5,586 research outputs found
Insights into the Design of Congestion Control Protocols for Multi-Hop Wireless Mesh Networks
The widespread deployment of multi-hop wireless mesh networks will depend on the performance seen by the user. Unfortunately, the most predominant transport protocol, TCP, performs poorly over such networks, even leading to starvation in some topologies. In this work, we characterize the root causes of starvation in 802.11 scheduled multi-hop wireless networks via simulations. We analyze the performance of three categories of transport protocols. (1) end-to-end protocols that require implicit feedback (TCP SACK), (2) Explicit feedback based protocols (XCP and VCP) and (3) Open-loop protocol (UDP). We ask and answer the following questions in relation to these protocols: (a) Why does starvation occur in different topologies? Is it intrinsic to TCP or, in general, to feedback-based protocols? or does it also occur in the case of open-loop transfers such as CBR over UDP? (a) What is the role of application behavior on transport layer performance in multi-hop wireless mesh networks? (b) Is sharing congestion in the wireless neighborhood essential for avoiding starvation? (c) For explicit feedback based transport protocols, such as XCP and VCP, what performance can be expected when their capacity estimate is inaccurate? Based on the insights derived from the above analysis, we design a rate-based protocol called VRate that uses the two ECN bits for conveying load feedback information. VRate achieves near optimal rates when configured with the correct capacity estimate
A Network Congestion control Protocol (NCP)
The transmission control protocol (TCP) which is the dominant
congestion control protocol at the transport layer is proved to have
many performance problems with the growth of the Internet. TCP for
instance results in throughput degradation for high bandwidth delay
product networks and is unfair for flows with high round trip delays.
There have been many patches and modifications to TCP all of which
inherit the problems of TCP in spite of some performance improve-
ments.
On the other hand there are clean-slate design approaches of the
Internet. The eXplicit Congestion control Protocol (XCP) and the
Rate Control Protocol (RCP) are the prominent clean slate congestion
control protocols. Nonetheless, the XCP protocol is also proved to
have its own performance problems some of which are its unfairness
to long flows (flows with high round trip delay), and many per-packet
computations at the router. As shown in this paper RCP also makes
gross approximation to its important component that it may only give
the performance reports shown in the literature for specific choices of
its parameter values and traffic patterns.
In this paper we present a new congestion control protocol called
Network congestion Control Protocol (NCP). We show that NCP can
outperform both TCP, XCP and RCP in terms of among other things
fairness and file download times.unpublishe
Towards an incremental deployment of ERN protocols: a proposal for an E2E-ERN hybrid protocol
We propose an architecture based on a hybrid E2E-ERN approach to allow incremental deployment of ERN (Explicit Rate Notification) protocols in heterogeneous networks. The proposed IP-ERN architecture combines E2E (End-to-End)and ERN protocols and uses the minimum between both congestion windows to perform. Without introducing complex operation, the resulting E2E-ERN protocol provides inter and intra protocol fairness and benefits from all ERN protocol advantages when possible. We detail the principle of this novel IP-ERN architecture and show that this architecture is highly adaptive to the network dynamic and is compliant with IPv4, IPv6 as well as IP-in-IP tunneling solutions
FAST TCP: Motivation, Architecture, Algorithms, Performance
We describe FAST TCP, a new TCP congestion control algorithm for high-speed long-latency networks, from design to implementation. We highlight the approach taken by FAST TCP to address the four difficulties which the current TCP implementation has at large windows. We describe the architecture and summarize some of the algorithms implemented in our prototype. We characterize its equilibrium and stability properties. We evaluate it experimentally in terms of throughput, fairness, stability, and responsiveness
DTMsim - DTM channel simulation in ns
Dynamic Transfer Mode (DTM) is a ring based MAN technology that
provides a channel abstraction with a dynamically adjustable capacity.
TCP is a reliable end to end transport protocol capable of adjusting
its rate. The primary goal of this work is investigate the coupling
of dynamically allocating bandwidth to TCP flows with the affect this
has on the congestion control mechanism of TCP. In particular we
wanted to find scenerios where this scheme does not work, where either
all the link capacity is allocated to TCP or congestion collapse
occurs and no capacity is allocated to TCP. We have created a
simulation environment using ns-2 to investigate TCP over networks
which have a variable capacity link. We begin with a single TCP Tahoe
flow over a fixed bandwidth link and progressively add more complexity
to understand the behaviour of dynamically adjusting link capacity to
TCP and vice versa
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