OSPF-TE Extensions for General Network Element Constraints
draft-ietf-ccamp-gmpls-general-constraints-ospf-te-05
Network work group Fatai Zhang
Internet Draft Young Lee
Intended status: Standards Track Jianrui Han
Huawei
G. Bernstein
Grotto Networking
Yunbin Xu
CATR
Expires: December 26, 2013 June 26, 2013
OSPF-TE Extensions for General Network Element Constraints
draft-ietf-ccamp-gmpls-general-constraints-ospf-te-05.txt
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html
This Internet-Draft will expire on December 26, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
<Zhang> Expires December 2013 [Page 1]
Internet-Draft Generic Constraint OSPF-TE June 2013
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.
Abstract
Generalized Multiprotocol Label Switching can be used to control a
wide variety of technologies including packet switching (e.g., MPLS),
time-division (e.g., SONET/SDH, OTN), wavelength (lambdas), and
spatial switching (e.g., incoming port or fiber to outgoing port or
fiber). In some of these technologies network elements and links may
impose additional routing constraints such as asymmetric switch
connectivity, non-local label assignment, and label range
limitations on links. This document describes OSPF routing protocol
extensions to support these kinds of constraints under the control
of Generalized MPLS (GMPLS).
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 RFC-2119 [RFC2119].
Table of Contents
1. Introduction...................................................3
2. Node Information...............................................3
2.1. Connectivity Matrix.......................................4
3. Link Information...............................................5
3.1. Port Label Restrictions...................................5
4. Routing Procedures.............................................6
5. Scalability and Timeliness.....................................6
5.1. Different Sub-TLVs into Multiple LSAs.....................7
5.2. Decomposing a Connectivity Matrix into Multiple Matrices..7
6. Security Considerations........................................7
7. IANA Considerations............................................8
7.1. Node Information..........................................8
7.2. Link Information..........................................8
Zhang Expires December 2013 [Page 2]
Internet-Draft Generic Constraint OSPF-TE June 2013
8. References.....................................................8
8.1. Normative References......................................8
8.2. Informative References....................................9
9. Authors' Addresses .............................................9
Acknowledgment...................................................11
1. Introduction
Some data plane technologies that wish to make use of a GMPLS
control plane contain additional constraints on switching capability
and label assignment. In addition, some of these technologies should
be capable of performing non-local label assignment based on the
nature of the technology, e.g., wavelength continuity constraint in
WSON [RFC6163]. Such constraints can lead to the requirement for
link by link label availability in path computation and label
assignment.
[GEN-Encode] provides efficient encodings of information needed by
the routing and label assignment process in technologies such as
WSON and are potentially applicable to a wider range of
technologies.
This document defines extensions to the OSPF routing protocol based
on [GEN-Encode] to enhance the Traffic Engineering (TE) properties
of GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203].
The enhancements to the Traffic Engineering (TE) properties of GMPLS
TE links can be announced in OSPF TE LSAs. The TE LSA, which is an
opaque LSA with area flooding scope [RFC3630], has only one top-
level Type/Length/Value (TLV) triplet and has one or more nested
sub-TLVs for extensibility. The top-level TLV can take one of three
values (1) Router Address [RFC3630], (2) Link [RFC3630], (3) Generic
Node Attribute defined in Section 2. In this document, we enhance
the sub-TLVs for the Link TLV and define a new top-level TLV
(Generic Node Attribute TLV) in support of the general network
element constraints under the control of GMPLS.
The detailed encoding of OSPF extensions are not defined in this
document. [GEN-Encode] provides encoding detail.
2. Node Information
According to [GEN-Encode], the additional node information
representing node switching asymmetry constraints includes Node ID,
connectivity matrix. Except for the Node ID which should comply with
Zhang Expires December 2013 [Page 3]
Internet-Draft Generic Constraint OSPF-TE June 2013
Routing Address described in [RFC3630], the other pieces of
information are defined in this document.
This document defines a new top TLV named the Generic Node Attribute
TLV which carries attributes related to a general network element.
This Generic Node Attribute TLV contains one or more sub-TLVs
Per [GEN-Encode], we have identified the following new Sub-TLVs to
the Generic Node Attribute TLV. Detail description for each newly
defined Sub-TLV is provided in subsequent sections:
Sub-TLV Type Length Name
TBD variable Connectivity Matrix
In some specific technologies, e.g., WSON networks, Connectivity
Matrix sub-TLV may be optional, which depends on the control plane
implementations. Usually, for example, in WSON networks,
Connectivity Matrix sub-TLV may appear in the LSAs because WSON
switches are asymmetric at present. It is assumed that the switches
are symmetric switching, if there is no Connectivity Matrix sub-TLV
in the LSAs.
2.1. Connectivity Matrix
It is necessary to identify which ingress ports and labels can be
switched to some specific labels on a specific egress port, if the
switching devices in some technology are highly asymmetric.
The Connectivity Matrix is used to identify these restrictions,
which can represent either the potential connectivity matrix for
asymmetric switches (e.g. ROADMs and such) or fixed connectivity for
an asymmetric device such as a multiplexer as defined in [WSON-
Info].
The Connectivity Matrix is a sub-TLV (the type is TBD by IANA) of
the Generic Node Attribute TLV. The length is the length of value
field in octets. The meaning and format of this sub-TLV are defined
in Section 5.3 of [GEN-Encode]. One sub-TLV contains one matrix. The
Connectivity Matrix sub-TLV may occur more than once to contain
multi-matrices within the Generic Node Attribute TLV. In addition a
large connectivity matrix can be decomposed into smaller separate
matrices for transmission in multiple LSAs as described in Section 5.
Zhang Expires December 2013 [Page 4]
Internet-Draft Generic Constraint OSPF-TE June 2013
3. Link Information
The most common link sub-TLVs nested to link top-level TLV are
already defined in [RFC3630], [RFC4203]. For example, Link ID,
Administrative Group, Interface Switching Capability Descriptor
(ISCD), Link Protection Type, Shared Risk Link Group Information
(SRLG), and Traffic Engineering Metric are among the typical link
sub-TLVs.
Per [GEN-Encode], we add the following additional link sub-TLVs to
the link-TLV in this document.
Sub-TLV Type Length Name
TBD variable Port Label Restrictions
Generally all the sub-TLVs above are optional, which depends on the
control plane implementations. If it is default no restrictions on
labels, Port Label Restrictions sub-TLV may not appear in the LSAs.
3.1. Port Label Restrictions
Port label restrictions describe the label restrictions that the
network element (node) and link may impose on a port. These
restrictions represent what labels may or may not be used on a link
and are intended to be relatively static. More dynamic information
is contained in the information on available labels. Port label
restrictions are specified relative to the port in general or to a
specific connectivity matrix for increased modeling flexibility.
For example, Port Label Restrictions describes the wavelength
restrictions that the link and various optical devices such as OXCs,
ROADMs, and waveband multiplexers may impose on a port in WSON.
These restrictions represent what wavelength may or may not be used
on a link and are relatively static. The detailed information about
Port label restrictions is described in [WSON-Info].
The Port Label Restrictions is a sub-TLV (the type is TBD by IANA)
of the Link TLV. The length is the length of value field in octets.
The meaning and format of this sub-TLV are defined in Section 5.4 of
[GEN-Encode]. The Port Label Restrictions sub-TLV may occur more
than once to specify a complex port constraint within the link TLV.
Zhang Expires December 2013 [Page 5]
Internet-Draft Generic Constraint OSPF-TE June 2013
4. Routing Procedures
All the sub-TLVs are nested to top-level TLV(s) and contained in
Opaque LSAs. The flooding of Opaque LSAs must follow the rules
specified in [RFC2328], [RFC5250], [RFC3630], [RFC4203].
Considering the routing scalability issues in some cases, the
routing protocol should be capable of supporting the separation of
dynamic information from relatively static information to avoid
unnecessary updates of static information when dynamic information
is changed. A standard-compliant approach is to separate the dynamic
information sub-TLVs from the static information sub-TLVs, each
nested to top-level TLV ([RFC3630 and RFC5876]), and advertise them
in the separate OSPF TE LSAs.
For node information, since the Connectivity Matrix information is
static, the LSA containing the Generic Node Attribute TLV can be
updated with a lower frequency to avoid unnecessary updates.
For link information, a mechanism MAY be applied such that static
information and dynamic information of one TE link are contained in
separate Opaque LSAs. For example, the Port Label Restrictions
information sub-TLV could be nested to the top level link TLVs and
advertised in the separate LSAs.
Note that as with other TE information, an implementation SHOULD
take measures to avoid rapid and frequent updates of routing
information that could cause the routing network to become swamped.
A threshold mechanism MAY be applied such that updates are only
flooded when a number of changes have been made to the label
availability information (e.g., wavelength availability) within a
specific time. Such mechanisms MUST be configurable if they are
implemented.
5. Scalability and Timeliness
This document has defined four sub-TLVs for describing generic
routing contraints. The examples given in [Gen-Encode] show that
very large systems, in terms of label count or ports can be very
efficiently encoded. However there has been concern expressed that
some possible systems may produce LSAs that exceed the IP Maximum
Transmission Unit (MTU) and that methods be given to allow for the
splitting of general constraint LSAs into smaller LSA that are under
the MTU limit. This section presents a set of techniques that can be
used for this purpose.
Zhang Expires December 2013 [Page 6]
Internet-Draft Generic Constraint OSPF-TE June 2013
5.1. Different Sub-TLVs into Multiple LSAs
Two sub-TLVs are defined in this document:
1. Connectivity Matrix (Generic Node Attribute TLV)
2. Port Label Restrictions (Link TLV)
Except for the Connectivity Matrix all these are carried in an Link
TLV of which there can be at most one in an LSA [RFC3630]. Of these
sub-TLVs the Port Label Restrictions are relatively static, i.e.,
only would change with hardware changes or significant system
reconfiguration.
5.2. Decomposing a Connectivity Matrix into Multiple Matrices
In the highly unlikely event that a Connectivity matrix sub-TLV by
itself would result in an LSA exceeding the MTU, a single large
matrix can be decomposed into sub-matrices. Per [GEN-Encode] a
connectivity matrix just consists of pairs of input and output ports
that can reach each other and hence such this decomposition would be
straightforward. Each of these sub-matrices would get a unique
matrix identifier per [GEN-Encode].
From the point of view of a path computation process, prior to
receiving an LSA with a Connectivity Matrix sub-TLV, no connectivity
restrictions are assumed, i.e., the standard GMPLS assumption of any
port to any port reachability holds. Once a Connectivity Matrix sub-
TLV is received then path computation would know that connectivity
is restricted and use the information from all Connectivity Matrix
sub-TLVs received to understand the complete connectivity potential
of the system. Prior to receiving any Connectivity Matrix sub-TLVs
path computation may compute a path through the system when in fact
no path exists. In between the reception of an additional
Connectivity Matrix sub-TLV path computation may not be able to find
a path through the system when one actually exists. Both cases are
currently encountered and handled with existing GMPLS mechanisms.
Due to the reliability mechanisms in OSPF the phenomena of late or
missing Connectivity Matrix sub-TLVs would be relatively rare.
6. Security Considerations
This document does not introduce any further security issues other
than those discussed in [RFC 3630], [RFC 4203].
Zhang Expires December 2013 [Page 7]
Internet-Draft Generic Constraint OSPF-TE June 2013
7. IANA Considerations
[RFC3630] says that the top level Types in a TE LSA and Types for
sub-TLVs for each top level Types must be assigned by Expert Review,
and must be registered with IANA.
IANA is requested to allocate new Types for the TLV or sub-TLVs as
defined in Sections 2 and 3 as follows:
7.1. Node Information
This document introduces a new Top Level Node TLV (Generic Node
Attribute TLV) under the OSPF TE LSA defined in [RFC3630].
Value TLV Type
TBA Generic Node Attribute
This document also introduces the following sub-TLVs of Generic Node
Attribute TLV:
Type sub-TLV
TBD Connectivity Matrix
7.2. Link Information
This document introduces the following sub-TLV of TE Link TLV (Value
2):
Type sub-TLV
TBD Port Label Restrictions
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC5250] L. Berger, I. Bryskin, A. Zinin, R. Coltun "The OSPF
Opaque LSA Option", RFC 5250, July 2008.
Zhang Expires December 2013 [Page 8]
Internet-Draft Generic Constraint OSPF-TE June 2013
[RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic
Engineering (TE) Extensions to OSPF Version 2", RFC 3630,
September 2003.
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
Extensions in Support of Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4202, October 2005
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[GEN-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, " General
Network Element Constraint Encoding for GMPLS Controlled
Networks", work in progress: draft-ietf-ccamp-general-
constraint-encode.
[RFC6205] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, " Generalized
Labels for Lambda-Switching Capable Label Switching
Routers", RFC 6205, January 2011.
8.2. Informative References
[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and
PCE Control of Wavelength Switched Optical Networks
(WSON)", RFC 6163, February 2011.
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Model for Wavelength
Switched Optical Networks", work in progress: draft-ietf-
ccamp-rwa-info.
9. Authors' Addresses
Fatai Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28972912
Zhang Expires December 2013 [Page 9]
Internet-Draft Generic Constraint OSPF-TE June 2013
Email: zhangfatai@huawei.com
Young Lee
Huawei Technologies
1700 Alma Drive, Suite 100
Plano, TX 75075
USA
Phone: (972) 509-5599 (x2240)
Email: ylee@huawei.com
Jianrui Han
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28977943
Email: hanjianrui@huawei.com
Greg Bernstein
Grotto Networking
Fremont CA, USA
Phone: (510) 573-2237
Email: gregb@grotto-networking.com
Yunbin Xu
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Phone: +86-10-68094134
Email: xuyunbin@mail.ritt.com.cn
Guoying Zhang
China Academy of Telecommunication Research of MII
11 Yue Tan Nan Jie Beijing, P.R.China
Zhang Expires December 2013 [Page 10]
Internet-Draft Generic Constraint OSPF-TE June 2013
Phone: +86-10-68094272
Email: zhangguoying@mail.ritt.com.cn
Dan Li
Huawei Technologies Co., Ltd.
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzhen 518129 P.R.China
Phone: +86-755-28973237
Email: danli@huawei.com
Ming Chen
European Research Center
Huawei Technologies
Riesstr. 25, 80992 Munchen, Germany
Phone: 0049-89158834072
Email: minc@huawei.com
Yabin Ye
European Research Center
Huawei Technologies
Riesstr. 25, 80992 Munchen, Germany
Phone: 0049-89158834074
Email: yabin.ye@huawei.com
Acknowledgment
We thank Ming Chen and Yabin Ye from DICONNET Project who provided
valuable information for this document.
Intellectual Property
Zhang Expires December 2013 [Page 11]
Internet-Draft Generic Constraint OSPF-TE June 2013
The IETF Trust takes no position regarding the validity or scope of
any Intellectual Property Rights or other rights that might be
claimed to pertain to the implementation or use of the technology
described in any IETF Document or the extent to which any license
under such rights might or might not be available; nor does it
represent that it has made any independent effort to identify any
such rights.
Copies of Intellectual Property disclosures made to the IETF
Secretariat and any assurances of licenses to be made available, or
the result of an attempt made to obtain a general license or
permission for the use of such proprietary rights by implementers or
users of this specification can be obtained from the IETF on-line
IPR repository at http://www.ietf.org/ipr
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
any standard or specification contained in an IETF Document. Please
address the information to the IETF at ietf-ipr@ietf.org.
The definitive version of an IETF Document is that published by, or
under the auspices of, the IETF. Versions of IETF Documents that are
published by third parties, including those that are translated into
other languages, should not be considered to be definitive versions
of IETF Documents. The definitive version of these Legal Provisions
is that published by, or under the auspices of, the IETF. Versions
of these Legal Provisions that are published by third parties,
including those that are translated into other languages, should
not be considered to be definitive versions of these Legal
Provisions.
For the avoidance of doubt, each Contributor to the IETF Standards
Process licenses each Contribution that he or she makes as part of
the IETF Standards Process to the IETF Trust pursuant to the
provisions of RFC 5378. No language to the contrary, or terms,
conditions or rights that differ from or are inconsistent with the
rights and licenses granted under RFC 5378, shall have any effect
and shall be null and void, whether published or posted by such
Contributor, or included with or in such Contribution.
Disclaimer of Validity
All IETF Documents and the information contained therein are
provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION
HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET
Zhang Expires December 2013 [Page 12]
Internet-Draft Generic Constraint OSPF-TE June 2013
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 THEREIN
WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Full Copyright Statement
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License.
Zhang Expires December 2013 [Page 13]