draft-ietf-ccamp-gmpls-ason-reqts-00.txt   draft-ietf-ccamp-gmpls-ason-reqts-01.txt 
skipping to change at line 14 skipping to change at line 14
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: December 2003 A. Farrel (Movaz)
L. Ong (Ciena) L. Ong (Ciena)
June 2003 June 2003
Requirements for Generalized MPLS (GMPLS) Usage and Extensions Requirements for Generalized MPLS (GMPLS) Usage and Extensions
for Automatically Switched Optical Network (ASON) for Automatically Switched Optical Network (ASON)
draft-ietf-ccamp-gmpls-ason-reqts-00.txt draft-ietf-ccamp-gmpls-ason-reqts-01.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
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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 protocol 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
signalling protocol to support the capabilities of an Automatically GMPLS signalling protocol to support the capabilities of an
Switched Optical Network (ASON). This document provides a problem Automatically Switched Optical Network (ASON). This document
statement and additional requirements on the GMPLS signaling provides a problem statement and additional requirements on the
protocol to support the ASON functionality. GMPLS signaling protocol to support the ASON functionality.
D.Papadimitriou et al. - Expires December 2003 1 D.Papadimitriou et al. - Expires December 2003 1
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
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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 (see [RFC 3471]). It discusses functional suite of protocols. It discusses the functional requirements that
requirements that lead to additional extensions to GMPLS to support lead to additional and backward compatible extensions to GMPLS
the capabilities as specified in the above referenced document. A signaling (see [RFC 3471]) to support the capabilities as specified
terminology section is provided in Appendix. in the above referenced document. A terminology section is provided
in the Appendix.
Problem Statement: Problem Statement:
The Automatic Switched Optical Network (ASON) architecture describes The Automatically Switched Optical Network (ASON) architecture
the application of an automated control plane for supporting both describes the application of an automated control plane for
call and connection management services (for a detailed description supporting both call and connection management services (for a
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,
ASON model distinguishes reference points (representing points of the ASON model distinguishes reference points (representing points
protocol information exchange) defined (1) between an administrative of protocol information exchange) defined (1) between an
domain and a user (2) between administrative domains and (3) between administrative domain and a user, (2) between administrative domains
areas of the same administrative domain and when needed between and, (3) between areas of the same administrative domain and when
control components (or simply controllers) within areas. A full needed between control components (or simply controllers) within
description of the ASON terms and relationship between ASON model areas. A full description of the ASON terms and relationship between
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 signalling (and in
particular, [RFC 3471]) to provide call and connection management particular, [RFC 3471]) to provide call and connection management
(see [ITU-T G.7713]). The following functionality are expected from (see [ITU-T G.7713]). The following functionality is expected to be
the GMPLS protocol suite: (a) support for soft permanent connection supported and to be backward compatible with the GMPLS protocol
capability (b) support for call and connection separation (c) suite as currently defined by the IETF:
support for extended restart capabilities during control plane (a) soft permanent connection capability
failures (d) support for extended label usage (e) support for (b) call and connection separation
crankback capability (f) support for additional error cases. (c) call segments
(d) extended restart capabilities during control plane failures
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(e) extended label usage
(f) crankback capability
(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
the GMPLS protocol suite. the GMPLS protocol suite.
The next sections detail the requirements concerning the functions The next sections detail the requirements concerning the functions
including: including:
- Support for soft permanent connection capability - Support for soft permanent connection capability
- Support for call and connection separation - Support for call and connection separation
- 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
Note: support of the above functions is independent of any user-to- Also, the support of these functions is strictly independent and
network interface and therefore not constrained or restricted by its must be agnostic of any user-to-network interface and therefore not
implementation specifics (see [ITU-T G.8080] and [ITU-T G.7713]). constrained or restricted by its implementation specifics (see [ITU-
T G.8080] and [ITU-T G.7713]). However, end-to-end signaling should
be facilitated regardless of the administrative boundaries and
protocols within the network when at least some part of the network
operates using GMPLS signaling. The resulting requirement being that
there should be a clear mapping of signaling requests between GMPLS
systems and other systems which support GMPLS or utilize other
signaling protocols or some which may not support any signaling
protocols. For instance, Section 4.5 'Support for Extended Label
Usage' covers the requirements 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
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 ingress node. The latter then connection by communicating with the node that initiates the
sets the connection using the distributed GMPLS signaling protocol. switched connection (also known as the ingress node). The latter
For the SPC, the communication method between the EMS/NMS and the then sets the connection using the distributed GMPLS signaling
ingress node is beyond the scope of this document (so it is for any protocol. For the SPC, the communication method between the EMS/NMS
other function described in this document). and the ingress node is beyond the scope of this document (so it is
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 switched connection initiating network incoming interface of the ingress node with the switched connection
node (also referred to as 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.
--- --- --- --- --- --- --- ---
| 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 contrast, the connection over link #2 is set up using the
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distributed control plane. Thus the SPC is composed of the splicing distributed control plane. Thus the SPC is composed of the splicing
of link #1, #2 and #3. of link #1, #2 and #3.
Thus, to support the capability to request a 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 the 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 signalling
controller addresses. controller addresses.
Note that the association at the ingress node between the permanent
connection and the switched connection is an implementation matter
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
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 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. To each call multiple
connections may be associated. The call concept provides an abstract connections may be associated. The call concept provides an abstract
relationship between two users, where this relationship describes relationship between two users, where this relationship describes
(or verifies) at which 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
type 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 connection 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 network offers 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, - Facilitate upgrading strategy of the control plane operations,
where a call control (service provisioning) may be separate from where a call control (service provisioning) may be separate from
actual nodes hosting the connections (where the connection control actual nodes hosting the connections (where the connection control
may reside) 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
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- 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 LSR 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 Extended Restart Capabilities 4.3 Support for Call Segments
As described in [ITU-T G.8080], call segmentation may be applied
when a call crosses several administrative domains. As such, an end-
to-end call may consist of multiple call segments, when the call
traverses multiple administrative domains. Each call segment can
have one or more associated connections and the number of
connections associated with each call segment may not be the same
for a given end-to-end call.
The initiating caller interacts with a called party by means of one
or more intermediate call controllers located at the network edge
between administrative domains (i.e., inter-domain reference point)
and in particular at the user-to-network reference point. Their
functions are defined by the policies associated by interactions
between the administrative domain boundaries and between users and
the network.
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This capability allows for independent (policy based) choices of
signalling, concatenation, data plane protection and control plane
driven recovery paradigms in different administrative domains.
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. 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 connections
established before failure occurrence. 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, connections in the
process of being established (i.e. pending connection setup process of being established (i.e. pending connection setup
requests) should be released or continued (with 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, connections in the
process of being released must be released. 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.
4.4 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.
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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.
----- ----- ----- -----
| | --- --- | | | | --- --- | |
| 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 a 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
timeslot #4 (label=[4,0,0,0,0]). Thus by the time node Z receives timeslot #4 (label=[4,0,0,0,0]). Thus by the time node Z receives
the request from node A with label=[1,0,0,0,0], the node Z's local the request from node A with label=[1,0,0,0,0], the node Z's local
label and the timeslot no longer corresponds to the received label label and the timeslot no longer corresponds to the received label
and timeslot information. and timeslot information.
As such to support this capability, a label association mechanism As such, to support this capability, a label association mechanism
has to be used by the control plane node to map the received has to be used by the control plane node to map the received
(remote) label into a locally significant label. The information (remote) label into a locally significant label. The information
necessary to allow mapping from received label value to a locally necessary to allow mapping from received label value to a locally
significant label value may be derived in several ways including: significant label value may 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, this
implies that the discovery mechanism operates at the timeslot/label implies that the discovery mechanism operates at the timeslot/label
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
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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.
4.5 Support for Crankback 4.6 Support for Crankback
Crankback has been identified as a requirement for ASON networks. It Crankback has been identified as an important requirement for ASON
allows an LSP setup request to be retried on an alternate path that networks. It allows a connection setup request to be retried on an
detours around a blocked link or node upon a setup failure. alternate path that detours around a blocked link or node upon a
setup failure, for instance, because a link or a node along the
selected path has insufficient resources.
Crankback mechanisms can also be applied to LSP restoration by Crankback mechanisms may also be applied during connection recovery
indicating the location of the failure 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 LSPs, significantly improve the successful recovery ratio for failed
especially in situations where a large number of setup requests are connections, especially in situations where a large number of setup
simultaneously triggered. [GMPLS-CRANK] specifies crankback GMPLS- requests are simultaneously triggered.
based signalling mechanisms.
4.6 Support for Additional Error Cases The following mechanisms are assumed during crankback signalling
(see also [GMPLS-CRANK]):
- the blocking resource (link or node) must be identified and
returned in the error response message towards the repair node
(that may or may not be the ingress node); it is also assumed that
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this 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 satisfying the initial connection
constraints
- the re-initiation of the connection setup request from the repair
node (i.e. the node that has intercepted and processed the error
response message)
The following properties are expected for crankback signalling (see
[GMPLS-CRANK]):
- Error information persistence: the entity that computes the
alternate (re-routing) path should store the identifiers of the
blocking resources as indicated in the error message until the
connection is successfully established or until the node abandons
rerouting attempts. Since crankback may happen more than once while
establishing a specific connection, the history of all experienced
blockages for this connection should be maintained (at least until
the routing protocol updates the state of this information) to
perform an accurate path computation avoiding all blockages.
- Rerouting attempts limitation: to prevent an endless repetition of
connection setup attempts (using crankback information), the number
of retries should be strictly limited. The maximum number of
crankback rerouting attempts allowed can be limited per connection,
per node, per area or even per administrative domain.
- When the number of retries at a particular node or area is
exceeded, the node currently handling the failure reports the
error message upstream to the next repair node where further
rerouting attempts may be performed. It is important that the
crankback information provided indicates that re-routing
through this node will not succeed.
- When the maximum number of retries for a specific connection
has been exceeded, the repair node handling the current failure
should send an error message upstream indicating "Maximum
number of re-routings exceeded". This error message will be
sent back to the ingress node with no further rerouting
attempts. Then, the ingress node may choose to retry the
connection setup according to local policy but also re-use its
original path or compute a path that avoids the blocking
resources.
Note: after several retries, a given repair point may be unable to
compute a path to the destination node that avoids all of the
blockages. In this case, it must pass the error message upstream to
the next repair point.
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
connection.
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IDs for the Call or an invalid interface ID for the soft permanent
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. 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).
skipping to change at line 368 skipping to change at line 454
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]). signalling (see [RFC3471]).
6. Acknowledgements 6. Acknowledgements
The authors would like to thank Nic Larkin, Osama Aboul-Magd and The authors would like to thank Deborah Brungard, Nic Larkin, Osama
Dimitrios Pendarakis for their comments and contributions to the Aboul-Magd and Dimitrios Pendarakis for their comments and
previous version of this document. contributions to the previous version of this document.
7. References 7. References
Expires December 2003 7
7.1 Normative References 7.1 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 MPLS -
Signaling Functional Description," RFC 3471, January Signaling Functional Description," RFC 3471, January
skipping to change at line 398 skipping to change at line 481
[RFC-3471] L.Berger (Editor) et al., "Generalized MPLS - [RFC-3471] L.Berger (Editor) et al., "Generalized MPLS -
Signaling Functional Description," RFC 3471, January Signaling Functional Description," RFC 3471, January
03. 03.
[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, May 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, Progress," draft-ietf-ccamp-gmpls-sonet-sdh-08.txt,
Expires December 2003 9
February 2003. February 2003.
[GMPLS-OTN] D.Papadimitriou (Editor), "GMPLS Signalling [GMPLS-OTN] D.Papadimitriou (Editor), "GMPLS Signalling
Extensions for G.709 Optical Transport Networks Extensions for G.709 Optical Transport Networks
Control," Work in progress, draft-ietf-ccamp-gmpls- Control," Work in progress, draft-ietf-ccamp-gmpls-
g709-04.txt, May 2003. g709-04.txt, May 2003,
7.2 Informative References 7.2 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 8. Author's Addresses
Dimitri Papadimitriou (Alcatel) Dimitri Papadimitriou (Alcatel)
Francis Wellesplein 1, Francis Wellesplein 1,
B-2018 Antwerpen, Belgium B-2018 Antwerpen, Belgium
Expires December 2003 8
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
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
skipping to change at line 459 skipping to change at line 542
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
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Appendix - Terminology Appendix - Terminology
This draft defines the following terms: This draft defines 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.
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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.
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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
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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.
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 End of changes. 

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