Network Working Group G. Ash
Internet-Draft A. Morton
Intended status: Informational M. Dolly
Expires: July 10, 2010 P. Tarapore
C. Dvorak
AT&T Labs
Y. El Mghazli
Alcatel-Lucent
January 6, 2010
Y.1541-QOSM -- Y.1541 QoS Model for Networks Using Y.1541 QoS Classes
draft-ietf-nsis-y1541-qosm-08
Abstract
This draft describes a QoS-NSLP QoS model (QOSM) based on ITU-T
Recommendation Y.1541 Network QoS Classes and related signaling
requirements. Y.1541 specifies 8 classes of Network Performance
objectives, and the Y.1541-QOSM extensions include additional QSPEC
parameters and QOSM processing guidelines.
Requirements Language
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].
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 10, 2010.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Summary of ITU-T Recommendations Y.1541 & Signaling
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Y.1541 Classes . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Y.1541-QOSM Processing Requirements . . . . . . . . . . . 5
3. Additional QSPEC Parameters for Y.1541 QOSM . . . . . . . . . 6
3.1. Traffic Model (TMOD) Extension Parameter . . . . . . . . . 7
3.2. Restoration Priority Parameter . . . . . . . . . . . . . . 7
4. Y.1541-QOSM Considerations and Processing Example . . . . . . 9
4.1. Deployment Considerations . . . . . . . . . . . . . . . . 9
4.2. Applicable QSPEC Procedures . . . . . . . . . . . . . . . 9
4.3. QNE Processing Rules . . . . . . . . . . . . . . . . . . . 10
4.4. Processing Example . . . . . . . . . . . . . . . . . . . . 10
4.5. Bit-Level QSPEC Example . . . . . . . . . . . . . . . . . 12
4.6. Preemption Behaviour . . . . . . . . . . . . . . . . . . . 13
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
5.1. Assignment of QSPEC Parameter IDs . . . . . . . . . . . . 14
5.2. Restoration Priority Parameter Registry . . . . . . . . . 14
5.2.1. Restoration Priority Field . . . . . . . . . . . . . . 14
5.2.2. Time to Restore Field . . . . . . . . . . . . . . . . 15
5.2.3. Extent of Restoration Field . . . . . . . . . . . . . 15
5.2.4. Reserved Bits . . . . . . . . . . . . . . . . . . . . 15
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1. Normative References . . . . . . . . . . . . . . . . . . . 16
8.2. Informative References . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18
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1. Introduction
This draft describes a QoS model (QOSM) for NSIS QoS signaling layer
protocol (QoS-NSLP) application based on ITU-T Recommendation Y.1541
Network QoS Classes and related signaling requirements. [Y.1541]
currently specifies 8 classes of Network Performance objectives, and
the Y.1541-QOSM extensions include additional QSPEC parameters and
QOSM processing guidelines. The extensions are based on
standardization work in the ITU-T on QoS signaling requirements
[Y.1541] [TRQ-QoS-SIG] [E.361].
[I-D.ietf-nsis-qos-nslp] defines message types and control
information for the QoS-NSLP generic to all QOSMs. A QOSM is a
defined mechanism for achieving QoS as a whole. The specification of
a QOSM includes a description of its QSPEC parameter information, as
well as how that information should be treated or interpreted in the
network. The QSPEC [I-D.ietf-nsis-qspec] contains a set of
parameters and values describing the requested resources. It is
opaque to the QoS-NSLP and similar in purpose to the TSpec, RSpec and
AdSpec specified in [RFC2205] [RFC2210] . The QSPEC object contains
the QoS parameters defined by the QOSM. A QOSM provides a specific
set of parameters to be carried in the QSPEC. At each QoS NSIS
element (QNE), the QSPEC contents are interpreted by the resource
management function (RMF) for purposes of policy control and traffic
control, including admission control and configuration of the
scheduler.
2. Summary of ITU-T Recommendations Y.1541 & Signaling Requirements
As stated above, [Y.1541] is a specification of standardized QoS
classes for IP networks (a summary of these classes is given below).
Section 7 of [TRQ-QoS-SIG] specifies signaling features needed to
achieve end-to-end QoS in IP networks, with Y.1541 QoS classes as a
basis. [Y.1541] recommends a flexible allocation of the end-to-end
performance objectives (e.g., delay) across networks, rather than a
fixed per-network allocation. NSIS protocols already address most of
the requirements, this document identifies additional QSPEC
parameters and processing requirements needed to support the Y.1541
QOSM.
2.1. Y.1541 Classes
[Y.1541] proposes grouping services into QoS classes defined
according to the desired QoS performance objectives. These QoS
classes support a wide range of user applications. The classes group
objectives for one-way IP packet delay, IP packet delay variation, IP
packet loss ratio, etc., where the parameters themselves are defined
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in [Y.1540]. Classes 0 and 1 might be implemented using the DiffServ
EF PHB, and support interactive real-time applications. Classes 2,
3, and 4 might be implemented using the DiffServ AFxy PHB Group, and
support data transfer applications with various degrees of
interactivity. Class 5 generally corresponds to the DiffServ Default
PHB, has all the QoS parameters unspecified consistent with a best-
effort service. Classes 6 and 7 provide support for extremely loss-
sensitive user applications, such as high quality digital television,
TDM circuit emulation, and high capacity file transfers using TCP.
These classes are intended to serve as a basis for agreements between
end-users and service providers, and between service providers. They
support a wide range of user applications including point-to-point
telephony, data transfer, multimedia conferencing, and others. The
limited number of classes supports the requirement for feasible
implementation, particularly with respect to scale in global
networks.
The QoS classes apply to a packet flow, where [Y.1541] defines a
packet flow as the traffic associated with a given connection or
connectionless stream having the same source host, destination host,
class of service, and session identification. The characteristics of
each Y.1451 QoS class are summarized here:
Class 0: Real-time, highly interactive applications, sensitive to
jitter. Mean delay upper bound is 100 ms, delay variation is less
than 50 ms, and loss ratio is less than 10^-3. Application examples
include VoIP, Video Teleconference.
Class 1: Real-time, interactive applications, sensitive to jitter.
Mean delay upper bound is 400 ms, delay variation is less than 50 ms,
and loss ratio is less than 10^-3. Application examples include
VoIP, video teleconference.
Class 2: Highly interactive transaction data. Mean delay upper bound
is 100 ms, delay variation is unspecified, and loss ratio is less
than 10^-3. Application examples include signaling.
Class 3: Interactive transaction data. Mean delay upper bound is 400
ms, delay variation is unspecified, and loss ratio is less than
10^-3. Application examples include signaling.
Class 4: Low Loss Only applications. Mean delay upper bound is 1s,
delay variation is unspecified, and loss ratio is less than 10^-3.
Application examples include short transactions, bulk data, video
streaming
Class 5: Unspecified applications with unspecified mean delay, delay
variation, and loss ratio. Application examples include traditional
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applications of Default IP Networks
Class 6: Mean delay <= 100 ms, delay variation <= 50 ms, loss ratio
<= 10^-5. Applications that are highly sensitive to loss, such as
television transport, high-capacity TCP transfers, and TDM circuit
emulation.
Class 7: Mean delay <= 400 ms, delay variation <= 50 ms, loss ratio
<= 10^-5. Applications that are highly sensitive to loss, such as
television transport, high-capacity TCP transfers, and TDM circuit
emulation.
These classes enable SLAs to be defined between customers and network
service providers with respect to QoS requirements. The service
provider then needs to ensure that the requirements are recognized
and receive appropriate treatment across network layers.
Work is in progress to specify methods for combining local values of
performance metrics to estimate the performance of the complete path.
See section 8 of [Y.1541], [I-D.ietf-ippm-framework-compagg], and
[I-D.ietf-ippm-spatial-composition].
2.2. Y.1541-QOSM Processing Requirements
[TRQ-QoS-SIG] provides the requirements for signaling information
regarding IP-based QoS at the interface between the user and the
network (UNI) and across interfaces between different networks (NNI).
To meet specific network performance requirements specified for the
Y.1541 QoS classes [Y.1541] , a network needs to provide specific
user plane functionality at UNI and NNI interfaces. Dynamic network
provisioning at a UNI and/or NNI node allows the ability to
dynamically request a traffic contract for an IP flow from a specific
source node to one or more destination nodes. In response to the
request, the network determines if resources are available to satisfy
the request and provision the network.
For implementations to claim compliance with this memo, it MUST be
possible to derive the following service level parameters as part of
the process of requesting service:
a. Y.1541 QoS class, 32 bit integer, range : 0-7
b. rate (r), octets per second
c. peak rate (p), octets per second
d. bucket size (b), octets
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e. maximum packet size (M), octets, IP header + IP payload
f. DiffServ PHB class [RFC2475]
g. admission priority, 32 bit integer, range : 0-2
Compliant implementations MAY derive the following service level
parameters as part of the service request process:
h. peak bucket size (Bp)*, octets, 32 bit floating point number in
single-precision IEEE floating point format [IEEE754]
i. restoration priority*, multiple integer values defined in Section
3 below
All parameters except Bp and restoration priority have already been
specified in [I-D.ietf-nsis-qspec]. These additional parameters are
defined as
o Bp, The size of the peak-rate bucket in a dual token bucket
arrangement, essentially setting the maximum length of bursts in
the peak-rate stream. For example, see Annex B of [Y.1221]
o restoration priority, as defined in Section 3 of this memo
and their QSPEC Parameter format is specified in Section 3.
It MUST be possible to perform the following QoS-NSLP signaling
functions to meet Y.1541-QOSM requirements:
a. accumulate delay, delay variation and loss ratio across the end-
to-end connection, which may span multiple domains
b. enable negotiation of Y.1541 QoS class across domains.
c. enable negotiation of delay, delay variation, and loss ratio
across domains.
These signaling requirements are supported in
[I-D.ietf-nsis-qos-nslp] and the functions are illustrated in Section
4 of this memo.
3. Additional QSPEC Parameters for Y.1541 QOSM
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3.1. Traffic Model (TMOD) Extension Parameter
The traffic model (TMOD) extension parameter is represented by one
floating point number in single-precision IEEE floating point format
and one 32-bit reserved field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|E|N|r| 15 |r|r|r|r| 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Bucket Size [Bp] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: TMOD Extension
The Peak Bucket Size term, Bp, is represented as an IEEE floating
point value [IEEE754] in units of octets. The sign bit MUST be zero
(all values MUST be non-negative). Exponents less than 127 (i.e., 0)
are prohibited. Exponents greater than 162 (i.e., positive 35) are
discouraged, except for specifying a peak rate of infinity. Infinity
is represented with an exponent of all ones (255) and a sign bit and
mantissa of all zeros.
Reserved: These 4 octets are reserved. The Reserved octets MAY be
designated for other uses in the future. Senders conforming to this
version of the Y.1541 QOSM SHALL set the Reserved octets to zero.
Receivers conforming to this version of the Y.1541 QOSM SHALL ignore
the Reserved octets.
The QSPEC parameter behavior for the TMOD extended parameter is
similar to that defined in Section 3.3.1 of[I-D.ietf-nsis-qspec].
The new parameter (and all traffic-related parameters) are specified
independently from the Y.1541 class parameter.
3.2. Restoration Priority Parameter
Restoration priority is the urgency with which a service requires
successful restoration under failure conditions. Restoration
priority is achieved by provisioning sufficient backup capacity, as
necessary, and allowing relative priority for access to available
bandwidth when there is contention for restoration bandwidth.
Restoration priority is defined as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|M|E|N|r| 16 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rest. Priority| TTR | EOR | (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Restoration Priority Parameter
This parameter has three fields and a reserved area, as defined
below.
Restoration Priority Field (8-bit unsigned integer): 3 priority
values are listed here in the order of lowest priority to highest
priority:
0 - best effort
1 - normal
2 - high
These priority values are described in [Y.2172], where best effort
priority is the same as Priority level 3, normal priority is Priority
level 2, and high priority is the same as Priority level 1. There
are several ways to elaborate on restoration priority, and the two
current parameters are described below.
Time-to-Restore (TTR) Field (4-bit unsigned integer): Total amount of
time to restore traffic streams belonging to a given restoration
class impacted by the failure. This time period depends on the
technology deployed for restoration. A fast recovery period of < 200
ms is based on current experience with SONET rings and a slower
recovery period of 2 seconds is suggested in order to enable a voice
call to recover without being dropped. Accordingly, TTR restoration
suggested ranges are:
0 - Unspecified Time-to-Restore
1 - Best Time-to-Restore: <= 200 ms
2 - Normal Time-to-Restore <= 2 s
Extent of Restoration (EOR) Field (4-bit unsigned integer):
Percentage of traffic belonging to the restoration class that can be
restored. This percentage depends on the amount of spare capacity
engineered. All high priority restoration priority traffic, for
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example, may be "guaranteed" at 100% by the service provider. Other
classes may offer lesser chances for successful restoration. The
restoration extent for these lower priority classes depend on SLA
agreements developed between the service provider and the customer.
EOR values are assigned as follows:
0 - unspecified EOR
1 - high priority restored at 100%; medium priority restored at 100%
2 - high priority restored at 100%; medium priority restored at 80%
3 - high priority restored >= 80%; medium priority restored >= 80%
4 - high priority restored >= 80%; medium priority restored >= 60%
5 - high priority restored >= 60%; medium priority restored >= 60%
Reserved: These 2 octets are reserved. The Reserved bits MAY be
designated for other uses in the future. Senders conforming to this
version of the Y.1541 QOSM SHALL set the Reserved bits to zero.
Receivers conforming to this version of the Y.1541 QOSM SHALL ignore
the Reserved bits.
4. Y.1541-QOSM Considerations and Processing Example
In this Section we illustrate the operation of the Y.1541 QOSM, and
show how current QoS-NSLP and QSPEC functionality is used. No new
processing capabilities are required to enable the Y.1541 QOSM
(excluding the two OPTIONAL new parameters specified in Section 3).
4.1. Deployment Considerations
[TRQ-QoS-SIG] emphasizes the deployment of Y.1541 QNEs at the borders
of supporting domains. There may be domain configurations where
interior QNEs are desirable, and the example below addresses this
possibility.
QNEs may be Stateful in some limited aspects, but obviously it is
preferable to deploy stateless QNEs.
4.2. Applicable QSPEC Procedures
All procedures defined in section 5.3 of [I-D.ietf-nsis-qspec] are
applicable to this QOSM.
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4.3. QNE Processing Rules
Section 7 of [TRQ-QoS-SIG] describes the information processing in
Y.1541 QNEs.
Section 8 of [Y.1541] defines the accumulation rules for individual
performance parameters (e.g., delay, jitter).
When a QNI specifies the Y.1541 QoS Class number, <Y.1541 QoS Class>,
it is a sufficient specification of objectives for the <Path
Latency>, <Path Jitter>, and <Path BER> parameters. As described
above in section 2, some Y.1541 Classes do not set objectives for all
the performance parameters above. For example, Classes 2, 3, and 4,
do not specify an objective for <Path Jitter> (referred to as IP
Packet Delay Variation). In the case that the QoS Class leaves a
parameter Unspecified, then that parameter need not be included in
the accumulation processing.
4.4. Processing Example
As described in the example given in Section 4.4 of
[I-D.ietf-nsis-qspec] and as illustrated in Figure 3, the QoS NSIS
initiator (QNI) initiates an end-to-end, inter-domain QoS NSLP
RESERVE message containing the Initiator QSPEC. In the case of the
Y.1541 QOSM, the Initiator QSPEC specifies the <Y.1541 QOS Class>,
<TMOD>, <TMOD Extension>, <Admission Priority>, <Restoration
Priority>, and perhaps other QSPEC parameters for the flow. As
described in Section 3, the TMOD extension parameter contains the
OPTIONAL, Y.1541-QOSM-specific terms; restoration priority is also an
OPTIONAL, Y.1541-QOSM-specific parameter.
As Figure 3 below shows, the RESERVE message may cross multiple
domains supporting different QOSMs. In this illustration, the
initiator QSPEC arrives in an QoS NSLP RESERVE message at the ingress
node of the local-QOSM domain. As described in
[I-D.ietf-nsis-qos-nslp] and [I-D.ietf-nsis-qspec], at the ingress
edge node of the local-QOSM domain, the end-to-end, inter-domain QoS-
NSLP message may trigger the generation of a local QSPEC, and the
initiator QSPEC encapsulated within the messages signaled through the
local domain. The local QSPEC is used for QoS processing in the
local-QOSM domain, and the Initiator QSPEC is used for QoS processing
outside the local domain. As specified in [I-D.ietf-nsis-qspec], if
any QNE cannot meet the requirements designated by the initiator
QSPEC to support an optional QSPEC parameter, with the M bit set to
zero for the parameter, for example, it cannot support the
accumulation of end-to-end delay with the <Path Latency> parameter,
the QNE sets the N flag (not supported flag) for the path latency
parameter to one.
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Also, the Y.1541-QOSM requires negotiation of the <Y.1541 QoS Class>
across domains. This negotiation can be done with the use of the
existing procedures already defined in [I-D.ietf-nsis-qos-nslp]. For
example, the QNI sets <Desired QoS>, <Minimum QoS>, <Available QoS>
objects to include <Y.1541 QoS Class>, which specifies objectives for
the <Path Latency>, <Path Jitter>, <Path BER> parameters. In the
case that the QoS Class leaves a parameter Unspecified, then that
parameter need not be included in the accumulation processing. The
QNE/domain SHOULD set the Y.1541 class and cumulative parameters,
e.g., <Path Latency>, that can be achieved in the <QoS Available>
object (but not less than specified in <Minimum QoS>). This could
include, for example, setting the <Y.1541 QoS Class> to a lower class
than specified in <QoS Desired> (but not lower than specified in
<Minimum QoS>). If the <Available QoS> fails to satisfy one or more
of the <Minimum QoS> objectives, the QNE/domain notifies the QNI and
the reservation is aborted. Otherwise, the QNR notifies the QNI of
the <QoS Available> for the reservation.
When the available <Y.1541 QoS Class> must be reduced from the
desired <Y.1541 QoS Class>, say because the delay objective has been
exceeded, then there is an incentive to respond with an available
value for delay in the <Path Latency> parameter. If the available
<Path Latency> is 150 ms (still useful for many applications) and the
desired QoS is Class 0 (with its 100 ms objective), then the response
would be that Class 0 cannot be achieved and Class 1 is available
(with its 400 ms objective). In addition, this QOSM allows the
response to include an available <Path Latency> = 150 ms, making
acceptance of the available <Y.1541 QoS Class> more likely. There
are many long paths where the propagation delay alone exceeds the
Y.1541 Class 0 objective, so this feature adds flexibility to commit
to exceed the Class 1 objective when possible.
This example illustrates Y.1541-QOSM negotiation of <Y.1541 QoS
Class> and cumulative parameter values that can be achieved end-to-
end. The example illustrates how the QNI can use the cumulative
values collected in <QoS Available> to decide if a lower <Y.1541 QoS
Class> than specified in <QoS Desired> is acceptable.
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|------| |------| |------| |------|
| e2e |<->| e2e |<------------------------->| e2e |<->| e2e |
| QOSM | | QOSM | | QOSM | | QOSM |
| | |------| |-------| |-------| |------| | |
| NSLP | | NSLP |<->| NSLP |<->| NSLP |<->| NSLP | | NSLP |
|Y.1541| |local | |local | |local | |local | |Y.1541|
| QOSM | | QOSM | | QOSM | | QOSM | | QOSM | | QOSM |
|------| |------| |-------| |-------| |------| |------|
-----------------------------------------------------------------
|------| |------| |-------| |-------| |------| |------|
| NTLP |<->| NTLP |<->| NTLP |<->| NTLP |<->| NTLP |<->| NTLP |
|------| |------| |-------| |-------| |------| |------|
QNI QNE QNE QNE QNE QNR
(End) (Ingress Edge) (Interior) (Interior) (Egress Edge) (End)
Figure 3: Example of Y.1541-QOSM Operation
4.5. Bit-Level QSPEC Example
This is an example where the QOS Desired specification contains the
TMOD-1 parameters and TMOD extended parameters defined in this
specification, as well as the Y.1541 Class parameter. The QOS
Available specification utilizes the Latency, Jitter, and Loss
parameters to enable accumulation of these parameters for easy
comparison with the objectives desired fir the Y.1541 Class.
This example assumes that all the parameters MUST be supported by the
QNEs, so all M-flags have been set to "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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Vers.|QType=I|QSPEC Proc.=0/1|0|R|R|R| Length = 24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E|r|r|r| Type = 0 (QoS Des.) |r|r|r|r| Length = 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|r| ID = 1 <TMOD-1> |r|r|r|r| Length = 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TMOD Rate-1 [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TMOD Size-1 [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Data Rate-1 [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Policed Unit-1 [m] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Packet Size [M] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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|1|E|N|r| 15 |r|r|r|r| 2 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Bucket Size [Bp] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|N|r| 14 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Y.1541 QoS Cls.| (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E|r|r|r| Type = 1 (QoS Avail) |r|r|r|r| Length = 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|N|r| 3 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Latency (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|N|r| 4 |r|r|r|r| 4 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Jitter STAT1(variance) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT2(99.9%-ile) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT3(minimum Latency) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Path Jitter STAT4(Reserved) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|N|r| 5 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Packet Loss Ratio (32-bit floating point) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|N|r| 14 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Y.1541 QoS Cls.| (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: An Example QSPEC (Initiator)
where 32-bit floating point numbers are as specified in [IEEE754].
4.6. Preemption Behaviour
The default QNI behaviour of tearing down a preempted reservation is
followed in the Y.1541 QOSM. The restoration priority parameter
described above does not rely on preemption.
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5. IANA Considerations
This section defines additional codepoint assignments in the QSPEC
Parameter ID registry and requests the establishment of one new
registry for the Restoration Priority Parameter (and assigns initial
values), in accordance with BCP 26 [RFC5226]. It also defines the
procedural requirements to be followed by IANA in allocating new
codepoints for the new Registry.
5.1. Assignment of QSPEC Parameter IDs
This document specifies the following QSPEC parameters to be assigned
within the QSPEC Parameter ID registry created in
[I-D.ietf-nsis-qspec]:
<TMOD Extension> parameter (Section 3.1 above, suggested ID=15)
<Restoration Priority> parameter (Section 3.2 above, suggested ID=16)
5.2. Restoration Priority Parameter Registry
The Registry for Restoration Priority contains assignments for three
fields in the 4 octet word, and a Reserved section of the word.
This specification creates the following registry with the structure
as defined below:
5.2.1. Restoration Priority Field
The Restoration Priority Field is 8 bits in length.
The following values are allocated by this specification:
0-2: assigned as specified in Section 3.2:
0: best-effort priority
1: normal priority
2: high priority
The allocation policies for further values are as follows:
3-63: Specification Required
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5.2.2. Time to Restore Field
The Time to Restore Field is 4 bits in length.
The following values are allocated by this specification:
0-2: assigned as specified in Section 3.2:
0 - Unspecified Time-to-Restore
1 - Best Time-to-Restore: <= 200 ms
2 - Normal Time-to-Restore <= 2 s
The allocation policies for further values are as follows:
3-15: Specification Required
5.2.3. Extent of Restoration Field
The Extent of Restoration (EOR) Field is 4 bits in length.
The following values are allocated by this specification:
0-5: assigned as specified in Section 3.2:
EOR values are assigned as follows:
0 - unspecified EOR
1 - high priority restored at 100%; medium priority restored at 100%
2 - high priority restored at 100%; medium priority restored at 80%
3 - high priority restored >= 80%; medium priority restored >= 80%
4 - high priority restored >= 80%; medium priority restored >= 60%
5 - high priority restored >= 60%; medium priority restored >= 60%
The allocation policies for further values are as follows:
6-15: Specification Required
5.2.4. Reserved Bits
The remaining bits in the Restoration Priority Parameter are
Reserved. The Reserved bits MAY be designated for other uses in the
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future.
6. Security Considerations
The security considerations of [I-D.ietf-nsis-qos-nslp] and
[I-D.ietf-nsis-qspec] apply to this Document.
The restoration priority parameter raises possibilities for theft of
service attacks because users could claim an emergency priority for
their flows without real need, thereby effectively preventing serious
emergency calls to get through. Several options exist for countering
such attacks, for example
- only some user groups (e.g. the police) are authorized to set the
emergency priority bit
- any user is authorized to employ the emergency priority bit for
particular destination addresses (e.g. police or fire departments)
There are no other known security considerations based on this
document.
7. Acknowledgements
The authors thank Attila Bader, Cornelia Kappler, Sven Van den Bosch,
and Hannes Tschofenig for helpful comments and discussion.
8. References
8.1. Normative References
[I-D.ietf-nsis-qos-nslp]
Manner, J., Karagiannis, G., and A. McDonald, "NSLP for
Quality-of-Service Signaling", draft-ietf-nsis-qos-nslp-17
(work in progress), October 2009.
[I-D.ietf-nsis-qspec]
Bader, A., Ash, G., Kappler, C., and D. Oran, "QoS NSLP
QSPEC Template", draft-ietf-nsis-qspec-22 (work in
progress), November 2009.
[IEEE754] ANSI/IEEE, "ANSI/IEEE 754-1985, IEEE Standard for Binary
Floating-Point Arithmetic", 1985.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
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Requirement Levels", BCP 14, RFC 2119, March 1997.
[TRQ-QoS-SIG]
ITU-T Supplement 51 to the Q-Series, "Signaling
Requirements for IP-QoS", January 2004.
[Y.1221] ITU-T Recommendation Y.1541, "Traffic control and
congestion control in IP based networks", March 2002.
[Y.1540] ITU-T Recommendation Y.1540, "Internet protocol data
communication service - IP packet transfer and
availability performance parameters", December 2007.
[Y.1541] ITU-T Recommendation Y.1541, "Network Performance
Objectives for IP-Based Services", February 2006.
[Y.2172] ITU-T Recommendation Y.1540, "Service restoration priority
levels in Next Generation Networks", June 2007.
8.2. Informative References
[E.361] ITU-T Recommendation E.361, "QoS Routing Support for
Interworking of QoS Service Classes Across Routing
Technologies", May 2003.
[I-D.ietf-ippm-framework-compagg]
Morton, A., "Framework for Metric Composition",
draft-ietf-ippm-framework-compagg-09 (work in progress),
December 2009.
[I-D.ietf-ippm-spatial-composition]
Morton, A. and E. Stephan, "Spatial Composition of
Metrics", draft-ietf-ippm-spatial-composition-10 (work in
progress), October 2009.
[RFC2205] Braden, B., Zhang, L., Berson, S., Herzog, S., and S.
Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
Functional Specification", RFC 2205, September 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.,
and W. Weiss, "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
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May 2008.
Authors' Addresses
Jerry Ash
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone:
Fax:
Email: gash5107@yahoo.com
URI:
Al Morton
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone: +1 732 420 1571
Fax: +1 732 368 1192
Email: acmorton@att.com
URI: http://home.comcast.net/~acmacm/
Martin Dolly
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone:
Fax:
Email: mdolly@att.com
URI:
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Percy Tarapore
AT&T Labs
200 Laurel Avenue South
Middletown,, NJ 07748
USA
Phone:
Fax:
Email: tarapore@att.com
URI:
Chuck Dvorak
AT&T Labs
180 Park Ave Bldg 2
Florham Park,, NJ 07932
USA
Phone: + 1 973-236-6700
Fax:
Email: cdvorak@att.com
URI: http:
Yacine El Mghazli
Alcatel-Lucent
Route de Nozay
Marcoussis cedex, 91460
France
Phone: +33 1 69 63 41 87
Fax:
Email: yacine.el_mghazli@alcatel.fr
URI:
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