Network Working Group H. Long
Internet Draft M.Ye
Intended status: Standards Track Huawei Technologies Co., Ltd
G. Mirsky
Ericsson
A Alessandro
Telecom Italia S.p.A
Expires: January 2014 July 3, 2013
OSPF Routing Extension for links with variable discrete bandwidth
draft-long-ccamp-ospf-availability-extension-00.txt
Abstract
Packet switching network may contain links with variable discrete
bandwidth, e.g., copper, radio, etc. The bandwidth of such link may
change discretely in reaction to changing external environment.
Availability is typically used for describing such links during
network planning. This document describes an extension for OSPF
routing for route computation in a Packet Switched Network (PSN)
which contains link with variable discrete bandwidth by introducing
an optional availability sub-TLV.
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This Internet-Draft will expire on January 7, 2009.
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Table of Contents
1. Introduction ................................................ 3
2. Overview .................................................... 3
3. Extension to OSPF Routing Protocol .......................... 4
3.1. Interface Switching Capacity Descriptor................. 4
3.2. ISCD Availability sub-TLV............................... 4
3.3. 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
ISCD Interface Switching Capacity Descriptor
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PE Provider Edge
LSA Link State Advertisement
1. Introduction
There are some data communication technologies that allow seamless
change of maximum physical bandwidth. For example, in mobile
backhaul network, microwave links are very popular for providing
connection of last hops. In case of heavy rain, to maintain the link
connectivity, the microwave link will lower the modulation level
since demodulating lower modulation level need lower signal-to-noise
ratio (SNR). This is called adaptive modulation technology [EN 302
217]. However, lower modulation level also means lower link
bandwidth. When link bandwidth reduces by modulation down-shifting,
high priority traffic can be maintained, while lower priority
traffic is dropped. Similarly the cooper links may change their
effective link bandwidth due to external interference.
The parameter, availability [G.827, F.1703, P.530], is often used to
describe the link capacity during network planning. 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, voice service usually needs "five
nines" availability, while non-real time data packets may needs four
or three nines availability.
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 support in routing signaling.
The extension reuses the reserved field in the ISCD and also
introduces an optional availability sub-TLV.
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 PE node(s).
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To setup a label switching path (LSP), a PE node may collect link
information which is spread in OSPF TE LSA message by network nodes
to get know about the network topology, and calculate out a LSP
route based on the network topology, and send the calculated LSP
route to signaling to initiate a PATH/RESV message for setting up
the LSP.
3. Extension to OSPF Routing Protocol
3.1. Interface Switching Capacity Descriptor
The Interface Switching Capacity Descriptor (ISCD) sub-TLV [RFC 4203]
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switching Cap | Encoding | AI | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ Switching Capacity Information ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD, 16 bits;
Length: 16 bits;
AI: ISCD Availability sub-TLV index, 8 bits
This field is the index of availability sub-TLV for this ISCD
sub-TLV.
3.2. ISCD Availability sub-TLV
The 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Availability Information |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Type: TBD, 16 bits;
Length: 16 bits;
Index: 8 bits
This field is the index of this availability sub-TLV,
referred by the AI field of the ISCD sub-TLV.
Availability Information: 32 bits
This field is a 32-bit IEEE floating point number which
describes the 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.
3.3. 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
that how much bandwidth a link can support for a specified
availability. This information is used for path calculation by the
PE node(s).
4. Security Considerations
This document does not introduce new security considerations to the
existing OSPF protocol.
5. IANA Considerations
TBD
6. References
6.1. Normative References
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 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.
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[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.
[RFC4203] Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4203, October 2005.
[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
6.2. Informative References
[MCOS] Minei, I., Gan, D., Kompella, K., and X. Li, "Extensions
for Differentiated Services-aware Traffic Engineered
LSPs", Work in Progress, June 2006.
7. Acknowledgments
Authors' Addresses
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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
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