Zigmantas L. Budrikis

A generic flow control protocol for B-ISDN

A generic flow control (GFC) protocol is proposed to regulate multiple terminals within the broadband-ISDN customer premises network. The GFC protocol is based on multipriority distributed queuing preceded by a traffic shaping function, and meets the requirements for flexible allocation of service parameters, control of jitter and guarantee of bandwidth. This GFC protocol provides the necessary flexibility to match the constant bit rate (CBR) jitter performance and variable bit rate (VBR) service requirements to the particular service type. It integrates well with usage parameter control without imposing excessive burstiness on each virtual connection cell stream delivered to the network. By allowing connectionless users to access at the lowest priority, only when no higher priority users are queued, there is no reduction in guaranteed capacity available for other VBR and CBR users.<<ETX>>

Extended distributed queueing for integrated services

A method for supporting time-constrained and nontime-constrained integrated services on a shared dual bus network is presented. The method is an extension of the basic distributed queue protocol defined in the IEEE 802.6 distributed-queue dual-bus (DQDB) MAN standard. The extended distributed queueing protocol differs from the basic protocol in allowing more than one outstanding request in the distributed queue at any one time. Used at the high priority and in conjunction with segment stream shaping and subscribed service limiting, the extended protocol provides bearer services with guaranteed bandwidth and bounded delays. Bearer services with fair but nonguaranteed bandwidth shares, suitable for nontime-constrained applications, are provided by the same protocol and bandwidth balancing operating at the lowest priority. A number of the desirable attributes of the proposed scheme are identified including the optimality of the delay variance introduced by the access protocol. An approximate analysis of the access delay experience by time-constrained streams is presented. >

Establishing a real time VBR connection over an ATM network

The conclusion of this paper flows from the principle of delay constancy. To achieve and maintain the delay constancy in the face of variable transfer delay, a pad-out buffer is used at the destination and the consumption of the first cell is delayed by a determinable amount. We examine the conditions under which the continuity throughout the session is preserved. We also conclude that the transfer of a real variable bit rate application by a deterministic bit rate transfer capability will be indistinguishable from a transfer by a statistical bit rate transfer capability.

Internet Transfer Capabilities for Time Critical Communications

Some time-critical communications, e.g. telephony, can frequently be conducted reasonably satisfactorily over the Internet, even when packets are transferred in connectionless mode. However, for any assured service with defined bounds on packet delay and loss, packet transfers need to be connection-oriented and the connections appropriately resourced. A virtual Internet connection with specified switching procedures, traffic capacity, and quality outcomes would, in analogy to transfer capabilities in ATM networks, be a defined Internet transfer capability. With appropriate transfer capabilities, an IP network could work with, or take the place of, traditional STM and ATM networks, as well as exceed them in capability. For instance, IP networking could be superior to STM and ATM in regard to multimedia communications.

Provision of real-time services over ATM using AAL type 2

1. MSTMCT Anew ATRIAdaptation Layer (AAL) type 2 has recentiy been defied in the ~-T to provide both high efficiency transmission of lowrate, shor~ and variable length packets in deky sensitive appfimtions for use in titure ~S/ ~~2000 Radio Access Ne~orks. This paper examines how to provide variable rate voice services over an AAL type 2 channel that can be charactertied by a constant transmission delay plus variable packet mdtiplexing delays and ce~ access dekys. To compensate for the variabfity in the delays, btiers are used at the source and the destination ends of the connection. Whenever a buffer ovefiows or underflow, the continuity of data flow over the AAL connection breaks down. h the papeq we determine the minimum she of btiers required at the source and the destination ends of the connection to provide the service. We ako derive the minimum source to sink delay.

The controlled cell transfer capability

A Controlled Cell Transfer (CCT) capability has been proposed to ITU for definition in Recommendation I.371. The CCT capability, if accepted, will bring the number of ATM transfer layer capabilities to five. The other four capabilities being Deterministic Bit Rate (DBR), Statistical Bit Rate (SBR), ATM Block Transfer (ABT) and Available Bit Rate (ABR). It is believed that this capability will endow the ATM network with LAN like service over the wide area. In this article, we discuss the features and mechanisms of the proposed CCT capability. We also discuss the applications that CCT is targeted at supporting and present results of simulation studies, highlighting the advantages of CCT.

Size and speed insensitive distributed queue network

A shared medium ATM switch in the form of a distributed queue dual bus (DQDB) network is described. Access to the network is in multiple stages, a separate stage for each branch of the network. Performance of the queue protocol is affected by distance within a stage, but not by distances between stages. In consequence a DQDT network can be of arbitrary extent without thereby limiting the rate, and DQDT networks can be designed with a speed-distance product that is orders of magnitude larger than is possible for DQDB, FDDI and other high speed LANs.