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: August 2016 February 19, 2016
OSPF Routing Extension for Links with Variable Discrete Bandwidth
draft-ietf-ccamp-ospf-availability-extension-04.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 in OSPF routing protocol. This extension can be
used for route computation in a network that contains links with
variable discrete bandwidth.
Status of this Memo
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Table of Contents
1. Introduction ................................................ 3
2. Overview .................................................... 3
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 ......................................... 5
6. References .................................................. 5
6.1. Normative References.................................... 5
6.2. Informative References.................................. 6
7. Acknowledgments ............................................. 6
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].
The following acronyms are used in this draft:
OSPF Open Shortest Path First
PSN Packet Switched Network
SNR Signal-to-noise Ratio
LSP Label Switched Path
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ISCD Interface Switching Capacity Descriptor
LSA Link State Advertisement
1. Introduction
Some data communication technologies, e.g., microwave, and copper,
allow seamless change of maximum physical bandwidth through a set of
known discrete values. The parameter availability [G.827, F.1703,
P.530] is often used to describe the link capacity during network
planning. The availability is a time scale that the requested
bandwidth is ensured. Assigning different availability classes to
different types of service over such kind of links provides more
efficient planning of link capacity. To set up an LSP across these
links, availability information is required for the nodes to verify
bandwidth satisfaction and make bandwidth reservation. The
availability information should be inherited 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. Since different service types may need different
availabilities guarantees, multiple <availability, bandwidth> pairs
may be required when signaling. The signaling extension for links
with discrete bandwidth is defined in [ASTE].
For the route computation, the availability information should be
provided along with bandwidth resource information. In this document,
an extension on Interface Switching Capacity Descriptor (ISCD)
[RFC4202] for availability information is defined to support in
routing signaling. The extension reuses the reserved field in the
ISCD and also introduces an optional Availability sub-TLV.
If there is a hop that cannot support the Availability sub-TLV, the
Availability sub-TLV should be ignored.
2. Overview
A node which has link(s) with variable bandwidth attached should
contain a <bandwidth, availability> information list in its OSPF TE
LSA messages. The list provides the information that how much
bandwidth a link can support for a specified availability. This
information is used for path calculation by the node(s).
To setup a label switching path (LSP), a node may collect link
information which is spread in OSPF TE LSA messages by network nodes
to get know about the network topology, calculate out an LSP route
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based on the network topology and send the calculated LSP route to
signaling to initiate a PATH/RESV message for setting up the LSP.
Availability information is required to carry in the signaling
message to better utilize the link bandwidth. The signaling
extension for availability can be found in [ASTE].
3. Extension to OSPF Routing Protocol
3.1. ISCD Availability sub-TLV
The Interface Switching Capacity Descriptor (ISCD) sub-TLV is
defined in Section 1.4 of [RFC 4203]. The ISCD Availability sub-TLV
is defined in this document as 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: 0x01, 16 bits;
Length: 16 bits;
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 capacity in the ISCD object which has the AI value
equal to Index of this sub-TLV. The value MUST be less than
1.
LSP Bandwidth at Availability level n: 32 bits
This field is a 32-bit IEEE floating point number which
describes the LSP Bandwidth at a certain Availability level
which was described in the Availability field.
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3.2. Signaling Process
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 doesn't support ISCD Availability sub-TLV SHOULD ignore
ISCD Availability sub-TLV.
4. Security Considerations
This document does not introduce new security considerations to the
existing OSPF protocol.
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. This document
proposes a suggested value for the Availability sub-TLV; it is
recommended that the suggested value be granted by IANA. Initial
values are as follows:
Type Length Format Description
--- ---- ------------------ -----------
0 - Reserved Reserved value
0x01 8 see Section 3.2 Availability
6. References
6.1. Normative References
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[ASTE] 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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6.2. Informative References
[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, March 1997
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V.,and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC4202] Kompella, K. and Rekhter, Y. (Editors), ''Routing
Extensions in Support of Generalized Multi-Protocol Label
Switching (GMPLS)", RFC 4202, October 2005.
[MCOS] Minei, I., Gan, D., Kompella, K., and X. Li, "Extensions
for Differentiated Services-aware Traffic Engineered
LSPs", Work in Progress, June 2006.
[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
[EN 302 217] ETSI standard, ''Fixed Radio Systems; Characteristics
and requirements for point-to-point equipment and
antennas'', April, 2009
7. Acknowledgments
The authors would like to thank Lou Berger for his comments on the
document.
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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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