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 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, and 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 learn the current status of any Internet-Draft, please check the ``1id-abstracts.txt'' listing contained in the internet-drafts Shadow Directories on ds.internic.net (US East Coast), nic.nordu.net (Europe), ftp.isi.edu (US West Coast), or munnari.oz.au (Pacific Rim). 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page i] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page ii] Internet Draft Integrated Services Over LANs February 1997 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page 1] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 2] Internet Draft Integrated Services Over LANs February 1997 - 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 3] Internet Draft Integrated Services Over LANs February 1997 - 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 4] Internet Draft Integrated Services Over LANs February 1997 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page 5] Internet Draft Integrated Services Over LANs February 1997 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page 6] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 7] Internet Draft Integrated Services Over LANs February 1997 - 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page 8] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 9] Internet Draft Integrated Services Over LANs February 1997 +-------------------------+ | +--------+ +------+ | | |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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 10] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 11] Internet Draft Integrated Services Over LANs February 1997 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. Ghanwani, Pace, Srinivasan Expires August 1997 [Page 12] Internet Draft Integrated Services Over LANs February 1997 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 Ghanwani, Pace, Srinivasan Expires August 1997 [Page 13] Internet Draft Integrated Services Over LANs February 1997 [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, [4] J. Wroclawski, "Specification of the Controlled-Load Network Element Service," Internet Draft, November 1996, [5] S. Shenker, C. Partridge and R. Guerin, "Specification of Guaranteed Quality of Service," Internet Draft, August 1996, [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]