draft-ietf-ccamp-gmpls-general-constraints-ospf-te-01.txt   draft-ietf-ccamp-gmpls-general-constraints-ospf-te-02.txt 
Network work group Fatai Zhang Network work group Fatai Zhang
Internet Draft Young Lee Internet Draft Young Lee
Intended status: Standards Track Jianrui Han Intended status: Standards Track Jianrui Han
Huawei Huawei
G. Bernstein G. Bernstein
Grotto Networking Grotto Networking
Yunbin Xu Yunbin Xu
CATR CATR
Expires: March 13, 2012 September 13, 2011 Expires: March 22, 2012 September 22, 2011
OSPF-TE Extensions for General Network Element Constraints OSPF-TE Extensions for General Network Element Constraints
draft-ietf-ccamp-gmpls-general-constraints-ospf-te-01.txt draft-ietf-ccamp-gmpls-general-constraints-ospf-te-02.txt
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with This Internet-Draft is submitted to IETF in full conformance with
the provisions of BCP 78 and BCP 79. the provisions of BCP 78 and BCP 79.
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Drafts. Drafts.
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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This Internet-Draft will expire on March 13, 2012. This Internet-Draft will expire on March 22, 2012.
Abstract Abstract
Generalized Multiprotocol Label Switching can be used to control a Generalized Multiprotocol Label Switching can be used to control a
wide variety of technologies including packet switching (e.g., MPLS), wide variety of technologies including packet switching (e.g., MPLS),
time-division (e.g., SONET/SDH, OTN), wavelength (lambdas), and time-division (e.g., SONET/SDH, OTN), wavelength (lambdas), and
spatial switching (e.g., incoming port or fiber to outgoing port or spatial switching (e.g., incoming port or fiber to outgoing port or
fiber). In some of these technologies network elements and links may fiber). In some of these technologies network elements and links may
impose additional routing constraints such as asymmetric switch impose additional routing constraints such as asymmetric switch
connectivity, non-local label assignment, and label range limitations connectivity, non-local label assignment, and label range limitations
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Table of Contents Table of Contents
1. Introduction ................................................ 2 1. Introduction ................................................ 2
2. Node Information ............................................ 3 2. Node Information ............................................ 3
2.1. Connectivity Matrix..................................... 4 2.1. Connectivity Matrix..................................... 4
3. Link Information ............................................ 4 3. Link Information ............................................ 4
3.1. Port Label Restrictions................................. 5 3.1. Port Label Restrictions................................. 5
3.2. Available Labels........................................ 5 3.2. Available Labels........................................ 5
3.3. Shared Backup Labels.................................... 6 3.3. Shared Backup Labels.................................... 6
4. Routing Procedures .......................................... 6 4. Routing Procedures .......................................... 6
5. Security Considerations...................................... 7 5. Scalability and Timeliness................................... 7
6. IANA Considerations ......................................... 7 5.1. Different Sub-TLVs into Multiple LSAs ...................7
6.1. Node Information........................................ 7 5.2. Decomposing a Connectivity Matrix into Multiple Matrices.8
6.2. Link Information........................................ 7 6. Security Considerations...................................... 8
7. References .................................................. 8 7. IANA Considerations ......................................... 8
7.1. Normative References.................................... 8 7.1. Node Information........................................ 8
7.2. Informative References.................................. 9 7.2. Link Information........................................ 9
8. Authors' Addresses .......................................... 9 8. References .................................................. 9
Acknowledgment ................................................ 11 8.1. Normative References.................................... 9
8.2. Informative References................................. 10
9. Authors' Addresses.......................................... 10
Acknowledgment ................................................ 12
1. Introduction 1. Introduction
Some data plane technologies that wish to make use of a GMPLS control Some data plane technologies that wish to make use of a GMPLS control
plane contain additional constraints on switching capability and plane contain additional constraints on switching capability and
label assignment. In addition, some of these technologies should be label assignment. In addition, some of these technologies should be
capable of performing non-local label assignment based on the nature capable of performing non-local label assignment based on the nature
of the technology, e.g., wavelength continuity constraint in WSON of the technology, e.g., wavelength continuity constraint in WSON
[RFC6163]. Such constraints can lead to the requirement for link by [RFC6163]. Such constraints can lead to the requirement for link by
link label availability in path computation and label assignment. link label availability in path computation and label assignment.
[GEN-Encode] provides efficient encodings of information needed by [GEN-Encode] provides efficient encodings of information needed by
the routing and label assignment process in technologies such as WSON the routing and label assignment process in technologies such as WSON
and are potentially applicable to a wider range of technologies. and are potentially applicable to a wider range of technologies.
This document defines extensions to the OSPF routing protocol based This document defines extensions to the OSPF routing protocol based
on [GEN-Encode] to enhance the Traffic Engineering (TE) properties of on [GEN-Encode] to enhance the Traffic Engineering (TE) properties of
GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203]. GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203].
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and are potentially applicable to a wider range of technologies. and are potentially applicable to a wider range of technologies.
This document defines extensions to the OSPF routing protocol based This document defines extensions to the OSPF routing protocol based
on [GEN-Encode] to enhance the Traffic Engineering (TE) properties of on [GEN-Encode] to enhance the Traffic Engineering (TE) properties of
GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203]. GMPLS TE which are defined in [RFC3630], [RFC4202], and [RFC4203].
The enhancements to the Traffic Engineering (TE) properties of GMPLS 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 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 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 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) for extensibility. The top-level TLV can take one of three values (1)
Router Address [RFC3630], (2) Link [RFC3630], (3) Node Attribute Router Address [RFC3630], (2) Link [RFC3630], (3) Generic Node
[RFC5786]. In this document, we enhance the sub-TLVs for the Link TLV Attribute defined in Section 2. In this document, we enhance the sub-
and Node Attribute TLV in support of the general network element TLVs for the Link TLV and define a new top-level TLV (Generic Node
constraints under the control of GMPLS. 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 The detailed encoding of OSPF extensions are not defined in this
document. [GEN-Encode] provides encoding detail. document. [GEN-Encode] provides encoding detail.
2. Node Information 2. Node Information
According to [GEN-Encode], the additional node information According to [GEN-Encode], the additional node information
representing node switching asymmetry constraints includes Node ID, representing node switching asymmetry constraints includes Node ID,
connectivity matrix. Except for the Node ID which should comply with connectivity matrix. Except for the Node ID which should comply with
Routing Address described in [RFC3630], the other pieces of Routing Address described in [RFC3630], the other pieces of
information are defined in this document. information are defined in this document.
[RFC5786] defines a new top TLV named the Node Attribute TLV which This document defines a new top TLV named the Generic Node Attribute
carries attributes related to a router/node. This Node Attribute TLV TLV which carries attributes related to a general network element.
contains one or more sub-TLVs. This Generic Node Attribute TLV contains one or more sub-TLVs
Per [GEN-Encode], we have identified the following new Sub-TLVs to Per [GEN-Encode], we have identified the following new Sub-TLVs to
the Node Attribute TLV. Detail description for each newly defined the Generic Node Attribute TLV. Detail description for each newly
Sub-TLV is provided in subsequent sections: defined Sub-TLV is provided in subsequent sections:
Sub-TLV Type Length Name Sub-TLV Type Length Name
TBD variable Connectivity Matrix TBD variable Connectivity Matrix
In some specific technologies, e.g., WSON networks, Connectivity In some specific technologies, e.g., WSON networks, Connectivity
Matrix sub-TLV may be optional, which depends on the control plane Matrix sub-TLV may be optional, which depends on the control plane
implementations. Usually, for example, in WSON networks, Connectivity implementations. Usually, for example, in WSON networks, Connectivity
Matrix sub-TLV may appear in the LSAs because WSON switches are Matrix sub-TLV may appear in the LSAs because WSON switches are
asymmetric at present. It is assumed that the switches are symmetric asymmetric at present. It is assumed that the switches are symmetric
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It is necessary to identify which ingress ports and labels can be It is necessary to identify which ingress ports and labels can be
switched to some specific labels on a specific egress port, if the switched to some specific labels on a specific egress port, if the
switching devices in some technology are highly asymmetric. switching devices in some technology are highly asymmetric.
The Connectivity Matrix is used to identify these restrictions, which The Connectivity Matrix is used to identify these restrictions, which
can represent either the potential connectivity matrix for asymmetric can represent either the potential connectivity matrix for asymmetric
switches (e.g. ROADMs and such) or fixed connectivity for an switches (e.g. ROADMs and such) or fixed connectivity for an
asymmetric device such as a multiplexer as defined in [WSON-Info]. 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 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. Generic Node Attribute TLV. The length is the length of value field
The meaning and format of this sub-TLV are defined in Section 5.3 of in octets. The meaning and format of this sub-TLV are defined in
[GEN-Encode]. One sub-TLV contains one matrix. The Connectivity Section 5.3 of [GEN-Encode]. One sub-TLV contains one matrix. The
Matrix sub-TLV may occur more than once to contain multi-matrices Connectivity Matrix sub-TLV may occur more than once to contain
within the Node Attribute TLV. 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.
3. Link Information 3. Link Information
The most common link sub-TLVs nested to link top-level TLV are The most common link sub-TLVs nested to link top-level TLV are
already defined in [RFC3630], [RFC4203]. For example, Link ID, already defined in [RFC3630], [RFC4203]. For example, Link ID,
Administrative Group, Interface Switching Capability Descriptor Administrative Group, Interface Switching Capability Descriptor
(ISCD), Link Protection Type, Shared Risk Link Group Information (ISCD), Link Protection Type, Shared Risk Link Group Information
(SRLG), and Traffic Engineering Metric are among the typical link (SRLG), and Traffic Engineering Metric are among the typical link
sub-TLVs. sub-TLVs.
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The Shared Backup Labels is a sub-TLV (the type is TBD by IANA) of 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 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 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 [GEN-Encode]. The Shared Backup Labels sub-TLV may occur at most once
within the link TLV. within the link TLV.
4. Routing Procedures 4. Routing Procedures
All the sub-TLVs are nested to top-level TLV(s) and contained in 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 Opaque LSAs. The flooding of Opaque LSAs must follow the rules
specified in [RFC2328], [RFC2370], [RFC3630], [RFC4203] and [RFC5786]. specified in [RFC2328], [RFC5250], [RFC3630], [RFC4203].
Considering the routing scalability issues in some cases, the routing Considering the routing scalability issues in some cases, the routing
protocol should be capable of supporting the separation of dynamic protocol should be capable of supporting the separation of dynamic
information from relatively static information to avoid unnecessary information from relatively static information to avoid unnecessary
updates of static information when dynamic information is changed. A updates of static information when dynamic information is changed. A
standard-compliant approach is to separate the dynamic information standard-compliant approach is to separate the dynamic information
sub-TLVs from the static information sub-TLVs, each nested to top- sub-TLVs from the static information sub-TLVs, each nested to top-
level TLV ([RFC3630 and RFC5876]), and advertise them in the separate level TLV ([RFC3630 and RFC5876]), and advertise them in the separate
OSPF TE LSAs. OSPF TE LSAs.
For node information, since the Connectivity Matrix information is For node information, since the Connectivity Matrix information is
static, the LSA containing the Node Attribute TLV can be updated with static, the LSA containing the Generic Node Attribute TLV can be
a lower frequency to avoid unnecessary updates. updated with a lower frequency to avoid unnecessary updates.
For link information, a mechanism MAY be applied such that static For link information, a mechanism MAY be applied such that static
information and dynamic information of one TE link are contained in information and dynamic information of one TE link are contained in
separate Opaque LSAs. For example, the Port Label Restrictions separate Opaque LSAs. For example, the Port Label Restrictions
information sub-TLV and Available Labels information sub-TLV can be information sub-TLV and Available Labels information sub-TLV can be
nested to the top level link TLVs and advertised in the separate LSAs. nested to the top level link TLVs and advertised in the separate LSAs.
Note that as with other TE information, an implementation SHOULD take Note that as with other TE information, an implementation SHOULD take
measures to avoid rapid and frequent updates of routing information measures to avoid rapid and frequent updates of routing information
that could cause the routing network to become swamped. A threshold that could cause the routing network to become swamped. A threshold
mechanism MAY be applied such that updates are only flooded when a mechanism MAY be applied such that updates are only flooded when a
number of changes have been made to the label availability number of changes have been made to the label availability
information (e.g., wavelength availability) within a specific time. information (e.g., wavelength availability) within a specific time.
Such mechanisms MUST be configurable if they are implemented. Such mechanisms MUST be configurable if they are implemented.
5. Security Considerations 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.
5.1. Different Sub-TLVs into Multiple LSAs
Four sub-TLVs are defined in this document:
1. Connectivity Matrix (Generic Node Attribute TLV)
2. Port Label Restrictions (Link TLV)
3. Available Labels (Link TLV)
4. Shared Backup Labels (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. While the Available Labels and Shared Backup Labels
are dynamic, meaning that they may change with LSP setup or teardown
through the system. The most important technique for scalability and
OSPF bandwidth reduction is to separate the dynamic information sub-
TLVs from the static information sub-TLVs and advertise them in
separate OSPF TE LSAs[RFC3630 and RFC5250].
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 This document does not introduce any further security issues other
than those discussed in [RFC 3630], [RFC 4203]. than those discussed in [RFC 3630], [RFC 4203].
6. IANA Considerations 7. IANA Considerations
[RFC3630] says that the top level Types in a TE LSA and Types for [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, sub-TLVs for each top level Types must be assigned by Expert Review,
and must be registered with IANA. and must be registered with IANA.
IANA is requested to allocate new Types for the sub-TLVs as defined IANA is requested to allocate new Types for the TLV or sub-TLVs as
in Sections 2.1, 3.1, 3.2 and 3.3 as follows: defined in Sections 2 and 3 as follows:
6.1. Node Information 7.1. Node Information
This document introduces the following sub-TLVs of Node Attribute TLV This document introduces a new Top Level Node TLV (Generic Node
(Value TBD, see [RFC5786]): 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 Type sub-TLV
TBD Connectivity Matrix TBD Connectivity Matrix
6.2. Link Information 7.2. Link Information
This document introduces the following sub-TLVs of TE Link TLV (Value This document introduces the following sub-TLVs of TE Link TLV (Value
2): 2):
Type sub-TLV Type sub-TLV
TBD Port Label Restrictions TBD Port Label Restrictions
TBD Available Labels TBD Available Labels
TBD Shared Backup Labels TBD Shared Backup Labels
7. References 8. References
7.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC2370] Coltun, R., "The OSPF Opaque LSA Option", RFC 2370, July [RFC5250] L. Berger, I. Bryskin, A. Zinin, R. Coltun "The OSPF Opaque
1998. LSA Option", RFC 5250, July 2008.
[RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic Engineering [RFC3630] Katz, D., Kompella, K., and Yeung, D., "Traffic Engineering
(TE) Extensions to OSPF Version 2", RFC 3630, September (TE) Extensions to OSPF Version 2", RFC 3630, September
2003. 2003.
[RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions [RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, October 2005 (GMPLS)", RFC 4202, October 2005
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions in [RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions in
Support of Generalized Multi-Protocol Label Switching Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005. (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 [GEN-Encode] G. Bernstein, Y. Lee, D. Li, W. Imajuku, " General
Network Element Constraint Encoding for GMPLS Controlled Network Element Constraint Encoding for GMPLS Controlled
Networks", work in progress: draft-ietf-ccamp-general- Networks", work in progress: draft-ietf-ccamp-general-
constraint-encode-05.txt, May 2011. constraint-encode-05.txt, May 2011.
[RFC6205] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, " Generalized [RFC6205] T. Otani, H. Guo, K. Miyazaki, D. Caviglia, " Generalized
Labels for Lambda-Switching Capable Label Switching Labels for Lambda-Switching Capable Label Switching
Routers", work in progress: draft-ietf-ccamp-gmpls-g-694- Routers", work in progress: draft-ietf-ccamp-gmpls-g-694-
lambda-labels-11.txt, January 2011. lambda-labels-11.txt, January 2011.
7.2. Informative References 8.2. Informative References
[RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and [RFC6163] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS and
PCE Control of Wavelength Switched Optical Networks (WSON)", PCE Control of Wavelength Switched Optical Networks (WSON)",
work in progress: draft-ietf-ccamp-rwa-WSON-Framework- work in progress: draft-ietf-ccamp-rwa-WSON-Framework-
12.txt, February 2011. 12.txt, February 2011.
[WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and [WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
Wavelength Assignment Information Model for Wavelength Wavelength Assignment Information Model for Wavelength
Switched Optical Networks", work in progress: draft-ietf- Switched Optical Networks", work in progress: draft-ietf-
ccamp-rwa-info-12.txt, September 2011. ccamp-rwa-info-12.txt, September 2011.
8. Authors' Addresses 9. Authors' Addresses
Fatai Zhang Fatai Zhang
Huawei Technologies Huawei Technologies
F3-5-B R&D Center, Huawei Base F3-5-B R&D Center, Huawei Base
Bantian, Longgang District Bantian, Longgang District
Shenzhen 518129 P.R.China Shenzhen 518129 P.R.China
Phone: +86-755-28972912 Phone: +86-755-28972912
Email: zhangfatai@huawei.com Email: zhangfatai@huawei.com
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