Network Working Group H. Long, M.Ye
Internet Draft Huawei Technologies Co., Ltd
Intended status: Standards Track G. Mirsky
Ericsson
A Alessandro
Telecom Italia S.p.A
H. Shah
Ciena
Expires: January 2015 July 4, 2014
OSPF Routing Extension for Links with Variable Discrete Bandwidth
draft-long-ccamp-ospf-availability-extension-04.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 links with variable discrete bandwidth by introducing
an OPTIONAL Availability sub-TLV.
Status of this Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 4, 2014.
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Copyright Notice
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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............................... 5
3.3. Signaling Process....................................... 6
4. Security Considerations...................................... 6
5. IANA Considerations ......................................... 6
6. References .................................................. 6
6.1. Normative References.................................... 6
6.2. Informative References.................................. 7
7. Acknowledgments ............................................. 7
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
Some data communication technologies allow seamless change of
maximum physical bandwidth through a set of known discrete values.
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 MAY 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 reduced because
of 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. 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, 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
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bandwidth a link can support for a specified availability. This
information is used for path calculation by the PE node(s).
To setup an label switching path (LSP), a PE 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
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. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 3 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Max LSP Bandwidth at priority 7 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Switching Capacity-specific Information |
| (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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A new AI field is defined in this document.
AI: ISCD Availability sub-TLV index, 8 bits
This new field is the index of Availability sub-TLV for this
ISCD sub-TLV.
3.2. ISCD Availability sub-TLV
When the Switching Capability field is PSC-1, PSC-2, PSC-3, PSC-4,
the Switching Capability specific information field 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Availability level |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LSP Bandwidth at Availability level n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: 0x01, 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 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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3.3. 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
about how much bandwidth a link can support for a specified
availability. This information SHOULD be used for path calculation
by the PE 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 sub-
TLV
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
[ASTE] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
''RSVP-TE Signaling Extension for Links with Variable
Discrete Bandwidth'', Work in Progress, February, 2014
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
Himanshu Shah
Ciena Corp.
3939 North First Street
San Jose, CA 95134
US
Email: hshah@ciena.com
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