Internet Engineering Task Force A. Ghanwani
INTERNET DRAFT J. W. Pace
V. Srinivasan
IBM
February 1997
A Framework for Providing Integrated Services
Over Shared and Switched LAN Technologies
draft-ietf-issll-is802-framework-00.txt
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Abstract
Traditionally, LAN technologies such as ethernet and token ring have
been required to handle best effort services only. No standard
mechanism exists for providing bandwidth or delay guarantees on these
media. It is therefore not possible to provide guaranteed quality
of service as will be required by emerging and future multimedia
applications. The anticipated demand for real-time applications
on the Internet has led to the development of RSVP, a signaling
mechanism for performing resource reservation in the Internet.
Concurrently, the Integrated Services working group within the
IETF has been working on the definition of service classes called
"Integrated Services" which are expected to make use of RSVP.
Applications will use these service classes in order to obtain the
desired quality of service from the network. LAN technologies
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such as token ring and ethernet typically constitute the last hop
in Internet connections. There is therefore a need to enhance
these technologies so that they are able to support the Integrated
Services. In order to enable such services, it is necessary to
provide a resource management functions. This memo describes a
framework for providing the necessary functionality on shared and
switched LAN technologies.
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1. Introduction
The Internet has traditionally provided support for best effort
traffic only. However, with the recent advances in link layer
technology, and with numerous emerging real-time applications such
as video conferencing, Internet telephony, etc, there has been much
interest for supporting real-time services over the Internet. These
new requirements have led to the development of RSVP [3], a signaling
mechanism for providing resource reservation on the Internet. The
protocol is currently being standardized by the IETF. Simultaneously,
the Integrated Services working group of the IETF has been working on
the specification of various service classes. Each of these service
classes is designed to provide certain Quality of Service (QoS)
guarantees to traffic conforming to a specified set of parameters.
Applications are expected to use one of these classes depending on
their QoS requirements.
Legacy LAN technologies such as ethernet and token ring currently
lack the necessary functionality to support real-time traffic. They,
however, typically constitute the last mile between users and the
Internet backbone of campus networks. Furthermore, the development
of standards for high speed LANs such as gigabit ethernet favors the
likelihood that these technologies will eventually be deployed in the
backbone. It is therefore necessary to enhance these technologies so
that they are able to support end-to-end service guarantees such as
those defined by the Integrated Services.
In order to support real-time services, there must be some mechanism
for resource management at the link level. The ISSLL (Integrated
Services over Specific Link Layers) working group was chartered with
the purpose of exploring such mechanisms for various link layer
technologies. Resource management in this context encompasses the
functions of admission control, scheduling, traffic policing, path
selection, etc.
This document is concerned with specifying a framework for providing
Integrated Services over LAN technologies such as ethernet and
token ring. We begin by defining the scope of the solution to be
developed. A taxonomy of Layer 2 topologies is discussed with an
emphasis on the capabilities of each which can be leveraged for
enabling integrated services over these topologies. Next, the
requirements and goals for a resource management mechanism capable of
providing Integrated Services in a subnet are listed and discussed.
These functions will be provided by an entity which is referred to
as the Bandwidth Manager. We then discuss the various components
of the Bandwidth Manager. No assumptions have been made about the
technology or topology at the link layer. The framework is intended
to be as exhaustive as possible; this means that it is possible that
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all the functions discussed may not be supportable by a particular
topology/technology, but this should not preclude the usage of this
model for the technology.
2. Supporting Integrated Services Within a Subnet: Requirements and
Goals
This section discusses the requirements and goals which should drive
the design of an architecture for supporting Integrated Services
over legacy LAN technologies. The requirements refer to functions
and features which must be supported, while goals refer to functions
and features which are desirable, but are not an absolute necessity.
Many of the requirements and goals are driven by the functionality
supported by RSVP.
2.1. Requirements
- Resource Reservation: The mechanism must be capable of reserving
resources on a single segment or multiple segments and at
bridges/switches connecting them. It must be able to provide
reservations for both unicast and multicast sessions. It should
be possible to change the level of reservation while the session
is in progress.
- Admission Control: The mechanism must be able to estimate the
level of resources necessary to meet the QoS for a session based
on the existing reservations in order to decide whether or not
the session can be admitted. It should also be possible for a
host to query about the availability of resources. It must be
able to provide different types of QoS such as guaranteed delay,
guaranteed bandwidth, etc.
- Flow Separation and Scheduling: It is necessary to provide a
mechanism for traffic flow separation so that real-time flows can
be given preferential treatment over best effort flows. Packets
of real-time flows can then be isolated and scheduled according
to their service requirements. Scheduling algorithms can range
from simple static priority queueing to more complex algorithms
such as weighted fair queueing.
- Policing: Traffic policing must be performed in order to ensure
that sources adhere to their negotiated traffic specifications.
Policing must be implemented at the sources and must ensure
that violating traffic is either dropped or transmitted as best
effort.
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- Fault Tolerance and Recovery: The mechanism must be able to
function in the presence of failures; i.e. there should not be a
single point of failure. Back-up and failure recovery mechanisms
must be provided.
- Synchronization: There should be some mechanism for resolving
synchronization and deadlock issues. For instance, the case
where multiple sessions simultaneously request resources on a
common part of the network must be correctly handled.
- Soft state reservations: The mechanism must maintain soft-state
information about the reservations. This means that reservations
must be periodically refreshed if the reservation is to be
maintained; otherwise the reservation will expire after some
pre-specified interval.
- Centralized or distributed implementation: In the case of a
centralized implementation, a single entity manages the resources
of the entire subnet. This approach avoids synchronization and
deadlock problems but will not scale to subnets with a large
number of hosts. In a fully distributed implementation, each
segment will have a separate entity managing its resources. This
approach is scalable, but requires synchronization. Ideally,
implementation should be flexible; i.e. a centralized approach
may be used for small subnets and distributed approach, where
one or more segments is managed by a single entity, can be used
for larger subnets. Examples of centralized and distributed
implementations are discussed in Section 4.
- Network Management: The MIBs supported must be specified.
- Interaction with Existing Resource Management Controls: The
interaction with existing infrastructure would need to be
specified. For instance, FDDI has resource management with
its "Synchronous Bandwidth Manager". The BM for FDDI must be
designed so that it takes advantage of this.
2.2. Goals
- Independence from higher layer protocols: The mechanism should
be independent of higher layer protocols such as RSVP and IP.
Independence from RSVP is desirable so that it can interwork with
other reservation protocols such as STII. Independence from IP is
desirable so that it can interwork with protocols such as IPX,
NetBIOS, etc.
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- Receiver heterogeneity: The mechanism should support
heterogeneous receiver groups; i.e. the level of reservation may
be different for different receivers of a multicast group.
- Support for different filter styles: It is desirable to provide
support for the different filter as defined by RSVP such as fixed
filter, shared explicit and shared wildcard.
- Scalability: The mechanism and protocols should have a low
overhead and should scale to large receiver groups.
- Path Selection: In a bridged or switched LAN, it may be
worthwhile to do path selection, where possible, for a given
source-destination in order to utilize resources in an efficient
manner. Along with other mechanisms, such as source routing in
token ring networks and bridge filtering, path selection can
ensure optimum utilization of network resources. Frames will
appear only on those segments on which there are designated
receivers, or when the segment is on the path between the sender
and receiver.
3. Legacy LAN Topologies and Their Features
We are concerned with specifying a framework for Integrated
Services over legacy LAN technologies. These technologies include
ethernet/IEEE 802.3, token ring/IEEE 802.5 and FDDI. The extent to
which real-time services can be supported on a network depend to a
large degree on the available functions for providing priority media
access as well as the ability to identify packets of real-time flows
so that they can be given preferential treatment. This section
discusses some of the capabilities of these LAN technologies and
provides a taxonomy of topologies.
The basic topology of a legacy LAN network may be shared, switched
half duplex or switched full duplex. In the shared topology,
multiple stations may be connected to a single segment. Contention
for media access is resolved using protocols such as CSMA/CD in
ethernet and token passing in token ring and FDDI. Switched half
duplex, is essentially a shared topology with the restriction that
only a single station is attached per bridge/switch port, i.e. there
are only two stations contending for resources on any segment.
This topology is fast becoming popular with the need for increased
bandwidth. Finally, in a switched full duplex topology, there is a
single station per switch port and the media allows for full duplex
operation. Therefore, in this topology, there is no access control
such as CSMA/CD or token passing.
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Another important element in the discussion of topologies is the
ability to support priority handling of traffic. Priority provides
a coarse method for isolation between flows and allows opens the
possibility to easily support scheduling algorithms which give
preferential treatment to high priority flows. These functions are
key requirements as pointed out in Section 2. Native ethernet/802.3
does not include support for priority. Token ring/802.5 and FDDI on
the other hand support up to eight levels of priority. Three bits
of the frame control field are used for carrying the frame priority.
Equally important in token ring networks are the notions of reserved
priority and access priority. Reserved priority relates to the value
of priority which a station uses to reserve the token for the next
transmission on the ring. When a free token is circulating, only
those stations having an access priority greater than or equal to the
reserved priority in the token will be allowed to seize the token
for transmission. More recently, the IEEE 802.1 Standards Committee
has been working on the standards for expedited traffic classes in
bridges/switches [1]. The proposed standard requires a new frame
format for ethernet which carry three bits to indicate the frame
priority. This allows for the support of eight traffic classes.
The standard does not specify scheduling algorithms between traffic
classes, and indeed, a bridge/switch need not implement separate
queues for each traffic class.
Depending on the basic topology used and the ability to support
priority, there are six possible scenarios as follows:
1. Shared topology without priority: This category includes pure
shared media such as ethernet and legacy 802.3 networks which
are multi-access technologies with no support for priority media
access. A special case of this topology is one where only a
single device is attached to the port in the network. Shared
topology without priority offers no capability for isolation
between reserved/unreserved flows. No service guarantees can be
provided for this scenario.
2. Shared topology with priority: This category includes
ethernet/802.3 networks which implement the emerging IEEE 802.1p
standard, token ring/802.5 networks and FDDI networks. However,
shared ethernet with frame priority may offer limited support
for priority access because of the CSMA/CD protocol; at best
loose statistical service guarantees may be possible. On the
other hand, deterministic guarantees can be provided for token
ring media if the frame priority, reserved priority and access
priority are used in conjunction with appropriate hardware.
3. Switched half duplex topology without priority: This scenario
is a special case of shared topology without priority where
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there are only two device per segment (an end station and a
bridge/switch or two bridges/switches). This allows for higher
bandwidth per station. Due to the absence of priority and
the CSMA/CD protocol, little can be done to isolate flows for
scheduling.
4. Switched half duplex topology with priority: This scenario is
a special case of shared topology with priority but there are
now only two devices per segment. This reduces the contention
for resources. Ethernet/802.3 with this topology will likely
be able to support some statistical service guarantees. More
deterministic guarantees will be possible for token ring/802.5
media.
5. Switched full duplex topology without priority: This scenario
includes switched ethernet where the CSMA/CD protocol is no
longer used and full duplex operation is possible. Because
priority is not available, again, it is not possible to provide
flow isolation between best effort and reserved flows.
6. Switched full duplex topology with priority: This category is
similar to the above, but frame priority is also available This
topology provides best capabilities for priority access and, at
the very least, enables a coarse level of flow separation based
on frame priority and static priority scheduling.
There is also the possibility of hybrid topologies where two or more
of the above coexist. For instance, it is possible that within a
single subnet, there are some bridges/switches which support priority
and some which do not. If the flow in question traverses both kinds
of bridges/switches in the network, the least common denominator
will prevail. In other words, for that flow, the network will be
considered to be of the less capable of the topologies.
4. Architecture for Integrated Services in Legacy LANs
The functional requirements described in Section 2 will be performed
by an entity which we refer to as the Bandwidth Manager (BM). The BM
is responsible for providing mechanisms for an application (1) to
request QoS from the network. The major components of the BM are
discussed below.
----------------------------
1. We use "application" to indicate any higher layer protocol or
application
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4.1. Requester Module
The requester module (RM) provides an interface between higher layer
protocols (such as RSVP, STII, etc.) and the bandwidth manager. It
provides a set of primitives which define the mechanism by which the
various services of the BM are invoked. For instance, the higher
layer protocol will initiate the resource reservation at layer 2 by
providing the RM with the traffic descriptors and desired quality
of service. The RM then communicates with the other components of
the BM to perform admission control. The function of the RM must be
provided in every device (e.g. host, router) which might need to
initiate the resource reservation at the link layer.
4.2. Bandwidth Allocator
The bandwidth allocator (BA) is responsible for performing admission
control and tracking the allocation of resources in the subnet. A
host can request various services, e.g. bandwidth reservation,
changes in reservation, queries about resource availability, etc.
The communication between the host and the BA will take place
through the RM. The location of the BA will depend largely on the
implementation method. In a centralized implementation, the BA
may reside on a single station in the subnet. In a distributed
implementation, the functions of the BA may be provided in all the
hosts and bridges/switches as necessary.
4.3. Communication Protocols and Primitives
The protocols and primitives for communication between the various
components of the BM must be specified. These include the following:
- Communication between the higher layer protocols and the RM:
The BM must define primitives for the application to initiate
reservations, query the BA about available resources, and
change or delete reservations, etc. These primitives could be
implemented as an API for an application to invoke functions of
the BM via the RM.
- Communication between the RM and the BA: A protocol must be
defined for the communication between the RM and the BA. This
protocol will specify the messages which must be exchanged
between the RM and the BA in order to service various requests
by the application. Additionally, the protocol must specify a
method by which a RM can send a query message which will trigger
a response from its BA.
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- Communication between peer BAs: If there is more than one BA in
the subnet, a means must be specified for inter-BA communication.
Specifically, the BAs must be able to decide among themselves
about which BA would be responsible for which segments and
bridges or switches. Further, if a request is made for resource
reservation along the domain of multiple BAs, the BAs must be
able to handle such a scenario correctly. Inter-BA communication
will also be required to handle failures. When a BA fails,
another BA should assume its responsibility.
4.4. Implementation Scenarios
Example scenarios are provided below showing the location of the
the components of the bandwidth manager in centralized and fully
distributed implementations. Note that in either case, the RM
must be present on all end-stations/hosts which desire to make
reservations. Essentially, centralized or distributed refers to the
implementation of the BA, the component responsible for resource
reservation and admission control. In the figures below, "App"
refers to the application making use of the BM. It could either be a
user application, or a higher layer protocol process such as RSVP.
+---------+
.-->| BA |<--.
/ +---------+ \
/ .-->| Layer 2 |<--. \
/ / +---------+ \ \
/ / \ \
/ / \ \
+---------+ / / \ \ +---------+
| App |<----- /-/---------------------------\-\----->| App |
+---------+ / / \ \ +---------+
| RM |<----. / \ .--->| RM |
+---------+ / +---------+ +---------+ \ +---------+
| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |
+---------+ +---------+ +---------+ +---------+
RSVP Host/ Intermediate Intermediate RSVP Host/
Router Bridge/Switch Bridge/Switch Router
Figure 1: Bandwidth Manager with a centralized Bandwidth Allocator
Figure 1 shows a centralized implementation. Each host would contain
an RM. Intermediate bridges and switches in the network need not have
any functions of the BM since they will not be actively participating
in admission control. The RM at the station requesting a reservation
initiates communication with its BA. With this approach, the end
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host must be able to identify its BA. For larger subnets, a single
BA may not be able to handle the reservations for the entire subnet.
In that case it would be necessary to deploy multiple BAs, each
managing the resources of a non-overlapping subset of segments. In a
centralized implementation, the BA must maintain topology information
in order to be able to reserve resources on appropriate segments.
+---------+ +---------+
| App |<-------------------------------------------->| App |
+---------+ +---------+ +---------+ +---------+
| RM/BA |<------>| BA |<------>| BA |<------>| RM/BA |
+---------+ +---------+ +---------+ +---------+
| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |
+---------+ +---------+ +---------+ +---------+
RSVP Host/ Intermediate Intermediate RSVP Host/
Router Bridge/Switch Bridge/Switch Router
Figure 2: Bandwidth Manager with a fully distributed Bandwidth
Allocator
Figure 2 depicts the scenario of a fully distributed bandwidth
manager. In this case, all devices in the subnet must have some BM
functionality. All the end hosts are still required to have an RM.
In addition, all bridges and switches must participate in admission
control, but there is the possibility of relying on the link layer
for the maintenance of topology information.
Note that in the figures above, the arrows between peer layers are
used to indicate logical connectivity.
4.5. Logical Operation of the BM in Hosts/Routers and Layer 2 Domain
The figure below shows the location and logical operation of the
BM in hosts/routers and the Layer 2 domain. It is not possible to
provide an explicit example because of the inherent differences that
arise in centralized and distributed implementations discussed in
Section 4.4.
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+-------------------------+
| +--------+ +------+ |
| |Appli- <---> RM | |
| | cation | +--^---+ |
| +--------+ | | +-------------------------+
| || +--V---+ | | +------+ |
| || +------| BA <------------------------> BA | |
| || | +------+ | | +----------+ +-^-^|-+ |
| || | | | | |Forwarding| | || |
| || | | | | |Process <---+ || |
| || | | | | +---|------+ || |
| || | | | | | +---------+| |
| \/ | | | | | | | |
| +-----V-+ +--V---+ | | +---V--V+ +----V-+ |
| |Class- | |Sched-| | | |Class- | |Sched-| |
| | ifier |===>| uler |==========>| ifier |===>| uler |====>
| +-------+ +------+ | | +-------+ +------+ |
+-------------------------+ +-------------------------+
Host/Router Layer 2 Domain
----> Signaling/control
====> Data
Figure 3: The logical Operation of the BM in the hosts/routers and
the Layer 2 network.
The application, which may be RSVP or some other higher layer
reservation protocol requests resources by passing information to
the RM which includes the following: (i) MAC addresses of the
source and destination, (ii) traffic descriptors for the flow, and
(iii) quality of service desired. The RM then starts the process
of resource reservation at Layer 2 by contacting the local BA. The
local BA is responsible for admission control on the segment to which
the host/router is directly attached. If the reservation succeeds,
the local BA sets up the classifier and scheduler as required so
that the appropriate priority is used for the flow. The request
is then propagated to the the "remote" BA controlling the other
segments along the forwarding path. In a centralized implementation,
the BA resides in a server within the subnet. The classifier and
scheduler in the bridges/switches along the forwarding path are
implicitly set up by the priority carried in the data frames if the
reservation is successful. On the other hand, in a fully distributed
implementation, the remote BA resides in every bridge/switch
and the process of resource reservation would be performed on a
hop-by-hop basis. In this scenario, it would also be possible to use
sophisticated scheduling since the classifier can be explicitly set
up for each flow.
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5. Mapping Issues and Link Layer Support for IntServ Traffic Classes
As stated earlier, the Integrated Services working group has defined
many service classes offering varying degrees of QoS guarantees.
Initial effort will concentrate on enabling the controlled load
and guaranteed service classes [4,5]. The controlled load service
provides a loose guarantee, informally stated as "better than
best effort". The guaranteed service provides a delay bound which
the network guarantees will never be exceeded. The extent to
which these services can be supported at the link layer will be
technology dependent and will depend on many factors. Some of the
mapping issues in light of the emerging link layer standards are
discussed below. Further, considering the limitations of some of the
topologies under consideration, it may not be possible to satisfy
all the requirements for Integrated Services. In such cases, it is
to consider providing support for an approximation of the service
which may suffice in most practical instances. For example, it
may not be feasible to provide policing/shaping at each network
element (bridge/switch) as is specified in the controlled load
specification [4]. But if this task is left to the routers/hosts, a
good approximation to the service can be obtained.
5.1. Mapping of Services to Link Level Priority
The number of delay priorities and access methods of the technology
under consideration will determine how many and what services may be
supported. Native token ring, for instance, supports eight priority
levels while ethernet has no support for priorities. However, the
IEEE 802 standards committee is working on two new standards for
bridges related to multimedia traffic expediting, multicast filtering
and virtual LANs [1,2]. These standards allow for eight levels of
frame priority. The frame priority is signaled on an end-to-end
basis, unless overridden by bridge/switch management. Work is in
progress to address how each of these priorities will map to the
traffic classes supported by a bridge/switch; even though eight
levels of priority are allowed, a bridge/switch need not support
eight distinct service classes.
The priority that is used by a flow should depend on the quality
of service desired and whether the reservation was successful or
not. A flow, therefore should use the priority which best effort
traffic would use until told otherwise by the signaling mechanism.
The signaling mechanism will, upon successful completion of resource
reservation, specify the frame priority which the source must use.
More details on exact mapping of priorities to services is beyond
the scope of this document and will be a a part of another document
dedicated to addressing mapping issues.
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5.2. Supporting Receiver Heterogeneity
Receiver heterogeneity means that receivers within a group can each
have different QoS requirements; i.e. it is possible that, for a
given flow, some receivers make a reservation while others decide
to make use of best effort transport. RSVP allows heterogeneous
receivers within a group. However, handling the problem at layer
2 can be non-trivial. Consider for instance, the scenario in the
figure below.
+-----+
| R1 |
+-----+
|
v
+-----+ +-----+ +-----+
| R2 |<-----| SW |----->| R3 |
+-----+ +-----+ +-----+
Figure 4: An instance of receiver heterogeneity. R1 is the source.
R2 is a receiver which makes a reservation, and R3 is a receiver
which is satisfied with best effort service. SW is a Layer 2 device
(bridge/switch) participating in resource reservation.
In the figure above, R1 is the upstream router/source and R2 and R3
are downstream routers/destinations. R2 sends a RESV message to
reserve resources for the flow. R3 would like to simply receive
the flow using best effort transport. R1 sends PATH messages which
are multicast to both R2 and R3. R2 sends a RESV message to R1
requesting the reservation of resources. If the reservation is
successful at Layer 2, the frames addressed to the group will have a
high priority corresponding to the service requested by R3. At SW,
there must be some mechanism which forwards the packet using high
priority at the interface to R3 while using the priority for best
effort traffic at the interface to R2. This may involve changing the
contents of the frame itself, or ignoring the frame priority at the
interface to R2. Another possibility for supporting heterogeneous
receivers would be to have separate groups, one for each class of
receivers.
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5.3. Support for Different Reservation Styles
+-----+ +-----+ +-----+
| R1 | | R2 | | R3 |
+-----+ +-----+ +-----+
| | |
| v |
| +-----+ |
+--------->| SW |<---------+
+-----+
|
v
+-----+
| R4 |
+-----+
Figure 5: An illustration of filter styles. R1, R2, R3 and R4 are
RSVP hosts/routers which are members of the same group. SW is a
bridge/switch at Layer 2.
In the figure above, R1, R2 and R3 are upstream routers/sources. R4
is the downstream router/destination which is the receiver for all of
these flows. RSVP allows receiver R4 to specify reservations which
can apply to: (a) one specific sender only (fixed filter); (b) any
of two or more explicitly specified senders (shared explicit filter);
(c) any sender in the group (shared wildcard filter). Support for
the fixed filter is relatively straightforward. However, support for
the the other two styles has implications regarding policing; i.e.
the merged flows from the different sources should be policed so that
they conform to traffic parameters specified in the filter's Rspec.
6. Summary
This document has specified a framework for providing Integrated
Services over shared and switched LAN technologies. The ability to
provide QoS guarantees necessitates some form of admission control
and resource management. The requirements and goals of a resource
management scheme for subnets have been identified and discussed.
We refer to the entire resource management scheme as a Bandwidth
Manager. Architectural considerations were discussed and examples
were provided to illustrate possible implementations of a Bandwidth
Manager. Some of the issues involved in mapping the services from
higher layers to Layer 2 were discussed.
References
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[1] IEEE Standards for Local and Metropolitan Area Networks:
Draft Standard for Traffic Class and Dynamic Multicast Filtering
Services in Bridged Local Area Networks (Draft Supplement to
802.1D), P802.1p/D4, September, 1996.
[2] IEEE Standards for Local and Metropolitan Area Networks:
Draft Standard for Virtual Bridged Local Area Networks,
P802.1Q/D4, January, 1997.
[3] B. Braden, L. Zhang, S. Berson, S. Herzog and S. Jamin,
"Resource Reservation Protocol (RSVP) - Version 1 Functional
Specification," Internet Draft, November 1996,
<draft-ietf-rsvp-spec-14.txt>
[4] J. Wroclawski, "Specification of the Controlled-Load Network
Element Service," Internet Draft, November 1996,
<draft-ietf-intserv-ctrl-load-svc-04.txt>
[5] S. Shenker, C. Partridge and R. Guerin, "Specification of
Guaranteed Quality of Service," Internet Draft, August 1996,
<draft-ietf-intserv-guaranteed-svc-06.txt>
[6] R. Braden, D. Clark and S. Shenker, "Integrated Services in the
Internet Architecture: An Overview," RFC 1633, June 1994.
Acknowledgements
Much of the work presented in this document has benefited greatly
from discussion held at the meetings of the Integrated Services over
Specific Link Layers (ISSLL) working group. In particular we would
like to thank Eric Crawley, Don Hoffman, Mick Seaman, Andrew Smith
and Raj Yavatkar who have contributed to this effort via earlier
Internet drafts.
Authors' Address
Anoop Ghanwani
IBM Corporation
P. O. Box 12195
Research Triangle Park, NC 27709
Phone: +1-919-254-0260
Fax: +1-919-254-5410
Email: anoop@raleigh.ibm.com
Wayne Pace
Ghanwani, Pace, Srinivasan Expires August 1997 [Page 14]
Internet Draft Integrated Services Over LANs February 1997
IBM Corporation
P. O. Box 12195
Research Triangle Park, NC 27709
Phone: +1-919-254-4930
Fax: +1-919-254-5410
Email: pacew@raleigh.ibm.com
Vijay Srinivasan
IBM Corporation
P. O. Box 12195
Research Triangle Park, NC 27709
Phone: +1-919-254-2730
Fax: +1-919-254-5410
Email: vijay@raleigh.ibm.com
Ghanwani, Pace, Srinivasan Expires August 1997 [Page 15]
