109 research outputs found
GTFRC, a TCP friendly QoS-aware rate control for diffserv assured service
This study addresses the end-to-end congestion control support over the DiffServ Assured Forwarding (AF) class. The resulting Assured Service (AS) provides a minimum level of throughput guarantee. In this context, this article describes a new end-to-end mechanism for continuous transfer based on TCP-Friendly Rate Control (TFRC). The proposed approach modifies TFRC to take into account the QoS negotiated. This mechanism, named gTFRC, is able to reach the minimum throughput guarantee whatever the flow’s RTT and target rate. Simulation measurements and implementation over a real QoS testbed demonstrate the efficiency of this mechanism either in over-provisioned or exactly-provisioned network. In addition, we show that the gTFRC mechanism can be used in the same DiffServ/AF class with TCP or TFRC flows
gTFRC: a QoS-aware congestion control algorithm
This study addresses the end-to-end congestion control
support over the DiffServ Assured Forwarding (AF) class.
The resulting Assured Service (AS) provides a minimum
level of throughput guarantee. In this context, this paper describes a new end-to-end mechanism for continuous transfer based on TCP-Friendly Rate Control (TFRC) originally proposed in [11]. The proposed approach modifies TFRC to take into account the QoS negotiated. This mechanism, named gTFRC, is able to reach the minimum throughput guarantee whatever the flow's RTT and target rate. Simulation measurements show the efficiency of this mechanism either in over-provisioned or exactly-provisioned network. In addition, we show that the gTFRC mechanism can be used in the same DiffServ/AF class with TCP or TFRC flows
Proportional bandwidth distribution in IP networks implementing the assured forwarding PHB
Recent demands for new applications are giving rise
to an increasing need of Quality of Service (QoS).
Nowadays, most IP-based networks tend to use the
DiffServ architecture to provide end-to-end QoS.
Traffic conditioners are a key element in the
deployment of DiffServ. In this paper, we introduce a
new approach for traffic conditioning based on feedback
signaling among boundary nodes and traffic
conditioners. This new approach is intended to provide
a poportional distribution of excess bandwidth to endusers.
We evaluate through extensive simulations the
performance of our proposal in terms of final
throughput, considering contracted target rates and
distribution of spare bandwidth. Results show a high
level of fairness in the excess bandwidth allocation
among TCP sources under different network
conditions
Design, implementation and evaluation of a QoS-aware transport protocol
In the context of a reconfigurable transport protocol framework, we propose a QoS-aware Transport Protocol (QSTP), specifically designed to operate over QoS-enabled networks with bandwidth guarantee. QSTP combines QoS-aware TFRC congestion control mechanism, which takes into account the network-level bandwidth reservations, with a Selective ACKnowledgment (SACK) mechanism in order to provide a QoS-aware transport service that fill the gap between QoS enabled network services and QoS constraint applications. We have developed a prototype of this protocol in the user-space and conducted a large range of measurements to evaluate this proposal under various network conditions. Our results show that QSTP allows applications to reach their negotiated QoS over bandwidth guaranteed networks, such as DiffServ/AF network, where TCP fails. This protocol appears to be the first reliable protocol especially designed for QoS network architectures with bandwidth guarantee
End-to-end TCP performance of the couple CBM traffic conditioner and RIO buffer management in a three node topology
Despite the abundant literature written about the AF PHB,
no solution has been found to efficiently face up its two
goals, assuring a minimum rate to the users and offering a
fair distribution of the excess bandwidth if available. The
Counters Based Modified (CBM) traffic conditioner,
presented in a previous work, is able to achieve these
objectives in single-node topologies. This paper raises
issues with providing bandwidth assurance and spare
bandwidth distribution for TCP flows in more complex
topologies than usual. Simulation results explore the
effect of target rates, round trip times, and efficiency of
CBM when up to three network nodes implement service
differentiation, including in some cases the coexistence of
assured service and best-effort traffics.This work was supported by the Spanish Research
Council under projects TEC2004-05622-C04-02/TCM
and TIC2001-3339-C02-02
Counters-based modified traffic conditioner
Traffic conditioners play a key role in implementing the Assured Service in the framework
of the DiffServ approach. Many research papers have focused on finding the best traffic conditioner
able to assure contracted target rates and to fairly distribute the excess bandwidth among competing
sources. Nevertheless, none of the proposals presented so far accomplishes simultaneously both
features. We propose a traffic conditioner for the Internet Assured Service called Counters-Based
Modified (CBM) that strictly guarantees target rates and performs a fair share of the excess
bandwidth among TCP Reno sources. The ability of strictly providing the inbound bandwidth is
inherited from its predecessor the Counters-Based algorithm, and the fairness in the outbound
bandwidth distribution is met by probabilistically dropping OUT packets in the traffic conditioner. To
determine the dropping probability of an OUT packet, the amount of excess bandwidth and the
average RTT of all connections in the traffic conditioner have to be known. Although this fact implies
using some sort of signaling, it results more feasible than other proposed intelligent traffic
conditioners. The CBM traffic conditioner is evaluated under different conditions by simulation using
TCP Reno sources. Simulation results presented in this paper lead us to suggest it as a feasible
election for the traffic conditioner device implementation in DiffServ.This work was supported by the Spanish Research Council under grant FAR-IP TIC2000-1734-C03-03
Design and evaluation of an adaptive traffic conditioner in differentiated services networks
Abstract—We design and evaluate an adaptive traffic conditioner to improve application performance over the differentiated services assured forwarding behavior. The conditioner is adaptive because the marking algorithm changes based upon the current number of flows traversing through an edge router. If there are a small number of flows, the conditioner maintains and uses state information to intelligently protect critical TCP packets. On the other hand, if there are many flows going through the edge router, the conditioner only uses flow characteristics as indicated in the TCP packet headers to mark without requiring per flow state. Simulation results indicate that this adaptive conditioner improves throughput of data extensive applications like large FTP transfers, and achieves low packet delays and response times for Telnet and WWW traffic. I
A new proposal for assuring services in internet
In this paper we present a new mechanism
to provide an assured service in terms of target rate
and fair excess bandwidth, like the Internet Assured
Service. Research in Internet Assured Service faced
up both questions in separate ways proposing
different traffic conditioners to work with the RIO
buffer management, and proposing different
modifications to this buffer management, among
others. In this work, we suggest using a buffer
management scheme different from RIO that also
treats in-of-profile and out-of-profile packets
differently but avoiding interference between them.
This scheme is used together with the Counters Based
traffic conditioner because of its high accuracy in
guaranteeing target rates. We evaluate and compare
by simulation the performance of our proposal using
TCP RENO sources. One important issue to be
considered is that the proposal is a feasible
alternative to the standard architecture for
Differentiated Services in Internet.This work was supported by the Spanish
Research Council under grant TIC2000-1734-
C03-03
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