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Versions: 00 01 02 03 rfc2815                                           
   Internet Draft                                       M. Seaman
   Expires February 1999                                     3Com
   draft-ietf-issll-is802-svc-mapping-02.txt             A. Smith
                                                 Extreme Networks
                                                       E. Crawley
                                                   Argon Networks
                                                    J. Wroclawski
                                                          MIT LCS
                                                      August 1998

             Integrated Service Mappings on IEEE 802 Networks


   Status of this Memo

   This document is an Internet Draft.  Internet Drafts are working
   documents of the Internet Engineering Task Force (IETF), its Areas,
   and its Working Groups. Note that other groups may also distribute
   working documents as Internet Drafts.

   Internet Drafts are draft documents valid for a maximum of six
   months. Internet Drafts may be updated, replaced, or obsoleted by
   other documents at any time.  It is not appropriate to use Internet
   Drafts as reference material or to cite them other than as a "working
   draft" or "work in progress."

   To view the entire list of current Internet-Drafts, please check the
   "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
   Directories on ftp.is.co.za (Africa), ftp.nordu.net (Europe),
   munnari.oz.au (Pacific Rim), ftp.ietf.org (US East Coast), or
   ftp.isi.edu (US West Coast).

   This document is a product of the IS802 subgroup of the ISSLL working
   group of the Internet Engineering Task Force.  Comments are solicited
   and should be addressed to the working group's mailing list at
   issll@mercury.lcs.mit.edu and/or the authors.  Copyright (C) The
   Internet Society (1998). All Rights Reserved.

   Abstract

   This document describes mappings of IETF Integrated Services over
   LANs built from IEEE 802 network segments which may be interconnected
   by IEEE 802.1 MAC Bridges (switches) [1][2].

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   It describes parameter mappings for supporting Controlled Load [6]
   and Guaranteed Service [7] using the inherent capabilities of
   relevant IEEE 802 technologies and, in particular, 802.1D-1998
   queuing features in switches [2].

   These mappings are one component of the Integrated Services over IEEE
   802 LANs framework described in [5].


   1.  Introduction

   The IEEE 802.1 Interworking Task Group has developed a set of
   enhancements to the basic MAC Service provided in Bridged Local Area
   Networks (a.k.a. "switched LANs"). As a supplement to the original
   IEEE MAC Bridges standard, IEEE 802.1D-1990 [1], the updated IEEE
   802.1D-1998 [2] proposes differential traffic class queuing in
   switches and extends the capabilities of Ethernet/802.3 media to
   carry a traffic class indicator, or "user_priority" field, within
   data frames [8].

   The availability of this differential traffic queuing, together with
   additional mechanisms to provide admission control and signaling,
   allows IEEE 802 networks to support a close approximation of the
   IETF-defined Integrated Services capabilities [6][7]. This document
   describes methods for mapping the service classes and parameters of
   the IETF model into IEEE 802.1D network parameters.  A companion
   document [10] describes a signaling protocol for use with these
   mappings.  It is recommended that readers be familiar with the
   overall framework in which these mappings and signaling protocol are
   expected to be used; this framework is described fully in [5].

   Within this document, Section 2 describes the method by which end
   systems and routers bordering the IEEE Layer-2 cloud learn what
   traffic class should be used for each data flow's packets.  Section 3
   describes the approach recommended to map IP-level traffic flows to
   IEEE traffic classes within the Layer 2 network.  Section 4 describes
   the computation of Characterization Parameters by the layer 2
   network.  The remaining sections discuss some particular issues with
   the use of the RSVP/SBM signaling protocols, and describe the
   applicability of all of the above to different layer 2 network
   topologies.



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   2.  Flow Identification and Traffic Class Selection

   One model for supporting integrated services over specific link
   layers treats layer-2 devices very much as a special case of routers.
   In this model, switches and other devices along the data path make
   packet handling decisions based on the RSVP flow and filter
   specifications, and use these specifications to classify the
   corresponding data packets. The specifications could either be used
   directly, or could be used indirectly by mapping each RSVP session
   onto a layer-2 construct such as an ATM virtual circuit.

   This approach is inappropriate for use in the IEEE 802 environment.
   Filtering to the per-flow level becomes expensive with increasing
   switch speed; devices with such filtering capabilities are likely to
   have a very similar implementation complexity to IP routers, and may
   not make use of simpler mechanisms such as 802.1D user priority.

   The Integrated Services over IEEE 802 LANs framework [5] and this
   document use an "aggregated flow" approach based on use of layer 2
   traffic classes. In this model, each arriving flow is assigned to one
   of the available layer-2 classes, and traverses the 802 cloud in this
   class.  Traffic flows requiring similar service are grouped together
   into a single class, while the system's admission control and class
   selection rules ensure that the service requirements for flows in
   each of the classes are met.  In many situations this is a viable
   intermediate point between no QoS control and full router- type
   integrated services. The approach can work effectively even with
   switches implementing only the simplest differential traffic
   classification capability specified in the 802.1D model.

   In the aggregated flow model, traffic arriving at the boundary of a
   layer 2 cloud is tagged by the boundary device (end host or border
   router) with an appropriate traffic class, represented as an 802.1D
   "user_priority" value. Two fundamental questions are "who determines
   the correspondence between IP-level traffic flows and link-level
   classes?" and "how is this correspondence conveyed to the boundary
   devices that must mark the data frames?"

   One approach to answering these questions would be for the meanings
   of the classes to be universally defined. This document would then
   standardise the meanings of a set of classes; e.g. 1 = best effort, 2
   = 100 ms peak delay target, 3 = 10 ms peak delay target, 4 = 1 ms
   peak delay target, etc. The meanings of these universally defined
   classes could then be encoded directly in end stations, and the
   flow-to-class mappings computed directly in these devices.





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   This universal definition approach would be simple to implement, but
   is too rigid to map the wide range of possible user requirements onto
   the limited number of available 802.1D classes. The model described
   in [5] uses a more flexible mapping: clients ask "the network" which
   user_priority traffic class to use for a given traffic flow, as
   categorised by its flow-spec and layer-2 endpoints. The network
   provides a value back to the requester that is appropriate
   considering the current network topology, load conditions, other
   admitted flows, etc.  The task of configuring switches with this
   mapping (e.g. through network management, a switch-switch protocol or
   via some network-wide QoS-mapping directory service) is an order of
   magnitude less complex than performing the same function in end
   stations. Also, when new services (or other network reconfigurations)
   are added to such a network, the network elements will typically be
   the ones to be upgraded with new queuing algorithms etc. and can be
   provided with new mappings at this time.

   In this model, when a new session or "flow" requiring QoS support is
   created, a client must ask "the network" which user_priority traffic
   class to use for a given traffic flow, so that it can label the
   packets of the flow as it places them into the network. A
   request/response protocol is needed between client and network to
   return this information. The request can be piggy-backed onto an
   admission control request and the response can be piggy-backed onto
   an admission control acknowledgment. This "one pass" assignment has
   the benefit of completing the admission control transaction in a
   timely way and reducing the exposure to changing conditions that
   could occur if clients cached the knowledge for extensive periods. A
   set of extensions to the RSVP protocol for communicating this
   information have been defined[10].

   The network (i.e. the first network element encountered downstream
   from the client) must then answer the following questions:


   1. Which of the available traffic classes would be appropriate for
        this flow?
        In general, a newly arriving flow might be assigned to a number
        of classes. For example, if 10ms of delay is acceptable, the
        flow could potentially be assigned to either a 10ms delay class
        or a 1ms delay class. This packing problem is quite difficult to
        solve if the target parameters of the classes are allowed to
        change dynamically as flows arrive and depart.  It is quite
        simple if the target parameters of each class is held fixed, and
        the class table is simply searched to find a class appropriate





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        for the arriving flow. This document adopts the latter approach.


   2. Of the appropriate traffic classes, which if any have enough
        capacity available to accept the new flow?
        This is the admission control problem. It is necessary to
        compare the level of traffic currently assigned to each class
        with the available level of network resources (bandwidth,
        buffers, etc), to ensure that adding the new flow to the class
        will not cause the class's performance to go below its target
        values. This problem is compounded because in a priority queuing
        system adding traffic to a higher-priority class can affect the
        performance of lower-priority classes. The admission control
        algorithm for a system using the default 802 priority behavior
        must be reasonably sophisticated to provide acceptable results.

        If an acceptable class is found, the network returns the chosen
        user_priority value to the client.

        Note that the client may be an end station, a router at the edge
        of the layer 2 network, or a first switch acting as a proxy for
        a device that does not participate in these protocols for
        whatever reason. Note also that a device e.g. a server or router
        may choose to implement both the "client" as well as the
        "network" portion of this model so that it can select its own
        user_priority values. Such an implementation would generally be
        discouraged unless the device has a close tie-in with the
        network topology and resource allocation policies. It may,
        however, work acceptably in cases where there is known over-
        provisioning of resources.


   3.  Choosing a flow's IEEE 802 user_priority class

   This section describes the method by which IP-level flows are mapped
   into appropriate IEEE user_priority classes. The IP-level services
   considered are Best Effort, Controlled Load, and Guaranteed Service.

   The major issue is that admission control requests and application
   requirements are specified in terms of a multidimensional vector of
   parameters e.g. bandwidth, delay, jitter, service class.  This
   multidimensional space must be mapped onto a set of traffic classes
   whose default behaviour in L2 switches is unidimensional (i.e. strict
   priority default queuing). This priority queuing alone can provide
   only relative ordering between traffic classes. It can neither





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   enforce an absolute (quantifiable) delay bound for a traffic class,
   nor can it discriminate amongst Int-Serv flows within the aggregate
   in a traffic class. Therefore, it cannot provide the absolute control
   of packet loss and delay required for individual Int-Serv flows.

   To provide absolute control of loss and delay three things must
   occur:


   (1)  The amount of bandwidth available to the QoS-controlled flows
        must be known, and the number of flows admitted to the network
        (allowed to use the bandwidth) must be limited.

   (2)  A traffic scheduling mechanism is needed to give preferential
        service to flows with lower delay targets.

   (3)  Some mechanism must ensure that best-effort flows and QoS
        controlled flows that are exceeding their Tspecs do not damage
        the quality of service delivered to in-Tspec QoS controlled
        flows. This mechanism could be part of the traffic scheduler, or
        it could be a separate policing mechanism.

        For IEEE 802 networks, the first function (admission control) is
        provided by a Subnet Bandwidth Manager, as discussed below. We
        use the link-level user_priority mechanism at each switch and
        bridge to implement the second function (preferential service to
        flows with lower delay targets). Because a simple priority
        scheduler cannot provide policing (function three), policing for
        IEEE networks is generally implemented at the edge of the
        network by a layer-3 device. When this policing is performed
        only at the edges of the network it is of necessity approximate.
        This issue is discussed further in [5].


   3.1.  Context of admission control and delay bounds

   As described above, it is the combination of priority-based
   scheduling and admission control that creates quantified delay
   bounds. Thus, any attempt to quantify the delay bounds expected by a
   given traffic class has to made in the context of the admission
   control elements. Section 6 of the framework [5] provides for two
   different models of admission control - centralized or distributed
   Bandwidth Allocators.

   It is important to note that in this approach it is the admission





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   control algorithm that determines which of the Int-Serv services is
   being offered. Given a set of priority classes with delay targets, a
   relatively simple admission control algorithm can place flows into
   classes so that the bandwidth and delay behavior experienced by each
   flow corresponds to the requirements of the Controlled-Load service,
   but cannot offer the higher assurance of the Guaranteed service. To
   offer the Guaranteed service, the admission control algorithm must be
   much more stringent in its allocation of resources, and must also
   compute the C and D error terms required of this service.

   A delay bound can only be realized at the admission control element
   itself so any delay numbers attached to a traffic class represent the
   delay that a single element can allow for.  That element may
   represent a whole L2 domain or just a single L2 segment.

   With either admission control model, the delay bound has no scope
   outside of a L2 domain. The only requirement is that it be understood
   by all Bandwidth Allocators in the L2 domain and, for example, be
   exported as C and D terms to L3 devices implementing the Guaranteed
   Service. Thus, the end-to-end delay experienced by a flow can only be
   characterized by summing along the path using the usual RSVP
   mechanisms.


   3.2.  Default service mappings

   Table 1 presents the default mapping from delay targets to IEEE 802.1
   user_priority classes. However, these mappings must be viewed as
   defaults, and must be changeable.

   In order to simplify the task of changing mappings, this mapping
   table is held by *switches* (and routers if desired) but generally
   not by end-station hosts.  It is a read-write table. The values
   proposed below are defaults and can be overridden by management
   control so long as all switches agree to some extent (the required
   level of agreement requires further analysis).

   In future networks this mapping table might be adjusted dynamically
   and without human intervention. It is possible that some form of
   network-wide lookup service could be implemented that serviced
   requests from clients e.g. traffic_class = getQoSbyName("H.323
   video") and notified switches of what traffic categories they were
   likely to encounter and how to allocate those requests into traffic
   classes. Alternatively, the network's admission control mechanisms
   might directly adjust the mapping table to maximize the utilization





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   of network resources. Such mechanisms are for further study.

            user_priority  Service
              0            Default, assumed to be Best Effort
              1            reserved, "less than" Best Effort
              2            reserved
              3            reserved
              4            Delay Sensitive, no bound
              5            Delay Sensitive, 100ms bound
              6            Delay Sensitive, 10ms bound
              7            Network Control

       Table 1 - Example user_priority to service mappings

   The delay bounds numbers proposed above are for per-Bandwidth
   Allocator element delay targets and are derived from a subjective
   analysis of the needs of typical delay-sensitive applications e.g.
   voice, video. See Annex H of [2] for further discussion of the
   selection of these values. Although these values appear to address
   the needs of current video and voice technology, it should be noted
   that there is no requirement to adhere to these values and no
   dependence of IEEE 802.1 on these values.

   Note: These mappings are believed to be useful defaults but further
   implementation and usage experience is required. The mappings may be
   refined in future editions of this document.

   With this example set of mappings, delay-sensitive, admission
   controlled traffic flows are mapped to user_priority values in
   ascending order of their delay bound requirement. Note that the
   bounds are targets only - see [5] for a discussion of the effects of
   other non-conformant flows on delay bounds of other flows. Only by
   applying admission control to higher-priority classes can any
   promises be made to lower-priority classes.

   This set of mappings also leaves several classes as reserved for
   future definition.

   Note: this mapping does not dictate what mechanisms or algorithms a
   network element (e.g. an Ethernet switch) must perform to implement
   these mappings: this is an implementation choice and does not matter
   so long as the requirements for the particular service model are met.

   Note: these mappings apply primarily to networks constructed from
   devices that implement the priority-scheduling behavior defined as





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   the default in 802.1D. Some devices may implement more complex
   scheduling behaviors not based only on priority. In that circumstance
   these mappings might still be used, but other, more specialized
   mappings may be more appropriate.


   3.3.  Discussion

   The recommendation of classes 4, 5 and 6 for Delay Sensitive,
   Admission Controlled flows is somewhat arbitrary; any classes with
   priorities greater than that assigned to Best Effort can be used.
   Those proposed here have the advantage that, for transit through
   802.1D switches with only two-level strict priority queuing, all
   delay-sensitive traffic gets "high priority" treatment (the 802.1D
   default split is 0-3 and 4-7 for a device with 2 queues).

   The choice of the delay bound targets is tuned to an average expected
   application mix, and might be retuned by a network manager facing a
   widely different mix of user needs. The choice is potentially very
   significant: wise choice can lead to a much more efficient allocation
   of resources as well as greater (though still not very good)
   isolation between flows.

   Placing Network Control traffic at class 7 is necessary to protect
   important traffic such as route updates and network management.
   Unfortunately, placing this traffic higher in the user_priority
   ordering causes it to have a direct effect on the ability of devices
   to provide assurances to QoS controlled application traffic.
   Therefore, an estimate of the amount of Network Control traffic must
   be made by any device that is performing admission control (e.g.
   SBMs). This would be in terms of the parameters that are normally
   taken into account by the admission control algorithm. This estimate
   should be used in the admission control decisions for the lower
   classes (the estimate is likely to be a configuration parameter of
   SBMs).

   A traffic class such as class 1 for "less than best effort" might be
   useful for devices that wish to dynamically "penalty tag" all of the
   data of flows that are presently exceeding their allocation or Tspec.
   This provides a way to isolate flows that are exceeding their service
   limits from flows that are not, to avoid reducing the QoS delivered
   to flows that are within their contract. Data from such tagged flows
   might also be preferentially discarded by an overloaded downstream
   device.
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   A somewhat simpler approach would be to tag only the portion of a
   flow's packets that actually exceed the Tspec at any given instant as
   low priority. However, it is often considered to be a bad idea to
   treat flows in this way as it will likely cause significant re-
   ordering of the flow's packets, which is not desirable. Note that the
   default 802.1D treatment of user_priorities 1 and 2 is "less than"
   the default class 0.


   4.  Computation of integrated services characterization parameters by
   IEEE 802 devices

   The integrated service model requires that each network element that
   supports integrated services compute and make available certain
   "characterization parameters" describing the element's behavior.
   These parameters may be either generally applicable or specific to a
   particular QoS control service.  These parameters may be computed by
   calculation, measurement, or estimation. When a network element
   cannot compute its own parameters (for example, a simple link), we
   assume that the device sending onto or receiving data from the link
   will compute the link's parameters as well as it's own.

   The accuracy of calculation of these parameters may not be very
   critical; in some cases loose estimates are all that is required to
   provide a useful service. This is important in the IEEE 802 case,
   where it will be virtually impossible to compute parameters
   accurately for certain topologies and switch technologies. Indeed, it
   is an assumption of the use of this model by relatively simple
   switches (see [5] for a discussion of the different types of switch
   functionality that might be expected) that they merely provide values
   to describe the device and admit flows conservatively.

   The discussion below presents a general outline for the computation
   of these parameters, and points out some cases where the parameters
   must be computed accurately. Further specification of how to export
   these parameters is for further study.


   4.1.  General characterization parameters

   There are some general parameters [9] that a device will need to use
   and/or supply for all service types:

   *    Ingress link





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   *    Egress links and their MTUs, framing overheads and minimum
        packet sizes (see media-specific information presented above).

   *    available path bandwidth: updated hop-by-hop by any device along
        the path of the flow.

   *    minimum latency

        Of these parameters, the MTU and minimum packet size information
        must be reported accurately. Also, the "break bits" must be set
        correctly, both the overall bit that indicates the existence of
        QoS control support and the individual bits that specify support
        for a particular scheduling service. The available bandwidth
        should be reported as accurately as possible, but very loose
        estimates are acceptable. The minimum latency parameter should
        be determined and reported as accurately as possible if the
        element offers Guaranteed service, but may be loosely estimated
        or reported as zero if the element offers only Controlled-Load
        service.


   4.2.  Parameters to implement Guaranteed Service

   A network element supporting the Guaranteed Service must be able to
   determine the following parameters [7]:

   *    Constant delay bound through this device (in addition to any
        value provided by "minimum latency" above) and up to the
        receiver at the next network element for the packets of this
        flow if it were to be admitted.  This includes any access
        latency bound to the outgoing link as well as propagation delay
        across that link. This value is advertised as the "C" parameter
        of the Guaranteed Service.

   *    Rate-proportional delay bound through this device and up to the
        receiver at the next network element for the packets of this
        flow if it were to be admitted.  This value is advertised as the
        "D" parameter of the Guaranteed Service.

   *    Receive resources that would need to be associated with this
        flow (e.g. buffering, bandwidth) if it were to be admitted and
        not suffer packet loss if it kept within its supplied
        Tspec/Rspec. These values are used by the admission control
        algorithm to decide whether a new flow can be accepted by the
        device.





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   *    Transmit resources that would need to be associated with this
        flow (e.g. buffering, bandwidth, constant- and rate-proportional
        delay bounds) if it were to be admitted. These values are used
        by the admission control algorithm to decide whether a new flow
        can be accepted by the device.

   The exported characterization parameters for this service should be
   reported as accurately as possible. If estimations or approximations
   are used, they should err in whatever direction causes the user to
   receive better performance than requested. For example, the C and D
   error terms should overestimate delay, rather than underestimate it.


   4.3.  Parameters to implement Controlled Load

   A network element implementing the Controlled Load service must be
   able to determine the following [6]:

   *    Receive resources that would need to be associated with this
        flow (e.g. buffering) if it were to be admitted. These values
        are used by the admission control algorithm to decide whether a
        new flow can be accepted by the device.

   *    Transmit resources that would need to be associated with this
        flow (e.g. buffering) if it were to be admitted. These values
        are used by the admission control algorithm to decide whether a
        new flow can be accepted by the device.

   The Controlled Load service does not export any service-specific
   characterization parameters. Internal resource allocation estimates
   should ensure that the service quality remains high when considering
   the statistical aggregation of Controlled Load flows into 802 traffic
   classes.


   4.4.  Parameters to implement Best Effort

   For a network element that implements only best effort service there
   are no explicit parameters that need to be characterized. Note that
   an integrated services aware network element that implements only
   best effort service will set the "break bit" described in [11].








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   5.  Merging of RSVP/SBM objects

   Where reservations that use the SBM protocol's TCLASS object [10]
   need to be merged, an algorithm needs to be defined that is
   consistent with the mappings to individual user_priority values in
   use in the network.

   A merged reservation must receive at least as good a service as the
   best of the component reservations. In the circumstances considered
   here, this translates into placing the merged reservation into the
   lowest delay class of those that could be used for the individual
   reservations.

   For the example mappings proposed in this document, the merging
   device should merge to the "highest" priority value of the values
   received in TCLASS objects of the PATH/RESV messages where "highest"
   is defined as follows:

              Lowest  ------->   Highest
                1, 2, 0, 3, 4, 5, 6, 7

   Note: this counter-intuitive ordering is an artifact of the *default*
   relative treatment of user_priority values in the IEEE 802.1D
   specification (see Annex H of [2]). If a device has been configured
   to apply non-default treatment of user_priority values then it should
   adjust this merging operation accordingly.



   6.  Applicability of these service mappings

   Switches using layer-2-only standards (e.g. 802.1D-1990, 802.1D-
   1998) need to inter-operate with routers and layer-3 switches. Wide
   deployment of such 802.1D-1998 switches will occur in a number of
   roles in the network: "desktop switches" provide dedicated 10/100
   Mbps links to end stations and high speed core switches often act as
   central campus switching points for layer-3 devices. Layer-2 devices
   will have to operate in all of the following scenarios:

   *    every device along a network path is layer-3 capable and
        intrusive into the full data stream

   *    only the edge devices are pure layer-2





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   *    every alternate device lacks layer-3 functionality

   *    most devices lack layer-3 functionality except for some key
        control points such as router firewalls, for example.

   Where int-serv flows pass through equipment which does not support
   Integrated Services or 802.1D traffic management and which places all
   packets through the same queuing and overload-dropping paths, it is
   obvious that some of a flow's desired service parameters become more
   difficult to support. In particular, the two integrated service
   classes studied here, Controlled Load and Guaranteed Service, both
   assume that flows will be policed and kept "insulated" from
   misbehaving other flows or from best effort traffic during their
   passage through the network. This cannot be done within an IEEE 802
   network using devices with the default user_priority function; in
   this case policing must be approximated at the network edges.

   In addition, in order to provide a Guaranteed Service, *all*
   switching elements along the path must participate in special
   treatment for packets in such flows: where there is a "break" in
   guaranteed service, all bets are off. Thus, a network path that
   includes even a single switch transmitting onto a shared or half-
   duplex LAN segment is unlikely to be able to provide a very good
   approximation to Guaranteed Service. For Controlled Load service, the
   requirements on the switches and link types are less stringent
   although it is still necessary to provide differential queueing and
   buffering in switches for CL flows over best effort in order to
   approximate CL service. Note that users receive indication of such
   breaks in the path through the "break bits" described in [11]. These
   bits must be correctly set when IEEE 802 devices that cannot provide
   a specific service exist in a network.

   Other approaches might be to pass more information between switches
   about the capabilities of their neighbours and to route around non-
   QoS-capable switches: such methods are for further study. And of
   course the easiest solution of all is to upgrade links and switches
   to higher capacities.











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   7.  References

   [1]  "MAC Bridges", ISO/IEC 10038, ANSI/IEEE Std 802.1D-1993

   [2]  "Information technology - Telecommunications and information
        exchange between systems - Local and metropolitan area networks
        - Common specifications - Part 3: Media Access Control (MAC)
        Bridges: Revision (Incorporating IEEE P802.1p: Traffic Class
        Expediting and Dynamic Multicast Filtering", ISO/IEC Final CD
        15802-3 IEEE P802.1D/D15, November 1997

   [3]  Clark, D. et al. "Integrated Services in the Internet
        Architecture: an Overview" RFC1633, June 1994

   [4]  Braden, R., L. Zhang, S. Berson, S. Herzog, S. Jamin, "Resource
        Reservation Protocol (RSVP) - Version 1 Functional
        Specification", RFC 2205, September 1997

   [5]  Ghanwani, A., Pace, W., Srinivasan, V., Smith, A., Seaman, M.,
        "A Framework for Providing Integrated Services Over Shared and
        Switched LAN Technologies", Internet Draft, March 1998 <draft-
        ietf-issll-is802-framework-04>

   [6]  Wroclawski, J., "Specification of the Controlled-Load Network
        Element Service", RFC 2211, September 1997

   [7]  Schenker, S., Partridge, C., Guerin, R., "Specification of
        Guaranteed Quality of Service", RFC 2212 September 1997

   [8]
        "IEEE Standards for Local and Metropolitan Area Networks: for
        Virtual Bridged Local Area Networks", March 1998, IEEE Draft
        Standard P802.1Q/D10

   [9]  Shenker, S., Wroclawski, J., "General Characterization
        Parameters for Integrated Service Network Elements", RFC 2215,
        September 1997

   [10] Yavatkar, R., Hoffman, D., Bernet, Y., Baker, F., Speer, M.,
        "SBM (Subnet Bandwidth Manager): A Protocol for Admission
        Control over IEEE 802-style Networks", Internet Draft, March
        1998 <draft-ietf-issll-sbm-06>

   [11] Wroclawski, J., "The use of RSVP with IETF Integrated Services",
        RFC 2210, September 1997.





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   8.  Security Considerations

   Any use of QoS requires examination of security considerations
   because it leaves the possibility open for denial of service or theft
   of service attacks. This document introduces no new security issues
   on top of those discussed in the companion ISSLL documents [5] and
   [10].  Any use of these service mappings assumes that all requests
   for service are authenticated appropriately.


   9. Acknowledgments

   This document draws heavily on the work of the ISSLL WG of the IETF
   and the IEEE P802.1 Interworking Task Group.





   9.  Authors' Addresses

        Mick Seaman
        3Com Corp.
        5400 Bayfront Plaza
        Santa Clara CA 95052-8145
        USA
        +1 (408) 764 5000
        mick_seaman@3com.com

        Andrew Smith
        Extreme Networks
        10460 Bandley Drive
        Cupertino CA 95014
        USA
        +1 (408) 863 2821
        andrew@extremenetworks.com

        Eric Crawley
        Argon Networks
        25 Porter Rd.
        Littleton MA 01460
        USA
        +1 (978) 486 0665
        esc@argon.com




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        John Wroclawski
        MIT Laboratory for Computer Science
        545 Technology Sq.
        Cambridge, MA  02139
        USA
        +1 (617) 253 7885
        jtw@lcs.mit.edu




   Table of Contents

   1 Introduction .................................................    2
   2 Flow Identification and Traffic Class Selection ..............    3
   3 Choosing a flow's IEEE 802 user_priority class ...............    5
   3.1 Context of admission control and delay bounds ..............    6
   3.2 Default service mappings ...................................    7
   3.3 Discussion .................................................    9
   4  Computation  of   integrated   services   characterization
        parameters by IEEE 802 devices ............................   10
   4.1 General characterization parameters ........................   10
   4.2 Parameters to implement Guaranteed Service .................   11
   4.3 Parameters to implement Controlled Load ....................   12
   4.4 Parameters to implement Best Effort ........................   12
   5 Merging of RSVP/SBM objects ..................................   13
   6 Applicability of these service mappings ......................   13
   7 References ...................................................   15
   8 Security Considerations ......................................   16
   9 Authors' Addresses ...........................................   16


















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