draft-ietf-ccamp-gmpls-ason-reqts-01.txt   draft-ietf-ccamp-gmpls-ason-reqts-02.txt 
CCAMP Working Group D. Papadimitriou (Alcatel) CCAMP Working Group D. Papadimitriou (Alcatel)
Internet Draft Z. Lin (New York City Transit) Internet Draft Z. Lin (New York City Transit)
Category: Informational J. Drake (Calient) Category: Informational J. Drake (Calient)
J. Ash (ATT) J. Ash (ATT)
Expiration Date: December 2003 A. Farrel (Movaz) Expiration Date: February 2004 A. Farrel (Old Dog Consulting)
L. Ong (Ciena) L. Ong (Ciena)
June 2003 August 2003
Requirements for Generalized MPLS (GMPLS) Usage and Extensions Requirements for Generalized MPLS (GMPLS) Signaling Usage
for Automatically Switched Optical Network (ASON) and Extensions for Automatically Switched Optical Network (ASON)
draft-ietf-ccamp-gmpls-ason-reqts-01.txt draft-ietf-ccamp-gmpls-ason-reqts-02.txt
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC-2026. all provisions of Section 10 of RFC-2026.
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. Internet-Drafts are draft documents valid for a maximum of Drafts. Internet-Drafts are draft documents valid for a maximum of
skipping to change at line 38 skipping to change at line 38
progress." progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
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1. Abstract 1. Abstract
The Generalized MPLS (GMPLS) suite of protocol has been defined to The Generalized MPLS (GMPLS) suite of protocols has been defined to
control different switching technologies as well as different control different switching technologies as well as different
applications. These include support for requesting TDM connections applications. These include support for requesting TDM connections
including SONET/SDH and Optical Transport Networks (OTNs). including SONET/SDH and Optical Transport Networks (OTNs).
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 signalling protocol to support the capabilities of an GMPLS signaling protocol to support the capabilities of an
Automatically Switched Optical Network (ASON). This document Automatically Switched Optical Network (ASON). This document
provides a problem statement and additional requirements on the provides a problem statement and additional requirements on the
GMPLS signaling protocol to support the ASON functionality. GMPLS signaling protocol to support the ASON functionality.
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2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC-2119. this document are to be interpreted as described in RFC-2119.
3. Introduction 3. Introduction
The GMPLS suite of protocol specifications provides support for The GMPLS suite of protocol specifications provides support for
controlling different switching technologies as well as different controlling different switching technologies as well as different
applications. These include support for requesting TDM connections applications. These include support for requesting TDM connections
including SONET/SDH (see ANSI T1.105 and ITU-T G.707, respectively) including SONET/SDH (see ANSI T1.105 and ITU-T G.707, respectively)
as well as Optical Transport Networks (see ITU-T G.709). In as well as Optical Transport Networks (see ITU-T G.709). In
addition, there are certain capabilities that are needed to support addition, there are certain capabilities that are needed to support
Automatically Switched Optical Networks control planes (their Automatically Switched Optical Networks control planes (their
architecture is defined in [ITU-T G.8080]). These include generic architecture is defined in [ITU-T G.8080]). These include generic
capabilities such as call and connection separation and more capabilities such as call and connection separation, and more
specific capabilities such as support of soft permanent connections. specific capabilities such as support of soft permanent connections.
This document concentrates on the signaling aspects of the GMPLS This document concentrates on the signaling aspects of the GMPLS
suite of protocols. It discusses the functional requirements that suite of protocols. It discusses the functional requirements that
lead to additional and backward compatible extensions to GMPLS lead to additional and backward compatible extensions to GMPLS
signaling (see [RFC 3471]) to support the capabilities as specified signaling (see [RFC 3471] and [RFC 3473]) to support the
in the above referenced document. A terminology section is provided capabilities as specified in the above referenced document. A
in the Appendix. description of backward compatibility considerations is provided in
Section 5. A terminology section is provided in the Appendix.
Problem Statement: 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]). detailed description see [ITU-T G.8080]).
The ASON control plane specification is meant to be applicable to The ASON control plane specification is meant to be applicable to
different transport technologies (e.g., SDH/SONET, OTN) in various different transport technologies (e.g., SDH/SONET, OTN) in various
networking environments (e.g., inter-carrier, intra-carrier). Also, networking environments (e.g., inter-carrier, intra-carrier). Also,
the ASON model distinguishes reference points (representing points the ASON model distinguishes reference points (representing points
of protocol information exchange) defined (1) between an of protocol information exchange) defined (1) between an
administrative domain and a user, (2) between administrative domains administrative domain and a user, (2) between administrative domains
and, (3) between areas of the same administrative domain and when and, (3) between areas of the same administrative domain and when
needed between control components (or simply controllers) within needed between control components (or simply controllers) within
areas. A full description of the ASON terms and relationship between areas. A full description of the ASON terms and relationship between
ASON model and GMPLS protocol suite may be found in [IPO-ASON]. ASON model and GMPLS protocol suite may be found in [IPO-ASON].
This document describes the use of GMPLS signalling (and in This document describes the use of GMPLS signaling (in particular,
particular, [RFC 3471]) to provide call and connection management [RFC 3471] and [RFC 3473]) to provide call and connection management
(see [ITU-T G.7713]). The following functionality is expected to be (see [ITU-T G.7713]). The following functionality is expected to be
supported and to be backward compatible with the GMPLS protocol supported and to be backward compatible with the GMPLS protocol
suite as currently defined by the IETF: suite as currently defined by the IETF:
(a) soft permanent connection capability (a) soft permanent connection capability
(b) call and connection separation (b) call and connection separation
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(c) call segments (c) call segments
(d) extended restart capabilities during control plane failures (d) extended restart capabilities during control plane failures
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(e) extended label usage (e) extended label usage
(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 applicability statements regarding how the GMPLS suite of The applicability statements regarding how the GMPLS suite of
protocols may be applied to the ASON architecture can be found in protocols may be applied to the ASON architecture can be found in
[IPO-ASON] and [IPO-REQS]. The former includes a summary of the ASON [IPO-ASON] and [IPO-REQS]. The former includes a summary of the ASON
functions as well as a detailed discussion of the applicability of functions as well as a detailed discussion of the applicability of
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- Support for call segments - Support for call segments
- Support for extended restart capabilities during control plane - Support for extended restart capabilities during control plane
failures failures
- Support for extended label usage - Support for extended label usage
- Support for crankback capability - Support for crankback capability
- Support for additional error cases - Support for additional error cases
Also, the support of these functions is strictly independent and Also, the support of these functions is strictly independent and
must be agnostic of any user-to-network interface and therefore not must be agnostic of any user-to-network interface and therefore not
constrained or restricted by its implementation specifics (see [ITU- constrained or restricted by its implementation specifics (see [ITU-
T G.8080] and [ITU-T G.7713]). However, end-to-end signaling should T G.8080] and [ITU-T G.7713]).
be facilitated regardless of the administrative boundaries and
protocols within the network when at least some part of the network In support of the G.8080 end-to-end call model across different
operates using GMPLS signaling. The resulting requirement being that signaling domains, end-to-end signaling should be facilitated
there should be a clear mapping of signaling requests between GMPLS regardless of the administrative boundaries and protocols within the
systems and other systems which support GMPLS or utilize other network. The resulting requirement being that there needs to be a
signaling protocols or some which may not support any signaling clear mapping of signaling requests between GMPLS control domains
protocols. For instance, Section 4.5 'Support for Extended Label and non-GMPLS control domains. This document provides signalling
Usage' covers the requirements when nodes do not support any requirements for G.8080 distributed call and connection management
signaling protocols. based on GMPLS, within a GMPLS based control domain and between
GMPLS based control domains. It does not restrict use of other
protocols within a control domain. Interworking aspects, including
mapping of non-GMPLS protocol signaling requests and support of non-
GMPLS address formats, is outside the scope of this document.
Compatibility aspects of non-GMPLS systems (nodes) within a GMPLS
control domain i.e. the support of GMPLS systems and other systems
which utilize other signaling protocols or some which may not
support any signaling protocols is described. For instance, Section
4.5 'Support for Extended Label Usage' covers the requirements when
a non-GMPLS capable sub-network is introduced or when nodes do not
support any signaling protocols.
4.1 Support for Soft Permanent Connection (SPC) Capability 4.1 Support for Soft Permanent Connection (SPC) Capability
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An SPC is a combination of a permanent connection at the source An SPC is a combination of a permanent connection at the source
user-to-network side, a permanent connection at the destination user-to-network side, a permanent connection at the destination
user-to-network side, and a switched connection within the network. user-to-network side, and a switched connection within the network.
An Element Management System (EMS) or a Network Management System An Element Management System (EMS) or a Network Management System
(NMS) typically initiates the establishment of the switched (NMS) typically initiates the establishment of the switched
connection by communicating with the node that initiates the connection by communicating with the node that initiates the
switched connection (also known as the ingress node). The latter switched connection (also known as the ingress node). The latter
then sets the connection using the distributed GMPLS signaling then sets the connection using the distributed GMPLS signaling
protocol. For the SPC, the communication method between the EMS/NMS protocol. For the SPC, the communication method between the EMS/NMS
and the ingress node is beyond the scope of this document (so it is and the ingress node is beyond the scope of this document (so it is
for any other function described in this document). for any other function described in this document).
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The end-to-end connection is thus created by associating the The end-to-end connection is thus created by associating the
incoming interface of the ingress node with the switched connection incoming interface of the ingress node with the switched connection
within the network, and the outgoing interface of the switched within the network, and the outgoing interface of the switched
connection terminating network node (also referred to as egress connection terminating network node (also referred to as egress
node). An SPC connection is illustrated in the following Figure, node). An SPC connection is illustrated in the following Figure,
which shows user's node A connected to a provider's node B via link which shows user's node A connected to a provider's node B via link
#1, user's node Z connected to a provider's node Y via link #3, and #1, user's node Z connected to a provider's node Y via link #3, and
an abstract link #2 connecting provider's node B and node Y. an abstract link #2 connecting provider's node B and node Y.
--- --- --- --- --- --- --- ---
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Thus, to support the capability to request an SPC connection: 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 the case
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 signalling 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
under the control of the EMS/NMS and is not within the scope of the under the control of the EMS/NMS and is not within the scope of the
signaling protocol. It is, therefore, outside the scope of this signaling protocol. It is, therefore, outside the scope of this
document. document.
4.2 Support for Call and Connection Separation 4.2 Support for Call and Connection Separation
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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 as a service provided between two end-points, where
several calls may exist between them. To each call multiple several calls may exist between them. Multiple connections may be
connections may be associated. The call concept provides an abstract associated to each call. The call concept provides an abstract
relationship between two users, where this relationship describes relationship between two users, where this relationship describes
(or verifies) to what extent the users are willing to offer (or (or verifies) to what extent the users are willing to offer (or
accept) service to each other. Therefore, a call does not provide accept) service to each other. Therefore, a call does not provide
the actual connectivity for transmitting user traffic, but only the actual connectivity for transmitting user traffic, but only
builds a relationship by which subsequent connections may be made. builds a relationship by which subsequent connections may be made.
A property of a call is to contain zero, one or multiple A property of a call is to contain zero, one or multiple
connections. Within the same call, connections may be of different connections. Within the same call, connections may be of different
types and each connection may exist independently of other types and each connection may exist independently of other
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connections, i.e., each connection is setup and released with connections, i.e., each connection is setup and released with
separate Path/Resv messages. For example, a call may contain a set separate Path/Resv messages. For example, a call may contain a set
of basic connections and virtually concatenated connections (see of basic connections and virtually concatenated connections (see
[GMPLS-SONET] for corresponding connection signaling extensions). [GMPLS-SONET] for corresponding connection signaling extensions).
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.
In essence, a call allows: In essence, a call allows:
- Support for virtual concatenation where each connection can travel - Support for virtual concatenation where each connection can travel
on different diverse paths on different diverse paths
- Facilitate upgrading strategy of the control plane operations, - An upgrade strategy for control plane operations, where a call
where a call control (service provisioning) may be separate from 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
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, which
may result in decreasing contention during resource reservation may result in decreasing contention during resource reservation
- General treatment of multiple connections which may be associated - General treatment of multiple connections which may be associated
for several purposes; for example a pair of working and recovery 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.
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 allow for end-to- should include a call identification mechanism and allow for end-to-
end call capability exchange. 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, 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 LSR 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 on
the call identification conventions between parties involved in the the call identification conventions between parties involved in the
call setup process. 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 As described in [ITU-T G.8080], call segmentation may be applied
when a call crosses several administrative domains. As such, an end- when a call crosses several administrative domains. As such, an end-
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to-end call may consist of multiple call segments, when the call to-end call may consist of multiple call segments, when the call
traverses multiple administrative domains. Each call segment can traverses multiple administrative domains. Each call segment can
have one or more associated connections and the number of have one or more associated connections and the number of
connections associated with each call segment may not be the same connections associated with each call segment may not be the same
for a given end-to-end call. for a given end-to-end call.
The initiating caller interacts with a called party by means of one The initiating caller interacts with a called party by means of one
or more intermediate call controllers located at the network edge or more intermediate call controllers located at the network edge
between administrative domains (i.e., inter-domain reference point) between administrative domains (i.e., inter-domain reference point)
and in particular at the user-to-network reference point. Their and in particular at the user-to-network reference point. Their
functions are defined by the policies associated by interactions functions are defined by the policies associated by interactions
between the administrative domain boundaries and between users and between the administrative domain boundaries and between users and
the network. the network.
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This capability allows for independent (policy based) choices of This capability allows for independent (policy based) choices of
signalling, concatenation, data plane protection and control plane signaling, concatenation, data plane protection and control plane
driven recovery paradigms in different administrative domains. driven recovery paradigms in different administrative 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 Various types of failures may occur affecting the ASON control
plane. Requirements placed on the control plane failure recovery by plane. Requirements placed on the control plane failure recovery by
[ITU-T G.8080] include: [ITU-T G.8080] include:
- Any control plane failure must not result in releasing established - Any control plane failure must not result in releasing established
connections. calls and connections.
- Upon recovery from a control plane failure, the recovered node - Upon recovery from a control plane failure, the recovered node
must have the ability to recover the status of the connections must have the ability to recover the status of the calls and
established before failure occurrence. connections established before failure occurrence.
- Upon recovery from a control plane failure, the recovered node - Upon recovery from a control plane failure, the recovered node
must have the ability to recover the connectivity information of must have the ability to recover the connectivity information of
its neighbors. its neighbors.
- Upon recovery from a control plane failure, connections in the - Upon recovery from a control plane failure, calls and connections
process of being established (i.e. pending connection setup in the process of being established (i.e. pending call/connection
requests) should be released or continued (with setup). setup requests) should be released or continued (with setup).
- Upon recovery from a control plane failure, connections in the - Upon recovery from a control plane failure, calls and connections
process of being released must be released. in the process of being released must be released.
- Upon recovery from a control plane failure, a call must have - Upon recovery from a control plane failure, a call must have
the ability to re-synchronize with its associated connections. the ability to re-synchronize with its associated connections.
4.5 Support for Extended Label Usage 4.5 Support for Extended Label Usage
Labels are defined in GMPLS (see [RFC 3471]) to provide information Labels are defined in GMPLS (see [RFC 3471]) to provide information
on the resources used on link local basis for a particular on the resources used on link local basis for a particular
connection. The labels may range from specifying a particular connection. The labels may range from specifying a particular
timeslot, a particular wavelength to a particular port/fiber. timeslot, a particular wavelength to a particular port/fiber.
In the ASON context, the value of a label MAY not be consistently In the ASON context, the value of a label MAY not be consistently
the same across a link. For example, the figure below illustrates the same across a link. For example, the figure below illustrates
the case where two GMPLS capable nodes (A and Z) are interconnected the case where two GMPLS capable nodes (A and Z) are interconnected
across two non-GMPLS capable nodes (B and C), where these nodes are across two non-GMPLS capable nodes (B and C), where these nodes are
all SONET/SDH nodes providing, e.g., a VC-4 service. all SONET/SDH nodes providing, e.g., a VC-4 service.
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----- ----- ----- -----
| | --- --- | | | | --- --- | |
| 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 local label MAY not be significant to the neighbor node since
the association between the local and the remote label may not the 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 where the timeslots are mapped 1:1 across the interface.
However, once a non-GMPLS capable sub-network is introduced between However, once a non-GMPLS capable sub-network is introduced between
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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 re-arrangement capability for the timeslots) label scoping MAY
become 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 [GMPLS-
SONET]) may be mapped onto node B's outgoing VC-4's timeslot #6 SONET]) may be mapped onto node B's outgoing VC-4's timeslot #6
(label=[6,0,0,0,0]) may be mapped onto node C's outgoing VC-4's (label=[6,0,0,0,0]) may be mapped onto node C's outgoing VC-4's
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level before the connection request is processed at the ingress level before the connection request is processed at the ingress
node. Note that in the case where two nodes are directly connected, node. Note that in the case where two nodes are directly connected,
no association is required. In particular, for directly connected no association is required. In particular, for directly connected
TDM interfaces no mapping function (at all) is required due to the TDM interfaces no mapping function (at all) is required due to the
implicit label structure (see [GMPLS-SONET] and [GMPLS-OTN]). In implicit label structure (see [GMPLS-SONET] and [GMPLS-OTN]). In
such instances, the label association function provides a one-to-one such instances, the label association function provides a one-to-one
mapping of the received to local label values. mapping of the received to local label values.
4.6 Support for Crankback 4.6 Support for Crankback
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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. It allows a connection setup request to be retried on an
alternate path that detours around a blocked link or node upon a alternate path that detours around a blocked link or node upon a
setup failure, for instance, because a link or a node along the setup failure, for instance, because a link or a node along the
selected path has insufficient resources. selected path has 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 signalling The following mechanisms are assumed during crankback signaling (see
(see also [GMPLS-CRANK]): also [GMPLS-CRANK]):
- the blocking resource (link or node) must be identified and - the blocking resource (link or node) must be identified and
returned in the error response message towards the repair node returned in the error response message towards the repair node
(that may or may not be the ingress node); it is also assumed that (that may or may not be the ingress node); it is also assumed that
Expires December 2003 7
this process will occur within a limited period of time this process will occur within a limited period of time
- the computation (from the repair node) of an alternate path around - the computation (from the repair node) of an alternate path around
the blocking link or node satisfying the initial connection the blocking link or node satisfying the initial connection
constraints constraints
- the re-initiation of the connection setup request from the repair - the re-initiation of the connection setup request from the repair
node (i.e. the node that has intercepted and processed the error node (i.e. the node that has intercepted and processed the error
response message) response message)
The following properties are expected for crankback signalling (see The following properties are expected for crankback signaling (see
[GMPLS-CRANK]): [GMPLS-CRANK]):
- 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 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 while rerouting attempts. Since crankback may happen more than once while
establishing a specific connection, the history of all experienced establishing a specific connection, the history of all experienced
blockages for this connection should be maintained (at least until blockages for this connection should be maintained (at least until
the routing protocol updates the state of this information) to the routing protocol updates the state of this information) to
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per node, per area or even per administrative domain. per node, per area or even per administrative domain.
- When the number of retries at a particular node or area is - When the number of retries at a particular node or area is
exceeded, the node currently handling the failure reports the exceeded, the node currently handling the failure reports the
error message upstream to the next repair node where further error message upstream to the next repair node where further
rerouting attempts may be performed. It is important that the rerouting attempts may be performed. It is important that the
crankback information provided indicates that re-routing crankback information provided indicates that re-routing
through this node will not succeed. 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 failure has been exceeded, the repair node handling the current failure
should send an error message upstream indicating "Maximum should send an error message upstream indicating "Maximum
D.Papadimitriou et al. - Expires February 2004 8
number of re-routings exceeded". This error message will be number of re-routings exceeded". This error message will be
sent back to the ingress node with no further rerouting sent back to the ingress node with no further rerouting
attempts. Then, the ingress node may choose to retry the attempts. Then, the ingress node may choose to retry the
connection setup according to local policy but also re-use its connection setup according to local policy but also re-use its
original path or compute a path that avoids the blocking original path or compute a path that avoids the blocking
resources. 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 to
the next repair point. 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
Expires December 2003 8
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 include
unauthorized request for the particular capability. unauthorized request for the particular capability.
- Errors associated with incorrect specification of the service - Errors associated with incorrect specification of the service
level. level.
5. Security Considerations 5. Backward Compatibility
As noted above, any extensions to the GMPLS signaling protocol in
support of the requirements described in this document must be
backward compatible.
Backward compatibility means that in a network of nodes, some of
which support GMPLS signaling extensions to facilitate the functions
described in this document, and some of which do not, it must be
possible to set up conventional connections (as described by [RFC
3473]) between any arbitrary pair of nodes and traversing any
arbitrary set of nodes. Further, the use of any GMPLS signaling
extensions to set up calls or connections that support the functions
described in this document must not perturb existing conventional
connections.
Additionally, when transit nodes, that do not need to participate in
the new functions described in this document, lie on the path of a
call or connection, the GMPLS signaling extensions must be such that
those transit nodes are able to participate in the establishment of
the call or connection by passing the setup information onwards,
unmodified.
Lastly, when a transit or egress node is called upon to support a
function described in this document, but does not, the GMPLS
signaling extensions must be such that they can be rejected by pre-
D.Papadimitriou et al. - Expires February 2004 9
existing GMPLS signaling mechanisms in a way that is not detrimental
to the network as a whole.
6. Security Considerations
Per [ITU-T G.8080], a connection cannot be established until the Per [ITU-T G.8080], a connection cannot be established until the
associated call has been set up. Also, policy and authentication associated call has been set up. 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
signalling (see [RFC3471]). signaling (see [RFC3471]).
6. Acknowledgements 7. Acknowledgements
The authors would like to thank Deborah Brungard, Nic Larkin, Osama The authors would like to thank Deborah Brungard, Nic Larkin, Osama
Aboul-Magd and Dimitrios Pendarakis for their comments and Aboul-Magd and Dimitrios Pendarakis for their comments and
contributions to the previous version of this document. contributions to the previous version of this document.
7. References 8. References
7.1 Normative References 8.1 Normative References
[RFC-2026] S.Bradner, "The Internet Standards Process -- [RFC-2026] S.Bradner, "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996. Revision 3", BCP 9, RFC 2026, October 1996.
[RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate [RFC-2119] S.Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC-3209] D.Awduche et al., "RSVP-TE: Extensions to RSVP for [RFC-3209] D.Awduche et al., "RSVP-TE: Extensions to RSVP for
LSP Tunnels," RFC 3209, December 2001. LSP Tunnels," RFC 3209, December 2001.
[RFC-3471] L.Berger (Editor) et al., "Generalized MPLS - [RFC-3471] L.Berger (Editor) et al., "Generalized Multi-
Signaling Functional Description," RFC 3471, January Protocol Label Switching (GMPLS) - Signaling
03. Functional Description," RFC 3471, January 2003.
[RFC-3473] L.Berger (Editor) et al., "Generalized Multi-Protocol
Label Switching (GMPLS) Signaling - Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE)
Extensions," RFC 3473, January 2003.
[ITUT G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the [ITUT G.8080] ITU-T Rec. G.8080/Y.1304, "Architecture for the
Automatically Switched Optical Network (ASON)," Automatically Switched Optical Network (ASON),"
November 2001 (and Revision, January 2003). November 2001 (and Revision, January 2003).
[GMPLS-CRANK] A.Farrel (Editor), "Crankback Routing Extensions for [GMPLS-CRANK] A.Farrel (Editor), "Crankback Routing Extensions for
MPLS Signaling," Work in Progress, draft-iwata-mpls- MPLS Signaling," Work in Progress, draft-iwata-mpls-
crankback-06.txt, June 2003. crankback-06.txt, June 2003.
[GMPLS-SONET] E.Mannie and D.Papadimitriou (Editors), "GMPLS [GMPLS-SONET] E.Mannie and D.Papadimitriou (Editors), "GMPLS
Extensions for SONET and SDH Control, Work in Extensions for SONET and SDH Control, Work in
Progress," draft-ietf-ccamp-gmpls-sonet-sdh-08.txt,
Expires December 2003 9 D.Papadimitriou et al. - Expires February 2004 10
Progress," draft-ietf-ccamp-gmpls-sonet-sdh-08.txt,
February 2003. February 2003.
[GMPLS-OTN] D.Papadimitriou (Editor), "GMPLS Signalling [GMPLS-OTN] D.Papadimitriou (Editor), "GMPLS Signaling Extensions
Extensions for G.709 Optical Transport Networks for G.709 Optical Transport Networks Control," Work
Control," Work in progress, draft-ietf-ccamp-gmpls- in progress, draft-ietf-ccamp-gmpls-g709-04.txt, May
g709-04.txt, May 2003, 2003.
7.2 Informative References 8.2 Informative References
[IPO-ASON] Aboul-Magd (Editor) et al., "Automatic Switched [IPO-ASON] Aboul-Magd (Editor) et al., "Automatic Switched
Optical Network (ASON) Architecture and Its Related Optical Network (ASON) Architecture and Its Related
Protocols," Work in progress, draft-ietf-ipo-ason- Protocols," Work in progress, draft-ietf-ipo-ason-
02.txt, March 2002. 02.txt, March 2002.
[IPO-REQS] Y.Xue (Editor) et al., "Optical Network Service [IPO-REQS] Y.Xue (Editor) et al., "Optical Network Service
Requirements," Work in progress, draft-ietf-ipo- Requirements," Work in progress, draft-ietf-ipo-
carrier-requirements-05.txt. carrier-requirements-05.txt.
[ITUT G.7713] ITU-T Rec. G.7713/Y.1304, "Distributed Call and [ITUT G.7713] ITU-T Rec. G.7713/Y.1304, "Distributed Call and
Connection Management," November 2001. Connection Management," November 2001.
8. Author's Addresses 9. Author's Addresses
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Francis Wellesplein 1, Francis Wellesplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Email: dimitri.papadimitriou@alcatel.be Email: dimitri.papadimitriou@alcatel.be
Zhi-Wei Lin (New York City Transit) Zhi-Wei Lin (New York City Transit)
2 Broadway, Room C3.25 2 Broadway, Room C3.25
New York, NY 10004 New York, NY 10004, USA
Email: zhiwlin@nyct.com Email: zhiwlin@nyct.com
John Drake (Calient) John Drake (Calient)
5853 Rue Ferrari, 5853 Rue Ferrari,
San Jose, CA 95138, USA San Jose, CA 95138, USA
Email: jdrake@calient.net Email: jdrake@calient.net
Adrian Farrel (Movaz Networks) Adrian Farrel (Old Dog Consulting)
7926 Jones Branch Drive, Email: adrian@olddog.co.uk
McLean, VA 22102, USA
Email: afarrel@movaz.com
Gerald R. Ash (ATT) Gerald R. Ash (ATT)
AT&T Labs, Room MT D5-2A01 AT&T Labs, Room MT D5-2A01
200 Laurel Avenue 200 Laurel Avenue
Middletown, NJ 07748, USA Middletown, NJ 07748, USA
Email: gash@att.com Email: gash@att.com
Lyndon Ong (Ciena) Lyndon Ong (Ciena)
5965 Silver Creek Valley Road 5965 Silver Creek Valley Road
San Jose, CA 95138, USA San Jose, CA 95138, USA
Email: lyong@ciena.com Email: lyong@ciena.com
Expires December 2003 10 D.Papadimitriou et al. - Expires February 2004 11
Appendix - Terminology Appendix - Terminology
This draft defines the following terms: This document makes use of the following terms:
Administrative domain: See Recommendation G.805. Administrative domain: See Recommendation 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 connections that allows the transport of user information between
the ingress and egress points of a sub-network. the ingress and egress points of a sub-network.
skipping to change at line 590 skipping to change at line 634
fault, configuration, accounting and security management fault, configuration, accounting and security management
Management domain: See Recommendation G.805. Management domain: See Recommendation 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; it is equivalent to the Transport
Network defined in G.805. Network defined in G.805.
Expires December 2003 11 D.Papadimitriou et al. - Expires February 2004 12
Full Copyright Statement Full Copyright Statement
"Copyright (C) The Internet Society (2003). All Rights Reserved. "Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph kind, provided that the above copyright notice and this paragraph
skipping to change at line 620 skipping to change at line 664
The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. revoked by the Internet Society or its successors or assigns.
This document and the information contained herein is provided on an This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Expires December 2003 12 D.Papadimitriou et al. - Expires February 2004 13
 End of changes. 

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