One document matched: draft-ietf-ccamp-gmpls-general-constraints-ospf-te-01.txt
Differences from draft-ietf-ccamp-gmpls-general-constraints-ospf-te-00.txt
Network work group Fatai Zhang
Internet Draft Young Lee
Intended status: Standards Track Jianrui Han
Huawei
G. Bernstein
Grotto Networking
Yunbin Xu
CATR
Expires: March 13, 2012 September 13, 2011
OSPF-TE Extensions for General Network Element Constraints
draft-ietf-ccamp-gmpls-general-constraints-ospf-te-01.txt
Status of this Memo
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This Internet-Draft will expire on March 13, 2012.
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
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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 ................................................ 2
2. Node Information ............................................ 3
2.1. Connectivity Matrix..................................... 4
3. Link Information ............................................ 4
3.1. Port Label Restrictions................................. 5
3.2. Available Labels........................................ 5
3.3. Shared Backup Labels.................................... 6
4. Routing Procedures .......................................... 6
5. Security Considerations...................................... 7
6. IANA Considerations ......................................... 7
6.1. Node Information........................................ 7
6.2. Link Information........................................ 7
7. References .................................................. 8
7.1. Normative References.................................... 8
7.2. Informative References.................................. 9
8. 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.
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[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) Node Attribute
[RFC5786]. In this document, we enhance the sub-TLVs for the Link TLV
and 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
Routing Address described in [RFC3630], the other pieces of
information are defined in this document.
[RFC5786] defines a new top TLV named the Node Attribute TLV which
carries attributes related to a router/node. This Node Attribute TLV
contains one or more sub-TLVs.
Per [GEN-Encode], we have identified the following new Sub-TLVs to
the 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.
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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
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 Node Attribute TLV.
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
TBD variable Available Labels
TBD variable Shared Backup Labels
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.
In order to be able to compute label assignment, Available Labels
sub-TLV may appear in the LSAs. For example, in WSON networks,
without available wavelength information, path computation need guess
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what lambdas may be available (high blocking probability or
distributed wavelength assignment may be used).
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.
3.2. Available Labels
Available Labels indicates the labels available for use on a link as
described in [GEN-Encode]. The Available Labels 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 5.1 of [GEN-Encode]. The Available Labels sub-TLV
may occur at most once within the link TLV.
Note that there are five approaches for Label Set which is used to
represent the Available Labels described in [GEN-Encode]. Usually, it
depends on the implementation to one of the approaches. In WSON
networks, considering that the continuity of the available or
unavailable wavelength set can be scattered for the dynamic
wavelength availability, so it may burden the routing to reorganize
the wavelength set information when the Inclusive (/Exclusive) List
(/Range) approaches are used to represent Available Wavelengths
information. Therefore, it is RECOMMENDED that only the Bitmap Set be
used for representation Available Wavelengths information.
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The "Base Label" and "Last Label" in label set defined in [GEN-Encode]
corresponds to base wavelength label and last wavelength label in
WSON, the format of which is described as follows:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Grid | C.S. | Reserved | n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The detailed information related to wavelength label can be referred
to [RFC6205].
3.3. Shared Backup Labels
Shared Backup Labels indicates the labels available for shared backup
use on a link as described in [GEN-Encode].
The Shared Backup Labels 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 5.2 of
[GEN-Encode]. The Shared Backup Labels sub-TLV may occur at most once
within the link TLV.
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], [RFC2370], [RFC3630], [RFC4203] and [RFC5786].
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 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
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information sub-TLV and Available Labels information sub-TLV can 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. Security Considerations
This document does not introduce any further security issues other
than those discussed in [RFC 3630], [RFC 4203].
6. 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 sub-TLVs as defined
in Sections 2.1, 3.1, 3.2 and 3.3 as follows:
6.1. Node Information
This document introduces the following sub-TLVs of Node Attribute TLV
(Value TBD, see [RFC5786]):
Type sub-TLV
TBD Connectivity Matrix
6.2. Link Information
This document introduces the following sub-TLVs of TE Link TLV (Value
2):
Type sub-TLV
TBD Port Label Restrictions
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TBD Available Labels
TBD Shared Backup Labels
7. References
7.1. 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.
[RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July
1998.
[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.
[RFC5786] R. Aggarwal and K. Kompella, "Advertising a Router's Local
Addresses in OSPF Traffic Engineering (TE) Extensions", RFC
5786, March 2010.
[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-05.txt, May 2011.
[RFC6205] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, " Generalized
Labels for Lambda-Switching Capable Label Switching
Routers", work in progress: draft-ietf-ccamp-gmpls-g-694-
lambda-labels-11.txt, January 2011.
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7.2. Informative References
[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and
PCE Control of Wavelength Switched Optical Networks (WSON)",
work in progress: draft-ietf-ccamp-rwa-WSON-Framework-
12.txt, 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-12.txt, September 2011.
8. 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
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
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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
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
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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.
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