Network Working Group H. Long, M.Ye
Internet Draft Huawei Technologies Co., Ltd
Intended status: Standards Track G. Mirsky
Ericsson
A.D'Alessandro
Telecom Italia S.p.A
H. Shah
Ciena
Expires: April 2017 October 8, 2016
OSPF-TE Link Availability Extension for Links with Variable Discrete
Bandwidth
draft-ietf-ccamp-ospf-availability-extension-07.txt
Abstract
A network may contain links with variable discrete bandwidth, e.g.,
copper, radio, etc. The bandwidth of such links may change
discretely in reaction to changing external environment.
Availability is typically used for describing such links during
network planning. This document introduces an optional ISCD
Availability sub-TLV to extend the Generalized Multi-Protocol Label
Switching (GMPLS) Open Shortest Path First (OSPF) routing protocol.
This extension can be used for route computation in a network that
contains links with variable discrete bandwidth. Note, this document
only covers the mechanisms by which the availability information is
distributed. The mechanisms by which availability information of a
link is determined and the use of the distributed information for
route computation are outside the scope of this document.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Drafts.
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months and may be updated, replaced, or obsoleted by other documents
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Table of Contents
1. Introduction ................................................ 3
2. Overview .................................................... 4
3. Extension to OSPF Routing Protocol........................... 4
3.1. ISCD Availability sub-TLV............................... 4
3.2. Signaling Process....................................... 5
4. Security Considerations...................................... 5
5. IANA Considerations ......................................... 6
6. References .................................................. 6
6.1. Normative References.................................... 6
6.2. Informative References.................................. 7
7. Acknowledgments ............................................. 8
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].
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The following acronyms are used in this draft:
GMPLS Generalized Multi-Protocol Label Switching
LSA Link State Advertisement
ISCD Interface Switching Capacity Descriptor
LSP Label Switched Path
OSPF Open Shortest Path First
PSN Packet Switched Network
SNR Signal-to-noise Ratio
SONET-SDH Synchronous Optical Network - Synchronous Digital
Hierarchy
SPF Shortest Path First
1. Introduction
Some data plane technologies, e.g., microwave, and copper, allow
seamless change of maximum physical bandwidth through a set of known
discrete values. The parameter, availability, as described in
[G.827], [F.1703] and [P.530] is often used to describe the link
capacity. The availability is a time scale, representing a proportion
of the operating time that the requested bandwidth is ensured. To
set up an LSP across these links, availability information is
required by the nodes to verify the bandwidth before making a
bandwidth reservation. Assigning different availability classes
over such links provides for a more efficient planning of link
capacity to support different types of services. The link
availability information will be determined by the operator and
statically configured. It will usually be determined from the
availability requirements of the services expected to be carried on
the LSP. For example, voice service usually needs ''five nines''
availability, while non-real time services may adequately perform at
four or three nines availability. For the route computation, both
the availability information and the bandwidth resource information
are needed. Since different service types may need different
availability guarantees, multiple <availability, bandwidth> pairs
may be required to be associated with a link.
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In this document, an extension on Interface Switching Capacity
Descriptor (ISCD) [RFC4202] for availability information is defined.
The signaling extension to support links with discrete bandwidth is
defined in [ETPAI].
2. Overview
A node which has link(s) with variable bandwidth attached should
include a < availability, bandwidth> information list in its OSPF TE
LSA messages. The list provides the mapping between the link nominal
bandwidth and its availability level. This information is used for
path calculation by the node(s).The setup of a Label Switched Path
requires this information to be flooded in the network and used by
the nodes or the PCE for the path computation. In this document, an
extension to Interface Switching Capacity Descriptor (ISCD) [RFC4202]
for availability information is defined. The computed path can then
be provisioned via the signaling protocol[ETPAI].
Note, the mechanisms described in this document only distribute
availability information. The methods for measuring the information
or using the information for route computation are outside the scope
of this document.
3. TE Metric Extension to OSPF-TE
3.1. ISCD Availability sub-TLV
The ISCD sub-TLV is defined in Section 1.4 of [RFC4203]. The ISCD
Availability sub-TLV defined in this document is a sub-TLV of ISCD.
The Switching Capability specific information field of ISCD MAY
include one or more ISCD Availability sub-TLV(s). The ISCD
Availability sub-TLV has the following format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Availability level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP Bandwidth at Availability level n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBA by IANA, suggested value is 0x01, 16 bits;
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Length: A 16 bits field that expresses the length of the TLV in
bytes;
Availability level: 32 bits
This field is a 32-bit IEEE floating point number which
describes the decimal value of availability guarantee of the
switching capability in the ISCD object. The value MUST be
less than 1. The Availability level is usually expressed in
the value of 0.99/0.999/0.9999/0.99999.
LSP Bandwidth at Availability level n: 32 bits
This field is a 32-bit IEEE floating point number which
describes the LSP Bandwidth for the Availability level
represented in the Availability field. The units are bytes
per second.
3.2. Processing Procedures
A node which has link(s) with variable bandwidth attached SHOULD
contain one or more ISCD Availability sub-TLVs in its OSPF TE LSA
messages. Each ISCD Availability sub-TLV provides the information
about how much bandwidth a link can support for a specified
availability. This information SHOULD be used for path calculation
by the node(s).
A node that does not support the ISCD Availability sub-TLV SHOULD
ignore ISCD Availability sub-TLV but it SHOULD be included in LSAs
sent to OSPF neighbors [RFC3630]. If a node who supports ISCD
Availability sub-TLVs does not receive the TLV, it SHOULD assume
that the link is with fixed bandwidth, and the availability can be
interpreted as the highest availability value, e.g., five nines.
It's not allowed to send multiple ISCD Availability sub-TLVs for the
same availability level.
4. Security Considerations
This document does not introduce security issues beyond those
discussed in [RFC4203]. As with [RFC4203], it specifies the content
of an Opaque LSAs in OSPFv2. As Opaque LSAs are not used for
Shortest Path First (SPF) computation or normal routing, the
extensions specified here have no direct effect on IP routing.
Tampering with GMPLS TE LSAs may have an impact on the ability to
set up connections in the underlying data plane network. As the
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additional availability information may represent information that
an operator may wish to keep private, consideration should be given
to securing this information.[RFC3630] notes that the security
mechanisms described in [RFC2328] apply to Opaque LSAs carried in
OSPFv2. An analysis of the security of OSPF is provided in [RFC6863]
and applies to the extensions to OSPF as described in this document.
Any new mechanisms developed to protect the transmission of
information carried in Opaque LSAs will also automatically protect
the extensions defined in this document.
Please refer to [RFC5920] for details on security threats; defensive
techniques; monitoring, detection, and reporting of security attacks;
and requirements.
5. IANA Considerations
This document introduces an Availability sub-TLV of the ISCD sub-TLV
of the TE Link TLV in the TE Opaque LSA for OSPF v2. IANA is
requested to create a new sub-registry, the ''Types for sub-TLV of
Interface Switching Capability Descriptor'' registry under the "Open
Shortest Path First (OSPF) Traffic Engineering TLVs" registry, see
http://www.iana.org/assignments/ospf-traffic-eng-tlvs.
This document proposes a suggested value for the Availability sub-
TLV; it is requested that the suggested value be granted by IANA.
Type Description Reference
--- ------------------ -----------
0 Reserved [This ID]
0x01 Availability [This ID]
The registration procedure for this registry is Standards Action as
defined in [RFC5226].
6. References
6.1. Normative References
[RFC4202] Kompella, K. and Rekhter, Y. (Editors), ''Routing
Extensions in Support of Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4202, October 2005.
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[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
6.2. Informative References
[RFC2119] Bradner, S., ''Key words for use in RFCs to Indicate
Requirement Levels'', RFC 2119, March 1997.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998.
[RFC3630] Katz, D., Kompella, K., and D. Yeung, ''Traffic Engineering
(TE) Extensions to OSPF Version 2'', RFC 3630, September
2003.
[RFC5226] Narten,T. and H. Alvestrand, ''Guidelines for Writing an
IANA Considerations Section in RFCs'', RFC 5226, May 2008.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS Networks",
RFC 5920, July 2010.
[RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security
According to the Keying and Authentication for Routing
Protocols (KARP) Design Guide", RFC 6863, March 2013.
[G.827] ITU-T Recommendation, ''Availability performance parameters
and objectives for end-to-end international constant bit-
rate digital paths'', September, 2003.
[F.1703] ITU-R Recommendation, ''Availability objectives for real
digital fixed wireless links used in 27 500 km
hypothetical reference paths and connections'', January,
2005.
[P.530] ITU-R Recommendation,'' Propagation data and prediction
methods required for the design of terrestrial line-of-
sight systems'', February, 2012
[ETPAI] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
''Ethernet Traffic Parameters with Availability
Information'', Work in Progress, June, 2015
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7. Acknowledgments
The authors would like to thank Acee Lindem, Daniele Ceccarelli, Lou
Berger for their comments on the document.
Authors' Addresses
Hao Long
Huawei Technologies Co., Ltd.
No.1899, Xiyuan Avenue, Hi-tech Western District
Chengdu 611731, P.R.China
Phone: +86-18615778750
Email: longhao@huawei.com
Min Ye
Huawei Technologies Co., Ltd.
No.1899, Xiyuan Avenue, Hi-tech Western District
Chengdu 611731, P.R.China
Email: amy.yemin@huawei.com
Greg Mirsky
Ericsson
Email: gregory.mirsky@ericsson.com
Alessandro D'Alessandro
Telecom Italia S.p.A
Email: alessandro.dalessandro@telecomitalia.it
Himanshu Shah
Ciena Corp.
3939 North First Street
San Jose, CA 95134
US
Email: hshah@ciena.com
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