Internet Draft Lou Berger (LabN)
Category: Experimental Attila Takacs (Ericsson)
Expiration Date: October 29, 2008 Diego Caviglia (Ericsson)
Don Fedyk (Nortel)
Julien Meuric (France Telecom)
April 29, 2008
GMPLS Asymmetric Bandwidth Bidirectional Label Switched Paths (LSPs)
draft-ietf-ccamp-asymm-bw-bidir-lsps-01.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 Label Switched Paths (LSPs). The presented
approach is applicable to any switching technology and builds on the
original RSVP model for the transport of traffic related parameters.
The procedures described in this document are experimental.
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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 ......................... 5
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 ..................................... 9
5.3 UPSTREAM_ADSPEC Object .................................... 9
6 Security Considerations ................................... 9
7 References ................................................ 9
7.1 Normative References ...................................... 9
7.2 Informative References .................................... 10
8 Authors' 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
Full Copyright Statement .................................. 14
Intellectual Property ..................................... 14
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1. Introduction
GMPLS, see [RFC3473], introduced explicit support for bidirectional
Label Switched Paths (LSPs). The defined support matched the
switching technologies covered by GMPLS, notably Time Division
Multiplexing (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 of the support of bidirectional LSPs with
asymmetric bandwidth. (That is, bidirectional LSPs that have
different bandwidth reservations in each direction.) This discussion
motivated the extensions defined in this document, which may be used
with any switching technology to signal asymmetric bandwidth
bidirectional LSPs. The procedures described in this document are
experimental.
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 in favor of the more generic approach presented below. 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.
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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].
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 differ in
that they relate to traffic flowing in the upstream direction while
the existing objects relate to traffic flowing in the downstream
direction. The new objects also differ in that they are used on
messages in the opposite directions.
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 describes the traffic flow that originates
at the egress. 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.
When an UPSTREAM_TSPEC object is received by an ingress, the ingress
MAY determine that the original reservation is insufficient to
satisfy the traffic flow. In this case, the ingress MAY issue a Path
message with an updated UPSTREAM_FLOWSPEC object to modify the
resources requested for the upstream traffic flow. This modification
might require the LSP to be re-routed, and in extreme cases might
result in the LSP being torn down when sufficient resources are not
available.
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
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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.
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, PathTear, PathErr and Notify
(via sender descriptor)
UPSTREAM_TSPEC Resv, ResvConf, ResvTear, ResvErr and
Notify (via flow descriptor list)
UPSTREAM_ADSPEC Resv, ResvConf, ResvTear, ResvErr 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> ]
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<SE flow descriptor> ::= <FLOWSPEC>
<UPSTREAM_TSPEC> [ <UPSTREAM_ADSPEC> ]
<SE filter spec list>
<SE filter spec list> is unmodified by this document.
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 will not recognize the new class numbers
and should 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)
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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)
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]. Specifically the UPSTREAM_TSPEC,
UPSTREAM_ADSPEC and UPSTREAM_FLOWSPEC objects. These object parallel
the exiting SENDER_TSPEC, ADSPEC and FLOWSPEC objects but are used in
the opposite direction. As such, any vulnerabilities that are due to
the use of the old objects now apply to messages flowing in the
reverse direction.
From a message standpoint, this document 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 message or neighbor related security considerations.
See [RFC3473] for relevant security considerations, and [SEC-
FRAMEWORK] for a more general discussion on RSVP-TE security
discussions.
7. References
7.1. Normative References
[RFC2205] Braden, R. Ed. et al, "Resource ReserVation Protocol
-- Version 1 Functional Specification", RFC 2205,
September 1997.
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[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.
7.2. Informative References
[GMPLS-PBBTE] Fedyk, D., et al "GMPLS control of Ethernet" ,
draft-ietf-ccamp-gmpls-ethernet-pbb-te-00.txt, Work in
progress, April 2008.
[MEF-TRAFFIC] Papadimitriou, D., "MEF Ethernet Traffic
Parameters,"
draft-ietf-ccamp-ethernet-traffic-parameters-04.txt,
Work in progress, April 2008.
[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.
[SEC-FRAMEWORK] Fang, L., Ed., "Security Framework for MPLS and
GMPLS Networks",
draft-ietf-mpls-mpls-and-gmpls-security-framework-02.txt,
Work in progress, February 2008.
8. Authors' Addresses
Lou Berger
LabN Consulting, L.L.C.
Email: lberger@labn.net
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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
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 its implementation
is NOT RECOMMENDED.
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. In particular this approach is technology specific; it
uses the ADSPEC object to carry traffic parameters for upstream data
and requires MEF Ethernet Traffic Parameter while the approach
presented above is suitable for use with any technology.
The generalized asymmetric bandwidth bidirectional LSP presented in
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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.
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
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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.
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.
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