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24 RFC 5975
IETF Internet Draft NSIS Working Group G. Ash
Internet Draft AT&T
<draft-ietf-nsis-qspec-15.txt> A. Bader
Expiration Date: August 2007 Ericsson
C. Kappler
Siemens Networks GmbH & Co KG
D. Oran
Cisco Systems, Inc.
February 2007
QoS NSLP QSPEC Template
Status of this Memo
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This Internet-Draft will expire on July 21, 2007.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Abstract
The QoS NSLP protocol is used to signal QoS reservations and is
independent of a specific QoS model (QOSM) such as IntServ or
DiffServ. Rather, all information specific to a QOSM is encapsulated
in a separate object, the QSPEC. This document defines a template
for the QSPEC including a number of QSPEC parameters. The QSPEC
parameters provide a common language to be re-used in several QOSMs
Ash, et. al. <draft-ietf-nsis-qspec-15.txt> [Page 1]
Internet Draft QoS-NSLP QSPEC Template February 2007
and thereby aim to ensure the extensibility and interoperability of
QoS NSLP. The node initiating the NSIS signaling adds an initiator
QSPEC, which indicates the QSPEC parameters that must be interpreted
by the downstream nodes less the reservation fails, thereby ensuring
the intention of the NSIS initiator is preserved along the signaling
path.
Table of Contents
1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. QSPEC Framework . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1 QoS Models . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 QSPEC Objects . . . . . . . . . . . . . . . . . . . . . . . 8
4.3 QSPEC Parameters . . . . . . . . . . . . . . . . . . . . . 10
4.3.1 Traffic Model Parameter . . . . . . . . . . . . . . . 10
4.3.2 Constraints Parameters . . . . . . . . . . . . . . . 11
4.3.3 Traffic Handling Directives . . . . . . . . . . . . . 13
4.3.4 Traffic Classifiers . . . . . . . . . . . . . . . . . 13
4.4 Example of QSPEC Processing . . . . . . . . . . . . . . . . 14
5. QSPEC Processing & Procedures . . . . . . . . . . . . . . . . . 17
5.1 Local QSPEC Definition & Processing . . . . . . . . . . . . 17
5.2 Reservation Success/Failure, QSPEC Error Codes, & INFO_SPEC
Notification . . . . . . . . . . . . . . . . . . . . . . . 18
5.2.1 Reservation Failure & Error E-Flag . . . . . . . . . 19
5.2.2 QSPEC Parameter Not Supported N-Flag . . . . . . . . 20
5.2.3 INFO_SPEC Coding of Reservation Outcome . . . . . . . 20
5.2.4 QNE Generation of a RESPONSE message . . . . . . . . 21
5.2.5 Special Case of Local QSPEC . . . . . . . . . . . . . 22
5.3 QSPEC Procedures . . . . . . . . . . . . . . . . . . . . . 22
5.3.1 Sender-Initiated Reservations . . . . . . . . . . . . 22
5.3.2 Receiver-Initiated Reservations . . . . . . . . . . . 24
5.3.3 Resource Queries . . . . . . . . . . . . . . . . . . 26
5.3.4 Bidirectional Reservations . . . . . . . . . . . . . 26
5.3.5 Preemption . . . . . . . . . . . . . . . . . . . . . 26
5.4 QSPEC Extensibility . . . . . . . . . . . . . . . . . . . . 27
6. QSPEC Functional Specification . . . . . . . . . . . . . . . . 27
6.1 General QSPEC Formats . . . . . . . . . . . . . . . . . . . 27
6.2 QSPEC Parameter Coding . . . . . . . . . . . . . . . . . . 30
6.2.1 <TMOD-1> Parameter . . . . . . . . . . . . . . . . . 30
6.2.2 <TMOD-2> Parameter . . . . . . . . . . . . . . . . . 31
6.2.3 <Path Latency> Parameter . . . . . . . . . . . . . . 32
6.2.4 <Path Jitter> Parameter . . . . . . . . . . . . . . . 32
6.2.5 <Path PLR> Parameter . . . . . . . . . . . . . . . . 33
6.2.6 <Path PER> Parameter . . . . . . . . . . . . . . . . 34
6.2.7 <Slack Term> Parameter . . . . . . . . . . . . . . . 34
6.2.8 <Preemption Priority> & <Defending Priority>
Parameters . . . . . . . . . . . . . . . . . . . . . 35
6.2.9 <Admission Priority> Parameter . . . . . . . . . . . 35
6.2.10 <RPH Priority> Parameter . . . . . . . . . . . . . . 36
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6.2.11 <Excess Treatment> Parameter . . . . . . . . . . . . 37
6.2.12 <PHB Class> Parameter . . . . . . . . . . . . . . . 39
6.2.13 <DSTE Class Type> Parameter . . . . . . . . . . . . 40
6.2.14 <Y.1541 QoS Class> Parameter . . . . . . . . . . . . 40
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 41
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 41
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 46
10. Normative References . . . . . . . . . . . . . . . . . . . . . 46
11. Informative References . . . . . . . . . . . . . . . . . . . . 47
12. Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 48
Appendix A. Mapping of QoS Desired, QoS Available and QoS Reserved
of NSIS onto AdSpec, TSpec and RSpec of RSVP IntServ . 48
Appendix B. Change History & Open Issues . . . . . . . . . . . . . 49
B.1 Change History (since Version -04) . . . . . . . . 49
B.2 Open Issues . . . . . . . . . . . . . . . . . . . 53
Intellectual Property Statement . . . . . . . . . . . . . . . . . 53
Full Copyright Statement . . . . . . . . . . . . . . . . . . . . . 54
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].
1. Contributors
This document is the result of the NSIS Working Group effort. In
addition to the authors/editors listed in Section 12, the following
people contributed to the document:
Chuck Dvorak
AT&T
Room 2A37
180 Park Avenue, Building 2
Florham Park, NJ 07932
Phone: + 1 973-236-6700
Fax:+1 973-236-7453
Email: cdvorak@research.att.com
Yacine El Mghazli
Alcatel
Route de Nozay
91460 Marcoussis cedex
FRANCE
Phone: +33 1 69 63 41 87
Email: yacine.el_mghazli@alcatel.fr
Georgios Karagiannis
University of Twente
P.O. BOX 217
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Internet Draft QoS-NSLP QSPEC Template February 2007
7500 AE Enschede
The Netherlands
Email: g.karagiannis@ewi.utwente.nl
Andrew McDonald
Siemens/Roke Manor Research
Roke Manor Research Ltd.
Romsey, Hants SO51 0ZN
UK
Email: andrew.mcdonald@roke.co.uk
Al Morton
AT&T
Room D3-3C06
200 S. Laurel Avenue
Middletown, NJ 07748
Phone: + 1 732 420-1571
Fax: +.1 732 368-1192
Email: acmorton@att.com
Percy Tarapore
AT&T
Room D1-33
200 S. Laurel Avenue
Middletown, NJ 07748
Phone: + 1 732 420-4172
Email: tarapore@.att.com
Lars Westberg
Ericsson Research
Torshamnsgatan 23
SE-164 80 Stockholm, Sweden
Email: Lars.Westberg@ericsson.com
2. Introduction
The QoS NSIS signaling layer protocol (NSLP) [QoS-SIG] establishes
and maintains state at nodes along the path of a data flow for the
purpose of providing forwarding resources (QoS) for that flow. The
design of QoS NSLP is conceptually similar to RSVP [RFC2205], and
meets the requirements of [RFC3726].
A QoS-enabled domain supports a particular QoS model (QOSM), which is
a method to achieve QoS for a traffic flow. A QOSM incorporates QoS
provisioning methods and a QoS architecture. It defines the behavior
of the resource management function (RMF) defined in [QoS-SIG],
including inputs and outputs. Examples of QOSMs are IntServ, DiffServ
admission control, and those specified in [Y.1541-QOSM, CL-QOSM,
RMD-QOSM].
The QoS NSLP protocol is used to signal QoS reservations and supports
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signaling for different QOSMs. All information specific to a QOSM is
encapsulated in the QoS specification (QSPEC) object, and this
document defines a template for the QSPEC.
QSPEC parameters include, for example, a mandatory traffic model
(TMOD) parameter, constraints parameters, such as path latency and
path jitter, traffic handling directives, such as excess treatment,
and traffic classifiers such as PHB class.
QSPEC objects loosely correspond to the TSpec, RSpec and AdSpec
objects specified in RSVP and may contain, respectively, a
description of QoS desired, QoS reserved, and QoS available.
Going beyond RSVP functionality, the QSPEC also allows indicating
a range of acceptable QoS by defining a QSPEC object denoting
minimum QoS. Usage of these QSPEC objects is not bound to particular
message types thus allowing for flexibility. A QSPEC object
collecting information about available resources may travel in any
QoS NSLP message, for example a QUERY message or a RESERVE message.
The QSPEC travels in QoS NSLP messages but is opaque to the QoS NSLP,
and is only interpreted by the RMF.
Interoperability between QoS NSIS entities (QNEs) in different
domains is enhanced by the definition of a common set of QSPEC
parameters. A QoS NSIS initiator (QNI) initiating the QoS NSLP
signaling adds an initiator QSPEC object containing parameters
describing the desired QoS, normally based on the QOSM it supports.
QSPEC parameters flagged by the QNI must be interpreted by all QNEs
in the path, else the reservation fails. In contrast, QSPEC
parameters not flagged by the QNI may be skipped if not understood.
Additional QSPEC parameters can be defined by QOSM specification
documents, and thereby ensure the extensibility and flexibility of
QoS NSLP.
A local QSPEC can be defined in a local domain with the initiator
QSPEC encapsulated, which is functionally consistent with the
initiator QSPEC in terms of defined source traffic (TMOD parameter)
and other constraints. A local QSPEC, for example, can enable
simpler processing by QNEs within the local domain.
In Section 4.4 a worked example of QSPEC processing is provided.
3. Terminology
Initiator QSPEC: A QSPEC Type. The initiator QSPEC is included into
a QoS NSLP message by the QNI/QNR. It travels end-to-end to the
QNR/QNI and is never removed.
Local QSPEC: A QSPEC Type. A local QSPEC is used in a local domain
and is domain specific. It encapsulates the initiator QSPEC and is
removed at the egress of the local domain.
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Minimum QoS: Minimum QoS is a QSPEC object that MAY be supported by
any QNE. Together with a description of QoS Desired or QoS
Available, it allows the QNI to specify a QoS range, i.e. an upper
and lower bound. If the QoS Desired cannot be reserved, QNEs are
going to decrease the reservation until the minimum QoS is hit.
QNE: QoS NSIS Entity, a node supporting QoS NSLP.
QNI: QoS NSIS Initiator, a node initiating QoS NSLP signaling.
QNR: QoS NSIS Receiver, a node terminating QoS NSLP signaling.
QoS Available: QSPEC object containing parameters describing the
available resources. They are used to collect information along a
reservation path.
QoS Desired: QSPEC object containing parameters describing the
desired QoS for which the sender requests reservation.
QoS Model (QOSM): a method to achieve QoS for a traffic flow, e.g.,
IntServ Controlled Load; specifies what sub-set of QSPEC QoS
constraints & traffic handling directives a QNE implementing that
QOSM is capable of supporting & how resources will be managed by the
RMF.
QoS Reserved: QSPEC object containing parameters describing the
reserved resources and related QoS parameters.
QSPEC: QSPEC is the object of QoS NSLP containing all QoS-specific
information.
QSPEC parameter: Any parameter appearing in a QSPEC; for
example, traffic model (TMOD), path latency, and excess treatment
parameters.
QSPEC Object: Main building blocks containing a QSPEC parameter set
that is input or output of an RMF operation.
Resource Management Function (RMF): Functions that are related to
resource management and processing of QSPEC parameters.
4. QSPEC Framework
The overall framework for the QoS NSLP is that [QoS-SIG] defines QoS
signaling and semantics, the QSPEC template defines the container and
semantics for QoS parameters and objects, and QOSM specifications
define QoS methods and procedures for using QoS signaling and QSPEC
parameters/objects within specific QoS deployments. QoS NSLP is a
generic QoS signaling protocol that can signal for many QOSMs.
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4.1 QoS Models
A QOSM is a method to achieve QoS for a traffic flow, e.g., IntServ
controlled load [CL-QOSM], resource management with DiffServ
[RMD-QOSM], and QoS signaling for Y.1541 QoS classes [Y.1541-QOSM].
A QOSM specifies a set of QSPEC parameters that describe the QoS
desired and how resources will be managed by the RMF. The RMF
implements functions that are related to resource management and
processes the QSPEC parameters.
QOSMs affect the operation of the RMF in NSIS-capable nodes, the
information carried in QSPEC objects, and may under some
circumstances (e.g. aggregation) cause a separate NSLP session to be
instantiated by having the RMF as a QNI. QOSM specifications may
define RMF triggers that cause the QoS NSLP to run semantics within
the underlying QoS NSLP signaling state and messaging processing
rules, as defined in Section 5.2 of [QoS-SIG]. New QoS NSLP message
processing rules can only be defined in Standards Track extensions to
the QoS NSLP. If a QOSM specification defines triggers that deviate
from existing standard QoS NSLP processing rules (must be standards
track in that case), the fallback for QNEs not supporting that QOSM
is to use the standard QoS NSLP state transition/message processing
rules.
The QOSM specification includes how the requested QoS resources will
be described and how they will be managed by the RMF. For this
purpose, the QOSM specification defines a set of QSPEC parameters it
uses to describe the desired QoS and resource control in the RMF, and
it may define additional QSPEC parameters.
When a QoS NSLP message travels through different domains, it may
encounter different QOSMs. Since QOSM use different QSPEC parameters
for describing resources, the QSPEC parameters included by the QNI
may not be understood in other domains. The QNI therefore can flag
those QSPEC parameters it considers vital with the M-flag. QSPEC
parameters with the M-flag set must be interpreted by the downstream
QNEs, or the reservation fails. QSPEC parameters without the M-flag
set should be interpreted by the downstream QNEs, but may be ignored
if not understood.
A QOSM specification MUST include the following:
- role of QNEs, e.g., location, frequency, statefulness, etc.
- QSPEC definition including QSPEC parameters
- QSPEC procedures applicable to this QOSM
- QNE processing rules describing how QSPEC information is treated
and interpreted in the RMF, e.g.,
admission control, scheduling, policy control, QoS parameter
accumulation (e.g., delay).
- at least one bit-level QSPEC example
- QSPEC parameter behavior for new QSPEC parameters the QOSM
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specification defines
- define what happens in case of preemption if the default QNI
behavior (tear down preempted reservation) is not followed (see
Section 5.3.5)
A QOSM specification MAY include the following:
- define additional QOSM-specific error codes, as discussed in
Section 5.2.3
- can state which QoS-NSLP options a QOSM wants to use, when
several options are available for a QOSM (e.g., local QSPEC to
either be a) tunneled or b) encapsulate initiator QSPEC).
QOSMs are free, subject to IANA registration and review rules, to
extend QSPECs by adding parameters of any of the kinds supported by
the standard QSPEC. This includes traffic description parameters,
constraint parameters and traffic handling directives. QOSMs are not
permitted, however, to reinterpret or redefine the standard QSPEC
parameters specified in this document. Note that signaling
functionality is only defined by the QoS NSLP document [QoS-SIG] and
not by this document or by QOSM specification documents.
4.2 QSPEC Objects
The QSPEC is the object of QoS NSLP containing QSPEC objects and
parameters. QSPEC objects are the main building blocks of the QSPEC
parameter set that is input or output of an RMF operation. QSPEC
parameters are the parameters appearing in a QSPEC, which must
include traffic (TMOD), and may optionally include constraints (e.g.,
path latency), traffic handling directives (e.g., excess treatment),
and traffic classifiers (e.g., PHB class). The RMF implements
functions that are related to resource management and processes the
QSPEC parameters.
The QSPEC consists of a QSPEC version number and QSPEC objects.
Later QSPEC versions MUST be backward compatible with earlier QSPEC
versions. That is, a version n+1 device must support a version n
(or earlier) QSPEC parameters. A new QSPEC version MUST be defined
whenever this document is reissued, for example, whenever a new QSPEC
parameter is added. QSPEC parameters in a new QSPEC version MUST be
a superset of those in the previous QSPEC version. QSPEC version is
assigned by IANA.
This document provides a template for the QSPEC in order to promote
interoperability between QOSMs. Figure 1 illustrates how the QSPEC
is composed of up to four QSPEC objects, namely QoS Desired, QoS
Available, QoS Reserved and Minimum QoS. Each of these QSPEC objects
consists of a number of QSPEC parameters. A given QSPEC may contain
only a subset of the QSPEC objects, e.g. QoS Desired. The QSPEC
objects QoS Desired, QoS Available and QoS Reserved MUST be supported
by QNEs. Minimum QoS MAY be supported.
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Internet Draft QoS-NSLP QSPEC Template February 2007
+---------------------------------------+
| QSPEC Objects |
+---------------------------------------+
\________________ ______________________/
V
+----------+----------+---------+-------+
|QoS Desir.|QoS Avail.|QoS Rsrv.|Min QoS|
+----------+----------+---------+-------+
\____ ____/\___ _____/\___ ____/\__ ___/
V V V V
+-------------+... +-------------+...
|QSPEC Para. 1| |QSPEC Para. n|
+-------------+... +-------------+...
Figure 1: Structure of the QSPEC
The QoS Desired Object describe the resources the QNI desires to
reserve and hence this is a read-only QSPEC object in that the QSPEC
parameters carried in the object may not be overwritten. QoS Desired
is always included in a RESERVE message.
The QoS Available Object travels in a RESERVE or QUERY message and
collects information on the resources currently available on the
path. Hence QoS Available in this case is a read-write object, which
means the QSPEC parameters contained in QoS Available may be updated,
but they cannot be deleted). Each
QNE MUST inspect all parameters of this QSPEC object, and if
resources available to this QNE are less than what a particular
parameter says currently, the QNE MUST adapt this parameter
accordingly. Hence when the message arrives at the recipient of the
message, <QoS Available> reflects the bottleneck of the resources
currently available on a path. It can be used in a QUERY message,
for example, to collect the available resources along a data path.
When QoS Available travels in a RESPONSE message, it in fact just
transports the result of a previous measurement performed by a
RESERVE or QUERY message back to the initiator. Therefore in this
case, QoS Available is read-only.
QoS Reserved reflects the resources that were reserved. It is a
read-only object.
Minimum QoS does not have an equivalent in RSVP. It allows the QNI
to define a range of acceptable QoS levels by including both the
desired QoS value and the minimum acceptable QoS in the same message.
Parameters cannot be overwritten in this QSPEC object. The desired
QoS is included with a QoS Desired and/or a QoS Available QSPEC
object seeded to the desired QoS value. The minimum acceptable QoS
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value MAY be coded in the Minimum QoS QSPEC object. As the message
travels towards the QNR, QoS Available is updated by QNEs on the
path. If its value drops below the value of Minimum QoS the
reservation fails and is aborted. When this method is employed, the
QNR SHOULD signal back to the QNI the value of QoS Available
attained in the end, because the reservation MAY need to be adapted
accordingly.
Note that the relationship of QSPEC objects to RSVP objects is
covered in Appendix A.
4.3 QSPEC Parameters
QSPEC parameters provide a common language for building QSPEC
objects. This document defines a number of QSPEC parameters,
additional parameters may be defined in separate QOSM specification
documents. For example, QSPEC parameters are defined in [RMD-QOSM]
and [Y.1541-QOSM].
One QSPEC parameter, <TMOD>, is special. It provides a description
of the traffic for which resources are reserved. This parameter must
be included by the QNI and it must be interpreted by all QNEs. All
other QSPEC parameters are populated by a QNI if they are applicable
to the underlying QoS desired. For these QSPEC parameters, the QNI
sets the M-flag if they must be interpreted by downstream QNEs. If
QNEs cannot interpret the parameter the reservation fails. QSPEC
parameters populated by a QNI without the M-flag set should be
interpreted by downstream QNEs, but may be ignored if not understood.
In this document the term 'interpret' means, in relation to RMF
processing of QSPEC parameters, that the RMF processes the QSPEC
parameter according to the commonly accepted normative procedures
specified by references given for each QSPEC parameter. Note that a
QNE need only interpret a QSPEC parameter if it is populated in the
QSPEC object by the QNI; if not populated in the QSPEC, the QNE does
not interpret it of course.
Note that when an ingress QNE in a local domain defines a local QSPEC
and encapsulates the initiator QSPEC, the QNEs in the interior local
domain need only process the local QSPEC and can ignore the initiator
(encapsulated) QSPEC. However, edge QNEs in the local domain indeed
must interpret the QSPEC parameters populated in the initiator QSPEC
with the M-flag set and should interpret QSPEC parameters populated
in the initiator QSPEC without the M-flag set.
As described in the previous section, QoS parameters may be
overwritten depending on which QSPEC object, and which message, they
appear in.
4.3.1 Traffic Model Parameter
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The <Traffic Model> (TMOD) parameter is mandatory for the QNI to
include in the initiator QSPEC and mandatory for downstream QNEs to
interpret. The traffic description specified by the TMOD parameter
is a container consisting of 4 sub-parameters:
o rate (r)
o bucket size (b)
o peak rate (p)
o minimum policed unit (m)
All 4 of the sub-parameters MUST be included in the TMOD parameter.
The TMOD parameter is a mathematically complete way to describe the
traffic source [WROCLAWSKI]. If, for example, TMOD is set to specify
bandwidth only, then set r = peak rate = p, b = large, m = large. As
another example if TMOD is set for TCP traffic, then set r = average
rate, b = large, p = large.
When the TMOD parameter in included in QoS Available, it provides
information, for example, about the TMOD resources available along
the path followed by a data flow. The value of TMOD at a QNE is an
estimate of the TMOD resources the QNE has available for packets
following the path up to the next QNE, including its outgoing link,
if this link exists. Furthermore, the QNI MUST account for the
resources of the ingress link, if this link exists. Computation of
the value of this parameter SHOULD take into account all information
available to the QNE about the path, taking into consideration
administrative and policy controls, as well as physical resources.
The composed value is the minimum of the QNE's value and the
previously composed value for r, b, and p, and the maximum of the
QNE's value and the previously composed value for m. This quantity,
when composed end-to-end, informs the QNR (or QNI in a RESPONSE
message) of the minimal TMOD resources along the path from QNI to
QNR.
4.3.2 Constraints Parameters
<Path Latency>, <Path Jitter>, <Path PLR>, and <Path PER> are QSPEC
parameters describing the desired path latency, path jitter and path
bit error rate respectively. Since these parameters are cumulative,
an individual QNE cannot decide whether the desired path latency,
etc., is available, and hence they cannot decide whether a
reservation fails. Rather, when these parameters are included in
<Desired QoS>, the QNI SHOULD also include corresponding parameters
in a QoS Available QSPEC object in order to facilitate collecting
this information.
The <Path Latency> parameter accumulates the latency of the packet
forwarding process associated with each QNE, where the latency is
defined to be the mean packet delay added by each QNE. This delay
results from speed-of-light propagation delay, from packet processing
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limitations, or both. The mean delay reflects the variable queuing
delay that may be present. Each QNE MUST add the propagation delay
of its outgoing link, if this link exists. Furthermore, the QNI MUST
add the propagation delay of the ingress link, if this link exists.
The composition rule for the <Path Latency> parameter is summation
with a clamp of (2**32 - 1) on the maximum value. This quantity,
when composed end-to-end, informs the QNR (or QNI in a RESPONSE
message) of the minimal packet delay along the path from QNI to QNR.
The purpose of this parameter is to provide a minimum path latency
for use with services which provide estimates or bounds on additional
path delay [RFC2212].
The <Path Jitter> parameter accumulates the jitter of the packet
forwarding process associated with each QNE, where the jitter is
defined to be the nominal jitter added by each QNE. IP packet
jitter, or delay variation, is defined in [RFC3393], Section 3.4
(Type-P-One-way-ipdv), and where the selection function includes the
packet with minimum delay such that the distribution is equivalent to
2-point delay variation in [Y.1540]. The suggested evaluation
interval is 1 minute. This jitter results from packet processing
limitations, and includes any variable queuing delay which may be
present. Each QNE MUST add the jitter of its outgoing link, if this
link exists. Furthermore, the QNI MUST add the jitter of the ingress
link, if this link exists. The composition method for the <Path
Jitter> parameter is the combination of several statistics describing
the delay variation distribution with a clamp on the maximum value
(note that the methods of accumulation and estimation of nominal QNE
jitter are specified in clause 8 of [Y.1541]). This quantity, when
composed end-to-end, informs the QNR (or QNI in a RESPONSE message)
of the nominal packet jitter along the path from QNI to QNR. The
purpose of this parameter is to provide a nominal path jitter for use
with services that provide estimates or bounds on additional path
delay [RFC2212].
The <Path PLR> parameter accumulates the packet loss rate (PLR) of
the packet forwarding process associated with each QNE, where the PLR
is defined to be the PLR added by each QNE. Each QNE MUST add the
PLR of its outgoing link, if this link exists. Furthermore, the QNI
MUST add the PLR of the ingress link, if this link exists. The
composition rule for the <Path PLR> parameter is summation with a
clamp on the maximum value (this assumes sufficiently low PLR values
such that summation error is not significant, however a more accurate
composition function is specified in clause 8 of [Y.1541]). This
quantity, when composed end-to-end, informs the QNR (or QNI in a
RESPONSE message) of the minimal packet PLR along the path from QNI
to QNR.
The <Path PER> parameter accumulates the packet error rate (PER) of
the packet forwarding process associated with each QNE, where the PER
is defined to be the PER added by each QNE. Each QNE MUST add the
PER of its outgoing link, if this link exists. Furthermore, the QNI
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MUST add the PER of the ingress link, if this link exists. The
composition rule for the <Path PER> parameter is summation with a
clamp on the maximum value (this assumes sufficiently low PER values
such that summation error is not significant, however a more accurate
composition function is specified in clause 8 of [Y.1541]). This
quantity, when composed end-to-end, informs the QNR (or QNI in a
RESPONSE message) of the minimal packet PER along the path from QNI
to QNR.
The slack term parameter is the difference between desired delay and
delay obtained by using bandwidth reservation, and which is used to
reduce the resource reservation for a flow [RFC2212]. This is an
QSPEC parameter.
The <Preemption Priority> parameter is the priority of the new flow
compared with the <Defending Priority> of previously admitted flows.
Once a flow is admitted, the preemption priority becomes irrelevant.
The <Defending Priority> parameter is used to compare with the
preemption priority of new flows. For any specific flow, its
preemption priority MUST always be less than or equal to the
defending priority. <Admission Priority> and <RPH Priority> provide
an essential way to differentiate flows for emergency services, ETS,
E911, etc., and assign them a higher admission priority than normal
priority flows and best-effort priority flows.
4.3.3 Traffic Handling Directives
An application MAY like to reserve resources for packets and also
specify a specific traffic handling behavior, such as <Excess
Treatment>. In addition, an application MAY like to define RMF
triggers that cause the QoS NSLP to run semantics within the
underlying QoS NSLP signaling state and messaging processing rules,
as defined in Section 5.2 of [QoS-SIG]. Note, however, that new QoS
NSLP message processing rules can only be defined in Standards Track
extensions to the QoS NSLP.
As with constraints parameters and other QSPEC parameters,
traffic-handling-directives parameters may be defined in QOSM
specifications in order to provide support for QOSM-specific resource
management functions. Such QOSM-specific parameters are already
defined, for example, in [RMD-QOSM], [CL-QOSM] and [Y.1541-QOSM].
The <Excess Treatment> parameter describes how the QNE will process
excess traffic, that is, out-of-profile traffic. Excess traffic MAY
be dropped, shaped and/or remarked. The excess treatment parameter is
initially set by the QNI and cannot be overwritten.
4.3.4 Traffic Classifiers
An application MAY like to reserve resources for packets with a
particular DiffServ per-hop behavior (PHB) [RFC2475]. Note that PHB
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class is normally set by a downstream QNE to tell the QNI how to mark
traffic to ensure treatment committed by admission control. An
application MAY like to reserve resources for packets with a
particular QoS class, e.g. Y.1541 QoS class [Y.1541] or
DiffServ-aware MPLS traffic engineering (DSTE) class type [RFC3564,
RFC4124]. These parameters are useful in various QOSMs, e.g.,
[RMD-QOSM], [Y.1541-QOSM], and other QOSMs yet to be defined (e.g.,
DSTE-QOSM). This is intended to provide guidelines to QOSMs on how
to encode these parameters; use of the PHB class parameter is
illustrated in the example in the following section.
4.4 Example of QSPEC Processing
This section illustrates the operation and use of the QSPEC within
the NSLP. The example configuration in shown in Figure 2.
+----------+ /-------\ /--------\ /--------\
| Laptop | | Home | | Cable | | DiffServ |
| Computer |-----| Network |-----| Network |-----| Network |----+
+----------+ | No QOSM | |DQOS QOSM | | RMD QOSM | |
\-------/ \--------/ \--------/ |
|
+-----------------------------------------------+
|
| /--------\ +----------+
| | "X"G | | Handheld |
+---| Wireless |-----| Device |
| XG QOSM | +----------+
\--------/
Figure 2: Example Configuration to Illustrate QoS-NSLP/QSPEC
Operation
In this configuration, a laptop computer and a handheld wireless
device are the endpoints for some application that has QoS
requirements. Assume initially that the two endpoints are stationary
during the application session, later we consider mobile endpoints.
For this session, the laptop computer is connected to a home network
that has no QoS support. The home network is connected to a
CableLabs-type cable access network with dynamic QoS (DQOS) support,
such as specified in the [DQOS] for cable access networks. That
network is connected to a DiffServ core network that uses the RMD
QOSM [RMD-QOSM]. On the other side of the DiffServ core is a
wireless access network built on generation "X" technology with QoS
support as defined by generation "X". And finally the handheld
endpoint is connected to the wireless access network.
We assume that the Laptop is the QNI and handheld device is the QNR.
The QNI will signal an initiator QSPEC object to achieve the QoS
desired on the path. The QNI would normally signal a reservation
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according to the requirements of its supported QOSM. Furthermore,
the QNI would most likely support the QOSM that matches its
functionality. For example, the default QOSM for mobile phones might
be the XG-QOSM, while the CL-QOSM might be the default for
workstations.
The QNI sets QoS Desired, QoS Available and possibly Minimum
QoS QSPEC objects in the initiator QSPEC, and initializes QoS
Available to QoS Desired. Each QNE on the path reads and
interprets those parameters in the initiator QSPEC and checks to see
if QoS Available resources can be reserved. If not, the QNE reduces
the respective parameter values in QoS Available and reserves these
values. The minimum parameter values are given in Minimum QoS, if
populated, otherwise zero if Minimum QoS is not included. If one or
more parameters in QoS Available fails to satisfy the corresponding
minimum values in Minimum QoS, the QNE generates a RESPONSE message
to the QNI and the reservation is aborted. Otherwise, the QNR
generates a RESPONSE to the QNI with the QoS Available for the
reservation. If a QNE cannot reserve QoS Desired resources, the
reservation fails.
The QNI populates QSPEC parameters to ensure correct treatment of its
traffic in domains down the path. Let us assume the QNI wants to
achieve IntServ-Controlled Load-like QoS guarantees, and also is
interested in what path latency it can achieve. Additionally, to
ensure correct treatment further down the path, the QNI includes <PHB
Class> in <QoS Desired>. The QNI therefore includes in the QSPEC
QoS Desired = <TMOD> <PHB Class>
QoS Available = <TMOD> <Path Latency>
Since <Path Latency> and <QoS Class> are not vital parameters from
the QNI's perspective, it does not raise their M-flags.
There are three possibilities when a RESERVE message is received at a
QNE at a domain border (we illustrate these possibilities in the
example):
- the QNE just leaves the QSPEC as-is.
- the QNE can add a local QSPEC and encapsulate the initiator QSPEC
(see discussion in Section 5.1; this is new in QoS NSLP, RSVP does
not do this).
- the QNE can tunnel the initiator RESERVE message through its domain
and issue its own local RESERVE message. For this new local
RESERVE message, the QNE acts as the QNI, and the QSPEC in the
domain is an initiator QSPEC. A similar procedure is also used by
RSVP in making aggregate reservations, in which case there is not a
new intra-domain (aggregate) RESERVE for each newly arriving
interdomain (per-flow) RESERVE, but the aggregate reservation is
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updated by the border QNE (QNI) as need be. This is also how RMD
works [RMD-QOSM].
For example, at the RMD domain, a local RESERVE with its own RMD
initiator QSPEC corresponding to the RMD-QOSM is generated based on
the original initiator QSPEC according to the procedures described in
Section 4.5 of [QoS-SIG] and in [RMD-QOSM]. For example, the ingress
QNE to the RMD domain maps the TMOD parameters contained in the
original initiator QSPEC into the equivalent TMOD parameter
representing only the peak bandwidth in the local QSPEC. The local
RMD QSPEC for example also needs <PHB Class>, which in this case was
provided by the QNI.
Furthermore, the node at the egress to the RMD domain updates QoS
Available on behalf of the entire RMD domain if it can. If it
cannot (since the M-flag is not set for <Path Latency>) it raises the
parameter-specific, 'not-supported' flag, warning the QNR that the
final latency value in QoS Available is imprecise.
In the XG domain, the initiator QSPEC is translated into a local
QSPEC using a similar procedure as described above. The local QSPEC
becomes the current QSPEC used within the XG domain, that is, the
it becomes the first QSPEC on the stack, and the initiator QSPEC is
second. This saves the QNEs within the XG domain the trouble of
re-translating the initiator QSPEC, and simplifies processing in
the local domain. At the egress edge of the XG domain, the
translated local QSPEC is popped, and the initiator QSPEC returns to
the number one position.
If the reservation was successful, eventually the RESERVE request
arrives at the QNR (otherwise the QNE at which the reservation failed
would have aborted the RESERVE and sent an error RESPONSE back to the
QNI). If the RII was included in the QoS NSLP message, the QNR
generates a positive RESPONSE with QSPEC objects QoS Reserved and
QoS Available. The parameters appearing in QoS Reserved are the
same as in QoS Desired, with values copied from QoS Available.
Hence, the QNR includes the following QSPEC objects in the RESPONSE:
QoS Reserved = <TMOD> <PHB Class>
QoS Available = <TMOD> <Path Latency>
If the handheld device on the right of Figure 2 is mobile, and moves
through different "XG" wireless networks, then the QoS might change
on the path since different XG wireless networks might support
different QOSMs. As a result, QoS NSLP/QSPEC processing will have to
renegotiate the QoS Available on the path. From a QSPEC
perspective, this is like a new reservation on the new section of the
path and is basically the same as any other rerouting event - to the
QNEs on the new path it looks like a new reservation. That is, in
this mobile scenario, the new segment may support a different QOSM
than the old segment, and the QNI would now signal a new reservation
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(explicitly, or implicitly with the next refreshing RESERVE message)
to account for the different QOSM in the XG wireless domain. Further
details on rerouting are specified in [QoS-SIG].
For bit-level examples of QSPECs see the documents specifying QOSMs
[CL-QOSM, Y.1541-QOSM, RMD-QOSM].
5. QSPEC Processing & Procedures
The QNI sets the M-flag for each QSPEC parameter it populates that
must be interpreted by downstream QNEs. If a QNE does not support
parameter it sets the N-flag and fails the reservation. If the QNE
supports the parameter but cannot meet the resources requested by the
parameter, it sets the E-flag and fails the reservation.
If the M-flag is not set, the downstream QNE SHOULD interpret the
parameter. If the QNE does not support the parameter it sets the
N-flag and forwards the reservation. If the QNE supports the
parameter but cannot meet the resources requested by the parameter,
it sets the E-flag and fails the reservation.
5.1 Local QSPEC Definition & Processing
A QNE at the edge of a local domain may either a) translate the
initiator QSPEC into a local QSPEC and encapsulate the initiator
QSPEC in the RESERVE message, or b) tunnel the initiator QSPEC
through the local domain and reserve resources by generating a new
RESERVE message through the local domain containing the local QSPEC.
In either case the initiator QSPEC parameters are interpreted at the
local domain edges.
A local QSPEC may allow a simpler control plane in a local domain.
The edge nodes in the local domain must interpret the initiator
QSPEC parameters. They can either initiate a parallel session with
local QSPEC or define a local QSPEC and encapsulate the initiator
QSPEC, as illustrated in Figure 3. As defined in Section 6, the
QSPEC type identifies where the QSPEC is an initiator QSPEC or a
local QSPEC.
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+--------------------------------+
| QSPEC Type = Local QSPEC | Common QSPEC Header
+================================+\
| Local-QSPEC Parameter 1 | \
+--------------------------------+ \
| .... | Local-QSPEC Parameters
+--------------------------------+ /
| Local-QSPEC Parameter n | /
+--------------------------------+/
| +----------------------------+ |
| |QSPEC Type = Initiator QSPEC| |
| +============================+ |
| | | | Encapsulated Initiator QSPEC
| | .... | |
| +----------------------------+ |
+--------------------------------+
Figure 3. Defining a Local QSPEC
Here the QoS-NSLP only sees and passes one QSPEC up to the RMF. The
type of the QSPEC thus may change within a local domain. Hence
o the QNI signals its QoS requirements with the initiator QSPEC,
o the ingress edge QNE in the local domain translates the
initiator QSPEC parameters to equivalent parameters in the local
QSPEC,
o the QNEs in the local domain only interpret the local QSPEC
parameters
o the egress QNE in the local domain processes the local QSPEC and
also interprets the QSPEC parameters in the initiator QSPEC.
The local QSPEC MUST be consistent with the initiator QSPEC. That
is, it MUST NOT specify a lower level of resources than specified
by the initiator QSPEC. For example, in RMD the TMOD parameters
contained in the original initiator QSPEC are mapped into the
equivalent TMOD parameter representing only the peak bandwidth in the
local QSPEC.
Note that it is possible to use, at the same time, both a) tunneling
a QSPEC through a local domain by initiating a new RESERVE at the
domain edge, and b) defining a local QSPEC and encapsulating the
initiator QSPEC, as defined above.
5.2 Reservation Success/Failure, QSPEC Error Codes, & INFO_SPEC
Notification
A reservation may not be successful for several reasons:
- a reservation may fail because the desired resources are not
available. This is a reservation failure condition.
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- a reservation may fail because the QSPEC is erroneous, or because
of a QNE fault. This is an error condition.
A reservation may be successful even though some parameters could not
be interpreted or updated properly:
- a QSPEC parameter cannot be interpreted because it is an unknown
QSPEC parameter type. This is a QSPEC parameter not supported
condition. The reservation however does not fail. The QNI can
still decide whether to keep or tear down the reservation depending
on the procedures specified by the QNI's QOSM.
The following sections describe the handling of unsuccessful
reservations and reservations where some parameters could not be met
in more detail, as follows:
- details on flags used inside the QSPEC to convey information on
success or failure of individual parameters. The formats and
semantics of all flags are given in Section 6.
- the content of the INFO_SPEC [QoS-SIG], which carries a code
indicating the outcome of reservations.
- the generation of a RESPONSE message to the QNI containing both
QSPEC and INFO_SPEC objects.
5.2.1 Reservation Failure & Error E-Flag
The QSPEC parameters each have a 'reservation failure error E-flag'
to indicate which (if any) parameters could not be satisfied. When a
resource cannot be satisfied for a particular parameter, the QNE
detecting the problem raises the E-flag in this parameter. Note that
all QSPEC parameters MUST be examined by the RMF and appropriately
flagged. Additionally, the E-flag in the corresponding QSPEC object
MUST be raised. If the reservation failure problem cannot be located
at the parameter level, only the E-flag in the QSPEC object is
raised.
When an RMF cannot interpret the QSPEC because the coding is
erroneous, it raises corresponding reservation failure E-flags in the
QSPEC. Normally all QSPEC parameters MUST be examined by the RMF
and the erroneous parameters appropriately flagged. In some cases,
however, an error condition may occur and the E-flag of the
error-causing QSPEC parameter is raised (if possible), but the
processing of further parameters may be aborted.
Note that if the QSPEC and/or any QSPEC parameter is found to be
erroneous, then any QSPEC parameters not satisfied are ignored and
the E-Flags in the QSPEC object MUST NOT be set for those parameters
(unless they are erroneous).
Whether E-flags denote reservation failure or error can be determined
by the corresponding error code in the INFO_SPEC in QoS NSLP, as
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discussed below.
5.2.2 QSPEC Parameter Not Supported N-Flag
Each QSPEC parameter has an associated 'not supported N-flag'. If
the not supported N-flag is set, then at least one QNE along the data
transmission path between the QNI and QNR cannot interpret the
specified QSPEC parameter. A QNE MUST set the not supported N-flag
if it cannot interpret the QSPEC parameter. If the M-flag for the
parameter is not set, the message should continue to be forwarded but
with the N-flag set, and the QNI has the option of tearing the
reservation.
If a QNE in the path does not support a QSPEC parameter, e.g.,
<Path Latency>, and sets the N-flag, then downstream QNEs that
support the parameter SHOULD still update the parameter, even if the
N-flag is set. However, the presence of the N-flag will make the
cumulative value unreliable, and the QNI/QNR decides whether or not
to accept the reservation with the N-flag set.
5.2.3 INFO_SPEC Coding of Reservation Outcome
As prescribed by [QoS-SIG], the RESPONSE message always contains the
INFO_SPEC with an appropriate 'error' code. It usually also contains
a QSPEC with QSPEC objects, as described in Section 5.3 on QSPEC
Procedures. The RESPONSE message MAY omit the QSPEC in case of a
successful reservation.
The following guidelines are provided in setting the error codes in
the INFO_SPEC, based on the codes provided in Section 5.1.3.6 of
[QoS-SIG]:
- INFO_SPEC error class 0x02 (Success) / 0x01 (Reservation Success):
This code is set when all QSPEC parameters have been satisfied. In
this case no E-Flag is set, however one or more N-flags may be set.
- INFO_SPEC error class 0x04 (Transient Failure) / 0x08 (Reservation
Failure):
This code is set when at least one QSPEC parameter could not be
satisfied, or when a QSPEC parameter with M-flag could not be
interpreted. E-flags are set for the parameters that could not be
satisfied up to the QNE issuing the RESPONSE message. The N-flag is
set for those parameters that could not be interpreted by at least
one QNE. In this case QNEs receiving the RESPONSE message MUST
remove the corresponding reservation.
- INFO_SPEC error class 0x03 (Protocol Error) / 0x0c (Malformed
QSPEC):
Some QSPEC parameters had associated errors, E-Flags are set for
parameters that had errors, and the QNE where the error was found
rejects the reservation.
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- INFO_SPEC error class 0x06 (QoS Model Error):
QOSM error codes can be defined by QOSM specification documents. A
registry is defined in Section 8 IANA Considerations.
5.2.4 QNE Generation of a RESPONSE message
- Successful Reservation Condition
When a RESERVE message arrives at a QNR and no E-Flag is set, the
reservation is successful. A RESPONSE message may be generated with
INFO_SPEC code 'Reservation Success' as described above and in the
QSPEC Procedures described in Section 5.3.
- Reservation Failure Condition
When a QNE detects that a reservation failure occurs for at least one
parameter, the QNE sets the E-Flags for the QSPEC parameters and
QSPEC object that failed to be satisfied. According to [QoS-SIG],
the QNE behavior depends on whether it is stateful or not. When a
stateful QNE determines the reservation failed, it formulates a
RESPONSE message that includes an INFO_SPEC with the 'reservation
failure' error code and QSPEC object. The QSPEC in the RESPONSE
message includes the failed QSPEC parameters marked with the E-Flag
to clearly identify them.
The default action for a stateless QoS NSLP QNE that detects a
reservation failure condition is that it MUST continue to forward the
RESERVE message to the next stateful QNE, with the E-Flags
appropriately set for each QSPEC parameter. The next stateful QNE
then formulates the RESPONSE message as described above.
- Malformed QSPEC Error Condition
When a stateful QNE detects that one or more QSPEC parameters are
erroneous, the QNE sets the error code 'malformed QSPEC' in the
INFO_SPEC. In this case the QSPEC object with the E-Flags
appropriately set for the erroneous parameters is returned within
the INFO_SPEC object. The QSPEC object can be truncated or fully
included within the INFO_SPEC.
According to [QoS-SIG], the QNE behavior depends on whether it is
stateful or not. When a stateful QNE determines a malformed QSPEC
error condition, it formulates a RESPONSE message that includes an
INFO_SPEC with the 'malformed QSPEC' error code and QSPEC object.
The QSPEC in the RESPONSE message includes, if possible, only the
erroneous QSPEC parameters and no others. The erroneous QSPEC
parameter(s) are marked with the E-Flag to clearly identify them. If
QSPEC parameters are returned in the INFO-SPEC that are not marked
with the E-flag, then any values of these parameters are irrelevant
and MUST be ignored by the QNI.
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The default action for a stateless QoS NSLP QNE that detects a
Malformed QSPEC error condition is that it MUST continue to forward
the RESERVE message to the next stateful QNE, with the E-Flags
appropriately set for each QSPEC parameter. The next stateful QNE
will then act as described in [QoS-SIG].
A 'malformed QSPEC' error code takes precedence over the 'reservation
failure' error code, and therefore the case of reservation failure
and QSPEC/RMF error conditions are disjoint and the same E-Flag can
be used in both cases without ambiguity.
5.2.5 Special Case of Local QSPEC
When an unsuccessful reservation problem occurs inside a local domain
where a local QSPEC is used, only the topmost (local) QSPEC is
affected (e.g. E-flags are raised, etc.). The encapsulated
initiator QSPEC is untouched. When the message (RESPONSE in case of
stateful QNEs, RESERVE in case of stateless QNEs) however reaches the
edge of the local domain, the local QSPEC is removed. The edge QNE
must update the initiator QSPEC on behalf of the entire domain,
reflecting the information received in the local QSPEC. This update
concerns both parameter values and flags.
5.3 QSPEC Procedures
While the QSPEC template aims to put minimal restrictions on usage of
QSPEC objects, interoperability between QNEs and between QOSMs must
be ensured. We therefore give below an exhaustive list of QSPEC
object combinations for the message sequences described in QoS NSLP
[QoS-SIG]. A specific QOSM may prescribe that only a subset of the
procedures listed below may be used.
Note that QoS NSLP does not mandate the usage of a RESPONSE message.
In fact, a RESPONSE message will only be generated if the QNI
includes an RII (Request Identification Information) in the RESERVE
message. Some of the QSPEC procedures below, however, are only
meaningful when a RESPONSE message is possible. The QNI SHOULD in
these cases include an RII.
5.3.1 Sender-Initiated Reservations
Here the QNI issues a RESERVE message, which may be replied to by a
RESPONSE message. The following 3 cases for QSPEC object usage
exist:
ID | RESERVE | RESPONSE
---------------------------------------------------------------
1 | QoS Desired | QoS Reserved
2 | QoS Desired, QoS Avail. | QoS Reserved, QoS Avail.
3 | QoS Desired, QoS Avail., Min. QoS | QoS Reserved, QoS Avail.
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Case 1:
If only QoS Desired is included in the RESERVE message, the implicit
assumption is that exactly these resources must be reserved. If this
is not possible the reservation fails. The parameters in QoS
Reserved are copied from the parameters in QoS Desired. If the
reservation is successful, the RESPONSE message can be omitted in
this case. If a RESPONSE message was requested by a QNE on the
path, the QSPEC in the RESPONSE message can be omitted.
Case 2:
When QoS Available is included in the RESERVE message also, some
parameters will appear only in QoS Available and not in QoS Desired.
It is assumed that the value of these parameters is collected for
informational purposes only (e.g. path latency).
However, some parameters in QoS Available can be the same as in QoS
Desired. For these parameters the implicit message is that the QNI
would be satisfied by a reservation with lower parameter values than
specified in QoS Desired. For these parameters, the QNI seeds the
parameter values in QoS Available to those in QoS Desired (except for
cumulative parameters such as <path latency>).
Each QNE interprets the parameters in QoS
Available according to its current capabilities. Reservations in
each QNE are hence based on current parameter values in QoS Available
(and additionally those parameters that only appear in QoS Desired).
The drawback of this approach is that, if the resulting resource
reservation becomes gradually smaller towards the QNR, QNEs close to
the QNI have an oversized reservation, possibly resulting in
unnecessary costs for the user. Of course, in the RESPONSE the QNI
learns what the actual reservation is (from the QoS RESERVED object)
and can immediately issue a properly sized refreshing RESERVE. The
advantage of the approach is that the reservation is performed in
half-a-roundtrip time.
The QSPEC parameter IDs and values included in the QoS Reserved
object in the RESPONSE message MUST be the same as those in the QoS
Desired object in the RESERVE message. For those QSPEC parameters
that were also included in the QoS Available object in the RESERVE
message, their value is copied into the QoS Desired object. For the
other QSPEC parameters, the value is copied from the QoS Desired
object (the reservation would fail if the corresponding QoS could
not be reserved).
All parameters in the QoS Available object in the RESPONSE message
are copied with their values from the QoS Available object in the
RESERVE message (irrespective of whether they have also been copied
into the QoS Desired object). Note that the parameters in the QoS
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Available object can be overwritten in the RESERVE message, whereas
they cannot be overwritten in the RESPONSE message.
In this case, the QNI SHOULD request a RESPONSE message since it will
otherwise not learn what QoS is available.
Case 3:
This case is handled as case 2, except that the reservation fails
when QoS Available becomes less than Minimum QoS for one parameter.
If a parameter appears in the QoS Available object but not in the
Minimum QoS object it is assumed that there is no minimum value for
this parameter.
Regarding <Traffic Handling Directives>, the default rule is that all
QSPEC parameters that have been included in the RESERVE message by
the QNI are also included in the RESPONSE message by the QNR with the
value they had when arriving at the QNR. When traveling in the
RESPONSE message, all <Traffic Handling Directives> parameters are
read-only. Note that a QOSM specification may define its own
<Traffic Handling Directives> parameters and processing rules.
5.3.2 Receiver-Initiated Reservations
Here the QNR issues a QUERY message which is replied to by the QNI
with a RESERVE message if the reservation was successful. The QNR in
turn sends a RESPONSE message to the QNI. The following 3 cases for
QSPEC object usage exist:
ID| QUERY | RESERVE | RESPONSE
---------------------------------------------------------------------
1 |QoS Des. | QoS Des. | QoS Res.
2 |QoS Des.,Min. QoS | QoS Des.,QoS Avl.,(Min QoS)| QoS Res.,QoS Avl.
3 |Qos Des.,QoS Avl. | QoS Des.,QoS Avl. | QoS Res.
Cases 1 and 2:
The idea is that the sender (QNR in this scenario) needs to inform
the receiver (QNI in this scenario) about the QoS it desires. To
this end the sender sends a QUERY message to the receiver including a
QoS Desired QSPEC object. If the QoS is negotiable it additionally
includes a (possibly zero) Minimum QoS object, as in Case 2.
The RESERVE message includes the QoS Available object if the sender
signaled that QoS is negotiable (i.e. it included the Minimum QoS
object). If the Minimum QoS object received from the sender is
included in the QUERY message, the QNR also includes the Minimum QoS
object in the RESERVE message.
For a successful reservation, the RESPONSE message in case 1 is
optional (as is the QSPEC inside). In case 2 however, the RESPONSE
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message is necessary in order for the QNI to learn about the QoS
available.
Case 4:
This is the 'RSVP-style' scenario. The sender (QNR in this scenario)
issues a QUERY message with a QoS Desired object informing the
receiver (QNI in this scenario) about the QoS it desires as above.
It also includes a QoS Available object to collect path properties.
Note that here path properties are collected with the QUERY message,
whereas in the previous case 2 path properties were collected in the
RESERVE message.
Some parameters in the QoS Available object may the same as in the
QoS Desired object. For these parameters the implicit message is
that the sender would be satisfied by a reservation with lower
parameter values than specified in QoS Desired.
It is possible for the QoS Available object to contain parameters
that do not appear in the QoS Desired object. It is assumed that the
value of these parameters is collected for informational purposes
only (e.g. path latency). Parameter values in the QoS Available
object are seeded according to the sender's capabilities. Each QNE
remaps or approximately interprets the parameter values according to
its current capabilities.
The receiver (QNI in this scenario) signals the QoS Desired object as
follows: For those parameters that appear in both the QoS Available
object and QoS Desired object in the QUERY message, it takes the
(possibly remapped) QSPEC parameter values from the QoS Available
object. For those parameters that only appear in the QoS Desired
object, it adopts the parameter values from the QoS Desired object.
The parameters in the QoS Available QSPEC object in the RESERVE
message are copied with their values from the QoS Available QSPEC
object in the QUERY message. Note that the parameters in the QoS
Available object can be overwritten in the QUERY message, whereas
they are cannot be overwritten in the RESERVE message.
The advantage of this model compared to the sender-initiated
reservation is that the situation of over-reservation in QNEs close
to the QNI as described above does not occur. On the other hand, the
QUERY message may find, for example, a particular bandwidth is not
available. When the actual reservation is performed, however, the
desired bandwidth may meanwhile have become free. That is, the 'RSVP
style' may result in a smaller reservation than necessary.
The sender includes all QSPEC parameters it cares about in the QUERY
message. Parameters that can be overwritten are updated by QNEs as
the QUERY message travels towards the receiver. The receiver
includes all QSPEC parameters arriving in the QUERY message also in
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the RESERVE message, with the value they had when arriving at the
receiver. Again, QOSM-specific QSPEC parameters and procedures may
be defined in QOSM specification documents.
Also in this scenario, the QNI SHOULD request a RESPONSE message
since it will otherwise not learn what QoS is available.
Regarding <Traffic Handling Directives>, the default rule is that all
QSPEC parameters that have been included in the RESERVE message by
the QNI are also included in the RESPONSE message by the QNR with the
value they had when arriving at the QNR. When traveling in the
RESPONSE message, all <Traffic Handling Directives> parameters are
read-only. Note that a QOSM specification may define its own
<Traffic Handling Directives> parameters and processing rules.
5.3.3 Resource Queries
Here the QNI issues a QUERY message in order to investigate what
resources are currently available. The QNR replies with a RESPONSE
message.
ID | QUERY | RESPONSE
--------------------------------------------
1 | QoS Available | QoS Available
Note that the QoS Available object when traveling in the QUERY
message can be overwritten, whereas in the RESPONSE message cannot be
overwritten.
Regarding <Traffic Handling Directives>, the default rule is that all
QSPEC parameters that have been included in the RESERVE message by
the QNI are also included in the RESPONSE message by the QNR with the
value they had when arriving at the QNR. When traveling in the
RESPONSE message, all <Traffic Handling Directives> parameters are
read-only. Note that a QOSM specification may define its own
<Traffic Handling Directives> parameters and processing rules.
5.3.4 Bidirectional Reservations
On a QSPEC level, bidirectional reservations are no different from
uni-directional reservations, since QSPECs for different directions
never travel in the same message.
5.3.5 Preemption
A flow can be preempted by a QNE based on the values of the QSPEC
Priority parameter (see Section 6.2.8). In this case the reservation
state for this flow is torn down in this QNE, and the QNE sends a
NOTIFY message to the QNI, as described in [QoS-SIG]. The NOTIFY
message carries an INFO_SPEC with the error code as described in
[QOS-SIG]. A QOSM specification document may specify whether a
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NOTIFY message also carries a QSPEC object. The QNI would normally
tear down the preempted reservation by sending a RESERVE message with
the TEAR flag set using the SII of the preempted reservation.
However, the QNI can follow other procedures as specified in its QOSM
specification document.
5.4 QSPEC Extensibility
The set of QSPEC parameters defined herein is at this point in time
considered complete. Additional QSPEC parameters may be defined in
the future. However, since this requires an update of all QNEs, this
should be considered carefully. The definition of new QSPEC
parameter requires standards action and an update of this document.
Such an update also needs a new QSPEC version number. Furthermore,
all QOSM definitions must be updated to include how the new QSPEC
parameter is to be interpreted in the respective QOSM.
Additional QSPEC parameters MAY need to be defined in the future
and are defined in separate informational documents specific to a
given QOSM. For example, QSPEC parameters are defined in
[RMD-QOSM] and [Y.1541-QOSM].
Guidelines on the technical criteria to be followed in evaluating
requests for new codepoint assignments for QSPEC objects and QSPEC
parameters are given in Section 8 (IANA Considerations).
Guidelines on the technical criteria to be followed in evaluating
requests for new codepoint assignments beyond QSPEC objects and
QSPEC parameters for the NSIS protocol suite are given in a separate
NSIS extensibility document [NSIS-EXTENSIBILITY].
6. QSPEC Functional Specification
This section defines the encodings of the QSPEC parameters. We first
give the general QSPEC formats and then the formats of the QSPEC
objects and parameters.
Network byte order ('big-endian') for all 16- and 32-bit integers, as
well as 32-bit floating point numbers, are as specified in [RFC4506,
IEEE754, NETWORK-BYTE-ORDER].
6.1 General QSPEC Formats
The format of the QSPEC closely follows that used in GIST [GIST] and
QoS NSLP [QoS-SIG]. Every object (and parameter) has the following
general format:
o The overall format is Type-Length-Value (in that order).
o Some parts of the type field are set aside for control flags.
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o Length has the units of 32-bit words, and measures the length of
Value. If there is no Value, Length=0. The Object length
excludes the header.
o Value is a whole number of 32-bit words. If there is any padding
required, the length and location MUST be defined by the
object-specific format information; objects that contain variable
length types may need to include additional length subfields to do
so.
o Any part of the object used for padding or defined as reserved("r")
MUST be set to 0 on transmission and MUST be ignored on reception.
o Empty QSPECs and empty QSPEC Objects MUST NOT be used.
o Duplicate objects, duplicate parameters, and/or multiple
occurrences of a parameter MUST NOT be used.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Common QSPEC Header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// QSPEC Objects //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Common QSPEC Header is a fixed 4-byte long object containing the
QOSM ID and an identifier for the QSPEC Procedure (see Section 5.3):
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. | QSPEC Type | QSPEC Proc. | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note that a length field is not necessary since the overall length of
the QSPEC is contained in the higher level QoS NSLP data object.
Vers.: Identifies the QSPEC version number. It is assigned by IANA.
QSPEC Type: Identifies the particular type of QSPEC, e.g., initiator
QSPEC or local QSPEC.
QSPEC Proc.: Identifies the QSPEC procedure and is composed of two
times 4 bits. The first set of bits identifies the
Message Sequence, the second set identifies the QSPEC
Object Combination used for this particular message
sequence:
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0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|Mes.Sq |Obj.Cmb|
+-+-+-+-+-+-+-+-+
The Message Sequence field can attain the following
values:
0: Sender-Initiated Reservations
1: Receiver-Initiated Reservations
2: Resource Queries
The Object Combination field can take the values between
1 and 3 indicated in the tables in Section 5.3:
Message Sequence: 0
Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.1
Message Sequence: 1
Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.2
Message Sequence: 2
Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.3
The QSPEC Objects field is a collection of
QSPEC objects (QoS Desired, QoS Available, etc.), which share a
common format and each contain several parameters.
QSPEC objects share a common header 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|E|r|r|r| Object Type |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E Flag: Set if an error occurs on object level
Object Type = 0: QoS Desired (parameters cannot be overwritten)
= 1: QoS Available (parameters may be overwritten; see
Section 4.3)
= 2: QoS Reserved (parameters cannot be overwritten)
= 3: Minimum QoS (parameters cannot be overwritten)
The r bits are reserved.
Each QSPEC or QSPEC parameter within an object is similarly
encoded in TLV format using a similar parameter header:
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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| Parameter ID |r|r|r|r| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
M Flag: When set indicates the subsequent parameter MUST be
interpreted. Otherwise the parameter can be ignored if not
understood.
E Flag: When set indicates either a) a reservation failure where the
QSPEC parameter is not met, or b) an error occurred when this
parameter was being interpreted (see Section 5.2.1).
N Flag: Not-supported QSPEC parameter flag (see Section 5.2.2).
Parameter ID: Assigned to each parameter (see below)
Parameters are usually coded individually, for example, the <Excess
Treatment> parameter (Section 6.2.11). However, it is also possible
to combine several sub-parameters into one parameter field, which is
called 'container coding'. This coding is useful if either a) the
sub-parameters always occur together, as for example the several
sub-parameters that jointly make up the TMOD, or b) in order
to make coding more efficient when the length of each sub-parameter
value is much less than a 32-bit word (as for example described in
[RMD-QOSM]) and to avoid header overload. When a container is
defined, the Parameter ID and the M, E, and N flags refer to the
container. Examples of container parameters are <TMOD> (specified
below) and the PHR container parameter specified in [RMD-QOSM].
6.2 QSPEC Parameter Coding
6.2.1 <TMOD-1> Parameter
<TMOD-1> = <r> <b> <p> <m> [RFC2210, RFC2215]
The above notation means that the 4 <TMOD-1> sub-parameters must all
be populated in the <TMOD-1> parameter. Note that a second TMOD
QSPEC parameter <TMOD-2> is specified below in Section 6.2.2. The
references in the following sections point to the normative
procedures for processing the <TMOD> sub-parameters.
The coding for the <TMOD-1> parameter is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1|E|0|r| 1 |r|r|r|r| 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 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) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The <TMOD> parameters are represented by three floating point
numbers in single-precision IEEE floating point format followed by
one 32-bit integer in network byte order. The first floating point
value is the rate (r), the second floating point value is the bucket
size (b), the third floating point is the peak rate (p), and the
first unsigned integer is the minimum policed unit (m).
When r, b, and p terms are represented as IEEE floating point values,
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 zeroes.
6.2.2 <TMOD-2> Parameter [RFC2215]
A second, QSPEC <TMOD-2> parameter is specified, as could be needed
for example to support DiffServ applications.
Parameter Values:
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| 2 |r|r|r|r| 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TMOD Rate-2 [r] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TMOD Size-2 [b] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peak Data Rate-2 [p] (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Policed Unit-2 [m] (32-bit unsigned integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When r, b, and p terms are represented as IEEE floating point values,
the sign bit MUST be zero (all values MUST be non-negative).
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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 zeroes.
6.2.3 <Path Latency> Parameter [RFC2210, RFC2215]
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| 3 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Latency (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path Latency is a single 32-bit integer in network byte order.
The composition rule for the <Path Latency> parameter is summation
with a clamp of (2**32 - 1) on the maximum value. The latencies are
average values reported in units of one microsecond. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a latency value between 1 and 2**28
(somewhat over two minutes) and the total latency added across all
QNEs can range as high as (2**32)-2. If the sum of the different
elements delays exceeds (2**32)-2, the end-to-end advertised delay
SHOULD be reported as indeterminate. A QNE that cannot accurately
predict the latency of packets it is processing MUST raise the
not-supported flagand either leave the value of Path Latency as is,
or add its best estimate of its lower bound. A raised not-supported
flagflag indicates the value of Path Latency is a lower bound of the
real Path Latency. The distinguished value (2**32)-1 is taken to
mean indeterminate latency because the composition function limits
the composed sum to this value, it indicates the range of the
composition calculation was exceeded.
6.2.4 <Path Jitter> Parameter
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| 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) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path Jitter is a set of four 32-bit integers in network byte
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order. The Path Jitter parameter is the combination of four
statistics describing the Jitter distribution with a clamp of
(2**32 - 1) on the maximum of each value. The jitter STATs are
reported in units of one microsecond. A system with resolution less
than one microsecond MUST set unused digits to zero. An individual
QNE can advertise jitter values between 1 and 2**28 (somewhat over
two minutes) and the total jitter computed across all QNEs can range
as high as (2**32)-2. If the combination of the different element
values exceeds (2**32)-2, the end-to-end advertised jitter SHOULD be
reported as indeterminate. A QNE that cannot accurately predict the
jitter of packets it is processing MUST raise the not-supported flag
and either leave the value of Path Jitter as is, or add its best
estimate of its STAT values. A raised not-supported flag indicates
the value of Path Jitter is a lower bound of the real Path Jitter.
The distinguished value (2**32)-1 is taken to mean indeterminate
jitter. A QNE that cannot accurately predict the jitter of packets
it is processing SHOULD set its local path jitter parameter to this
value. Because the composition function limits the total to this
value, receipt of this value at a network element or application
indicates that the true path jitter is not known. This MAY happen
because one or more network elements could not supply a value, or
because the range of the composition calculation was exceeded.
NOTE: The Jitter composition function makes use of the <Path Latency>
parameter. Composition functions for loss, latency and jitter may be
found in [Y.1541].
6.2.5 <Path PLR> Parameter
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| 5 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Packet Loss Ratio (32-bit floating point) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path PLR is a single 32-bit single precision IEEE floating point
number in network byte order. The composition rule for the <Path
PLR> parameter is summation with a clamp of 10^-1 on the maximum
value. The PLRs are reported in units of 10^-11. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a PLR value between zero and 10^-2
and the total PLR added across all QNEs can range as high as 10^-1.
If the sum of the different elements values exceeds 10^-1, the
end-to-end advertised PLR SHOULD be reported as indeterminate. A QNE
that cannot accurately predict the PLR of packets it is processing
MUST raise the not-supported flag and either leave the value of Path
PLR as is, or add its best estimate of its lower bound. A raised
not-supported flag indicates the value of Path PLR is a lower bound
of the real Path PLR. The distinguished value 10^-1 is taken to mean
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indeterminate PLR. A QNE which cannot accurately predict the PLR of
packets it is processing SHOULD set its local path PLR parameter to
this value. Because the composition function limits the composed sum
to this value, receipt of this value at a network element or
application indicates that the true path PLR is not known. This MAY
happen because one or more network elements could not supply a value,
or because the range of the composition calculation was exceeded.
6.2.6 <Path PER> Parameter
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| 6 |r|r|r|r| 1 |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
| Path Packet Error Ratio (32-bit floating point) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The Path PER is a single 32-bit single precision IEEE floating point
number in network byte order. The composition rule for the <Path
PER> parameter is summation with a clamp of 10^-1 on the maximum
value. The PERs are reported in units of 10^-11. A system with
resolution less than one microsecond MUST set unused digits to zero.
An individual QNE can advertise a PER value between zero and 10^-2
and the total PER added across all QNEs can range as high as 10^-1.
If the sum of the different elements values exceeds 10^-1, the
end-to-end advertised PER SHOULD be reported as indeterminate. A QNE
that cannot accurately predict the PER of packets it is processing
MUST raise the not-supported flag and either leave the value of Path
PER as is, or add its best estimate of its lower bound. A raised
not-supported flag indicates the value of Path PER is a lower bound
of the real Path PER. The distinguished value 10^-1 is taken to mean
indeterminate PER. A QNE which cannot accurately predict the PER of
packets it is processing SHOULD set its local path PER parameter to
this value. Because the composition function limits the composed sum
to this value, receipt of this value at a network element or
application indicates that the true path PER is not known. This MAY
happen because one or more network elements could not supply a value,
or because the range of the composition calculation was exceeded.
6.2.7 <Slack Term> Parameter [RFC2212, RFC2215]
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| 7 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Slack Term [S] (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Slack term S MUST be nonnegative and is measured in microseconds.
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The Slack term, S, is represented as a 32-bit integer. Its value
can range from 0 to (2**32)-1 microseconds.
6.2.8 <Preemption Priority> & <Defending Priority> Parameters
[RFC3181]
The coding for the <Preemption Priority> & <Defending Priority>
sub-parameters is as follows:
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|0|r| 8 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preemption Priority | Defending Priority |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Preemption Priority: The priority of the new flow compared with the
defending priority of previously admitted flows. Higher values
represent higher priority.
Defending Priority: Once a flow is admitted, the preemption priority
becomes irrelevant. Instead, its defending priority is used to
compare with the preemption priority of new flows.
As specified in [RFC3181], <Preemption Priority> and <Defending
Priority> are 16-bit integer values and both MUST be populated if the
parameter is used.
6.2.9 <Admission Priority> Parameter [Y.1571]
The coding for the <Admission Priority> parameter is as follows:
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|0|r| 9 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Admis.Priority| (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
High priority flows, normal priority flows, and best-effort priority
flows can have access to resources depending on their admission
priority value, as described in [Y.1571], as follows:
Admission Priority:
0 - best-effort priority flow
1 - normal priority flow
2 - high priority flow
255 - not used
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A reservation without an <Admission Priority> parameter (i.e.,
set to 255) MUST be treated as a reservation with an <Admission
Priority> = 1.
6.2.10 <RPH Priority> Parameter [RFC4412]
The coding for the <RPH Priority> parameter is as follows:
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|0|r| 10 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RPH Namespace | RPH Priority | (Reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[RFC4412] defines a resource priority header (RPH) with parameters
"RPH Namespace" and "RPH Priority" combination, and if populated is
applicable only to flows with high admission priority, as follows:
RPH Namespace:
0 - dsn
1 - drsn
2 - q735
3 - ets
4 - wps
255 - not used
RPH Priority:
Each namespace has a finite list of relative priority-values. Each
is listed here in the order of lowest priority to highest priority
(note that dsn and drsn priority values are TBD):
4 - q735.4
3 - q735.3
2 - q735.2
1 - q735.1
0 - q735.0
4 - ets.4
3 - ets.3
2 - ets.2
1 - ets.1
0 - ets.0
4 - wps.4
3 - wps.3
2 - wps.2
1 - wps.1
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0 - wps.0
Note that the <Admission Priority> parameter MAY be used in
combination with the <RPH Priority> parameter, which depends on the
supported QOSM. Furthermore, if more then one RPH namespace is
supported by a QOSM, then the QOSM MUST specify how the mapping
between the priorities belonging to the different RPH namespaces are
mapped to each other.
Note also that additional work is needed to communicate these flow
priority values to bearer-level network elements
[VERTICAL-INTERFACE].
For the 4 priority parameters, the following cases are permissible
(procedures specified in references):
1 parameter: <Admission Priority> [Y.1571]
2 parameters: <Admission Priority>, <RPH Priority> [RFC4412]
2 parameters: <Preemption Priority>, <Defending Priority> [RFC3181]
3 parameters: <Preemption Priority>, <Defending Priority>,
<Admission Priority> [3GPP-1, 3GPP-2, 3GPP-3]
4 parameters: <Preemption Priority>, <Defending Priority>,
<Admission Priority>, <RPH Priority> [3GPP-1, 3GPP-2,
3GPP-3]
It is permissible to have <Admission Priority> without <RPH
Priority>, but not permissible to have <RPH Priority> without
<Admission Priority> (alternatively <RPH Priority> is ignored in
instances without <Admission Priority>).
eMLPP-like functionality (as defined in [3GPP-1, 3GPP-2]) specifies
use of <Admission Priority> corresponding to the 'queuing allowed'
part of eMLPP as well as <Preemption/Defending Priority>
corresponding to the 'preemption capable' and 'may be preempted'
parts of eMLPP.
6.2.11 <Excess Treatment> Parameter
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|0|r| 11 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Excess Trtmnt | Remark Value | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Excess Treatment: Indicates how the QNE SHOULD process out-of-profile
traffic, that is, traffic not covered by the <Traffic> parameter.
The excess treatment parameter is set by the QNI. It cannot be
overwritten. Allowed values are as follows:
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0: drop
1: shape
2: remark
3: no metering or policing is permitted
The default excess treatment in case that none is specified is that
there are no guarantees to excess traffic, i.e. a QNE can do whatever
it finds suitable.
When excess treatment is set to 'drop', all marked traffic MUST be
dropped by the QNE/RMF.
When excess treatment is set to 'shape', it is expected that the
QoS Desired object carries a TMOD parameter. Excess traffic
is to be shaped to this TMOD. When the shaping causes
unbounded queue growth at the shaper traffic can be dropped.
When excess treatment is set to 'remark', the excess treatment
parameter MUST carry the remark value, and the remark values and
procedures MUST be specified in the QOSM specification document.
For example, packets may be remarked to drop remarked to pertain to a
particular QoS class". In the latter case, remarking relates to a
DiffServ-type model, where packets arrive marked as belonging to a
certain QoS class, and when they are identified as excess, they
should then be remarked to a different QoS Class.
If 'no metering or policing is permitted' is signaled, the QNE should
accept the excess treatment parameter set by the sender with special
care so that excess traffic should not cause a problem. To request
the Null Meter [RFC3290] is especially strong, and should be used
with caution.
A NULL metering application [RFC2997] would not include the traffic
profile, and conceptually it should be possible to support this with
the QSPEC. A QSPEC without a traffic profile is not excluded by the
current specification. However, note that the traffic profile is
important even in those cases when the excess treatment is not
specified, e.g., in negotiating bandwidth for the best effort
aggregate. However, a "NULL Service QOSM" would need to be specified
where the desired QNE Behavior and the corresponding QSPEC format are
described.
As an example behavior for a NULL metering, in the properly
configured DiffServ router, the resources are shared between the
aggregates by the scheduling disciplines. Thus, if the incoming rate
increases, it will influence the state of a queue within that
aggregate, while all the other aggregates will be provided sufficient
bandwidth resources. NULL metering is useful for best effort and
signaling data, where there is no need to meter and police this data
as it will be policed implicitly by the allocated bandwidth and,
possibly, active queue management mechanism.
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6.2.12 <PHB Class> Parameter [RFC3140]
The coding for the <PHB Class> parameter is as follows:
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|0|r| 12 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSCP |0 0 0 0 0 0 0 0 0 0| (Reserved) |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
As prescribed in RFC 3140, the encoding for a single PHB is the
recommended DSCP value for that PHB, left-justified in the 16 bit
field, with bits 6 through 15 set to zero.
The encoding for a set of PHBs is the numerically smallest of the set
of encodings for the various PHBs in the set, with bit 14 set to 1.
(Thus for the AF1x PHBs, the encoding is that of the AF11 PHB, with
bit 14 set to 1.)
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DSCP |0 0 0 0 0 0 0 0 X 0|
+---+---+---+---+---+---+---+---+
PHBs not defined by standards action, i.e., experimental or local use
PHBs as allowed by [RFC2474]. In this case an arbitrary 12 bit PHB
identification code, assigned by the IANA, is placed left-justified
in the 16 bit field. Bit 15 is set to 1, and bit 14 is zero for a
single PHB or 1 for a set of PHBs. Bits 12 and 13 are zero.
0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PHD ID CODE |0 0 X 0|
+---+---+---+---+---+---+---+---+
Bits 12 and 13 are reserved either for expansion of the PHB
identification code, or for other use, at some point in the future.
In both cases, when a single PHBID is used to identify a set of PHBs
(i.e., bit 14 is set to 1), that set of PHBs MUST constitute a PHB
Scheduling Class (i.e., use of PHBs from the set MUST NOT cause
intra-microflow traffic reordering when different PHBs from the set
are applied to traffic in the same microflow). The set of AF1x PHBs
[RFC2597] is an example of a PHB Scheduling Class. Sets of PHBs
that do not constitute a PHB Scheduling Class can be identified by
using more than one PHBID.
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The registries needed to use RFC 3140 already exist, see
[DSCP-REGISTRY, PHBID-CODES-REGISTRY]. Hence, no new registry needs
to be created for this purpose.
6.2.13 <DSTE Class Type> Parameter [RFC4124]
The coding for the <DSTE Class Type> parameter is as follows:
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|0|r| 13 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|DSTE Cls. Type | (Reserved) |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
DSTE Class Type: Indicates the DSTE class type. Values currently
allowed are 0, 1, 2, 3, 4, 5, 6, 7. A value of 255 (all 1's) means
that the <DSTE Class Type> parameter is not used.
6.2.14 <Y.1541 QoS Class> Parameter [Y.1541]
The coding for the <Y.1541 QoS Class> parameter is as follows:
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|0|r| 14 |r|r|r|r| 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Y.1541 QoS Cls.| (Reserved) |
+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
Y.1541 QoS Class: Indicates the Y.1541 QoS Class. Values currently
allowed are 0, 1, 2, 3, 4, 5, 6, 7. A value of 255 (all 1's) means
that the <Y.1541 QoS Class> parameter is not used.
Class 0:
Mean delay <= 100 ms, delay variation <= 50 ms, loss ratio <= 10^-3.
Real-time, highly interactive applications, sensitive to jitter.
Application examples include VoIP, Video Teleconference.
Class 1:
Mean delay <= 400 ms, delay variation <= 50 ms, loss ratio <= 10^-3.
Real-time, interactive applications, sensitive to jitter.
Application examples include VoIP, Video Teleconference.
Class 2:
Mean delay <= 100 ms, delay variation unspecified, loss ratio <=
10^-3. Highly interactive transaction data. Application examples
include signaling.
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Class 3:
Mean delay <= 400 ms, delay variation unspecified, loss ratio <=
10^-3. Interactive transaction data. Application examples include
signaling.
Class 4:
Mean delay <= 1 sec, delay variation unspecified, loss ratio <=
10^-3. Low Loss Only applications. Application examples include
short transactions, bulk data, video streaming.
Class 5:
Mean delay unspecified, delay variation unspecified, loss ratio
unspecified. Unspecified applications. Application examples include
traditional 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.
7. Security Considerations
The 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)
8. IANA Considerations
This section defines the registries and initial codepoint assignments
for the QSPEC template, in accordance with BCP 26 RFC 2434 [RFC2434].
It also defines the procedural requirements to be followed by IANA in
allocating new codepoints.
This specification creates the following registries with the
structures as defined below:
Object Types (12 bits):
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The following values are allocated by this specification:
0-4: assigned as specified in Section 6:
Object Type = 0: QoS Desired
= 1: QoS Available
= 2: QoS Reserved
= 3: Minimum QoS
The allocation policies for further values are as follows:
5-63: Standards Action
64-127: Private/Experimental Use
128-4095: Reserved
(Note: 'Reserved' just means 'do not give these out'.)
QSPEC Version (4 bits):
The following value is allocated by this specification:
0: assigned to Version 0 QSPEC
The allocation policies for further values are as follows:
1-15: Standards Action
A specification is required to depreciate, delete, or modify QSPEC
versions.
QSPEC Type (8 bits):
The following values are allocated by this specification:
0: Initiator QSPEC
1: Local QSPEC
The allocation policies for further values are as follows:
2-63: Standards Action
64-255: Reserved
QSPEC Procedure (8 bits):
Broken down into
Message Sequence (4 bits):
The following values are allocated by this specification:
0-2: assigned as specified in Section 6.1:
Message Sequence 0:
Semantic: QSPEC Procedure = Sender-Initiated Reservations
(see Section 5.3.1)
Message Sequence 1:
Semantic: QSPEC Procedure = Receiver-Initiated Reservations
(see Section 5.3.2)
Message Sequence 2:
Semantic: QSPEC Procedure = Resource Queries (see Section 6.4.3)
The allocation policies for further values are as follows:
3-15: Standards Action
Object Combination (4 bits):
The following values are allocated by this specification:
The Object Combination field can take the values between
1 and 3 indicated in the tables in Section 6:
Message Sequence: 0
Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.1
Message Sequence: 1
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Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.2
Message Sequence: 2
Object Combination: 1, 2, 3
Semantic: see table in Section 5.3.3
The allocation policies for further values are as follows:
3-15: Standards Action
A specification is required to depreciate, delete, or modify QSPEC
Procedures.
Error Code (16 bits)
The allocation policies are as follows:
0-127: Specification Required
128-255: Private/Experimental Use
255-65535: Reserved
A specification is required to depreciate, delete, or modify Error
Codes.
Parameter ID (12 bits):
The following values are allocated by this specification:
1-14: assigned as specified in Section 6.2:
Parameter ID 1: <TMOD-1>
2: <TMOD-2>
3: <Path Latency>
4: <Path Jitter>
5: <Path PLR>
6: <Path PER>
7: <Slack Term>
8: <Preemption Priority> & <Defending Priority>
9: <Admission Priority>
10: <RPH Priority>
11: <Excess Treatment>
12: <PHB Class>
13: <DSTE Class Type>
14: <Y.1541 QoS Class>
The allocation policies for further values are as follows:
15-63: Standards Action (for QSPEC parameters)
64-127: Specification Required (for QSPEC parameters)
128-255: Private/Experimental Use
255-4095: Reserved
A specification is required to depreciate, delete, or modify
Parameter IDs. Note that if additional QSPEC parameters are
defined in the future, this requires a standards action equivalent to
reissuing this document as a QSPEC-bis.
Admission Priority Parameter (8 bits):
The following values are allocated by this specification:
0-2: assigned as specified in Section 6.2.9:
Admission Priority 0: best-effort priority flow
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1: normal priority flow
2: high priority flow
255: admission priority not used
The allocation policies for further values are as follows:
3-63: Standards Action
64-254: Reserved
RPH Namespace Parameter (16 bits):
Note that [RFC4412] creates a registry for RPH Namespace and Priority
values already (see Section 12.6 of [RFC4412]). A QSPEC registry is
also created because the assigned values are being mapped to QSPEC
parameter values. The following values are allocated by this
specification:
0-5: assigned as specified in Section 6.2.10:
The allocation policies for further values are as follows:
6-63: Standards Action
64-65535: Reserved
RPH Priority Parameter (8 bits):
dsn namespace:
The allocation policies are as follows:
0-63: Standards Action
64-255: Reserved
drsn namespace:
The allocation policies are as follows:
0-63: Standards Action
64-255: Reserved
Q735 namespace:
The following values are allocated by this specification:
0-4: assigned as specified in Section 6.2.10:
Q735 priority 4: q735.4
3: q735.3
2: q735.2
1: q735.1
0: q735.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
ets namespace:
The following values are allocated by this specification:
0-4: assigned as specified in Section 6.2.10:
ETS priority 4: ets.4
3: ets.3
2: ets.2
1: ets.1
0: ets.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
wts namespace:
The following values are allocated by this specification:
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0-4: assigned as specified in Section 6.2.10:
WPS priority 4: wps.4
3: wps.3
2: wps.2
1: wps.1
0: wps.0
The allocation policies for further values are as follows:
5-63: Standards Action
64-255: Reserved
Excess Treatment Parameter (8 bits):
The following values are allocated by this specification:
0-3: assigned as specified in Section 6.2.11:
Excess Treatment Parameter 0: drop
1: shape
2: remark
3: no metering or policing is
permitted
The allocation policies for further values are as follows:
4-63: Standards Action
64-255: Reserved
Remark Value (8 bits)
The allocation policies are as follows:
0-63: Specification Required
64-127: Private/Experimental Use
128-255: Reserved
DSTE Class Type Parameter (8 bits):
The following values are allocated by this specification:
0-7: assigned as specified in Section 6.2.13:
DSTE Class Type Parameter 0: DSTE Class Type 0
1: DSTE Class Type 1
2: DSTE Class Type 2
3: DSTE Class Type 3
4: DSTE Class Type 4
5: DSTE Class Type 5
6: DSTE Class Type 6
7: DSTE Class Type 7
The allocation policies for further values are as follows:
8-63: Standards Action
64-255: Reserved
Y.1541 QoS Class Parameter (8 bits):
The following values are allocated by this specification:
0-7: assigned as specified in Section 6.2.14:
Y.1541 QoS Class Parameter 0: Y.1541 QoS Class 0
1: Y.1541 QoS Class 1
2: Y.1541 QoS Class 2
3: Y.1541 QoS Class 3
4: Y.1541 QoS Class 4
5: Y.1541 QoS Class 5
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6: Y.1541 QoS Class 6
7: Y.1541 QoS Class 7
The allocation policies for further values are as follows:
8-63: Standards Action
64-255: Reserved
9. Acknowledgements
The authors would like to thank (in alphabetical order) David Black,
Ken Carlberg, Anna Charny, Christian Dickman, Adrian Farrel, Ruediger
Geib, Matthias Friedrich, Xiaoming Fu, Janet Gunn, Robert Hancock,
Chris Lang, Jukka Manner, Martin Stiemerling, An Nguyen, Dave Oran,
Tom Phelan, James Polk, Alexander Sayenko, John Rosenberg, Bernd
Schloer, Hannes Tschofenig, and Sven van den Bosch for their very
helpful suggestions.
10. Normative References
[3GPP-1] 3GPP TS 22.067 V7.0.0 (2006-03) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group
Services and System Aspects; enhanced Multi Level Precedence and
Preemption service (eMLPP) - Stage 1 (Release 7).
[3GPP-2] 3GPP TS 23.067 V7.1.0 (2006-03) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group Core
Network; enhanced Multi-Level Precedence and Preemption service
(eMLPP) - Stage 2 (Release 7).
[3GPP-3] 3GPP TS 24.067 V6.0.0 (2004-12) Technical Specification, 3rd
Generation Partnership Project; Technical Specification Group Core
Network; enhanced Multi-Level Precedence and Preemption service
(eMLPP) - Stage 3 (Release 6).
[GIST] Schulzrinne, H., Hancock, R., "GIST: General Internet
Signaling Transport," work in progress.
[QoS-SIG] Manner, J., et. al., "NSLP for Quality-of-Service
Signaling," work in progress.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2210] Wroclawski, J., "The Use of RSVP with IETF Integrated
Services", RFC 2210, September 1997.
[RFC2212] Shenker, S., et. al., "Specification of Guaranteed Quality
of Service," September 1997.
[RFC2215] Shenker, S., Wroclawski, J., "General Characterization
Parameters for Integrated Service Network Elements", RFC 2215, Sept.
1997.
[RFC3140] Black, D., et. al., "Per Hop Behavior Identification
Codes," June 2001.
[RFC3181] Herzog, S., "Signaled Preemption Priority Policy Element,"
RFC 3181, October 2001.
[RFC4124] Le Faucheur, F., et. al., "Protocol Extensions for Support
of Diffserv-aware MPLS Traffic Engineering," RFC 4124, June 2005.
[RFC4412] Schulzrinne, H., Polk, J., "Communications Resource
Priority for the Session Initiation Protocol(SIP)," RFC 4412,
Ash, et. al. <draft-ietf-nsis-qspec-15.txt> [Page 46]
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February 2006.
[RFC4506] Eisler, M., "XDR: External Data Representation Standard,"
RFC 4506, May 2006.
[Y.1541] ITU-T Recommendation Y.1541, "Network Performance Objectives
for IP-Based Services," February 2006.
[Y.1571] ITU-T Recommendation Y.1571, "Admission Control Priority
Levels in Next Generation Networks," July 2006.
11. Informative References
[DQOS] Cablelabs, "PacketCable Dynamic Quality of Service
Specification," CableLabs Specification PKT-SP-DQOS-I12-050812,
August 2005.
[IEEE754] Institute of Electrical and Electronics Engineers, "IEEE
Standard for Binary Floating-Point Arithmetic," ANSI/IEEE Standard
754-1985, August 1985.
[CL-QOSM] Kappler, C., "A QoS Model for Signaling IntServ
Controlled-Load Service with NSIS," work in progress.
[DSCP-REGISTRY] http://www.iana.org/assignments/dscp-registry
[NETWORK-BYTE-ORDER] Wikipedia, "Endianness,"
http://en.wikipedia.org/wiki/Endianness.
[NSIS-EXTENSIBILITY] Loughney, J., "NSIS Extensibility Model", work
in progress.
[PHBID-CODES-REGISTRY] http://www.iana.org/assignments/phbid-codes
[Q.2630] ITU-T Recommendation Q.2630.3: "AAL Type 2 Signaling
Protocol - Capability Set 3" Sep. 2003
[RFC2205] Braden, B., et. al., "Resource ReSerVation Protocol (RSVP)
-- Version 1 Functional Specification," RFC 2205, September 1997.
[RFC2434] Narten, T., Alvestrand, H., "Guidelines for Writing an
IANA Considerations Section in RFCs," RFC 3181, October 1998.
[RFC2474] Nichols, K., et. al., "Definition of the Differentiated
Services Field (DS Field) in the IPv4 and IPv6 Headers," RFC 2474,
December 1998.
[RFC2475] Blake, S., et. al., "An Architecture for Differentiated
Services", RFC 2475, December 1998.
[RFC2597] Heinanen, J., et. al., "Assured Forwarding PHB Group," RFC
2597, June 1999.
[RFC2997] Bernet, Y., et. al., "Specification of the Null Service
Type," RFC 2997, November 2000.
[RFC3140] Black, D., et. al., "Per Hop Behavior Identification
Codes," RFC 3140, June 2001.
[RFC3290] Bernet, Y., et. al., "An Informal Management Model for
Diffserv Routers," RFC 3290, May 2002.
[RFC3393] Demichelis, C., Chimento, P., "IP Packet Delay Variation
Metric for IP Performance Metrics (IPPM), RFC 3393, November 2002.
[RFC3564] Le Faucheur, F., et. al., Requirements for Support of
Differentiated Services-aware MPLS Traffic Engineering, RFC 3564,
July 2003
[RFC3726] Brunner, M., et. al., "Requirements for Signaling
Protocols", RFC 3726, April 2004.
[RMD-QOSM] Bader, A., et. al., "RMD-QOSM - The Resource Management
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in Diffserv QOS Model," work in progress.
[VERTICAL-INTERFACE] Dolly, M., Tarapore, P., Sayers, S., "Discussion
on Associating of Control Signaling Messages with Media Priority
Levels," T1S1.7 & PRQC, October 2004.
[WROCLAWSKI] Wroclawski, J., TBD.
[Y.1540] ITU-T Recommendation Y.1540, "Internet Protocol Data
Communication Service - IP Packet Transfer and Availability
Performance Parameters," December 2002.
[Y.1541-QOSM] Ash, J., et. al., "Y.1541-QOSM -- Y.1541 QoS Model for
Networks Using Y.1541 QoS Classes," work in progress.
12. Authors' Addresses
Gerald Ash (Editor)
AT&T
Room MT D5-2A01
200 Laurel Avenue
Middletown, NJ 07748, USA
Phone: +1-(732)-420-4578
Fax: +1-(732)-368-8659
Email: gash@att.com
Attila Bader (Editor)
Traffic Lab
Ericsson Research
Ericsson Hungary Ltd.
Laborc u. 1 H-1037
Budapest Hungary
Email: Attila.Bader@ericsson.com
Cornelia Kappler (Editor)
Siemens Networks GmbH & Co KG
Siemensdamm 62
Berlin 13627
Germany
Email: cornelia.kappler@siemens.com
David R. Oran (Editor)
Cisco Systems, Inc.
7 Ladyslipper Lane
Acton, MA 01720, USA
Email: oran@cisco.com
Appendix A. Mapping of QoS Desired, QoS Available and QoS Reserved of
NSIS onto AdSpec, TSpec and RSpec of RSVP IntServ
The union of QoS Desired, QoS Available and QoS Reserved can provide
all functionality of the objects specified in RSVP IntServ, however
it is difficult to provide an exact mapping.
In RSVP, the Sender TSpec specifies the traffic an application is
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going to send (e.g. TMOD). The AdSpec can collect path
characteristics (e.g. delay). Both are issued by the sender. The
receiver sends the FlowSpec which includes a Receiver TSpec
describing the resources reserved using the same parameters as the
Sender TSpec, as well as a RSpec which provides additional IntServ
QoS Model specific parameters, e.g. Rate and Slack.
The RSVP TSpec/AdSpec/RSpec seem quite tailored to receiver-initiated
signaling employed by RSVP, and the IntServ QoS Model. E.g. to the
knowledge of the authors it is not possible for the sender to specify
a desired maximum delay except implicitly and mutably by seeding the
AdSpec accordingly. Likewise, the RSpec is only meaningfully sent in
the receiver-issued RSVP RESERVE message. For this reason our
discussion at this point leads us to a slightly different mapping of
necessary functionality to objects, which should result in more
flexible signaling models.
Appendix B. Change History & Open Issues
B.1 Change History (since Version -04)
Version -05:
- fixed <QOSM hops> in Sec. 5 and 6.2 as discussed at Interim Meeting
- discarded QSPEC parameter <M> (Maximum packet size) since MTU
discovery is expected to be handled by procedure currently defined
by PMTUD WG
- added "container QSPEC parameter" in Sec. 6.1 to augment encoding
efficiency
- added the 'tunneled QSPEC parameter flag' to Sections 5 and 6
- revised Section 6.2.2 on SIP priorities
- added QSPEC procedures for "RSVP-style reservation", resource
queries and bidirectional reservations in Sec. 7.1
- reworked Section 7.2
Version -06:
- defined "not-supported flag" and "tunneled parameter flag"
(subsumes "QSPEC parameter flag")
- defined "error flag" for error handling
- updated bit error rate (BER) parameter to packet loss ratio (PLR)
parameter
- added packet error ratio (PER) parameter
- coding checked by independent expert
- coding updated to include RE flags in QSPEC objects and MENT flags
in QSPEC parameters
Version -07:
- added text (from David Black) on DiffServ QSPEC example in Section
6
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- re-numbered QSPEC parameter IDs to start with 0 (Section 7)
- expanded IANA Considerations Section 9
Version -08:
- update to 'RSVP-style' reservation in Section 6.1.2 to mirror what
is done in RSVP
- modified text (from David Black) on DiffServ QSPEC example in
Section 6.2
- update to general QSPEC parameter formats in Section 7.1 (length
restrictions, etc.)
- re-numbered QSPEC parameter IDs in Section 7.2
- modified <Excess Treatment> parameter values in Section 7.2.2
- update to reservation priority Section 7.2.7
- specify the 3 "STATS" in the <Path Jitter> parameter, Section
7.2.9.4
- minor updates to IANA Considerations Section 9
Version -09:
- remove the DiffServ example in Section 6.2 (intent is use text as a
basis for a separate DIFFSERV-QOSM I-D)
- update wording in example in Section 4.3, to reflect use of default
QOSM and QOSM selection by QNI
- make minor changes to Section 7.2.7.2, per the exchange on the list
- add comment on error codes, after the first paragraph in Section
4.5.1
Version -10:
- rewrote Section 2.0 for clarity
- added clarifications on QSPEC parameters in Section 4.2; added
discussion of forwarding options when a domain supports a different
QOSM than the QNI
- expanded Section 4.5 on error code handling, including redefined
E-Flag and editorial changes to the N-Flag and T-Flag discussions
- made some editorial clarifications in Section 4.6 on defining new
mandatory (QSPEC) parameters, and also reference the
[NSIS-EXTENSIBILITY] document
- Section 4.7 added to identify what a QOSM specification document
must include
- clarified the requirements in Section 5.0 for defining a new QSPEC
Version
- made editorial changes to Section 6, and added procedures for
handling preemption
- removed QOSM ID assignments in Section 9.0; clarified procedures
for defining new QSPEC parameters; added registry of QOSM error
codes
Version -11:
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- 'QSPEC-1 parameter' replaces 'mandatory QSPEC parameter'
- 'QSPEC-2 parameter' replaces 'optional QSPEC parameter'
- R-flag ('remapped parameter flag') introduced to denote remapping,
approximating, or otherwise not strictly interpreting a QSPEC
parameter
- T-flag ('tunneled parameter flag') eliminated and incorporated
within the R-flag
- Section 4 rewritten on QOSM concept, QSPEC processing, etc. to
provide a more logical flow of information
- read-write/read-only flag associated with QSPEC objects eliminated
and object itself defined as rw or ro without a flag
- <Non QOSM Hop> parameter redefined as non-QOSM-hop Q-flag
- Section 7 on QSPEC parameter definitions revised to clearly
separate QSPEC parameter coding from QSPEC parameter coding
- <Traffic>, <QoS Class>, and <Priority> QSPEC parameters mapped
to container parameters
- references updated to include normative references defining
procedures to 'strictly interpret' each QSPEC parameter
- Section 7.2.1 on PHB class updated to specify additional RFC 3140
cases
- Section 7.2.1 on excess treatment updated to specify excess
treatment behaviors
Version -12:
- Sections 4, 5, 6: Many editorial changes and rearrangements
- Moved example of QSPEC processing to Appendix A
- Section 7.2.2: Changed <Traffic Parameter> from a variable
length to a fixed length parameter
Version -13:
- notion of QOSMs played down
o language e.g. 'QNSLP/QSPEC can signal for different QOSMs across
multiple domains' replaced by notion that 'QNSLP/QSPEC allows
QNEs on the path to implement different data plane QoS mechanisms
that meet QSPEC constraints'
o a QOSM describes common capabilities among QNEs to act
consistently when requested to admit traffic & in treating
admitted traffic
o a QOSM ID need not be defined or signaled
o a QNE need not support any particular QOSM although a QNI
normally includes a QSPEC corresponding to a particular QOSM
- a 'QOSM specification'
o still provides a rigorous specification of a QOSM & what it does
o documents how a QNE interprets & treats various elements in QSPEC
o can define additional QSPEC parameters
- updated QOSM definition:
a method to achieve QoS for a traffic flow, e.g., IntServ
Controlled Load; specifies what sub-set of QSPEC QoS constraints &
traffic handling directives a QNE implementing that QOSM is capable
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of supporting & how resources will be managed by the RMF
- QSPEC1/QSPEC2 semantics replaced with following semantics:
o source traffic description (mandatory to include by QNI &
mandatory to interpret by downstream QNEs)
> specified by traffic model (TMOD-1) parameter consisting of
rate (r), bucket size (b), peak rate (p), minimum policed unit
(m) (mathematically complete way to describe traffic source)
> bandwidth only set r=p; b/m to large values (separate
bandwidth parameter not needed)
> TMOD-2 (optional to include)
o constraints (optional to include):
> Path Latency
> Path Jitter
> Path PLR
> Path PER
> Slack Term
> Priority (Preemption, Defending, Admission, RPH Priority)
o handling directives (optional to include):
> Excess Treatment
o traffic classifiers (optional to include):
> PHB Class (PHB class set by downstream QNE to tell QNI how to
mark traffic to ensure treatment committed by admission
control)
> DSTE Class Type
> Y.1541 QoS class
o eliminated:
> Bandwidth
> Ctot, Dtot, Csum, Dsum
- concept of remapping QSPEC parameters eliminated
- redefine 'interpret' a QSPEC parameter to mean 'must conform to
RFCs defining parameter & procedures (formerly called 'strictly
interpret')
- concept of local QSPECs retained
o allows simpler control plane in a local domain
o edge nodes
> must interpret initiator QSPEC parameters
> can either initiate parallel session with local QSPEC or
define a local QSPEC with encapsulated initiator QSPEC
o local QSPEC interpreted by local domain QNEs
o local QSPEC must be consistent with initiator QSPEC
> e.g., RMD can initiate a local QSPEC that contains TMOD =
bandwidth (sets r=p, b/m to large)
- QSPEC flags modified as follows:
o QNI sets M flag for each QSPEC parameter it populates that must
be interpreted or reservation fails
o if M flag set
> downstream QNE MUST interpret parameter or reservation fails
> if QNE does not support parameter it sets N flag & rejects
reservation
> if QNE supports parameter but cannot meet parameter, it sets E
flag & rejects reservation
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o if M flag not set
> downstream QNE SHOULD interpret parameter
> if QNE does not support parameter it sets the N flag &
optionally accepts or rejects reservation
> if QNE supports parameter but cannot meet parameter, it sets E
flag & optionally accepts or rejects reservation
o R (remapped parameter) flag & Q (non QOSM) flag eliminated
Version -14:
- Section 4.3.3 added text that QOSM specifications SHOULD NOT define
new RMF functions
- Section 5.1 added text that both mechanisms can be used
simultaneously: a) tunneling a QSPEC through a local domain and b)
defining a local QSPEC and encapsulating the initiator QSPEC
- Section 4.1 added text that signaling functionality is only defined
by the QoS NSLP document
- Section 4.1 added text that QOSMs are free to extend QSPECs by
adding parameters but are not permitted to reinterpret or redefine
the standard QSPEC parameters specified in this document
Version -15:
- editorial revisions made to Sections 4.1, 4.3.3, 5.3.1, 5.3.2, and
5.3.3 according to agreements on NSIS discussion list archive.
B.2 Open Issues
None.
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Ash, et. al. <draft-ietf-nsis-qspec-15.txt> [Page 53]
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