H. T. Kung, T. Blackwell, and A. Chapman, "Credit UPdate Protocol for Flow-Controlled ATM Networks: Statistical Multiplexing and Adaptive Credit Allocation," Proc. ACM SIGComm `94 Conference, University College, London, August, 1994.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....for the single connection case. Section 6 analyzes the proposed scheme s performance for the multiple connection case through exampies. The paper concludes with Section 7. 2 Rate vs. Credit, and Interworking The principles and control mechanisms of the rate and credit schemes are detailed in [1] and [3] Here, we focus on comparing them in terms of structures and performance and arguing for the need to integrate them. The rate scheme regulates a connection s bandwidth by directly controlling its source cell transmission rate according to network congestion information. Using RM (Resource ....

H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow-controlled ATM networks: sta- tistical multiplexing and adaptive credit allocation," in Proc. of ACM SIGCOMM, pp. 101-115, 1994.

....credit cells (thus based on time) can help system recover from possible loss of credit cells, but may introduce more overhead traffic. Sending a credit cell per N data cells is more economical since it keeps overhead traffic at a fixed percentage of data traffic. However, a credit check cell [3] needs to be sent periodically to ensure the recovery from possible loss of credit cells. There are two important features for the credit scheme described above. First, the scheme ensures strict lossless transmissions since Cbal is always smaller than, or equal to, currently available buffer space ....

H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow-controlled ATM networks: statistical multiplexing and adaptive credit allocation," in Proc. of ACM SIGCOMM, pp. 101-115, 1994.

....delay products, a large window size and possibly large buffers may be required for efficient bandwidth utilization. To partially cope with large bandwidth delay products, hop by hop window flow control has been proposed (also known as credit based flow control in ATM networks , e.g. see [15]) It is commonly believed that window based 1 This work was supported by the National Science Foundation under grants NCR 91 58618 and NCR 94 15684, by the Army Research Office under grant FRI DAAH04 95 1 0248, and by the Air Force Office of Scientific Research under grant F49620 95 10538 ....

H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow controlled ATM networks: statistical multiplexing and adaptive credit allocation, " Proceedings of SIGCOMM'94, pp. 101-115.

....information on network utilization. Some networks do provide very specific feedback to endpoints on available network bandwidth as part of traffic management (flow control) The most important example is Available Bit Rate (ABR) traffic over ATM networks, where rate based [5] or credit based [7, 20] flow control tells each source how fast it can send. This information is currently only used at the ATM layer, but could be made available to higher layer protocols or applications. The challenge in designing a portable interface is to find a way to cover the entire range from currently deployed ....

Kung, H., Blackwell, T., and Chapman, A. Credit update protocol for flow-controlled ATM networks: Statistical mulitplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols (August 1994), ACM, pp. 101--114.

....host. The i960 has its own set of request and response blocks that it can use to schedule cell transmission and to send receive packets from in the shared memory. The i960 has two major functions. First, it can serve as an accelerator for such tasks as link by link per VC creditbased flow control[18, 22], ATM Forum style rate control [7] and cell scheduling algorithms on transmit that are beyond the capability of the scheduler available on the ASIC. Second, the i960 can provide direct application access to the device by validating network operations and carrying out a request reply protocol with ....

H.T. Kung, T. Blackwell, and A. Chapman. Credit update protocol for flow-controlled ATM networks: Statistical mulitplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols, pages 101--114. ACM, August 1994.

....cells. In this section we first discuss the implementation of creditbased flow control; we then briefly outline one possible implementation of rate based flow control. There are many variants of credit based flow control. They differ in granularity of the credit (incremental [1] or in bursts [7, 8, 9]) the encoding of the credit (absolute or relative) and the buffer management strategy used by the receiver (per VC buffers, statistical sharing of buffers between VCs, etc. Credit Net implements per VC flow control based on the FCVC absolute credit scheme[8] We briefly explain the algorithm, ....

H. Kung, T. Blackwell, and A. Chapman. Credit update protocol for flow-controlled ATM networks: Statistical multiplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols, pages 101--114. ACM, August 1994.

....and evaluation is limited to static tra#c patterns, i.e. the e#ect of bursty tra#c is not considered. Most papers evaluating ATM flow control algorithms are based on simulation. The papers typically compare throughput using a specific flow control algorithm with throughput without flow control [13, 15, 17], or they focus on a class of algorithms and analyze how throughput and bu#er re0 8186 7780 5 97 10.00 1997 IEEE quirements change as a function of the flow control parameters [16, 27] Several ATM Forum contributions presented simulation results based on the test suite described above [3, 6, ....

.... host processor of the virtual port card runs the CUP algorithm and performs 0 8186 7780 5 97 10.00 1997 IEEE 0 5 10 15 20 25 0510 Propagation delay (msec) Throughput (Mbps) Credit static Credit adapt EPRCA EFCI f 500 EFCI f 2500 EFCI s 500 EFCI s 2500 periodic bu#er reallocation [15]. It is similar to the QFC algorithm [9] Rate control with EFCI This case and the following one implement two variants of the ATM Forum ABR congestion control mechanism[1, 4] To make implementation easier, we have simplified the format of the resource management cell, and we have not ....

H. T. Kung, T. Blackwell, and A. Chapman. Credit update protocol for flow-controlled ATM networks: Statistical multiplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols, pages 101--114. ACM, August 1994.

....on the feedback on network congestion. So, ABR service requires a closed loop congestion control scheme, dynamically regulating the cell transmission rate of each source according to congestion status. A number of flow control schemes have been proposed for ABR service. Among these, both credit [1] and rate [2, 3] schemes have received most attention [4] The credit scheme guarantees lossless transmission by applying direct control over buffer space for each connection in a hop by hop manner. However, the credit scheme cannot make a bandwidth guarantee for each connection since it is ....

....for the single connection case. Section 6 analyzes the proposed scheme s performance for the multiple connection case through examples. The paper concludes with Section 7. 2 Rate vs. Credit, and Interworking The principles and control mechanisms of the rate and credit schemes are detailed in [1] and [3] Here, we focus on comparing them in terms of structures and performance and arguing for the need to integrate them. The rate scheme regulates a connection s bandwidth by directly controlling its source cell transmission rate according to network congestion information. Using RM (Resource ....

H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow-controlled ATM networks: statistical multiplexing and adaptive credit allocation," in Proc. of ACM SIGCOMM, pp. 101--115, 1994.

....is mostly considered at the network level as a congestion control mechanism. The source starts to send traffic and the network monitors it. If congestion is observed at a switch, a feedback information is sent back via different protocols to the source to slow down the traffic [FLM92, KMR93, KBC95] QoS adaptation at the network level, hence congestion, can be avoided if sources negotiate a rate contract with the network and using traffic shaping mechanisms the sources obey the negotiated contract [SK94, Par94] 1.3 Outline of the Paper The paper is organized as follows: Section 2 ....

H.T. Kung, T. Blackwell, and A. Chapman. Credit Update Protocol for FlowControlled ATM Networks: Statistical Multiplexing and Adaptive Credit Allocation. In ACM SIGCOMM, pages 101--115, London, UK, 1995.

....EFCI bit in the ATM cell header, or of an explicit rate calculated by the switches. A second class consists of hop by hop, credit based flow control, in which the receiver on each link provides the sender with information on buffer status for each VC. Examples include DEC AN2 [12] and Credit Net [9, 8]. An overview of these algorithms can be found in [6, 13] A class of rate based algorithms is currently being standardized by the ATM Forum [14] although several companies are still pursuing a credit based alternative called Quantum Flow Control [5] The various flow control algorithms have been ....

H.T. Kung, T. Blackwell, and A. Chapman. Credit update protocol for flow-controlled ATM networks: Statistical mulitplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols, pages 101--114. ACM, August 1994.

....information on network utilization. Some networks do provide very specific feedback to endpoints on available network bandwidth as part of traffic management (flow control) The most important example is Available Bit Rate (ABR) traffic over ATM networks, where rate based [5] or credit based [7, 19] flow control tells each source how fast it can send. This information is currently only used at the ATM layer, but could be made available to higher layer protocols or applications. The challenge in designing a portable interface is to find a way to cover the entire range from currently deployed ....

Kung, H., Blackwell, T., and Chapman, A. Credit update protocol for flow-controlled ATM networks: Statistical mulitplexing and adaptive credit allocation. In Proceedings of the SIGCOMM '94 Symposium on Communications Architectures and Protocols (August 1994), ACM, pp. 101--114.

....credit cells (thus based on time) can help system recover from possible loss of credit cells, but may introduce more overhead traffic. Sending a credit cell per N data cells is more economical since it keeps overhead traffic at a fixed percentage of data traffic. However, a credit check cell [3] needs to be sent periodically to ensure the recovery from possible loss of credit cells. There are two important features for the credit scheme described above. First, the scheme ensures strict lossless transmissions since C bal is always smaller than, or equal to, currently available buffer ....

H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow-controlled ATM networks: statistical multiplexing and adaptive credit allocation," in Proc. of ACM SIGCOMM, pp. 101--115, 1994.

....At the network level, QoS adaptation is mostly considered as a congestion control mechanism. The source starts to send traffic and the network monitors it. If congestion is observed at a switch, feedback information is sent via different protocols to the source to slow the traffic [KMR93, KBC95] Congestion at the network level, and hence QoS adaptation, can be avoided if sources negotiate a rate contract with the network and the sources obey the negotiated contract using traffic shaping mechanisms [SK94] At the application level, the existing QoS adaptation services protocols monitor ....

H.T. Kung, T. Blackwell, and A. Chapman. Credit Update Protocol for Flow-Controlled ATM Networks: Statistical Multiplexing and Adaptive Credit Allocation. In ACM SIGCOMM, pages 101--115, London, UK, 1995.

....about what modifications might improve its performance further. More basic research as to which kinds of system architectures perform better would also be facilitated by building less sensitive systems. When comparing two different flow control architectures (e.g. rate based vs. credit based [34,35]) it would be much easier if both systems would yield reliable, repeatable performance numbers in tests. Another reason why less sensitive systems should be preferred is to facilitate end user selection of the best system for a given task. For instance, someone wanting to purchase a workstation ....

H.T. Kung and T. Blackwell, A. Chapman. Credit Update Protocol for Flow-Controlled ATM Networks: Statistical Multiplexing and Adaptive Credit Allocation. In Proceedings of ACM SIGCOMM `94.

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H. T. Kung, T. Blackwell, and A. Chapman, "Credit UPdate Protocol for Flow-Controlled ATM Networks: Statistical Multiplexing and Adaptive Credit Allocation," Proc. ACM SIGComm `94 Conference, University College, London, August, 1994.

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H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow controlled ATM networks: statistical multiplexing and adaptive credit allocation," Proceedings of SIGCOMM'94, pp. 101-1115.

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H. T. Kung, T. Blackwell, and A. Chapman, "Credit update protocol for flow controlled ATM networks: statistical multiplexing and adaptive credit allocation," Proceedings of SIGCOMM'94, pp. 101-1115.

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