Keshav S., Agrawala A. , Singh S., Design and analysis of a flow control algorithm for a network of rate allocating servers, in Protocols for High-Speed Networks II, Elsevier Science Publishers/North- Holland, April 1991.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....because connections (i.e. source destination pairs) are being set up and terminated, and because their sources do not maintain constant data rates. Recently, flow control mechanisms have been proposed where the source rate is dynamically regulated based on feedback from the intermediate nodes [4, 11, 14, 17, 19]. These so called end to end mechanisms attempt to adapt the source rate to the bottleneck rate in minimum time and with minimum packet delay or loss. Other mechanisms, referred to as gateway flow control mechanisms, determine which packets are discarded when the buffering capacity of a node is ....

....in acknowledgement packets. In the Internet TCP, the feedback consists of the arrival times (or lack of arrival) of acknowledgement packets [11] Other schemes rely on feedback information that includes average link utilization [19] interarrival times between successive acknowledgement packets [14], packet round trip delays [17] 12] etc. The feedback information is used to regulate the flow of data from the sources into the network. In rate based mechanisms, the source rate is regulated by adjusting interpacket gaps. Examples are found in the protocols NETBLT [4] VMTP [2] and XTP [3] ....

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Keshav S., Agrawala A. , Singh S., Design and analysis of a flow control algorithm for a network of rate allocating servers, in Protocols for High-Speed Networks II, Elsevier Science Publishers/North- Holland, April 1991.

....desirable to use a more structured queueing discipline that helps isolate the different TOS classes, for example, by using a separate queue for each TOS class. This concept of isolating traffic classes using structured queueing disciplines has been used recently in flow control studies, e.g. [11, 20, 6, 32, 14]. In this paper, we investigate the use of a structured queueing discipline with adaptive next hop TOS routing. Our approach We consider a simple two queue link scheduling discipline, henceforth referred to as type of service queueing. We consider two TOS: low delay and high throughput. With ....

S. Keshav, A. Agrawala, and S. Singh. Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers. In Proc. IFIP WG 6.1/WG 6.4 Second International Workshop on Protocols for High-Speed Networks, pages 55--72, Palo Alto, CA, November 1990.

....because connections (i.e. source destination pairs) are being set up and terminated, and because their sources do not maintain constant data rates. Recently, flow control mechanisms have been proposed where the source rate is dynamically regulated based on feedback from the intermediate nodes [9, 15, 37, 18, 25, 31, 13, 38, 19]. These mechanisms attempt to adapt the source rate to the bottleneck rate in minimum time and with minimum packet delay or loss. A variety of feedback schemes are possible. In the binary feedback scheme, which is used in DECNET [28] and is being advocated for ISO TP4 [23] and high speed networks ....

.... measures the times between sending a packet and receiving its acknowledgement and uses them to maintain a running roundtrip time estimate [15] Other schemes rely on feedback information that includes average link utilization [10, 31] interarrival times between successive acknowledgement packets [18], etc. There is also a variety of ways to regulate the source rate based on the feedback information. In rate based mechanisms, the source rate is regulated by adjusting interpacket gaps. Examples are found in the transport protocols NETBLT [9] and VMTP [7] although it is not clear in these ....

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S. Keshav, A. K. Agrawala, S. Singh, "Design and analysis of a flow control algorithm for a network of rate allocating servers", in Protocols for High-speed Networks II, Elsevier/North-Holland, April 1991.

....A related problem has been studied in relation to wide area networks. The problem in WANs is that the network wants to give a fair amount of bandwidth to each conversation passing over a link. Many algorithms for routing traffic fairly have been proposed for use in these wide area networks [3, 4]. These algorithms are able to support an arbitrary number of virtual networks (called conversations) but they require queues at each switch whose size is linear in the number of virtual networks. This bound is feasible for wide area networks because conversations are typically persistent, ....

Srinivasan Keshav, Ashok K. Agrawala, and Samar Singh. Design and analysis of a flow control algorithm for a network of rate allocating servers. Technical Report CS-TR-2492, University of Maryland, July 1990.

....host to another. Probes to measure round trip latency, packet loss probability, and peak bandwidth are typically done by sending groups of back to back packets to a server which echoes them back to the sender. These probes are referred to as NetDyn probes in [7] and [6] packet pair in [23] and [24], netnow probes in [30] fping probes [14] in Imeter [37] and bprobes in [10] Bprobes are used in VitalSigns NetMedic [41] product. As pointed out in earlier work on TCP dynamics [21] the spacing between these packets at the bottleneck link is preserved on higherbandwidth links and can be ....

S. Keshav, A. Agrawala, and S. Singh. Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers. In Proc. Second International Workshop on Protocols for High Speed Networks, 1990.

....to use a more structured queueing discipline that helps isolate the different TOS classes, 2 for example, by using a separate queue for each TOS class. This concept of isolating traffic classes using structured queueing disciplines has been used recently in flow control studies, e.g. 10] [11], 12] 13] 14] In this paper, we investigate the use of a structured queueing discipline with adaptive next hop TOS routing. Our approach We consider the following simple link scheduling discipline, henceforth referred to as TOS queueing. We consider two TOS classes: low delay and high ....

S. Keshav, A. Agrawala, and S. Singh, "Design and analysis of a flow control algorithm for a network of rate allocating servers", in IFIP WG 6.1/WG 6.4 Second International Workshop on Protocols for High-Speed Networks, Palo Alto, CA, November 1990, pp. 55--72.

....this method to see if max min fair throughput rates can be achieved, at least approximately, without computing the rates but without incurring large cross network delays. One approach is to dynamically adjust the window sizes so that they are no larger than necessary, as in [46] 55] Reference [56] is similar in spirit. Another possibility is to change the round robin discipline slightly, e.g. by randomly rearranging the polling order of the sessions from time to time. This might ensure that, even if small windows are used, the system enters very unfair configurations only rarely and only ....

S. Keshav, A. K. Agrawala, and S. Singh, "Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers," Proc. IFIP WG 6.1/6.2 2nd Internatl. Wkshp. on Protocols for High Speed Netwks., Nov.

....and (3) routing, which chooses routes to be taken by data packets to reach their destination. The interaction between these three components is crucial to the performance of the network. Existing work has studied the interaction between scheduling and flow control, assuming static routing (e.g. [7, 5, 6, 10, 4]) In this paper, we investigate the interaction between scheduling and adaptive routing. We consider a network supporting two traffic classes: delay sensitive traffic such as interactive traffic or real time traffic (e.g. audio) and throughput sensitive traffic such as FTP traffic. We consider ....

....routing with TOSQ converges to isolation much faster than routing with FCFS. We point out that, in general, related disciplines to TOSQ such as fair queueing [6] and other rate based scheduling disciplines 1 have shown several advantages over FCFS in their interaction with flow control (e.g. [6, 10]) Thus, gateways with such scheduling disciplines can also improve the routing by exploiting the scheduling structure when calculating link costs for the different types of service. Organization of the paper In Section 2, we give the model. In Section 3, we present a worst case analysis giving ....

S. Keshav, A. Agrawala, and S. Singh. Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers. In Proc. IFIP WG 6.1/WG 6.4 Second International Workshop on Protocols for High-Speed Networks, pages 55--72, Palo Alto, CA, November 1990.

....they are not widely implemented in current networks. The control theoretic Packet Pair Protocol, PP, monitors the service rate at the slowest (bottleneck) server in the path from the source to the destination, and uses a simple controltheoretic algorithm to adapt to changes in the service rate [12, 14]. The idea is that the source sends out all data as pairs of back to back packets, and measures the spacing between the acknowledgments. It can be shown analytically that in networks of Fair Queueing (or Round Robin like) servers, this spacing corresponds to the service rate at the bottleneck ....

S. Keshav, A. K. Agrawala and S. Singh, Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers, in Protocols for High Speed Networks II, Elsevier Science Publishers/North-Holland, April 1991.

....a common server or node, taking explicitly into account the kinds of mechanisms that operate within them. This would further illuminate the phenomena that lead to congestion. Finally, we would like to explore 2P in greater detail. A companion paper describes the implementation and simulation of 2P [KeAg90]. In conclusion, we claim that our deterministic model of a virtual circuit is both simple and powerful. Our analysis leads us naturally to a new scheme, 2P that has several desirable features. We hope to carry out a deeper analysis of 2P on the lines of this work in the future. DRAFT 30 DRAFT ....

S. Keshav, A. Agrawala and S. Singh, "Design and Analysis of Flow Control Algorithm for Networks of Rate Allocating Servers", in preparation.

....is achieved in one of two phases of queue buildup. The phase 2 buildup is as expected, and reflects the lack of information about the rate change for one round trip time. The amount of buildup is exactly the minimum predicted by multiplying the change in the service rate by the round trip time [33]. However, phase 4 buildup because of improper rate probing when several sources are in their startup phase, was somewhat unexpected. As it turns out, this effect dominates peak buffer occupancy. Fourth, we the simulations show that packet pair is robust to large changes in service rate, large ....

S. Keshav, A. K. Agrawala and S. Singh, Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers, in Protocols for High Speed Networks II, Elsevier Science Publishers/North-Holland, April 1991.

....the network state be observable. In recent work, we have shown that it is possible to measure network state easily if the servers at the output queues of the switches are of a type called a Rate Allocating Server and the transport protocol uses the Packet Pair probing technique (described below) [6 8]. Thus, in this paper, we will make the assumption that the queue service discipline is of the RAS type and that sources implement PacketPair. Our approach does not extend to First Come First Served (FCFS) networks, where there is no simple way to probe the network state. The paper is laid out as ....

S. Keshav, A. K. Agrawala and S. Singh, Design and Analysis of a Flow Control Algorithm for a Network of Rate Allocating Servers, in Protocols for High Speed Networks II, Elsevier Science Publishers/North-Holland, April 1991.

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Keshav, S., Agrawala, A., Singh,S, "Design and Analysis of A Flow Control Algorithm for a Network of Rate Allocating Servers", International Workshop on Protocols for High-Speed Networks, Palo Alto, Cal., November, 1990.

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