Internet Draft Lou Berger (LabN)
Category: Experimental Attila Takacs (Ericsson)
Expiration Date: September 12, 2008 Diego Caviglia (Ericsson)
Don Fedyk (Nortel)
Julien Meuric (France Telecom)
March 12, 2008
GMPLS Asymmetric Bandwidth Bidirectional LSPs
draft-ietf-ccamp-asymm-bw-bidir-lsps-00.txt
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Copyright Notice
Copyright (C) The IETF Trust (2008).
Abstract
This document defines a method for the support of GMPLS Asymmetric
Bandwidth Bidirectional LSPs. The presented approach is applicable
to any switching technology and builds on the original RSVP model for
the transport of traffic related parameters.
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Table of Contents
1 Introduction .............................................. 3
1.1 Background ................................................ 3
1.2 Approach Overview ......................................... 4
1.3 Conventions used in this document ......................... 4
2 Generalized Asymmetric Bandwidth Bidirectional LSPs ....... 5
2.1 UPSTREAM_FLOWSPEC Object .................................. 5
2.1.1 Procedures ................................................ 5
2.2 UPSTREAM_TSPEC Object ..................................... 6
2.2.1 Procedures ................................................ 6
2.3 UPSTREAM_ADSPEC Object .................................... 6
2.3.1 Procedures ................................................ 6
3 Packet Formats ............................................ 7
4 Compatibility ............................................. 8
5 IANA Considerations ....................................... 8
5.1 UPSTREAM_FLOWSPEC Object .................................. 8
5.2 UPSTREAM_TSPEC Object ..................................... 8
5.3 UPSTREAM_ADSPEC Object .................................... 9
6 Security Considerations ................................... 9
7 References ................................................ 9
7.1 Normative References ...................................... 9
7.2 Informative References .................................... 10
8 Author's Addresses ........................................ 10
A. Appendix A: Alternate Approach Using ADSPEC Object ........ 11
A.1. Applicability ............................................. 11
A.2. Overview .................................................. 12
A.3. Procedures ................................................ 13
A.4. Compatibility ............................................. 13
9 Full Copyright Statement .................................. 13
10 Intellectual Property ..................................... 14
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1. Introduction
GMPLS, see [RFC3473], introduced explicit support for bidirectional
LSPs. The defined support matched the switching technologies covered
by GMPLS, notably TDM and lambdas, and specifically only supported
bidirectional LSPs with symmetric bandwidth allocation. Symmetric
bandwidth requirements are conveyed using the semantics objects
defined in [RFC2205] and [RFC2210].
Recent work, see [GMPLS-PBBTE] and [MEF-TRAFFIC], has looked at
extending GMPLS to control Ethernet switching. In this context there
has been discussion on the support of bidirectional LSPs with
asymmetric bandwidth. This discussion motivated the extensions
defined in this document, which may be used with any switching
technology to signal asymmetric bandwidth bidirectional LSPs.
1.1. Background
Bandwidth parameters are transported within RSVP (see [RFC2210],
[RFC3209] and [RFC3473]) via several objects that are opaque to RSVP.
While opaque to RSVP, these objects support a particular model for
the communication of bandwidth information between an RSVP session
sender (ingress) and receiver (egress). The original model of
communication defined in [RFC2205] and maintained in [RFC3209] used
the SENDER_TSPEC and ADSPEC objects in Path messages and the FLOWSPEC
object in Resv messages. The SENDER_TSPEC object was used to
indicate a sender's data generation capabilities. The FLOWSPEC
object was issued by the receiver and indicated the resources that
should be allocated to the associated data traffic. The ADSPEC
object was used to inform the receiver and intermediate hops of the
actual resources allocated for the associated data traffic.
With the introduction of bidirectional LSPs in [RFC3473] the model of
communication of bandwidth parameters was implicitly changed. In the
context of [RFC3473] bidirectional LSPs, the SENDER_TSPEC object
indicates the desired resources for both upstream and downstream
directions. The FLOWSPEC object is simply confirmation of the
allocated resources. The definition of the ADSPEC object is either
unmodified, and only has meaning for downstream traffic, or is
implicitly or explicitly (see [RFC4606] and [MEF-TRAFFIC])
irrelevant.
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1.2. Approach Overview
The approach for supporting asymmetric bandwidth bidirectional LSPs
defined in this document builds on the original RSVP model for the
transport of traffic related parameters and GMPLS' support for
bidirectional LSPs. An alternative approach was considered and
rejected. For reference purposes only, the rejected approach is
summarized in Appendix A.
The defined approach is generic and can be applied to any switching
technology supported by GMPLS. With this approach, the existing
SENDER_TSPEC, ADSPEC and FLOWSPEC objects are complemented with the
addition of new UPSTREAM_TSPEC, UPSTREAM_ADSPEC and UPSTREAM_FLOWSPEC
objects. The existing objects are used in the original fashion
defined in [RFC2205] and [RFC2210], and refer only to traffic
associated with the LSP flowing in the downstream direction. The new
objects are used in exactly the same fashion as the old objects, but
refer to the upstream traffic flow. Figure 1 shows the bandwidth
related objects used for Asymmetric Bandwidth Bidirectional LSPs.
|---| Path |---|
| I |------------------->| E |
| n | -SENDER_TSPEC | g |
| g | -ADSPEC | r |
| r | -UPSTREAM_FLOWSPEC | e |
| e | | s |
| s | Resv | s |
| s |<-------------------| |
| | -FLOWSPEC | |
| | -UPSTREAM_TSPEC | |
| | -UPSTREAM_ADSPEC | |
|---| |---|
Figure 1: Generic Asymmetric Bandwidth Bidirectional LSPs
This extensions defined in this document are limited to P2P LSPs.
Support for P2MP bidirectional LSPs is not currently defined and, as
such, not covered in this document.
1.3. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
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2. Generalized Asymmetric Bandwidth Bidirectional LSPs
The setup of an asymmetric bandwidth bidirectional LSP is signaled
using the bidirectional procedures defined in [RFC3473] together with
the inclusion of the new UPSTREAM_FLOWSPEC, UPSTREAM_TSPEC and
UPSTREAM_ADSPEC objects.
The new upstream objects carry the same information and are used in
the same fashion as the existing downstream objects; they only differ
in that they relate to traffic flowing in the upstream direction
while the existing objects relate to traffic flowing in the
downstream direction.
2.1. UPSTREAM_FLOWSPEC Object
The format of an UPSTREAM_FLOWSPEC object is the same as a FLOWSPEC
object. This includes the definition of class types and their
formats. The class number of the UPSTREAM_FLOWSPEC object object is
TBA by IANA (of the form 0bbbbbbb).
2.1.1. Procedures
The Path message of an asymmetric bandwidth bidirectional LSP MUST
contain an UPSTREAM_FLOWSPEC object and MUST use the bidirectional
LSP formats and procedures defined in [RFC3473]. The C-Type of the
UPSTREAM_FLOWSPEC Object MUST match the C-Type of the SENDER_TSPEC
object used in the Path message. The contents of the
UPSTREAM_FLOWSPEC Object MUST be constructed using a consistent
format and procedures used to construct the FLOWSPEC object that will
be used for the LSP, e.g., [RFC2210] or [RFC4328].
Nodes processing a Path message containing an UPSTREAM_FLOWSPEC
Object MUST use the contents of the UPSTREAM_FLOWSPEC Object in the
upstream label and resource allocation procedure defined in Section
3.1 of [RFC3473]. Consistent with [RFC3473], a node that is unable
to allocate a label or internal resources based on the contents of
the UPSTREAM_FLOWSPEC Object, MUST issue a PathErr message with a
"Routing problem/MPLS label allocation failure" indication.
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2.2. UPSTREAM_TSPEC Object
The format of an UPSTREAM_TSPEC object is the same as a SENDER_TSPEC
object. This includes the definition of class types and their
formats. The class number of the UPSTREAM_TSPEC Object object is TBA
by IANA (of the form 0bbbbbbb).
2.2.1. Procedures
The UPSTREAM_TSPEC object MUST be included in any Resv message that
corresponds to a Path message containing an UPSTREAM_FLOWSPEC object.
The C-Type of the UPSTREAM_TSPEC object MUST match the C-Type of the
corresponding UPSTREAM_FLOWSPEC object. The contents of the
UPSTREAM_TSPEC Object MUST be constructed using a consistent format
and procedures used to construct the FLOWSPEC object that will be
used for the LSP, e.g., [RFC2210] or [RFC4328]. The contents of the
UPSTREAM_TSPEC Object MAY differ from contents of the
UPSTREAM_FLOWSPEC object based on application data transmission
requirements.
2.3. UPSTREAM_ADSPEC Object
The format of an UPSTREAM_ADSPEC object is the same as an ADSPEC
object. This includes the definition of class types and their
formats. The class number of the UPSTREAM_ADSPEC object is TBA by
IANA (of the form 0bbbbbbb).
2.3.1. Procedures
The UPSTREAM_ADSPEC object MAY be included in any Resv message that
corresponds to a Path message containing an UPSTREAM_FLOWSPEC object.
The C-Type of the UPSTREAM_TSPEC object MUST be consistent with the
C-Type of the corresponding UPSTREAM_FLOWSPEC object. The contents of
the UPSTREAM_ADSPEC Object MUST be constructed using a consistent
format and procedures used to construct the ADSPEC object that will
be used for the LSP, e.g., [RFC2210] or [MEF-TRAFFIC]. The
UPSTREAM_ADSPEC object is processed using the same procedures as the
ADSPEC object and as such, MAY be updated or added at transit nodes.
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3. Packet Formats
This section presents the RSVP message related formats as modified by
this section. Unmodified formats are not listed. Three new objects
are defined in this section:
Object name Applicable RSVP messages
--------------- ------------------------
UPSTREAM_FLOWSPEC Path and PathErr (via sender descriptor)
UPSTREAM_TSPEC Resv and Notify (via flow descriptor list)
UPSTREAM_ADSPEC Resv and Notify (via flow descriptor list)
The format of the sender description for bidirectional asymmetric
LSPs is:
<sender descriptor> ::= <SENDER_TEMPLATE> <SENDER_TSPEC>
[ <ADSPEC> ]
[ <RECORD_ROUTE> ]
[ <SUGGESTED_LABEL> ]
[ <RECOVERY_LABEL> ]
<UPSTREAM_LABEL>
<UPSTREAM_FLOWSPEC>
The format of the flow descriptor list for bidirectional asymmetric
LSPs is:
<flow descriptor list> ::= <FF flow descriptor list>
| <SE flow descriptor>
<FF flow descriptor list> ::= <FLOWSPEC>
<UPSTREAM_TSPEC> [ <UPSTREAM_ADSPEC> ]
<FILTER_SPEC>
<LABEL> [ <RECORD_ROUTE> ]
| <FF flow descriptor list>
<FF flow descriptor>
<FF flow descriptor> ::= [ <FLOWSPEC> ]
[ <UPSTREAM_TSPEC>] [ <UPSTREAM_ADSPEC> ]
<FILTER_SPEC> <LABEL>
[ <RECORD_ROUTE> ]
<SE flow descriptor> ::= <FLOWSPEC>
<UPSTREAM_TSPEC> [ <UPSTREAM_ADSPEC> ]
<SE filter spec list>
<SE filter spec list> is unmodified by this document.
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4. Compatibility
This extension reuses and extends semantics and procedures defined in
[RFC2205], [RFC3209] and [RFC3473] to support bidirectional LSPs with
asymmetric bandwidth. To indicate the use of asymmetric bandwidth
three new objects are defined. Each of these objects is defined with
class numbers in the form 0bbbbbbb. Per [RFC2205], nodes not
supporting this extension should not recognize the new class numbers
and respond with an "Unknown Object Class" error. The error message
will propagate to the ingress which can then take action to avoid the
path with the incompatible node, or may simply terminate the session.
5. IANA Considerations
IANA is requested to administer assignment of new values for
namespaces defined in this section and reviewed in this subsection.
Upon approval of this document, the IANA will make the assignments
described below in the "Class Names, Class Numbers, and Class Types"
section of the "RSVP PARAMETERS" registry located at
http://www.iana.org/assignments/rsvp-parameters
5.1. UPSTREAM_FLOWSPEC Object
A new class named UPSTREAM_FLOWSPEC will be created in the 0bbbbbbb
range (TBD suggested) with the following definition:
Class Types or C-types:
Same values as FLOWSPEC object (C-Num 9)
5.2. UPSTREAM_TSPEC Object
A new class named UPSTREAM_TSPEC will be created in the 0bbbbbbb
range (TBD suggested) with the following definition:
Class Types or C-types:
Same values as SENDER_TSPEC object (C-Num 12)
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5.3. UPSTREAM_ADSPEC Object
A new class named UPSTREAM_ADSPEC will be created in the 0bbbbbbb
range (TBD suggested) with the following definition:
Class Types or C-types:
Same values as ADSPEC object (C-Num 13)
6. Security Considerations
This document introduces new message objects for use in GMPLS
signaling [RFC3473]. It does not introduce any new signaling
messages, nor change the relationship between LSRs that are adjacent
in the control plane. As such, this document introduces no additional
security considerations. See [RFC3473] for relevant security
considerations.
7. References
7.1. Normative References
[MEF-TRAFFIC] Papadimitriou, D., "MEF Ethernet Traffic
Parameters,"
draft-ietf-ccamp-ethernet-traffic-parameters-03.txt,
Work in progress, November 2007.
[RFC2205] Braden, R. Ed. et al, "Resource ReserVation Protocol
-- Version 1 Functional Specification", RFC 2205,
September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services," RFC 2210, September 1997.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels," RFC 2119.
[RFC3209] Awduche, et al, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., Editor, "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling - Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
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7.2. Informative References
[GMPLS-PBBTE] Fedyk, D., et al "GMPLS control of Ethernet" ,
draft-fedyk-gmpls-ethernet-pbb-te-02.txt, Work in
progress, November 2007.
[RFC4606] Mannie, E., Papadimitriou, D., "Generalized
Multi-Protocol Label Switching (GMPLS) Extensions for
Synchronous Optical Network (SONET) and Synchronous
Digital Hierarchy (SDH) Control", RFC 4606, August 2006.
[RFC4328] Papadimitriou, D., Ed., "Generalized Multi-Protocol
Label Switching (GMPLS) Signaling Extensions for G.709
Optical Transport Networks Control", RFC 4328, January
2006.
8. Author's Addresses
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
Attila Takacs
Ericsson
1. Laborc u.
1037 Budapest, Hungary
Phone: +36-1-4377044
Email: attila.takacs@ericsson.com
Diego Caviglia
Ericsson
Via A. Negrone 1/A
Genova-Sestri Ponente, Italy
Phone: +390106003738
Email: diego.caviglia@ericsson.com
Don Fedyk
Nortel Networks
600 Technology Park Drive
Billerica, MA, USA 01821
Phone: +1-978-288-3041
Email: dwfedyk@nortel.com
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Julien Meuric
France Telecom
Research & Development
2, avenue Pierre Marzin
22307 Lannion Cedex - France
Phone: +33 2 96 05 28 28
Email: julien.meuric@orange-ftgroup.com
A. Appendix A: Alternate Approach Using ADSPEC Object
This section is included for historic purposes and SHOULD NOT be
implemented.
A.1. Applicability
This section presents an alternate method for the support of
asymmetric bandwidth bidirectional LSP establishment with a single
RSVP-TE signaling session. This approach differs in applicability and
generality from the approach presented in the main body of this
document.
The generalized asymmetric bandwidth bidirectional LSP presented in
the main body of this document has the benefit of being applicable to
any switching technology, but requires support for three new types of
object classes, i.e., the UPSTREAM_TSPEC, UPSTREAM_ADSPEC and
UPSTREAM_FLOWSPEC objects.
The solution presented in this section is based on the Ethernet
specific ADSPEC Object, and is referred to as the "ADSPEC Object"
approach. This approach limits applicability to cases where the
[MEF-TRAFFIC] traffic parameters are appropriate, and to switching
technologies that define no use for the ADSPEC object. While
ultimately it is this limited scope that has resulted in this
approach being relegated to an Appendix, the semantics of this
approach are quite simple in that they only require the definition of
a new ADSPEC object C-Type.
In summary, the "ADSPEC Object" approach presented in this section
SHOULD NOT be implemented.
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A.2. Overview
The "ADSPEC Object" approach is specific to Ethernet and uses [MEF-
TRAFFIC] traffic parameters. This approach is not generic and is
aimed at providing asymmetric bandwidth bidirectional LSPs for just
Ethernet transport. With this approach, the ADSPEC object carries
the traffic parameters for the upstream data flow. SENDER_TSPEC
object is used to indicate the traffic parameters for the downstream
data flow. The FLOWSPEC object provides confirmation of the allocated
downstream resources. Confirmation of the upstream resource
allocation is a Resv message, as any resource allocation failure for
the upstream direction will always result in a PathErr message.
Figure 2 shows the bandwidth related objects used in the first
approach.
|---| Path |---|
| I |----------------->| E |
| n | -SENDER_TSPEC | g |
| g | -ADSPEC | r |
| r | | e |
| e | Resv | s |
| s |<-----------------| s |
| s | -FLOWSPEC | |
|---| |---|
Figure 2: Asymmetric Bandwidth Bidirectional LSPs Using ADSPEC Object
In the "ADSPEC Object" approach, the setup of an asymmetric bandwidth
bidirectional LSP would be signaled using the bidirectional
procedures defined in [RFC3473] together with the inclusion of a new
ADSPEC object. The new ADSPEC object would be specific to Ethernet
and could be called the Ethernet Upstream Traffic Parameter ADSPEC
object. The Ethernet Upstream Traffic Parameter ADSPEC object would
use the Class-Number 13 and C-Type UNASSIGNED (this approach should
not be implemented). The format of the object would be the same as
the Ethernet SENDER_TSPEC object defined in [MEF-TRAFFIC].
This approach would not modify behavior of symmetric bandwidth LSPs.
Per [MEF-TRAFFIC], such LSPs are signaled without an ADSPEC or with
an INTSERV ADSPEC.
The defined approach could be reused to support asymmetric bandwidth
bidirectional LSPs for other types of switching technologies. All
that would be needed would be to define the proper ADSPEC object.
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A.3. Procedures
Using the approach presented in this section, the process of
establishing an asymmetric bandwidth bidirectional LSP would follow
the process of establishing symmetric bandwidth bidirectional LSP, as
defined in Section 3 of [RFC3473], with two modifications. These
modifications would be followed when an incoming Path message is
received containing an Upstream_Label object and the Ethernet
Upstream Traffic Parameter ADSPEC object.
The first modification to the symmetric bandwidth process would be
that when allocating the upstream label, the bandwidth associated
with the upstream label would be taken from the Ethernet Upstream
Traffic Parameter ADSPEC object, see Section 3.1 of [RFC3473].
Consistent with [RFC3473], a node that is unable to allocate a label
or internal resources based on the contents of the ADSPEC Object,
would issue a PathErr message with a "Routing problem/MPLS label
allocation failure" indication.
The second modification would be that the ADSPEC object would not be
modified by transit nodes.
A.4. Compatibility
The approach presented in this section reuses semantics and
procedures defined in [RFC3473]. To indicate the use of asymmetric
bandwidth a new ADSPEC object c-type would be defined. Per
[RFC2205], nodes not supporting the approach should not recognize
this new C-type and respond with an "Unknown object C-Type" error.
9. Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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10. Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed
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described in this document or the extent to which any license
under such rights might or might not be available; nor does it
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The IETF invites any interested party to bring to its attention
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proprietary rights that may cover technology that may be required
to implement this standard. Please address the information to the
IETF at ietf-ipr@ietf.org.
Acknowledgement
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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