprietary way. (We note, however, that be supported in a proprietary way. (We note, however, that
associated signaling is not a requirement for the GMPLS-based associated signaling is not a requirement for the GMPLS-based
control of SDH/SONET networks. Rather, it is just one option. Non- control of SDH/SONET networks. Rather, it is just one option. Non
associated signaling, as would happen with an out-of-band control associated signaling, as would happen with an out-of-band control
plane network is another equally valid option.) plane network is another equally valid option.)
Since IP encapsulated in SDH/SONET is efficient and widely used, the Since IP encapsulated in SDH/SONET is efficient and widely used, the
only real difference between an IP over WDM network and an IP over only real difference between an IP over WDM network and an IP over
SDH over WDM network is the layers at which the switching or SDH over WDM network is the layers at which the switching or
forwarding can take place. In the first case, it can take place at forwarding can take place. In the first case, it can take place at
the IP and optical layers. In the second case, it can take place at the IP and optical layers. In the second case, it can take place at
the IP, SDH/SONET, and optical layers. the IP, SDH/SONET, and optical layers.
skipping to change at line 649 skipping to change at line 615
Controlling the SDH/SONET multiplex implies deciding which of the Controlling the SDH/SONET multiplex implies deciding which of the
different switchable components of the SDH/SONET multiplex do we different switchable components of the SDH/SONET multiplex do we
wish to control using GMPLS. Essentially, every SDH/SONET element wish to control using GMPLS. Essentially, every SDH/SONET element
that is referenced by a pointer can be switched. These component that is referenced by a pointer can be switched. These component
signals are the VC-4, VC-3, VC-2, VC-12 and VC-11 in the SDH case; signals are the VC-4, VC-3, VC-2, VC-12 and VC-11 in the SDH case;
and the VT and STS SPEs in the SONET case. The SPEs in SONET do not and the VT and STS SPEs in the SONET case. The SPEs in SONET do not
have individual names, although they can be referred to simply as have individual names, although they can be referred to simply as
VT-N SPEs. We will refer to them by identifying the structure that VT-N SPEs. We will refer to them by identifying the structure that
contains them, namely STS-1, VT-6, VT-3, VT-2 and VT-1.5. contains them, namely STS-1, VT-6, VT-3, VT-2 and VT-1.5.
Internet Draft Expires March 2005 Page 12
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
The STS-1 SPE corresponds to a VC-3, a VT-6 SPE corresponds to a VC- The STS-1 SPE corresponds to a VC-3, a VT-6 SPE corresponds to a VC-
2, a VT-2 SPE corresponds to a VC-12, and a VT-1.5 SPE corresponds 2, a VT-2 SPE corresponds to a VC-12, and a VT-1.5 SPE corresponds
to a VC-11. The SONET VT-3 SPE has no correspondence in SDH, however to a VC-11. The SONET VT-3 SPE has no correspondence in SDH, however
SDH's VC-4 corresponds to SONET's STS-3c SPE. SDH's VC-4 corresponds to SONET's STS-3c SPE.
In addition, it is possible to concatenate some of the structures In addition, it is possible to concatenate some of the structures
that contain these elements to build larger elements. For instance, that contain these elements to build larger elements. For instance,
SDH allows the concatenation of X contiguous AU-4s to build a VC-4- SDH allows the concatenation of X contiguous AU-4s to build a VC-4-
Xc and of m contiguous TU-2s to build a VC-2-mc. In that case, a VC- Xc and of m contiguous TU-2s to build a VC-2-mc. In that case, a VC-
4-Xc or a VC-2-mc can be switched and controlled by GMPLS. SDH also 4-Xc or a VC-2-mc can be switched and controlled by GMPLS. SDH also
skipping to change at line 677 skipping to change at line 640
Let a SDH or SONET Terminal Multiplexer (TM), Add-Drop Multiplexer Let a SDH or SONET Terminal Multiplexer (TM), Add-Drop Multiplexer
(ADM) or cross-connect (i.e. a switch) be called an SDH/SONET LSR. A (ADM) or cross-connect (i.e. a switch) be called an SDH/SONET LSR. A
SDH/SONET path or circuit between two SDH/SONET LSRs now becomes a SDH/SONET path or circuit between two SDH/SONET LSRs now becomes a
GMPLS LSP. An SDH/SONET LSP is a logical connection between the GMPLS LSP. An SDH/SONET LSP is a logical connection between the
point at which a tributary signal (client layer) is adapted into its point at which a tributary signal (client layer) is adapted into its
virtual container, and the point at which it is extracted from its virtual container, and the point at which it is extracted from its
virtual container. virtual container.
To establish such an LSP, a signaling protocol is required to To establish such an LSP, a signaling protocol is required to
configure the input interface, switch fabric, and output interface configure the input interface, switch fabric, and output interface
of each SDH/SONET LSR along the path. An SDH/SONET LSP can be point- of each SDH/SONET LSR along the path. An SDH/SONET LSP can be
to-point or point-to-multipoint, but not multipoint-to-point, since point-to-point or point-to-multipoint, but not multipoint-to-point,
no merging is possible with SDH/SONET signals. since no merging is possible with SDH/SONET signals.
To facilitate the signaling and setup of SDH/SONET circuits, an To facilitate the signaling and setup of SDH/SONET circuits, an
SDH/SONET LSR must, therefore, identify each possible signal SDH/SONET LSR must, therefore, identify each possible signal
individually per interface, since each signal corresponds to a individually per interface, since each signal corresponds to a
potential LSP that can be established through the SDH/SONET LSR. It potential LSP that can be established through the SDH/SONET LSR. It
turns out, however, that not all SDH signals correspond to an LSP turns out, however, that not all SDH signals correspond to an LSP
and therefore not all of them need be identified. In fact, only and therefore not all of them need be identified. In fact, only
those signals that can be switched need identification. those signals that can be switched need identification.
3. Decomposition of the GMPLS Circuit-Switching Problem Space 3. Decomposition of the GMPLS Circuit-Switching Problem Space
skipping to change at line 704 skipping to change at line 667
applied to the optical switching problem space. applied to the optical switching problem space.
(i) Information needed to compute paths must be made globally (i) Information needed to compute paths must be made globally
available throughout the network. Since this is done via the link available throughout the network. Since this is done via the link
state routing protocol, any information of this nature must either state routing protocol, any information of this nature must either
be in the existing link state advertisements (LSAs) or the LSAs must be in the existing link state advertisements (LSAs) or the LSAs must
be supplemented to convey this information. For example, if it is be supplemented to convey this information. For example, if it is
desirable to offer different levels of service in a network based on desirable to offer different levels of service in a network based on
whether a circuit is routed over SDH/SONET lines that are ring whether a circuit is routed over SDH/SONET lines that are ring
protected versus being routed over those that are not ring protected protected versus being routed over those that are not ring protected
Internet Draft Expires March 2005 Page 13
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
(differentiation based on reliability), the type of protection on a (differentiation based on reliability), the type of protection on a
SDH/SONET line would be an important topological parameter that SDH/SONET line would be an important topological parameter that
would have to be distributed via the link state routing protocol. would have to be distributed via the link state routing protocol.
(ii) Information that is only needed between two "adjacent" switches (ii) Information that is only needed between two "adjacent" switches
for the purposes of connection establishment is appropriate for for the purposes of connection establishment is appropriate for
distribution via one of the label distribution protocols. In fact, distribution via one of the label distribution protocols. In fact,
this information can be thought of as the "virtual" label. For this information can be thought of as the "virtual" label. For
example, in SONET networks, when distributing information to example, in SONET networks, when distributing information to
switches concerning an end-to-end STS-1 path traversing a network, switches concerning an end-to-end STS-1 path traversing a network,
skipping to change at line 760 skipping to change at line 719
through a network is important to distribute via the routing through a network is important to distribute via the routing
protocol. In the TDM case, this information includes, but is not protocol. In the TDM case, this information includes, but is not
limited to: the available capacity of the network links, the limited to: the available capacity of the network links, the
switching and termination capabilities of the nodes and interfaces, switching and termination capabilities of the nodes and interfaces,
and the protection properties of the link. This is what is being and the protection properties of the link. This is what is being
proposed in the GMPLS extensions to IP routing protocols [12], [13], proposed in the GMPLS extensions to IP routing protocols [12], [13],
[14]. [14].
When applying routing to circuit switched networks it is useful to When applying routing to circuit switched networks it is useful to
compare and contrast this situation with the datagram routing case compare and contrast this situation with the datagram routing case
Internet Draft Expires March 2005 Page 14
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
[15]. In the case of routing datagrams, all routes on all nodes [15]. In the case of routing datagrams, all routes on all nodes
must be calculated exactly the same to avoid loops and "black must be calculated exactly the same to avoid loops and "black
holes". In circuit switching, this is not the case since routes are holes". In circuit switching, this is not the case since routes are
established per circuit and are fixed for that circuit. Hence, established per circuit and are fixed for that circuit. Hence,
unlike the datagram case, routing is not service impacting in the unlike the datagram case, routing is not service impacting in the
circuit switched case. This is helpful, because, to accommodate the circuit switched case. This is helpful, because, to accommodate the
optical layer, routing protocols need to be supplemented with new optical layer, routing protocols need to be supplemented with new
information, much more than the datagram case. This information is information, much more than the datagram case. This information is
also likely to be used in different ways for implementing different also likely to be used in different ways for implementing different
user services. Due to the increase in information transferred in user services. Due to the increase in information transferred in
skipping to change at line 814 skipping to change at line 769
Table 2. SDH/SONET switched signal groupings. Table 2. SDH/SONET switched signal groupings.
Signal Type SDH SONET Signal Type SDH SONET
Lower Order VC-11, VC-12, VC-2 VT-1.5 SPE, VT-2 SPE, Lower Order VC-11, VC-12, VC-2 VT-1.5 SPE, VT-2 SPE,
VT-3 SPE, VT-6 SPE VT-3 SPE, VT-6 SPE
Higher VC-3, VC-4 STS-1 SPE, STS-3c SPE Higher VC-3, VC-4 STS-1 SPE, STS-3c SPE
Order Order
Internet Draft Expires March 2005 Page 15
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
Manufacturers today differ in the types of switching capabilities Manufacturers today differ in the types of switching capabilities
their systems support. Many manufacturers today switch signals their systems support. Many manufacturers today switch signals
starting at VC-4 for SDH or STS-1 for SONET (i.e. the basic frame) starting at VC-4 for SDH or STS-1 for SONET (i.e. the basic frame)
and above (see Section 5.1.2 on concatenation), but they do not and above (see Section 5.1.2 on concatenation), but they do not
switch lower order signals. Some of them only allow the switching of switch lower order signals. Some of them only allow the switching of
entire aggregates (concatenated or not) of signals such as 16 VC-4s, entire aggregates (concatenated or not) of signals such as 16 VC-4s,
i.e. a complete STM-16, and nothing finer. Some go down to the VC-3 i.e. a complete STM-16, and nothing finer. Some go down to the VC-3
level for SDH. Finally, some offer highly integrated switches that level for SDH. Finally, some offer highly integrated switches that
switch at the VC-3/STS-1 level down to lower order signals such as switch at the VC-3/STS-1 level down to lower order signals such as
VC-12s. In order to cover the needs of all manufacturers and VC-12s. In order to cover the needs of all manufacturers and
skipping to change at line 870 skipping to change at line 821
(where the rest of the signal gets put in terms of STS-1 slot (where the rest of the signal gets put in terms of STS-1 slot
numbers) leads to the requirement for re-grooming (due to bandwidth numbers) leads to the requirement for re-grooming (due to bandwidth
fragmentation). fragmentation).
Due to these disadvantages some SONET framer manufacturers now Due to these disadvantages some SONET framer manufacturers now
support "flexible" or arbitrary concatenation, i.e., no restrictions support "flexible" or arbitrary concatenation, i.e., no restrictions
on the size of an STS-Mc (as long as M <= N) and no constraints on on the size of an STS-Mc (as long as M <= N) and no constraints on
the STS-1 timeslots used to convey it, i.e., the signals can use any the STS-1 timeslots used to convey it, i.e., the signals can use any
combination of available time slots. combination of available time slots.
Internet Draft Expires March 2005 Page 16
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
Standard and flexible concatenations are network services, while Standard and flexible concatenations are network services, while
virtual concatenation is a SDH/SONET end-system service approved by virtual concatenation is a SDH/SONET end-system service approved by
the Committee T1 of ANSI [5] and the ITU-T [4]. The essence of this the Committee T1 of ANSI [5] and the ITU-T [4]. The essence of this
service is to have SDH/SONET end systems "glue" together the VCs or service is to have SDH/SONET end systems "glue" together the VCs or
SPEs of separate signals rather than requiring that the signals be SPEs of separate signals rather than requiring that the signals be
carried through the network as a single unit. In one example of carried through the network as a single unit. In one example of
virtual concatenation, two end systems supporting this feature could virtual concatenation, two end systems supporting this feature could
essentially "inverse multiplex" two STS-1s into a STS-1-2v for the essentially "inverse multiplex" two STS-1s into a STS-1-2v for the
efficient transport of 100 Mbps Ethernet traffic. Note that this efficient transport of 100 Mbps Ethernet traffic. Note that this
inverse multiplexing process (or virtual concatenation) can be inverse multiplexing process (or virtual concatenation) can be
significantly easier to implement with SDH/SONET than packet switched significantly easier to implement with SDH/SONET than packet switched
circuits, because ensuring that timing and in-order frame delivery is circuits, because ensuring that timing and in-order frame delivery is
preserved may be simpler to establish using SDH/SONET rather than preserved may be simpler to establish using SDH/SONET rather than
packet switched circuits, where more sophisticated techniques may be packet switched circuits, where more sophisticated techniques may be
needed. needed.
Since virtual concatenation is provided by end systems, it is Since virtual concatenation is provided by end systems, it is
compatible with existing SDH/SONET networks. Virtual concatenation compatible with existing SDH/SONET networks. Virtual concatenation
is defined for both higher order signals and low order signals. is defined for both higher order signals and low order signals.
Table 3 shows the nomenclature and capacity for several lower-order Table 3 shows the nomenclature and capacity for several lower-order
virtually concatenated signals contained within different higher- virtually concatenated signals contained within different
order signals. higher-order signals.
Table 3 Capacity of Virtually Concatenated VTn-Xv (9/G.707) Table 3 Capacity of Virtually Concatenated VTn-Xv (9/G.707)
Carried In X Capacity In steps Carried In X Capacity In steps
of of
VT1.5/ STS-1/VC-3 1 to 28 1600kbit/s to 1600kbit/s VT1.5/ STS-1/VC-3 1 to 28 1600kbit/s to 1600kbit/s
VC-11-Xv 44800kbit/s VC-11-Xv 44800kbit/s
VT2/ STS-1/VC-3 1 to 21 2176kbit/s to 2176kbit/s VT2/ STS-1/VC-3 1 to 21 2176kbit/s to 2176kbit/s
skipping to change at line 924 skipping to change at line 872
The purposed of SDH/SONET is to carry its payload signals in a The purposed of SDH/SONET is to carry its payload signals in a
transparent manner. This can include some of the layers of SONET transparent manner. This can include some of the layers of SONET
itself. For example, situations where the path overhead can never be itself. For example, situations where the path overhead can never be
touched, since it actually belongs to the client. This was another touched, since it actually belongs to the client. This was another
reason for not coding an explicit label in the SDH/SONET path reason for not coding an explicit label in the SDH/SONET path
overhead. It may be useful to transport, multiplex and/or switch overhead. It may be useful to transport, multiplex and/or switch
lower layers of the SONET signal transparently. lower layers of the SONET signal transparently.
As mentioned in the introduction, SONET overhead is broken into As mentioned in the introduction, SONET overhead is broken into
Internet Draft Expires March 2005 Page 17
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
three layers: Section, Line and Path. Each of these layers is three layers: Section, Line and Path. Each of these layers is
concerned with fault and performance monitoring. The Section concerned with fault and performance monitoring. The Section
overhead is primarily concerned with framing, while the Line overhead is primarily concerned with framing, while the Line
overhead is primarily concerned with multiplexing and protection. To overhead is primarily concerned with multiplexing and protection. To
perform pipe multiplexing (that is, multiplexing of 50 Mbps or 150 perform pipe multiplexing (that is, multiplexing of 50 Mbps or 150
Mbps chunks), a SONET network element should be line terminating. Mbps chunks), a SONET network element should be line terminating.
However, not all SONET multiplexers/switches perform SONET pointer However, not all SONET multiplexers/switches perform SONET pointer
adjustments on all the STS-1s contained within a higher order SONET adjustments on all the STS-1s contained within a higher order SONET
signal passing through them. Alternatively, if they perform pointer signal passing through them. Alternatively, if they perform pointer
adjustments, they do not terminate the line overhead. For example, a adjustments, they do not terminate the line overhead. For example, a
skipping to change at line 975 skipping to change at line 919
4.2. Protection 4.2. Protection
SONET and SDH networks offer a variety of protection options at both SONET and SDH networks offer a variety of protection options at both
the SONET line (SDH multiplex section) and SDH/SONET path level the SONET line (SDH multiplex section) and SDH/SONET path level
[10], [11]. Standardized SONET line level protection techniques [10], [11]. Standardized SONET line level protection techniques
include: Linear 1+1 and linear 1:N automatic protection switching include: Linear 1+1 and linear 1:N automatic protection switching
(APS) and both two-fiber and four-fiber bi-directional line switched (APS) and both two-fiber and four-fiber bi-directional line switched
rings (BLSRs). At the path layer, SONET offers uni-directional path rings (BLSRs). At the path layer, SONET offers uni-directional path
switched ring protection. Likewise, standardized SDH multiplex switched ring protection. Likewise, standardized SDH multiplex
section protection techniques include linear 1+1 and 1:N automatic p section protection techniques include linear 1+1 and 1:N automatic p
protection switching and both two-fiber and four-fiber bi- protection switching and both two-fiber and four-fiber bi-directional
directional MS-SPRings (Multiplex Section-Shared Protection Rings). MS-SPRings (Multiplex Section-Shared Protection Rings).
At the path layer, SDH offers SNCP (sub-network connection At the path layer, SDH offers SNCP (sub-network connection
protection) ring protection. protection) ring protection.
Internet Draft Expires March 2005 Page 18
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
Both ring and 1:N line protection also allow for "extra traffic" to Both ring and 1:N line protection also allow for "extra traffic" to
be carried over the protection line when that line is not being be carried over the protection line when that line is not being
used, i.e., when it is not carrying traffic for a failed working used, i.e., when it is not carrying traffic for a failed working
line. These protection methods are summarized in Table 5. It should line. These protection methods are summarized in Table 5. It should
be noted that these protection methods are completely separate from be noted that these protection methods are completely separate from
any GMPLS layer protection or restoration mechanisms. any GMPLS layer protection or restoration mechanisms.
Table 5. Common SDH/SONET protection mechanisms. Table 5. Common SDH/SONET protection mechanisms.
Protection Type Extra Comments Protection Type Extra Comments
skipping to change at line 1034 skipping to change at line 976
UPSR (uni- No Dedicated protection via UPSR (uni- No Dedicated protection via
directional alternative ring path. directional alternative ring path.
path switched Typically used in access path switched Typically used in access
ring) networks. ring) networks.
It may be desirable to route some connections over lines that It may be desirable to route some connections over lines that
support protection of a given type, while others may be routed over support protection of a given type, while others may be routed over
unprotected lines, or as "extra traffic" over protection lines. unprotected lines, or as "extra traffic" over protection lines.
Also, to assist in the configuration of these various protection Also, to assist in the configuration of these various protection
methods it can be extremely valuable to advertise the link methods it can be extremely valuable to advertise the link
Internet Draft Expires March 2005 Page 19
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
protection attributes in the routing protocol, as is done in the protection attributes in the routing protocol, as is done in the
current GMPLS routing protocols. For example, suppose that a 1:N current GMPLS routing protocols. For example, suppose that a 1:N
protection group is being configured via two nodes. One must make protection group is being configured via two nodes. One must make
sure that the lines are "numbered the same" with respect to both sure that the lines are "numbered the same" with respect to both
ends of the connection or else the APS (K1/K2 byte) protocol will ends of the connection or else the APS (K1/K2 byte) protocol will
not correctly operate. not correctly operate.
Table 6. Parameters defining protection mechanisms. Table 6. Parameters defining protection mechanisms.
Protection Comments Protection Comments
skipping to change at line 1087 skipping to change at line 1025
line, Dedicated (1:1, 1+1)/Working Line, Enhanced (Ring) /Working line, Dedicated (1:1, 1+1)/Working Line, Enhanced (Ring) /Working
Line, represents the other. Line, represents the other.
There is also a potential implication for link bundling [16], [18] There is also a potential implication for link bundling [16], [18]
that is, for each link, the routing protocol could advertise whether that is, for each link, the routing protocol could advertise whether
that link is a working or protection link and possibly some that link is a working or protection link and possibly some
parameters from Table 6. A possible drawback of this scheme is that parameters from Table 6. A possible drawback of this scheme is that
the routing protocol would be burdened with advertising properties the routing protocol would be burdened with advertising properties
even for those protection links in the network that could not, in even for those protection links in the network that could not, in
fact, be used for routing working traffic, e.g., dedicated fact, be used for routing working traffic, e.g., dedicated
Internet Draft Expires March 2005 Page 20
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
protection links. An alternative method would be to bundle the protection links. An alternative method would be to bundle the
working and protection links together, and advertise the bundle working and protection links together, and advertise the bundle
instead. Now, for each bundled link, the protocol would have to instead. Now, for each bundled link, the protocol would have to
advertise the amount of bandwidth available on its working links, as advertise the amount of bandwidth available on its working links, as
well as the amount of bandwidth available on those protection links well as the amount of bandwidth available on those protection links
within the bundle that were capable of carrying "extra traffic." within the bundle that were capable of carrying "extra traffic."
This would reduce the amount of information to be advertised. An This would reduce the amount of information to be advertised. An
issue here would be to decide which types of working and protection issue here would be to decide which types of working and protection
links to bundle together. For instance, it might be preferable to links to bundle together. For instance, it might be preferable to
bundle working links (and their corresponding protection links) that bundle working links (and their corresponding protection links) that
skipping to change at line 1142 skipping to change at line 1076
aggregate bandwidth usage in terms of number of whole STS-1s aggregate bandwidth usage in terms of number of whole STS-1s
(dedicated to DS3s) used and the number of STS-1s dedicated to (dedicated to DS3s) used and the number of STS-1s dedicated to
carrying DS1s allocated for this purpose. This way a network carrying DS1s allocated for this purpose. This way a network
optimization program could try to determine the optimal placement of optimization program could try to determine the optimal placement of
DS3s and DS1s to minimize wasted bandwidth due to half-empty STS-1s DS3s and DS1s to minimize wasted bandwidth due to half-empty STS-1s
at various places within the transport network. Similarly consider at various places within the transport network. Similarly consider
the set of super rate SONET signals (STS-Nc). If the links between the set of super rate SONET signals (STS-Nc). If the links between
the two switches support flexible concatenation then the reporting the two switches support flexible concatenation then the reporting
is particularly straightforward since any of the STS-1s within an is particularly straightforward since any of the STS-1s within an
STS-M can be used to comprise the transported STS-Nc. However, if STS-M can be used to comprise the transported STS-Nc. However, if
Internet Draft Expires March 2005 Page 21
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
only standard concatenation is supported, then reporting gets only standard concatenation is supported, then reporting gets
trickier since there are constraints on where the STS-1s can be trickier since there are constraints on where the STS-1s can be
placed. SDH has still more options and constraints, hence it is not placed. SDH has still more options and constraints, hence it is not
yet clear which is the best way to advertise bandwidth resource yet clear which is the best way to advertise bandwidth resource
availability/usage in SDH/SONET. At present, the GMPLS routing availability/usage in SDH/SONET. At present, the GMPLS routing
protocol extensions define minimum and maximum values for available protocol extensions define minimum and maximum values for available
bandwidth, which allows a remote node to make some deductions about bandwidth, which allows a remote node to make some deductions about
the amount of capacity available at a remote link and the types of the amount of capacity available at a remote link and the types of
signals it can accommodate. However, due to the multiplexed nature signals it can accommodate. However, due to the multiplexed nature
of the signals, reporting of bandwidth particular to signal types of the signals, reporting of bandwidth particular to signal types
rather than as a single aggregate bit rate may be desirable. For rather than as a single aggregate bit rate may be desirable. For
details on why this may be the case, we refer the reader to ITU-T details on why this may be the case, we refer the reader to ITU-T
publications G.7715.1 [19] and to Chapter 12 of [20]. publications G.7715.1 [19] and to Chapter 12 of [20].
4.4. Path Computation 4.4. Path Computation
Although a link state routing protocol can be used to obtain network Although a link state routing protocol can be used to obtain network
topology and resource information, this does not imply the use of an topology and resource information, this does not imply the use of an
"open shortest path first" route [9]. The path must be open in the "open shortest path first" route [9]. The path must be open in the
sense that the links must be capable of supporting the desired sense that the links must be capable of supporting the desired
signal type and that capacity must be available to carry the signal type and that capacity must be available to carry the signal.
signal. Other constraints may include hop count, total delay Other constraints may include hop count, total delay (mostly
(mostly propagation), and underlying protection. In addition, it may propagation), and underlying protection. In addition, it may be
be desirable to route traffic in order to optimize overall network desirable to route traffic in order to optimize overall network
capacity, or reliability, or some combination of the two. Dikstra's capacity, or reliability, or some combination of the two. Dikstra's
algorithm computes the shortest path with respect to link weights algorithm computes the shortest path with respect to link weights
for a single connection at a time. This can be much different than for a single connection at a time. This can be much different than
the paths that would be selected in response to a request to set up the paths that would be selected in response to a request to set up
a batch of connections between a set of endpoints in order to a batch of connections between a set of endpoints in order to
optimize network link utilization. One can think of this along the optimize network link utilization. One can think of this along the
lines of global or local optimization of the network in time. lines of global or local optimization of the network in time.
Due to the complexity of some of the connection routing algorithms Due to the complexity of some of the connection routing algorithms
(high dimensionality, non-linear integer programming problems) and (high dimensionality, non-linear integer programming problems) and
skipping to change at line 1197 skipping to change at line 1127
routing algorithm. routing algorithm.
5. LSP Provisioning/Signaling for SDH/SONET 5. LSP Provisioning/Signaling for SDH/SONET
Traditionally, end-to-end circuit connections in SDH/SONET networks Traditionally, end-to-end circuit connections in SDH/SONET networks
have been set up via network management systems (NMSs), which issue have been set up via network management systems (NMSs), which issue
commands (usually under the control of a human operator) to the commands (usually under the control of a human operator) to the
various network elements involved in the circuit, via an equipment various network elements involved in the circuit, via an equipment
vendor's element management system (EMS). Very little multi-vendor vendor's element management system (EMS). Very little multi-vendor
interoperability has been achieved via management systems. Hence, interoperability has been achieved via management systems. Hence,
Internet Draft Expires March 2005 Page 22
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
end-to-end circuits in a multi-vendor environment typically require end-to-end circuits in a multi-vendor environment typically require
the use of multiple management systems and the infamous configuration the use of multiple management systems and the infamous configuration
via "yellow sticky notes". As discussed in Section 3, a common via "yellow sticky notes". As discussed in Section 3, a common
signaling protocol, such as RSVP with TE extensions or CR- LDP signaling protocol - such as RSVP with TE extensions or CR-LDP -
appropriately extended for circuit switching applications, could appropriately extended for circuit switching applications, could
therefore help to solve these interoperability problems. In this therefore help to solve these interoperability problems. In this
section, we examine the various components involved in the automated section, we examine the various components involved in the automated
provisioning of SDH/SONET LSPs. provisioning of SDH/SONET LSPs.
5.1. What do we Label in SDH/SONET? Frames or Circuits? 5.1. What do we Label in SDH/SONET? Frames or Circuits?
GMPLS was initially introduced to control asynchronous technologies GMPLS was initially introduced to control asynchronous technologies
like IP, where a label was attached to each individual block of like IP, where a label was attached to each individual block of
data, such as an IP packet or a Frame Relay frame. SONET and SDH, data, such as an IP packet or a Frame Relay frame. SONET and SDH,
skipping to change at line 1234 skipping to change at line 1160
It will be seen in what follows that each SONET or SDH "frame" It will be seen in what follows that each SONET or SDH "frame"
need not have its own label, nor is it necessary to switch frames need not have its own label, nor is it necessary to switch frames
individually. Rather, the unit that is switched is a "flow" individually. Rather, the unit that is switched is a "flow"
comprised of a continuous sequence of time slots that appear at a comprised of a continuous sequence of time slots that appear at a
given position in a frame. That is, we switch an individual SONET or given position in a frame. That is, we switch an individual SONET or
SDH signal, and a label associated with each given signal. SDH signal, and a label associated with each given signal.
For instance, the payload of an SDH STM-1 frame does not fully For instance, the payload of an SDH STM-1 frame does not fully
contain a complete unit of user data. In fact, the user data is contain a complete unit of user data. In fact, the user data is
contained in a virtual container (VC) that is allowed to float over contained in a virtual container (VC) that is allowed to float over
two contiguous frames for synchronization purposes. The H1-H2-H3 Au- two contiguous frames for synchronization purposes. The H1-H2-H3
n pointer bytes in the SDH overhead indicates the beginning of the Au-n pointer bytes in the SDH overhead indicates the beginning of the
VC in the payload. Thus, frames are now inter-related, since each VC in the payload. Thus, frames are now inter-related, since each
consecutive pair may share a common virtual container. From the consecutive pair may share a common virtual container. From the
point of view of GMPLS, therefore, it is not the successive frames point of view of GMPLS, therefore, it is not the successive frames
that are treated independently or labeled, but rather the entire that are treated independently or labeled, but rather the entire
user signal. An identical argument applies to SONET. user signal. An identical argument applies to SONET.
Observe also that the GMPLS signaling used to control the SDH/SONET Observe also that the GMPLS signaling used to control the SDH/SONET
multiplex must honor its hierarchy. In other words, the SDH/SONET multiplex must honor its hierarchy. In other words, the SDH/SONET
layer should not be viewed as homogeneous and flat, because this layer should not be viewed as homogeneous and flat, because this
would limit the scope of the services that SDH/SONET can provide. would limit the scope of the services that SDH/SONET can provide.
Instead, GMPLS tunnels should be used to dynamically and Instead, GMPLS tunnels should be used to dynamically and
hierarchically control the SDH/SONET multiplex. For example, one hierarchically control the SDH/SONET multiplex. For example, one
unstructured VC-4 LSP may be established between two nodes, and unstructured VC-4 LSP may be established between two nodes, and
later lower order LSPs (e.g. VC-12) may be created within that later lower order LSPs (e.g. VC-12) may be created within that
higher order LSP. This VC-4 LSP can, in fact, be established higher order LSP. This VC-4 LSP can, in fact, be established
between two non-adjacent internal nodes in an SDH network, and later between two non-adjacent internal nodes in an SDH network, and later
advertised by a routing protocol as a new (virtual) link called a advertised by a routing protocol as a new (virtual) link called a
Forwarding Adjacency (FA) [17]. Forwarding Adjacency (FA) [17].
Internet Draft Expires March 2005 Page 23
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
A SDH/SONET-LSR will have to identify each possible signal A SDH/SONET-LSR will have to identify each possible signal
individually per interface to fulfill the GMPLS operations. In order individually per interface to fulfill the GMPLS operations. In order
to stay transparent the LSR obviously should not touch the SDH/SONET to stay transparent the LSR obviously should not touch the SDH/SONET
overheads; this is why an explicit label is not encoded in the overheads; this is why an explicit label is not encoded in the
SDH/SONET overheads. Rather, a label is associated with each SDH/SONET overheads. Rather, a label is associated with each
individual signal. This approach is similar to the one considered individual signal. This approach is similar to the one considered
for lambda switching, except that it is more complex, since SONET for lambda switching, except that it is more complex, since SONET
and SDH define a richer multiplexing structure. Therefore a label and SDH define a richer multiplexing structure. Therefore a label
is associated with each signal, and is locally unique for each is associated with each signal, and is locally unique for each
signal at each interface. This signal could, and will most probably, signal at each interface. This signal could, and will most probably,
skipping to change at line 1310 skipping to change at line 1233
multiplex-based labeling. This is the idea that was incorporated in multiplex-based labeling. This is the idea that was incorporated in
the GMPLS signaling specifications for SDH/SONET [18]. the GMPLS signaling specifications for SDH/SONET [18].
5.3. Signaling Elements 5.3. Signaling Elements
In the preceding sections, we defined the meaning of a SDH/SONET In the preceding sections, we defined the meaning of a SDH/SONET
label and specified its structure. A question that arises naturally label and specified its structure. A question that arises naturally
at this point is the following. In an LSP or connection setup at this point is the following. In an LSP or connection setup
request, how do we specify the signal for which we want to establish request, how do we specify the signal for which we want to establish
a path (and for which we desire a label)? a path (and for which we desire a label)?
Internet Draft Expires March 2005 Page 24
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
Clearly, information that is required to completely specify the Clearly, information that is required to completely specify the
desired signal and its characteristics must be transferred via the desired signal and its characteristics must be transferred via the
label distribution protocol, so that the switches along the path can label distribution protocol, so that the switches along the path can
be configured to correctly handle and switch the signal. This be configured to correctly handle and switch the signal. This
information is specified in three parts [18], each of which refers information is specified in three parts [18], each of which refers
to a different network layer. to a different network layer.
1. GENERALIZED_LABEL REQUEST (as in [6], [7]), which contains three 1. GENERALIZED_LABEL REQUEST (as in [6], [7]), which contains three
parts: LSP Encoding Type, Switching Type, and G-PID. parts: LSP Encoding Type, Switching Type, and G-PID.
skipping to change at line 1366 skipping to change at line 1285
a virtually concatenated signal. a virtually concatenated signal.
- Third, some transparency (by using the Transparency field) - Third, some transparency (by using the Transparency field)
can be optionally specified when requesting a frame as can be optionally specified when requesting a frame as
signal rather than an SPE or VC based signal. signal rather than an SPE or VC based signal.
- Fourth, a multiplication (by using the Multiplier field) - Fourth, a multiplication (by using the Multiplier field)
can be optionally applied either directly on the Elementary can be optionally applied either directly on the Elementary
Signal, or on the contiguously concatenated signal obtained Signal, or on the contiguously concatenated signal obtained
from the first phase, or on the virtually concatenated signal from the first phase, or on the virtually concatenated signal
Internet Draft Expires March 2005 Page 25
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
obtained from the second phase, or on these signals combined obtained from the second phase, or on these signals combined
with some transparency. with some transparency.
Transparency indicates precisely which fields in these overheads Transparency indicates precisely which fields in these overheads
must be delivered unmodified at the other end of the LSP. An ingress must be delivered unmodified at the other end of the LSP. An ingress
LSR requesting transparency will pass these overhead fields that LSR requesting transparency will pass these overhead fields that
must be delivered to the egress LSR without any change. From the must be delivered to the egress LSR without any change. From the
ingress and egress LSRs point of views, these fields must be seen as ingress and egress LSRs point of views, these fields must be seen as
unmodified. unmodified.
skipping to change at line 1421 skipping to change at line 1336
TDM equipment, and the requirement to learn about the protection TDM equipment, and the requirement to learn about the protection
capabilities of underlying links, and how these influence the capabilities of underlying links, and how these influence the
available capacity advertisement in TDM networks. available capacity advertisement in TDM networks.
We focused briefly on path computation methods, pointing out that We focused briefly on path computation methods, pointing out that
these were not subject to standardization. We then examined optical these were not subject to standardization. We then examined optical
path provisioning or signaling, considering the issue of what path provisioning or signaling, considering the issue of what
constitutes an appropriate label for TDM circuits and how this label constitutes an appropriate label for TDM circuits and how this label
should be structured, and we focused on the importance of should be structured, and we focused on the importance of
hierarchical label allocation in a TDM network. Finally, we reviewed hierarchical label allocation in a TDM network. Finally, we reviewed
Internet Draft Expires March 2005 Page 26
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
the signaling elements involved when setting up an TDM circuit, the signaling elements involved when setting up an TDM circuit,
focusing on the nature of the LSP, the type of payload it carries, focusing on the nature of the LSP, the type of payload it carries,
and the characteristics of the links that the LSP wishes to use at and the characteristics of the links that the LSP wishes to use at
each hop along its path for achieving a certain reliability. each hop along its path for achieving a certain reliability.
7. Security Considerations 7. Security Considerations
This document describes the framework for GMPLS extensions for use This document describes the framework for GMPLS extensions for use
in SDH/SONET control. As such, it introduces no new security issues in SDH/SONET control. As such, it introduces no new security issues
with respect to GMPLS specifications. GMPLS protocol specifications with respect to GMPLS specifications. GMPLS protocol specifications
should identify and address security issues specific to protocol. should identify and address security issues specific to protocol.
Among the considerations that should be addressed by GMPLS protocol
specifications, are any security vulnerabilities that are introduced
by specific GMPLS extensions added in each specification.
8. Acknowledgments 8. Acknowledgments
We acknowledge all the participants of the MPLS and CCAMP WGs, whose We acknowledge all the participants of the MPLS and CCAMP WGs, whose
constant enquiry about GMPLS issues in TDM networks motivated the constant enquiry about GMPLS issues in TDM networks motivated the
writing of this document, and whose questions helped shape its writing of this document, and whose questions helped shape its
contents. Also, thanks to Kireeti Kompella for his careful reading contents. Also, thanks to Kireeti Kompella for his careful reading
of the last version of this document, and for his helpful comments of the last version of this document, and for his helpful comments
and feedback, and to Dimitri Papadimitriou for his review on behalf and feedback, and to Dimitri Papadimitriou for his review on behalf
of the Routing Area Directorate, which provided many useful inputs of the Routing Area Directorate, which provided many useful inputs
to help update the document to conform to the standards evolutions to help update the document to conform to the standards evolutions
skipping to change at line 1472 skipping to change at line 1387
Metanoia, Inc. Metanoia, Inc.
888 Villa Street, Suite 200B 888 Villa Street, Suite 200B
Mountain View, CA 94041 Mountain View, CA 94041
Phone: +1 408 530 8313 Phone: +1 408 530 8313
Email: v.sharma@ieee.org Email: v.sharma@ieee.org
Eric Gray Eric Gray
Marconi Communications Marconi Communications
E-mail: Eric.Gray@Marconi.com E-mail: Eric.Gray@Marconi.com
Internet Draft Expires March 2005 Page 27
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
10. References 10. References
10.1. Normative References 10.1. Normative References
[1] Bradner, S., "IETF Rights in Contributions" BCP 78, RFC 3667, [1] Bradner, S., "IETF Rights in Contributions" BCP 78, RFC 3667,
February, 2004. February, 2004.
[2] Bradner, S., "Intellectual Property Rights in IETF Technology", [2] Bradner, S., "Intellectual Property Rights in IETF Technology",
BCP 79, RFC 3668, February, 2004. BCP 79, RFC 3668, February, 2004.
skipping to change at line 1522 skipping to change at line 1434
Mag., Vol. 40, Issue 10, October 2000. Mag., Vol. 40, Issue 10, October 2000.
[10] ANSI T1.105.01-1995, Synchronous Optical Network (SONET) [10] ANSI T1.105.01-1995, Synchronous Optical Network (SONET)
Automatic Protection Switching, American National Standards Automatic Protection Switching, American National Standards
Institute. Institute.
[11] G.841, Types and Characteristics of SDH Network Protection [11] G.841, Types and Characteristics of SDH Network Protection
Architectures, ITU-T, July 1995. Architectures, ITU-T, July 1995.
[12] Kompella, K., et al, "Routing Extensions in Support of [12] Kompella, K., et al, "Routing Extensions in Support of
Generalized MPLS," Internet Draft, Work-in-Progress, draft- Generalized MPLS," Internet Draft, Work-in-Progress,
ietf-ccamp-gmpls-routing-09.txt, October 2003. draft-ietf-ccamp-gmpls-routing-09.txt, October 2003.
Internet Draft Expires March 2005 Page 28
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
[13] Kompella, K., et al, "OSPF Extensions in Support of Generalized [13] Kompella, K., et al, "OSPF Extensions in Support of Generalized
MPLS," Internet Draft, Work-in-Progress, draft-ietf-ccamp- MPLS," Internet Draft, Work-in-Progress,
ospf-extensions-12.txt, October 2003. draft-ietf-ccamp-ospf-extensions-12.txt, October 2003.
[14] Kompella, K., et al, "IS-IS Extensions in Support of [14] Kompella, K., et al, "IS-IS Extensions in Support of
Generalized MPLS," Internet Draft, Work-in-Progress, draft- Generalized MPLS," Internet Draft, Work-in-Progress,
ietf-isis-gmpls-extensions-16.txt, August 2002. draft-ietf-isis-gmpls-extensions-16.txt, August 2002.
[15] Bernstein, G., Sharma, V., Ong, L., "Inter-domain Optical [15] Bernstein, G., Sharma, V., Ong, L., "Inter-domain Optical
Routing, " OSA J. of Optical Networking, vol. 1, no. 2, pp. 80- Routing, " OSA J. of Optical Networking, vol. 1, no. 2, pp.
92. 80-92.
[16] Kompella, K., Rekhter, Y., and Berger, L., "Link Bundling in [16] Kompella, K., Rekhter, Y., and Berger, L., "Link Bundling in
MPLS Traffic Engineering", Internet Draft, Work-in-Progress, MPLS Traffic Engineering", Internet Draft, Work-in-Progress,
draft-ietf-mpls-bundle-04.txt, July 2002. draft-ietf-mpls-bundle-04.txt, July 2002.
[17] Kompella, K., Rekhter, Y., "LSP Hierarchy with Generalized [17] Kompella, K., Rekhter, Y., "LSP Hierarchy with Generalized
MPLS-TE", Internet Draft, Work-in-Progress, draft-ietf-mpls- MPLS-TE", Internet Draft, Work-in-Progress,
lsp-hierarchy-08.txt, September 2002. draft-ietf-mpls-lsp-hierarchy-08.txt, February 2002.
[18] Mannie, E. (Editor), "GMPLS Extensions for SONET and SDH [18] Mannie, E. (Editor), "GMPLS Extensions for SONET and SDH
Control", Internet Draft, Work-in-Progress, draft-ietf-ccamp- Control", Internet Draft, Work-in-Progress,
gmpls-sonet-sdh-08.txt, February 2003. draft-ietf-ccamp-gmpls-sonet-sdh-08.txt, February 2003.
[19] G.7715.1, ASON Routing Architecture and Requirements for Link- [19] G.7715.1, ASON Routing Architecture and Requirements for
State Protocols, International Telecommunications Union, Link-State Protocols, International Telecommunications Union,
February 2004. February 2004.
[20] Bernstein, G., Rajagopalan, R., and Saha, D., "Optical Network [20] Bernstein, G., Rajagopalan, R., and Saha, D., "Optical Network
Control: Protocols, Architectures, and Standards," Addison- Control: Protocols, Architectures, and Standards,"
Wesley, July 2003. Addison-Wesley, July 2003.
11. Intellectual Property Statement 11. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed to
to pertain to the implementation or use of the technology described pertain to the implementation or use of the technology described in
in this document or the extent to which any license under such this document or the extent to which any license under such rights
rights might or might not be available; nor does it represent that might or might not be available; nor does it represent that it has
it has made any independent effort to identify any such rights. made any independent effort to identify any such rights. Information
Information on the procedures with respect to rights in RFC on the procedures with respect to rights in RFC documents can be
documents can be found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr. at http://www.ietf.org/ipr.
Internet Draft Expires March 2005 Page 29
Bernstein, et al GMPLS based Control of SDH/SONET September 2004
The IETF invites any interested party to bring to its attention The IETF invites any interested party to bring to its attention
any copyrights, patents or patent applications, or other any copyrights, patents or patent applications, or other
proprietary rights that may cover technology that may be required proprietary rights that may cover technology that may be required
to implement this standard. Please address the information to the to implement this standard. Please address the information to the
IETF at ietf-ipr@ietf.org. IETF at ietf-ipr@ietf.org.
12. Disclaimer of Validity 12. Disclaimer
This document and the information contained herein are provided on This document and the information contained herein are provided on an
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
PARTICULAR PURPOSE.
13. Copyright Statement 13. Copyright Statement
"Copyright (C) The Internet Society (2004). This document is Copyright (C) The Internet Society (2004). This document is
subject to the rights, licenses and restrictions contained in BCP subject to the rights, licenses and restrictions contained in BCP
78, and except as set forth therein, the authors retain all their 78, and except as set forth therein, the authors retain all their
rights." rights.
14. Acknowledgement 14. IANA Considerations
There are no IANA considerations that apply to this document.
15. Acronyms
ANSI - American National Standards Institute
APS - Automatic Protection Switching
ATM - Asynchronous Transfer Mode
BLSR - Bi-directional Line Switch Ring
CPE - Customer Premise Equipment
DLCI - Data Link Connection Identifier
ETSI - European Telecommunication Standards Institute
FEC - Forwarding Equivalency Class
GMPLS - Generalized MPLS
IP - Internet Protocol
IS-IS - Intermediate System to Intermediate System (RP)
LDP - Label Distribution Protocol
LSP - Label Switched Path
LSR - Label Switching Router
MPLS - Multi-Protocol Label Switching
NMS - Network Management System
OSPF - Open Shortest Path First (RP)
PNNI - Private Network Node Interface
PPP - Point to Point Protocol
QoS - Quality of Service
RP - Routing Protocol
RSVP - ReSerVation Protocol
SDH - Synchronous Digital Hierarchy
SNMP - Simple Network Management Protocol
SONET - Synchronous Optical NETworking
SPE - SONET Payload Envelope
STM - Synchronous Transport Module (or Terminal Multiplexer)
STS - Synchronous Transport Signal
TDM - Time Division Multiplexer
TE - Traffic Engineering
TMN - Telecommunication Management Network
UPSR - Uni-directional Path Switch Ring
VC - Virtual Container (SDH) or Virtual Circuit
VCI - Virtual Circuit Identifier (ATM)
VPI - Virtual Path Identifier (ATM)
VT - Virtual Tributary
WDM - Wave-length Division Multiplexing
16. Acknowledgement
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
Internet Draft Expires March 2005 Page 30
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/