Conference Paper

An Analytical Model of a New Packet Marking Algorithm for TCP Flows.

Dipartimento di Ingegneria Elettrica, DIE, Università degli Studi di Palermo, 90128 Palermo, Italy
DOI: 10.1016/j.comnet.2005.09.003 Conference: Quality of Service in Multiservice IP Networks, Third International Workshop, QoS-IP 2005, Catania, Italy, February 2-4, 2005, Proceedings
Source: DBLP

ABSTRACT Abstract In Dieren tiated Services networks, packets may receive a dieren t treatment ac- cording to their Dieren tiated Services Code Point (DSCP) label. As a consequence, packet marking schemes can be devised to dieren tiate packets belonging to a same TCP o w, with the goal of improving the experienced performance. This paper presents an analytical model for an adaptive packet marking scheme proposed in our previous work. The model combines three specic sub-models aimed at de- scribing i) the TCP sources aggregate ii) the marker, and iii) the network status. Preliminary simulative results show quite accurate predictions for throughput and average queue occupancy. Besides, the research suggests new interesting guidelines to model queues fed by TCP trac. Key words: TCP Marking, Dieren tiated Services, Models

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Network devices put packets on an Internet link, and multiplex, or superpose, the packets from different active connections. Extensive empirical and theoretical studies of packet traffic variables --- arrivals, sizes, and packet counts --- demonstrate that the number of active connections has a dramatic effect on traffic characteristics. At low connection loads on an uncongested link --- that is, with little or no queueing on the link-input router --- the traffic variables are long-range dependent, creating burstiness: large variation in the traffic bit rate. As the load increases, the laws of superposition of marked point processes push the arrivals toward Poisson, the sizes toward independence, and reduces the variability of the counts relative to the mean. This begins a reduction in the burstiness; in network parlance, there are multiplexing gains. Once the connection load is sufficiently large, the network begins pushing back on the attraction to Poisson and independence by causing queueing on the link-input router. But if the link speed is high enough, the traffic can get quite close to Poisson and independence before the push-back begins in force; while some of the statistical properties are changed in this high-speed case, the push-back does not resurrect the burstiness. These results reverse the commonly-held presumption that Internet traffic is everywhere bursty and that multiplexing gains do not occur. Very simple statistical time series models --- fractional sum-difference (FSD) models --- describe the statistical variability of the traffic variables and their change toward Poisson and independence before significant queueing sets in, and can be used to generate open-loop packet arrivals and sizes for simulation studies. Both science and engineering are affec...
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper analyzes the stationary behavior of the TCP congestion window performing ideal congestion avoidance when the packet loss probability is not constant, but varies as a function of the window size. By neglecting the detailed window behavior during fast recovery, we are able to derive a Markov process that is then approximated by a continuous-time, continuous state-space process. The stationary distribution of this process is analyzed and derived numerically and then extrapolated to obtain the stationary distribution of the TCP window. This numerical analysis enables us to predict the behavior of the TCP congestion window when interacting with a router port performing Early Random Drop (or Random Early Detection) where the loss probability varies with the queue occupancy. Keywords---TCP, distribution, variable, loss. I. INTRODUCTION In this paper, we present a quantitative analysis of the stationary behavior of the evolution of the TCP congestion window (cwnd) ([1]) when the ...
    Proceedings - IEEE INFOCOM 02/1999; DOI:10.1109/INFCOM.1999.752179
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The differentiated services architecture provides router mechanisms for aggregate traffic, and edge mechanisms for individual flows, that together can be used to build services with varying delay and loss behavior. We compare the loss and delay behavior that can be provided using the services based on combinations of two router mechanisms, threshold dropping and priority scheduling and two packet marking mechanisms, edge-discarding and edge-marking. We compare the delay and loss behavior of the two router mechanisms coupled with edge-discarding for a wide range of traffic arrivals. We observe that priority scheduling provides lower expected delays to preferred traffic than threshold dropping. In addition, we find that a considerable additional link bandwidth is needed with threshold dropping to provide same delay behavior as priority scheduling. We further observe little difference in the loss incurred by preferred traffic under both router mechanisms, except when sources are extremely bursty, in which case threshold dropping performs better. We examine the throughput of a TCP connection that uses a service built upon threshold dropping and edge-marking. Our analysis shows that a significant improvement in throughput can be achieved. However, we find that in order to fully achieve the benefit of such a packet marking, the TCP window must take the edge-marking mechanism into consideration
    Global Telecommunications Conference, 1999. GLOBECOM '99; 02/1999
Show more

Preview (4 Sources)