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: August 2014 February 13, 2014
RSVP-TE Signaling Extension for Links with Variable Discrete
Bandwidth
draft-long-ccamp-rsvp-te-bandwidth-availability-03.txt
Abstract
Packet switching network may contain links with variable bandwidth,
e.g., copper, radio, etc. The bandwidth of such link is sensitive to
external environment. Availability is typically used for describing
the link during network planning. This document describes an
extension for RSVP-TE signaling for setting up a label switching
path (LSP) in a Packet Switched Network (PSN) network which contains
links with discretely variable bandwidth by introducing an optional
availability field in RSVP-TE signaling.
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Table of Contents
1. Introduction ................................................ 3
2. Overview .................................................... 4
3. Extension to RSVP-TE Signaling............................... 5
3.1.1. Availability sub-TLV............................... 5
3.2. FLOWSPEC Object......................................... 6
3.3. Signaling Process....................................... 6
4. Security Considerations...................................... 7
5. IANA Considerations ......................................... 7
5.1 Ethernet Bandwidth Profile TLV ......................... 7
6. References .................................................. 8
6.1. Normative References.................................... 8
6.2. Informative References.................................. 8
7. Acknowledgments ............................................. 9
Appendix A ..................................................... 9
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:
RSVP-TE Resource Reservation Protocol-Traffic Engineering
LSP Label Switched Path
PSN Packet Switched Network
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SNR Signal-to-noise Ratio
TLV Type Length Value
PE Provider Edge
LSA Link State Advertisement
1. Introduction
The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473]
specify the signaling message including the bandwidth request for
setting up a label switching path in a PSN network.
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 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. A more detailed
example on the bandwidth availability can be found in Appendix A.
Assigning different availability classes to different types of
service over such kind of links provides more efficient planning of
link capacity. To set up a 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
services may adequately perform at four or three nines availability.
Since different service types may need different availabilities
guarantee, multiple <availability, bandwidth> pairs may be required
when signaling.
If the availability requirement is not specified in the signaling
message, the bandwidth will be reserved as the highest availability.
For example, the bandwidth with 99.999% availability of a link is
100Mbps; the bandwidth with 99.99% availability is 200Mbps. When a
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video application requests for 120Mbps without availability
requirement, the system will compare 120Mbps with 100Mbps, therefore
cannot set up the LSP path. But in fact, video application doesn't
need 99.999% availability, 99.99% availability is enough. In this
case, the LSP could be set up if availability is specified in the
signaling message.
To fulfill LSP setup by signaling in these scenarios, this document
specifies a new availability sub-TLV as the sub-TLV of Ethernet
bandwidth profiles [RFC6003]. Multiple bandwidth profiles with
different availability can be carried in the SENDER_TSPEC object.
2. Overview
A PSN tunnel may span one or more links in a network. To setup a
label switching path (LSP), a PE node may collect link information
which is spread in routing message, e.g., OSPF TE LSA message, by
network nodes to get to know about the network topology, and
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.
In case that there is(are) link(s) with variable discrete bandwidth
in a network, a <bandwidth, availability> requirement list should be
specified for an LSP. Each <bandwidth, availability> pair in the
list means that listed bandwidth with specified availability is
required. The list could be inherited from the results of service
planning for the LSP.
A node which has link(s) with variable discrete 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). The
routing extension for availability can be found in [ARTE].
When a PE node initiates a PATH/RESV signaling to set up an LSP, the
PATH message SHOULD carry the <bandwidth, availability> requirement
list as bandwidth request. Intermediate node(s) will allocate the
bandwidth resource for each availability requirement from the
remaining bandwidth with corresponding availability. An error
message may be returned if any <bandwidth, availability> request
cannot be satisfied.
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3. Extension to RSVP-TE Signaling
The RSVP-TE signaling extension in this document is based on RFC6003:
a new sub-TLV for Ethernet Bandwidth Profile TLV is defined.
3.1.1. Availability sub-TLV
The Ethernet Bandwidth Profile TLV in RFC6003 has the following
format. A new filed is defined in this document as shown in Figure 1.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Pro|A| | Index | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CIR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CBS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EIR |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EBS |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: A new "AF" filed in Ethernet Bandwidth Profile TLV
A new filed is defined in this document:
AF filed (bit 2): Availability Field (AF)
If the AF filed is set to 1, Availability sub-TLV MUST be included
in the Bandwidth Profile TLV. If the AF field is set to value 0,
then an Availability sub-TLV SHOULD NOT be included. 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Availability |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Availability sub-TLV
Type (2 octets): TBD
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Length (2 octets): 4
Availability (4 octets): a 32-bit floating number describes
availability requirement for this bandwidth request. The value
must be less than 1.
As the Ethernet Bandwidth Profile TLV can be carried for one or more
times in the Ethernet SENDER_TSPEC object, the availability sub-TLV
can also be present for one or more times.
3.2. FLOWSPEC Object
The FLOWSPEC object (Class-Num = 9, Class-Type = TBD) has the same
format as the Ethernet SENDER_TSPEC object.
3.3. Signaling Process
The source node initiates PATH messages including one or more
Bandwidth Profile TLVs with different availability value in the
SENDER_TSPEC object. Each Bandwidth Profile TLV specifies the
portion of bandwidth request with referred availability requirement.
The destination node checks whether it can satisfy the bandwidth
requirements by comparing each bandwidth requirement inside the
SENDER_TSPEC objects with the remaining link sub-bandwidth resource
with respective availability guarantee when received the PATH
message.
o If all <bandwidth, availability> requirements can be
satisfied, it should reserve the bandwidth resource from each
remaining sub-bandwidth portion to set up this LSP. Optionally,
the higher availability bandwidth can be allocated to lower
availability request when the lower availability bandwidth
cannot satisfy the request.
o If at least one <bandwidth, availability> requirement cannot
be satisfied, it should generate PathErr message with the error
code "Admission Control Error" and the error value "Requested
Bandwidth Unavailable" (see [RFC2205]).
If two LSP request for the bandwidth with the same availability
requirement, a way to resolve the contention is comparing the node
ID, the node with the higher node ID will win the contention. More
details can be found in [RFC3473].
If a node does not support the Availability sub-TLV, then it MUST
ignore the sub-TLV and only use the bandwidth request in the
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Ethernet Bandwidth Profile TLV. The [RFC6003] states that a node
that does not support a flag should ignore it. Thus a legacy
implementation will ignore the Availability Flag.
4. Security Considerations
This document does not introduce new security considerations to the
existing RSVP-TE signaling protocol.
5. IANA Considerations
IANA maintains registries and sub-registries for RSVP-TE used by
GMPLS. IANA is requested to make allocations from these registries
as set out in the following sections.
5.1 Ethernet Bandwidth Profile TLV
IANA maintains a registry of GMPLS parameters called "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Parameters".
IANA has created a new sub-registry called "Ethernet Bandwidth
Profiles" to contain bit flags carried in the Ethernet Bandwidth
Profile TLV of the Ethernet SENDER_TSPEC object.
Bits are to be allocated by IETF Standards Action. Bits are numbered
from bit 0 as the low order bit. A new bit field is as follow:
Bit Hex Description Reference
--- ---- ------------------ -----------
2 0x03 Availability Field (AF) [This ID]
Sub-TLV types for Ethernet Bandwidth Profiles are to be allocated by
IETF Standard Action. Initial values are as follows:
Type Length Format Description
--- ---- ------------------ -----------
0 - Reserved Reserved value
TBD 4 see Section 3.1 Availability sub-
TLV
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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.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC6003] Papadimitriou, D. "Ethernet Traffic Parameters", RFC 6003,
October 2010.
[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
[ARTE] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
"OSPF Routing Extension for Links with Variable Discrete
Bandwidth", Work in Progress, December, 2013
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.
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7. Acknowledgments
The authors would like to thank Khuzema Pithewan, Lou Berger, Yuji
Tochio, Dieter Beller, and Autumn Liu for their comments on the
document.
Appendix A
Presuming that a link has three discrete bandwidth levels:
The link bandwidth under modulation level 1, e.g., QPSK, is 100M;
The link bandwidth under modulation level 2, e.g., 16QAM, is 200M;
The link bandwidth under modulation level 3, e.g., 256QAM, is 400M.
In sunny day, the modulation level 3 can be used to achieve 400M
link bandwidth.
A light rain with X mm/h rate triggers the system to change the
modulation level from level 3 to level 2, with bandwidth changing
from 400M to 200M. The probability of X mm/h rain in the local area
is 53 minutes in a year. Then the dropped 200M bandwidth has 99.99%
availability.
A heavy rain with Y(Y>X) mm/h rate triggers the system to change the
modulation level from level 2 to level 1, with bandwidth changing
from 200M to 100M. The probability of Y mm/h rain in the local area
is 26 minutes in a year. Then the dropped 100M bandwidth has 99.995%
availability.
For the 100M bandwidth of the modulation level 1, only the extreme
weather condition can cause the whole system unavailable, which only
happens for 5 minutes in a year. So the 100M bandwidth of the
modulation level 1 owns the availability of 999.99%.
In a word, the maximum bandwidth is 400Mbps. According to the
weather condition, the sub-bandwidth and its availability are shown
as follows:
Sub-bandwidth(Mbps) Availability
------------------ ------------
200 99.99%
100 99.995%
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100 99.999%
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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 (editor)
Huawei Technologies Co., Ltd.
No.1899, Xiyuan Avenue, Hi-tech Western District
Chengdu 611731, P.R.China
Email: amy.yemin@huawei.com
Greg Mirsky (editor)
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
Emial: hshah@ciena.com
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