draft-ietf-ccamp-gmpls-ason-reqts-07.txt   rfc4139.txt 
Network Working Group D. Papadimitriou (Alcatel) Network Working Group D. Papadimitriou
Internet Draft J. Drake (Calient) Request for Comments: 4139 Alcatel
Category: Informational J. Ash (ATT) Category: Informational J. Drake
Expiration Date: April 2005 A. Farrel (Old Dog Consulting) Boeing
L. Ong (Ciena) J. Ash
ATT
October 2004 A. Farrel
Old Dog Consulting
L. Ong
Ciena
July 2005
Requirements for Generalized MPLS (GMPLS) Signaling Usage Requirements for Generalized MPLS (GMPLS) Signaling Usage
and Extensions for Automatically Switched Optical Network (ASON) and Extensions for Automatically Switched Optical Network (ASON)
draft-ietf-ccamp-gmpls-ason-reqts-07.txt Status of This Memo
Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved. Copyright (C) The Internet Society (2005).
Abstract Abstract
The Generalized Multi-Protocol Label Switching (GMPLS) suite of The Generalized Multi-Protocol Label Switching (GMPLS) suite of
protocols has been defined to control different switching protocols has been defined to control different switching
technologies as well as different applications. These include support technologies and different applications. These include support for
for requesting Time Division Multiplexing (TDM) connections including requesting Time Division Multiplexing (TDM) connections, including
Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy
(SDH) and Optical Transport Networks (OTNs). (SDH) and Optical Transport Networks (OTNs).
D.Papadimitriou et al. - Expires April 2005 1
This document concentrates on the signaling aspects of the GMPLS This document concentrates on the signaling aspects of the GMPLS
suite of protocols. It identifies the features to be covered by the suite of protocols. It identifies the features to be covered by the
GMPLS signaling protocol to support the capabilities of an GMPLS signaling protocol to support the capabilities of an
Automatically Switched Optical Network (ASON). This document provides Automatically Switched Optical Network (ASON). This document
a problem statement and additional requirements on the GMPLS provides a problem statement and additional requirements for the
signaling protocol to support the ASON functionality. GMPLS signaling protocol to support the ASON functionality.
1. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
While [RFC2119] describes interpretations of these key words in terms
of protocol specifications and implementations, they are used in this
document to describe design requirements for protocol extensions.
2. Introduction 1. Introduction
The Generalized Multi-Protocol Label Switching (GMPLS) suite of The Generalized Multi-Protocol Label Switching (GMPLS) suite of
protocol specifications provides support for controlling different protocol specifications provides support for controlling different
switching technologies as well as different applications. These switching technologies and different applications. These include
include support for requesting Time Division Multiplexing (TDM) support for requesting Time Division Multiplexing (TDM) connections,
connections including Synchronous Optical Network (SONET)/Synchronous including Synchronous Optical Network (SONET)/Synchronous Digital
Digital Hierarchy (SDH) (see ANSI T1.105 and ITU-T G.707, Hierarchy (SDH) (see [ANSI-T1.105] and [ITU-T-G.707], respectively),
respectively) as well as Optical Transport Networks (see ITU-T and Optical Transport Networks (see [ITU-T-G.709]). In addition,
G.709). In addition, there are certain capabilities that are needed there are certain capabilities needed to support Automatically
to support Automatically Switched Optical Networks control planes Switched Optical Networks control planes (their architecture is
(their architecture is defined in [ITU-T G.8080]). These include defined in [ITU-T-G.8080]). These include generic capabilities such
generic capabilities such as call and connection separation, and more as call and connection separation, along with more specific
specific capabilities such as support of soft permanent connections. capabilities such as support of soft permanent connections.
This document concentrates on requirements related to the signaling This document concentrates on requirements related to the signaling
aspects of the GMPLS suite of protocols. It discusses functional aspects of the GMPLS suite of protocols. It discusses the functional
requirements required to support Automatically Switched Optical requirements required to support Automatically Switched Optical
Networks that may lead to additional extensions to GMPLS signaling Networks that may lead to additional extensions to GMPLS signaling
(see [RFC3471] and [RFC3473]) to support these capabilities. In (see [RFC3471] and [RFC3473]) to support these capabilities. In
addition to ASON signaling requirements, this document includes GMPLS addition to ASON signaling requirements, this document includes GMPLS
signaling requirements regarding backward compatibility (Section 5). signaling requirements that pertain to backward compatibility
A terminology section is provided in the Appendix. (Section 5). A terminology section is provided in the Appendix.
2. Conventions Used in This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
While [RFC2119] describes interpretations of these key words in terms
of protocol specifications and implementations, they are used in this
document to describe design requirements for protocol extensions.
3. Problem Statement 3. Problem Statement
The Automatically Switched Optical Network (ASON) architecture The Automatically Switched Optical Network (ASON) architecture
describes the application of an automated control plane for describes the application of an automated control plane for
supporting both call and connection management services (for a supporting both call and connection management services (for a
detailed description see [ITU-T G.8080]). The ASON architecture detailed description see [ITU-T-G.8080]). The ASON architecture
describes a reference architecture, i.e. it describes functional describes a reference architecture, (i.e., it describes functional
components, abstract interfaces, and interactions. components, abstract interfaces, and interactions).
The ASON model distinguishes reference points (representing points of The ASON model distinguishes reference points (representing points of
information exchange) defined (1) between a user (service requester) information exchange) defined (1) between a user (service requester)
and a service provider control domain, a.k.a. user-network interface
D.Papadimitriou et al. - Expires April 2005 2 (UNI), (2) between control domains, a.k.a. external network-network
and a service provider control domain a.k.a. user-network interface interface (E-NNI), and, (3) within a control domain, a.k.a. internal
(UNI), (2) between control domains a.k.a. external network-network network-network interface (I-NNI). The I-NNI and E-NNI interfaces
interface (E-NNI) and, (3) within a control domain a.k.a. internal are between protocol controllers, and may or may not use transport
network-network interface (I-NNI). The I-NNI and E-NNI interfaces are plane (physical) links. It must not be assumed that there is a one-
between protocol controllers, and may or may not use transport plane to-one relationship between control plane interfaces and transport
(physical) links. It must not be assumed that there is a one-to-one plane (physical) links, control plane entities and transport plane
relationship of control plane interfaces and transport plane entities, or control plane identifiers for transport plane resources.
(physical) links, or that there is a one-to-one relationship of
control plane entities and transport plane entities, or that there is
a one-to-one relationship of control plane identifiers for transport
plane resources.
This document describes requirements related to the use of GMPLS This document describes requirements related to the use of GMPLS
signaling (in particular, [RFC3471] and [RFC3473]) to provide call signaling (in particular, [RFC3471] and [RFC3473]) to provide call
and connection management (see [ITU-T G.7713]). The functionality to and connection management (see [ITU-T-G.7713]). The functionality to
be supported includes: be supported includes:
(a) soft permanent connection capability (a) soft permanent connection capability
(b) call and connection separation (b) call and connection separation
(c) call segments (c) call segments
(d) extended restart capabilities during control plane failures (d) extended restart capabilities during control plane failures
(e) extended label association (e) extended label association
(f) crankback capability (f) crankback capability
(g) additional error cases. (g) additional error cases
4. Requirements for Extending Applicability of GMPLS to ASON 4. Requirements for Extending Applicability of GMPLS to ASON
The next sections detail the signaling protocol requirements for The following sections detail the signaling protocol requirements for
GMPLS to support the ASON functions listed in Section 3. ASON defines GMPLS to support the ASON functions listed in Section 3. ASON
a reference model and functions (information elements) to enable end- defines a reference model and functions (information elements) to
to-end call and connection support by a protocol across the enable end-to-end call and connection support by a protocol across
respective interfaces, regardless of the particular choice of the respective interfaces, regardless of the particular choice of
protocol(s) used in a network. ASON does not restrict the use of protocol(s) used in a network. ASON does not restrict the use of
other protocols or the protocol-specific messages used to support the other protocols or the protocol-specific messages used to support the
ASON functions. Therefore, the support of these ASON functions by a ASON functions. Therefore, the support of these ASON functions by a
protocol shall not be restricted by (i.e. must be strictly protocol shall not be restricted by (i.e., must be strictly
independent of and agnostic to) any particular choice of UNI, I-NNI, independent of and agnostic to) any particular choice of UNI, I-NNI,
or E-NNI used elsewhere in the network. In order to allow for or E-NNI used elsewhere in the network. To allow for interworking
interworking between different protocol implementations, [ITU-T between different protocol implementations, [ITU-T-G.7713] recognizes
G.7713] recognizes an interworking function may be needed. that an interworking function may be needed.
In support of the G.8080 end-to-end call model across different In support of the G.8080 end-to-end call model across different
control domains, end-to-end signaling should be facilitated control domains, end-to-end signaling should be facilitated
regardless of the administrative boundaries, protocols within the regardless of the administrative boundaries, protocols within the
network or method of realization of connections within any part of network, or the method of realization of connections within any part
the network. This implies that there needs to be a clear mapping of of the network. This implies the need for a clear mapping of ASON
ASON signaling requests between GMPLS control domains and non-GMPLS signaling requests between GMPLS control domains and non-GMPLS
control domains. This document provides signaling requirements for control domains. This document provides signaling requirements for
G.8080 distributed call and connection management based on GMPLS, G.8080 distributed call and connection management based on GMPLS,
within a GMPLS based control domain (I-NNI) and between GMPLS based within a GMPLS based control domain (I-NNI), and between GMPLS based
control domains (E-NNI). It does not restrict use of other (non control domains (E-NNI). It does not restrict use of other (non
GMPLS) protocols to be used within a control domain or as an E-NNI or GMPLS) protocols to be used within a control domain or as an E-NNI or
UNI. Interworking aspects related to the use of non-GMPLS protocols UNI. Interworking aspects related to the use of non-GMPLS protocols,
such as UNI, E-NNI, or I-NNI -- including mapping of non-GMPLS
D.Papadimitriou et al. - Expires April 2005 3 protocol signaling requests to corresponding ASON signaling
as UNI, E-NNI, or I-NNI, including mapping of non-GMPLS protocol functionality and support of non-GMPLS address formats -- is not
signaling requests to corresponding ASON signaling functionality and within the scope of the GMPLS signaling protocol. Interworking
support of non-GMPLS address formats, is not within the scope of the aspects are implementation-specific and strictly under the
GMPLS signaling protocol. Interworking aspects are implementation- responsibility of the interworking function and, thus, outside the
specific and strictly under the responsibility of the interworking scope of this document.
function, and thus outside the scope of this document.
Any User-Network Interface (UNI) that is compliant with [RFC3473], By definition, any User-Network Interface (UNI) that is compliant
e.g. [GMPLS-OVERLAY] and [GMPLS-VPN] is considered, by definition, to with [RFC3473] (e.g., [GMPLS-OVERLAY] and [GMPLS-VPN]) is considered
be included within the GMPLS suite of protocols and MUST be supported to be included within the GMPLS suite of protocols and MUST be
by the ASON GMPLS signaling functionality. supported by the ASON GMPLS signaling functionality.
Compatibility aspects of non-GMPLS systems (nodes) within a GMPLS Compatibility aspects of non-GMPLS systems (nodes) within a GMPLS
control domain i.e. the support of GMPLS systems and other systems control domain (i.e., the support of GMPLS systems and other systems
which utilize other signaling protocols or some which may not support that utilize other signaling protocols or some that may not support
any signaling protocols is described. For instance, Section 4.5 any signaling protocols) is described. For example, Section 4.5,
'Support for Extended Label Association' covers the requirements when 'Support for Extended Label Association', covers the requirements for
a non-GMPLS capable sub-network is introduced or when nodes do not when a non-GMPLS capable sub-network is introduced or when nodes do
support any signaling protocols. not support any signaling protocols.
4.1 Support for Soft Permanent Connection (SPC) Capability 4.1. Support for Soft Permanent Connection (SPC) Capability
An SPC is a combination of a permanent connection at the source user- A Soft Permanent Connection (SPC) is a combination of a permanent
to-network side, a permanent connection at the destination user-to- connection at the source user-to-network side, a permanent connection
network side, and a switched connection within the network. An at the destination user-to-network side, and a switched connection
Element Management System (EMS) or a Network Management System (NMS) within the network. An Element Management System (EMS) or a Network
typically initiates the establishment of the switched connection by Management System (NMS) typically initiates the establishment of the
communicating with the node that initiates the switched connection switched connection by communicating with the node that initiates the
(also known as the ingress node). The latter then sets the connection switched connection (also known as the ingress node). The latter
using the distributed GMPLS signaling protocol. For the SPC, the then sets the connection using the distributed GMPLS signaling
communication method between the EMS/NMS and the ingress node is protocol. For the SPC, the communication method between the EMS/NMS
beyond the scope of this document (so it is for any other function and the ingress node is beyond the scope of this document (as it is
described in this document). for any other function described in this document).
The end-to-end connection is thus created by associating the incoming The end-to-end connection is thus created by associating the incoming
interface of the ingress node with the switched connection within the interface of the ingress node with the switched connection within the
network, and the outgoing interface of the switched connection network, along with the outgoing interface of the switched connection
terminating network node (also referred to as egress node). An SPC terminating network node (also referred to as egress node). An SPC
connection is illustrated in the following Figure. This shows user's connection is illustrated in the following figure. This shows the
node A connected to a provider's node B via link #1, user's node Z user's node A connected to a provider's node B via link #1, the
connected to a provider's node Y via link #3, and an abstract link #2 user's node Z connected to a provider's node Y via link #3, and an
connecting provider's node B and node Y. Nodes B and Y are referred abstract link #2 connecting the provider's node B and node Y. Nodes
to as the ingress and egress (respectively) of the network switched B and Y are referred to as the ingress and egress (respectively) of
connection. the network switched connection.
--- --- --- --- --- --- --- ---
| A |--1--| B |-----2-//------| Y |--3--| Z | | A |--1--| B |-----2-//------| Y |--3--| Z |
--- --- --- --- --- --- --- ---
In this instance, the connection on link #1 and link #3 are both In this instance, the connection on link #1 and link #3 are both
provisioned (permanent connections that may be simple links). In provisioned (permanent connections that may be simple links). In
contrast, the connection over link #2 is set up using the distributed contrast, the connection over link #2 is set up using the distributed
control plane. Thus, the SPC is composed of the stitching of link
#1, #2, and #3.
D.Papadimitriou et al. - Expires April 2005 4 Thus, to support the capability of requesting an SPC connection:
control plane. Thus the SPC is composed of the stitching of link #1,
#2 and #3.
Thus, to support the capability to request an SPC connection:
- The GMPLS signaling protocol MUST be capable of supporting the - The GMPLS signaling protocol MUST be capable of supporting the
ability to indicate the outgoing link and label information used ability to indicate the outgoing link and label information used
when setting up the destination provisioned connection. when setting up the destination provisioned connection.
- In addition, due to the inter-domain applicability of ASON - In addition, due to the inter-domain applicability of ASON
networks, the GMPLS signaling protocol SHOULD also support networks, the GMPLS signaling protocol SHOULD also support
indication of the service level requested for the SPC. In the case indication of the service level requested for the SPC. In cases
where an SPC spans multiple domains, indication of both source and where an SPC spans multiple domains, indication of both source and
destination endpoints controlling the SPC request MAY be needed. destination endpoints controlling the SPC request MAY be needed.
These MAY be done via the source and destination signaling These MAY be done via the source and destination signaling
controller addresses. controller addresses.
Note that the association at the ingress node between the permanent Note that the association at the ingress node, between the permanent
connection and the switched connection is an implementation matter connection and the switched connection, is an implementation matter
that may be under the control of the EMS/NMS and is not within the that may be under the control of the EMS/NMS and is not within the
scope of the signaling protocol. It is, therefore, outside the scope scope of the signaling protocol. Therefore, it is outside the scope
of this document. of this document.
4.2 Support for Call and Connection Separation 4.2. Support for Call and Connection Separation
A call may be simply described as "An association between endpoints A call may be simply described as "An association between endpoints
that supports an instance of a service" [ITU-T G.8080]. Thus, it can that supports an instance of a service" [ITU-T-G.8080]. Thus, it can
be considered as a service provided between two end-points, where be considered a service provided between two end-points, wherein
several calls may exist between them. Multiple connections may be several calls may exist between them. Multiple connections may be
associated to each call. The call concept provides an abstract associated with each call. The call concept provides an abstract
relationship between two users, where this relationship describes (or relationship between two users. This relationship describes (or
verifies) to what extent the users are willing to offer (or accept) verifies) the extent to which users are willing to offer (or accept)
service to each other. Therefore, a call does not provide the actual service to/from each other. Therefore, a call does not provide the
connectivity for transmitting user traffic, but only builds a actual connectivity for transmitting user traffic; it only builds a
relationship by which subsequent connections may be made. relationship by which subsequent connections may be made.
A call MAY be associated with zero, one or multiple connections. For A call MAY be associated with zero, one, or multiple connections.
the same call, connections MAY be of different types and each For the same call, connections MAY be of different types and each
connection MAY exist independently of other connections, i.e., each connection MAY exist independently of other connections (i.e., each
connection is setup and released with separate signaling messages. connection is setup and released with separate signaling messages).
The concept of the call allows for a better flexibility in how end- The concept of the call allows for a better flexibility in how end-
points set up connections and how networks offer services to users. points set up connections and how networks offer services to users.
For example, a call allows: For example, a call allows:
- An upgrade strategy for control plane operations, where a call - An upgrade strategy for control plane operations, where a call
control component (service provisioning) may be separate from the control component (service provisioning) may be separate from the
actual nodes hosting the connections (where the connection control actual nodes hosting the connections (where the connection control
component may reside) component may reside).
- Identification of the call initiator (with both network call - Identification of the call initiator (with both network call
controller as well as destination user) prior to connection, which controller, as well as destination user) prior to connection,
may result in decreasing contention during resource reservation which may result in decreasing contention during resource
- General treatment of multiple connections which may be associated reservation.
for several purposes; for example a pair of working and recovery
- General treatment of multiple connections, which may be associated
for several purposes; for example, a pair of working and recovery
connections may belong to the same call. connections may belong to the same call.
D.Papadimitriou et al. - Expires April 2005 5
To support the introduction of the call concept, GMPLS signaling To support the introduction of the call concept, GMPLS signaling
SHOULD include a call identification mechanism and SHOULD allow for SHOULD include a call identification mechanism and SHOULD allow for
end-to-end call capability exchange. end-to-end call capability exchange.
For instance, a feasible structure for the call identifier (to For instance, a feasible structure for the call identifier (to
guarantee global uniqueness) MAY concatenate a globally unique fixed guarantee global uniqueness) MAY concatenate a globally unique fixed
ID (e.g., may be composed of country code, carrier code) with an ID (e.g., may be composed of country code or carrier code) with an
operator specific ID (where the operator specific ID may be composed operator specific ID (where the operator specific ID may be composed
of a unique access point code - such as source node address - and a of a unique access point code - such as source node address - and a
local identifier). Other formats SHALL also be possible depending on local identifier). Other formats SHALL also be possible, depending
the call identification conventions between parties involved in the on the call identification conventions between the parties involved
call setup process. in the call setup process.
4.3 Support for Call Segments 4.3. Support for Call Segments
As described in [ITU-T G.8080], call segmentation MAY be applied when As described in [ITU-T-G.8080], call segmentation MAY be applied when
a call crosses several control domains. As such, an end-to-end call a call crosses several control domains. As such, when the call
MAY consist of multiple call segments, when the call traverses traverses multiple control domains, an end-to-end call MAY consist of
multiple control domains. For a given end-to-end call, each call multiple call segments. For a given end-to-end call, each call
segment MAY have one or more associated connections and the number of segment MAY have one or more associated connections, and the number
connections associated with each call segment MAY be different. of connections associated with each call segment MAY be different.
The initiating caller interacts with the called party by means of one The initiating caller interacts with the called party by means of one
or more intermediate network call controllers located at control or more intermediate network call controllers, located at control
domain boundaries (i.e., at inter-domain reference points, UNI or E- domain boundaries (i.e., at inter-domain reference points, UNI or
NNI). Call segment capabilities are defined by the policies E-NNI). Call segment capabilities are defined by the policies
associated at these reference points. associated at these reference points.
This capability allows for independent (policy based) choices of This capability allows for independent (policy based) choices of
signaling, concatenation, data plane protection and control plane signaling, concatenation, data plane protection, and control plane
driven recovery paradigms in different control domains. driven recovery paradigms in different control domains.
4.4 Support for Extended Restart Capabilities 4.4. Support for Extended Restart Capabilities
Various types of failures may occur affecting the ASON control plane. Various types of failures may occur, affecting the ASON control
Requirements placed on the control plane failure recovery by [ITU-T plane. Requirements placed on control plane failure recovery by
G.8080] include: [ITU-T-G.8080] include:
- Any control plane failure (i.e. single or multiple control channel - Any control plane failure (i.e., single or multiple control
and/or controller failure and any combination) MUST NOT result in channel and/or controller failure and any combination thereof)
releasing established calls and connections (including the MUST NOT result in releasing established calls and connections
corresponding transport plane connections). (including the corresponding transport plane connections).
- Upon recovery from a control plane failure, the recovered control - Upon recovery from a control plane failure, the recovered control
entity MUST have the ability to recover the status of the calls entity MUST have the ability to recover the status of the calls
and connections established before failure occurrence. and the connections established before failure occurrence.
- Upon recovery from a control plane failure, the recovered control - Upon recovery from a control plane failure, the recovered control
entity MUST have the ability to recover the connectivity entity MUST have the ability to recover the connectivity
information of its neighbors. information of its neighbors.
D.Papadimitriou et al. - Expires April 2005 6
- Upon recovery from a control plane failure, the recovered control - Upon recovery from a control plane failure, the recovered control
entity MUST have the ability to recover the association between entity MUST have the ability to recover the association between
the call and its associated connections. the call and its associated connections.
- Upon recovery from a control plane failure, calls and connections - Upon recovery from a control plane failure, calls and connections
in the process of being established (i.e. pending call/connection in the process of being established (i.e., pending call/connection
setup requests) SHOULD be released or continued (with setup). setup requests) SHOULD be released or continued (with setup).
- Upon recovery from a control plane failure, calls and connections - Upon recovery from a control plane failure, calls and connections
in the process of being released MUST be released. in the process of being released MUST be released.
4.5 Support for Extended Label Association 4.5. Support for Extended Label Association
It is an ASON requirement to enable support for G.805 serial compound It is an ASON requirement to enable support for G.805 [ITU-T-G.805]
links. The text below provides an illustrative example of such a serial compound links. The text below provides an illustrative
scenario, and the associated requirements. example of such a scenario, and the associated requirements.
Labels are defined in GMPLS (see [RFC3471]) to provide information on Labels are defined in GMPLS (see [RFC3471]) to provide information on
the resources used on link local basis for a particular connection. the resources used on a link local basis for a particular connection.
The labels may range from specifying a particular timeslot, a The labels may range from specifying a particular timeslot,
particular wavelength to a particular port/fiber. In the ASON indicating a particular wavelength, or to identifying a particular
context, the value of a label may not be consistently the same across port/fiber. In the ASON context, the value of a label may not be
a link. For example, the figure below illustrates the case where two consistent across a link. For example, the figure below illustrates
GMPLS capable nodes (A and Z) are interconnected across two non-GMPLS the case where two GMPLS capable nodes (A and Z) are interconnected
capable nodes (B and C), where these nodes are all SONET/SDH nodes across two non-GMPLS capable nodes (B and C), where all of these
providing, e.g., a VC-4 service. nodes are SONET/SDH nodes, providing, for example, a VC-4 service.
----- ----- ----- -----
| | --- --- | | | | --- --- | |
| A |---| B |---| C |---| Z | | A |---| B |---| C |---| Z |
| | --- --- | | | | --- --- | |
----- ----- ----- -----
Labels have an associated implicit imposed structure based on Labels have an associated implicit imposed structure based on
[GMPLS-SONET] and [GMPLS-OTN]. Thus, once the local label is [GMPLS-SONET] and [GMPLS-OTN]. Thus, once the local label is
exchanged with its neighboring control plane node, the structure of exchanged with its neighboring control plane node, the structure of
the local label may not be significant to the neighbor node since the the local label may not be significant to the neighbor node, as the
association between the local and the remote label may not association between the local and the remote label may not
necessarily be the same. This issue does not present a problem in necessarily be the same. This issue does not present a problem in
simple point-to-point connections between two control plane-enabled simple point-to-point connections between two control plane-enabled
nodes where the timeslots are mapped 1:1 across the interface. nodes in which the timeslots are mapped 1:1 across the interface.
However, once a non-GMPLS capable sub-network is introduced between However, if a non-GMPLS capable sub-network is introduced between
these nodes (as in the above figure, where the sub-network provides these nodes (as in the above figure, where the sub-network provides
re-arrangement capability for the timeslots) label scoping may become re-arrangement capability for the timeslots), label scoping may
an issue. become an issue.
In this context, there is an implicit assumption that the data plane In this context, there is an implicit assumption that the data plane
connections between the GMPLS capable edges already exist prior to connections between the GMPLS capable edges already exist prior to
any connection request. For instance, node A's outgoing VC-4's any connection request. For instance, node A's outgoing VC-4's
timeslot #1 (with SUKLM label=[1,0,0,0,0]) as defined in [GMPLS- timeslot #1 (with SUKLM label=[1,0,0,0,0]), as defined in
SONET]) may be mapped onto node B's outgoing VC-4's timeslot #6 [GMPLS-SONET]), may be mapped onto node B's outgoing VC-4's timeslot
(label=[6,0,0,0,0]) may be mapped onto node C's outgoing VC-4's #6 (label=[6,0,0,0,0]), or may be mapped onto node C's outgoing VC-
4's timeslot #4 (label=[4,0,0,0,0]). Thus, by the time node Z
D.Papadimitriou et al. - Expires April 2005 7 receives the request from node A with label=[1,0,0,0,0], node Z's
timeslot #4 (label=[4,0,0,0,0]). Thus by the time node Z receives the local label and timeslot no longer correspond to the received label
request from node A with label=[1,0,0,0,0], the node Z's local label and timeslot information.
and the timeslot no longer corresponds to the received label and
timeslot information.
As such, to support this capability, a label association mechanism As such, to support this capability, a label association mechanism
SHOULD be used by the control plane node to map the received (remote) SHOULD be used by the control plane node to map the received (remote)
label into a locally significant label. The information necessary to label into a locally significant label. The information necessary to
allow mapping from received label value to a locally significant allow mapping from a received label value to a locally significant
label value can be derived in several ways including: label value can be derived in several ways including:
- Manual provisioning of the label association - Manual provisioning of the label association
- Discovery of the label association - Discovery of the label association
Either method MAY be used. In case of dynamic association, this Either method MAY be used. In case of dynamic association, the
implies that the discovery mechanism operates at the timeslot/label discovery mechanism operates at the timeslot/label level before the
level before the connection request is processed at the ingress node. connection request is processed at the ingress node. Note that in
Note that in the case where two nodes are directly connected, no the case where two nodes are directly connected, no association is
association is required. In particular, for directly connected TDM required. In particular, for directly connected TDM interfaces, no
interfaces no mapping function (at all) is required due to the mapping function (at all) is required due to the implicit label
implicit label structure (see [GMPLS-SONET] and [GMPLS-OTN]). In such structure (see [GMPLS-SONET] and [GMPLS-OTN]). In these instances,
instances, the label association function provides a one-to-one the label association function provides a one-to-one mapping of the
mapping of the received to local label values. received to local label values.
4.6 Support for Crankback 4.6. Support for Crankback
Crankback has been identified as an important requirement for ASON Crankback has been identified as an important requirement for ASON
networks. It allows a connection setup request to be retried on an networks. Upon a setup failure, it allows a connection setup request
alternate path that detours around a blocked link or node upon a to be retried on an alternate path that detours around a blocked link
setup failure, for instance, because a link or a node along the or node (e.g., because a link or a node along the selected path has
selected path has insufficient resources. insufficient resources).
Crankback mechanisms MAY also be applied during connection recovery Crankback mechanisms MAY also be applied during connection recovery
by indicating the location of the failed link or node. This would by indicating the location of the failed link or node. This would
significantly improve the successful recovery ratio for failed significantly improve the successful recovery ratio for failed
connections, especially in situations where a large number of setup connections, especially in situations where a large number of setup
requests are simultaneously triggered. requests are simultaneously triggered.
The following mechanisms are assumed during crankback signaling: The following mechanisms are assumed during crankback signaling:
- the blocking resource (link or node) MUST be identified and
returned in the error response message towards the repair node - The blocking resource (link or node) MUST be identified and
(that may or may not be the ingress node); it is also assumed that returned in the error response message to the repair node (that
this process will occur within a limited period of time may or may not be the ingress node); it is also assumed that this
- the computation (from the repair node) of an alternate path around process will occur within a limited period of time.
- The computation (from the repair node) of an alternate path around
the blocking link or node that satisfies the initial connection the blocking link or node that satisfies the initial connection
constraints constraints.
- the re-initiation of the connection setup request from the repair
node (i.e. the node that has intercepted and processed the error - The re-initiation of the connection setup request from the repair
response message) node (i.e., the node that has intercepted and processed the error
response message).
The following properties are expected for crankback signaling: The following properties are expected for crankback signaling:
- Error information persistence: the entity that computes the - Error information persistence: the entity that computes the
alternate (re-routing) path SHOULD store the identifiers of the alternate (re-routing) path SHOULD store the identifiers of the
blocking resources, as indicated in the error message, until the
D.Papadimitriou et al. - Expires April 2005 8
blocking resources as indicated in the error message until the
connection is successfully established or until the node abandons connection is successfully established or until the node abandons
rerouting attempts. Since crankback may happen more than once rerouting attempts. Since crankback may happen more than once
while establishing a specific connection, the history of all while establishing a specific connection, the history of all
experienced blockages for this connection SHOULD be maintained (at experienced blockages for this connection SHOULD be maintained (at
least until the routing protocol updates the state of this least until the routing protocol updates the state of this
information) to perform an accurate path computation avoiding all information) to perform an accurate path computation that will
blockages. avoid all blockages.
- Rerouting attempts limitation: to prevent an endless repetition of - Rerouting attempts limitation: to prevent an endless repetition of
connection setup attempts (using crankback information), the connection setup attempts (using crankback information), the
number of retries SHOULD be strictly limited. The maximum number of number of retries SHOULD be strictly limited. The maximum number
crankback rerouting attempts allowed MAY be limited per connection of crankback rerouting attempts allowed MAY be limited per
or per node: connection or per node:
- When the number of retries at a particular node is exceeded, the
node currently handling the failure reports the error message - When the number of retries at a particular node is exceeded,
upstream to the next repair node where further rerouting attempts the node that is currently handling the failure reports the
MAY be performed. It is important that the crankback information error message upstream to the next repair node, where further
provided indicates that re-routing through this node will not rerouting attempts MAY be performed. It is important that the
succeed. crankback information provided indicate that re-routing through
this node will not succeed.
- When the maximum number of retries for a specific connection - When the maximum number of retries for a specific connection
has been exceeded, the repair node handling the current has been exceeded, the repair node that is handling the current
failure SHOULD send an error message upstream indicating failure SHOULD send an error message upstream to indicate the
"Maximum number of re-routings exceeded". This error message "Maximum number of re-routings exceeded". This error message
will be sent back to the ingress node with no further will be sent back to the ingress node with no further rerouting
rerouting attempts. Then, the ingress node MAY choose to attempts. Then, the ingress node MAY choose to retry the
retry the connection setup according to local policy but also connection setup according to local policy, using its original
re-use its original path or compute a path that avoids the path, or computing a path that avoids the blocking resources.
blocking resources.
Note: after several retries, a given repair point MAY be unable to Note: After several retries, a given repair point MAY be unable to
compute a path to the destination node that avoids all of the compute a path to the destination node that avoids all of the
blockages. In this case, it MUST pass the error message upstream to blockages. In this case, it MUST pass the error message upstream
the next repair point. to the next repair point.
4.7 Support for Additional Error Cases 4.7. Support for Additional Error Cases
To support the ASON network, the following additional category of To support the ASON network, the following additional category of
error cases are defined: error cases are defined:
- Errors associated with basic call and soft permanent connection - Errors associated with basic call and soft permanent connection
support. For example, these MAY include incorrect assignment of support. For example, these MAY include incorrect assignment of
IDs for the Call or an invalid interface ID for the soft permanent IDs for the Call or an invalid interface ID for the soft permanent
connection. connection.
- Errors associated with policy failure during processing of the new - Errors associated with policy failure during processing of the new
call and soft permanent connection capabilities. These MAY include call and soft permanent connection capabilities. These MAY
unauthorized request for the particular capability. include unauthorized requests for the particular capability.
- Errors associated with incorrect specification of the service - Errors associated with incorrect specification of the service
level. level.
5. Backward Compatibility 5. Backward Compatibility
D.Papadimitriou et al. - Expires April 2005 9
As noted above, in support of GMPLS protocol requirements, any As noted above, in support of GMPLS protocol requirements, any
extensions to the GMPLS signaling protocol in support of the extensions to the GMPLS signaling protocol, in support of the
requirements described in this document MUST be backward compatible. requirements described in this document, MUST be backward compatible.
Backward compatibility means that in a network of nodes, some of Backward compatibility means that in a network of nodes, where some
which support GMPLS signaling extensions to facilitate the functions support GMPLS signaling extensions to facilitate the functions
described in this document, and some of which do not, it MUST be described in this document, and some do not, it MUST be possible to
possible to set up conventional connections (as described by [RFC set up conventional connections (as described by [RFC3473]) between
3473]) between any arbitrary pair of nodes and traversing any any arbitrary pair of nodes and to traverse any arbitrary set of
arbitrary set of nodes. Further, the use of any GMPLS signaling nodes. Further, the use of any GMPLS signaling extensions to set up
extensions to set up calls or connections that support the functions calls or connections that support the functions described in this
described in this document MUST not perturb existing conventional document MUST not perturb existing conventional connections.
connections.
Additionally, when transit nodes, that do not need to participate in Additionally, when transit nodes that do not need to participate in
the new functions described in this document, lie on the path of a the new functions described in this document lie on the path of a
call or connection, the GMPLS signaling extensions MUST be such that call or connection, the GMPLS signaling extensions MUST be such that
those transit nodes are able to participate in the establishment of those transit nodes are able to participate in the establishment of a
the call or connection by passing the setup information onwards, call or connection by passing the setup information onwards,
unmodified. unmodified.
Lastly, when a transit or egress node is called upon to support a Lastly, when a transit or egress node is called upon to support a
function described in this document, but does not, the GMPLS function described in this document, but does not support the
signaling extensions MUST be such that they can be rejected by pre- function, the GMPLS signaling extensions MUST be such that they can
existing GMPLS signaling mechanisms in a way that is not detrimental be rejected by pre-existing GMPLS signaling mechanisms in a way that
to the network as a whole. is not detrimental to the network as a whole.
6. Security Considerations 6. Security Considerations
Per [ITU-T G.8080], it is not possible to establish a connection in Per [ITU-T-G.8080], it is not possible to establish a connection in
advance of call setup completion. Also, policy and authentication advance of call setup completion. Also, policy and authentication
procedures are applied prior to the establishment of the call (and procedures are applied prior to the establishment of the call (and
can then also be restricted to connection establishment in the can then also be restricted to connection establishment in the
context of this call). context of this call).
This document introduces no new security requirements to GMPLS This document introduces no new security requirements to GMPLS
signaling (see [RFC3471]). signaling (see [RFC3471]).
7. Acknowledgements 7. Acknowledgements
The authors would like to thank Nic Larkin, Osama Aboul-Magd and The authors would like to thank Nic Larkin, Osama Aboul-Magd, and
Dimitrios Pendarakis for their contribution to the previous version Dimitrios Pendarakis for their contribution to the previous version
of this document, Zhi-Wei Lin for his contribution to this document, of this document, Zhi-Wei Lin for his contribution to this document,
Deborah Brungard for her input and guidance in our understanding of Deborah Brungard for her input and guidance in our understanding of
the ASON model, and Gert Grammel for his decryption effort during the the ASON model, and Gert Grammel for his decryption effort during the
reduction of some parts of this document. reduction of some parts of this document.
8. References 8. References
8.1 Normative References 8.1. Normative References
[RFC2026] S.Bradner, "The Internet Standards Process --
D.Papadimitriou et al. - Expires April 2005 10
Revision 3", BCP 9, RFC 2026, October 1996.
[RFC2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] D.Awduche et al., "RSVP-TE: Extensions to RSVP for [RFC3471] Berger, L., "Generalized Multi-Protocol Label
LSP Tunnels," RFC 3209, December 2001. Switching (GMPLS) Signaling Functional Description",
RFC 3471, January 2003.
[RFC3471] L.Berger (Editor) et al., "Generalized Multi-
Protocol Label Switching (GMPLS) - Signaling
Functional Description," RFC 3471, January 2003.
[RFC3473] L.Berger (Editor) et al., "Generalized Multi-Protocol
Label Switching (GMPLS) Signaling - Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE)
Extensions," RFC 3473, January 2003.
[RFC3667] S.Bradner, "IETF Rights in Contributions", BCP 78, [RFC3473] Berger, L., "Generalized Multi-Protocol Label
RFC 3667, February 2004. Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[RFC3668] S.Bradner, Ed., "Intellectual Property Rights in IETF 8.2. Informative References
Technology", BCP 79, RFC 3668, February 2004.
8.2 Informative References [ANSI-T1.105] ANSI, "Synchronous Optical Network (SONET): Basic
Description Including Multiplex Structure, Rates, and
Formats", T1.105, October 2000.
[GMPLS-OTN] D.Papadimitriou (Editor), "GMPLS Signaling Extensions [GMPLS-OTN] Papadimitriou, D., Ed., "Generalized MPLS (GMPLS)
for G.709 Optical Transport Networks Control," Work Signaling Extensions for G.709 Optical Transport
in progress, draft-ietf-ccamp-gmpls-g709-08.txt, Networks Control", Work in Progress, January 2005.
September 2004.
[GMPLS-OVERLAY]G.Swallow et al., "GMPLS RSVP Support for Overlay [GMPLS-OVERLAY] Swallow, G., Drake, J., Ishimatsu, H., and Y.
Model," Work in Progress, draft-ietf-ccamp-gmpls- Rekhter, "Generalize Multiprotocol Label Switching
overlay-05.txt, October 2004. (GMPLS) User-Network Interface (UNI): Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE)
Support for the Overlay Model", Work in Progress,
October 2004.
[GMPLS-SONET] E.Mannie and D.Papadimitriou (Editors), "GMPLS [GMPLS-SONET] Mannie, E. and D. Papadimitriou, "Generalized Multi-
Extensions for SONET and SDH Control, Work in Protocol Label Switching (GMPLS) Extensions for
Progress," draft-ietf-ccamp-gmpls-sonet-sdh-08.txt, Synchronous Optical Network (SONET) and Synchronous
February 2003. Digital Hierarchy (SDH) Control", RFC 3946, October
2004.
[GMPLS-VPN] H.Ould-Brahim and Y.Rekhter (Editors), "GVPN Services: [GMPLS-VPN] Ould-Brahim, H. and Y. Rekhter, Eds., "GVPN Services:
Generalized VPN Services using BGP and GMPLS Generalized VPN Services using BGP and GMPLS
Toolkit," Work in Progress, draft-ouldbrahim-ppvpn- Toolkit", Work in Progress, May 2004.
gvpn-bgpgmpls-05.txt, May 2004.
For information on the availability of the following documents,
please see http://www.itu.int.
[ITU-T G.7713] ITU-T "Distributed Call and Connection Management,"
Recommentation G.7713/Y.1304, November 2001.
[ITU-T G.8080] ITU-T "Architecture for the Automatically Switched
Optical Network (ASON)," Recommendation G.8080/
D.Papadimitriou et al. - Expires April 2005 11
Y.1304, November 2001 (and Revision, January 2003).
9. Author's Addresses
Dimitri Papadimitriou (Alcatel)
Francis Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be
John Drake (Calient) [ITU-T-G.707] ITU-T, "Network Node Interface for the Synchronous
5853 Rue Ferrari, Digital Hierarchy (SDH)", Recommendation G.707,
San Jose, CA 95138, USA October 2000.
EMail: jdrake@calient.net
Adrian Farrel [ITU-T-G.709] ITU-T, "Interface for the Optical Transport Network
Old Dog Consulting (OTN)", Recommendation G.709 (and Amendment 1),
Phone: +44 (0) 1978 860944 February 2001 (October 2001). http://www.itu.int
EMail: adrian@olddog.co.uk
Gerald R. Ash (ATT) [ITU-T-G.7713] ITU-T "Distributed Call and Connection Management",
AT&T Labs, Room MT D5-2A01 Recommendation G.7713/Y.1304, November 2001.
200 Laurel Avenue http://www.itu.int
Middletown, NJ 07748, USA
EMail: gash@att.com
Lyndon Ong (Ciena) [ITU-T-G.805] ITU-T, "Generic functional architecture of transport
5965 Silver Creek Valley Road networks)", Recommendation G.805, March 2000.
San Jose, CA 95138, USA http://www.itu.int
EMail: lyong@ciena.com
D.Papadimitriou et al. - Expires April 2005 12 [ITU-T-G.8080] ITU-T "Architecture for the Automatically Switched
Optical Network (ASON)", Recommendation
G.8080/Y.1304, November 2001 (and Revision, January
2003). http://www.itu.int
Appendix - Terminology Appendix - Terminology
This document makes use of the following terms: This document makes use of the following terms:
Administrative domain: See Recommendation G.805. Administrative domain: See Recommendation G.805 [ITU-T-G.805].
Call: association between endpoints that supports an instance of a Call: Association between endpoints that supports an instance of a
service. service.
Connection: concatenation of link connections and sub-network Connection: Concatenation of link connections and sub-network
connections that allows the transport of user information between the connections that allows the transport of user information between the
ingress and egress points of a sub-network. ingress and egress points of a sub-network.
Control plane: performs the call control and connection control Control Plane: Performs the call control and connection control
functions. Through signaling, the control plane sets up and releases functions. The control plane sets up and releases connections
connections, and may restore a connection in case of a failure. through signaling, and may restore a connection in case of a failure.
(Control) Domain: represents a collection of entities that are (Control) Domain: Represents a collection of entities that are
grouped for a particular purpose. G.8080 applies this G.805 grouped for a particular purpose. G.8080 applies this G.805
recommendation concept (that defines two particular forms, the recommendation concept (that defines two particular forms: the
administrative domain and the management domain) to the control plane administrative domain and the management domain) to the control plane
in the form of a control domain. The entities that are grouped in a in the form of a control domain. Entities grouped in a control
control domain are components of the control plane. domain are components of the control plane.
External NNI (E-NNI): interfaces are located between protocol External NNI (E-NNI): Interfaces are located between protocol
controllers between control domains. controllers that are situated between control domains.
Internal NNI (I-NNI): interfaces are located between protocol Internal NNI (I-NNI): Interfaces are located between protocol
controllers within control domains. controllers within control domains.
Link: See Recommendation G.805. Link: See Recommendation G.805 [ITU-T-G.805].
Management plane: performs management functions for the Transport Management Plane: Performs management functions for the Transport
Plane, the control plane and the system as a whole. It also provides Plane, the control plane, and the system as a whole. It also
coordination between all the planes. The following management provides coordination between all the planes. The following
functional areas are performed in the management plane: performance, management functional areas are performed in the management plane:
fault, configuration, accounting and security management performance, fault, configuration, accounting, and security
management.
Management domain: See Recommendation G.805. Management Domain: See Recommendation G.805 [ITU-T-G.805].
Transport plane: provides bi-directional or unidirectional transfer Transport Plane: Provides bi-directional or unidirectional transfer
of user information, from one location to another. It can also of user information, from one location to another. It can also
provide transfer of some control and network management information. provide transfer of some control and network management information.
The Transport Plane is layered; it is equivalent to the Transport The Transport Plane is layered and is equivalent to the Transport
Network defined in G.805. Network defined in G.805 [ITU-T-G.805].
User Network Interface (UNI): interfaces are located between protocol User Network Interface (UNI): Interfaces are located between protocol
controllers between a user and a control domain. controllers, between a user and a control domain.
D.Papadimitriou et al. - Expires April 2005 13 Authors' Addresses
Intellectual Property Statement Dimitri Papadimitriou
Alcatel
Francis Wellesplein 1,
B-2018 Antwerpen, Belgium
Phone: +32 3 2408491
EMail: dimitri.papadimitriou@alcatel.be
John Drake
Boeing Satellite Systems
2300 East Imperial Highway
El Segundo, CA 90245
EMail: John.E.Drake2@boeing.com
Adrian Farrel
Old Dog Consulting
Phone: +44 (0) 1978 860944
EMail: adrian@olddog.co.uk
Gerald R. Ash
ATT
AT&T Labs, Room MT D5-2A01
200 Laurel Avenue
Middletown, NJ 07748, USA
EMail: gash@att.com
Lyndon Ong
Ciena
PO Box 308
Cupertino, CA 95015, USA
EMail: lyong@ciena.com
Full Copyright Statement
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INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
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Acknowledgment 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.
D.Papadimitriou et al. - Expires April 2005 14
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