4,175 research outputs found
Compound TCP with Random Losses
We analyze the performance of a single, long-lived, Compound TCP (CTCP) connection in the presence of random packet losses. CTCP is a new version of TCP implemented in Microsoft Windows to improve the performance on networks with large bandwidth delay-products. We derive a Markovian model for the CTCP sending window and compute the steady state distribution of the window and the average throughput of a CTCP connection. We observe that the previous approximation, using a ``typical cycle", underestimates the average window and its variance while the Markovian model gives more accurate results. We use our model to compare CTCP and TCP Reno. We notice that CTCP gives always a throughput equal or greater than Reno, while relative performance in terms of jitter depends on the specific network scenario: CTCP generates more jitter for moderate-high drop rate values, while the opposite is true for low drop rate values
Asymptotic Approximations for TCP Compound
In this paper, we derive an approximation for throughput of TCP Compound
connections under random losses. Throughput expressions for TCP Compound under
a deterministic loss model exist in the literature. These are obtained assuming
the window sizes are continuous, i.e., a fluid behaviour is assumed. We
validate this model theoretically. We show that under the deterministic loss
model, the TCP window evolution for TCP Compound is periodic and is independent
of the initial window size. We then consider the case when packets are lost
randomly and independently of each other. We discuss Markov chain models to
analyze performance of TCP in this scenario. We use insights from the
deterministic loss model to get an appropriate scaling for the window size
process and show that these scaled processes, indexed by p, the packet error
rate, converge to a limit Markov chain process as p goes to 0. We show the
existence and uniqueness of the stationary distribution for this limit process.
Using the stationary distribution for the limit process, we obtain
approximations for throughput, under random losses, for TCP Compound when
packet error rates are small. We compare our results with ns2 simulations which
show a good match.Comment: Longer version for NCC 201
Analysis of Multiple Flows using Different High Speed TCP protocols on a General Network
We develop analytical tools for performance analysis of multiple TCP flows
(which could be using TCP CUBIC, TCP Compound, TCP New Reno) passing through a
multi-hop network. We first compute average window size for a single TCP
connection (using CUBIC or Compound TCP) under random losses. We then consider
two techniques to compute steady state throughput for different TCP flows in a
multi-hop network. In the first technique, we approximate the queues as M/G/1
queues. In the second technique, we use an optimization program whose solution
approximates the steady state throughput of the different flows. Our results
match well with ns2 simulations.Comment: Submitted to Performance Evaluatio
End-to-End Algebraic Network Coding for Wireless TCP/IP Networks
The Transmission Control Protocol (TCP) was designed to provide reliable
transport services in wired networks. In such networks, packet losses mainly
occur due to congestion. Hence, TCP was designed to apply congestion avoidance
techniques to cope with packet losses. Nowadays, TCP is also utilized in
wireless networks where, besides congestion, numerous other reasons for packet
losses exist. This results in reduced throughput and increased transmission
round-trip time when the state of the wireless channel is bad. We propose a new
network layer, that transparently sits below the transport layer and hides non
congestion-imposed packet losses from TCP. The network coding in this new layer
is based on the well-known class of Maximum Distance Separable (MDS) codes.Comment: Accepted for the 17th International Conference on Telecommunications
2010 (ICT2010), Doha, Qatar, April 4 - 7, 2010. 6 pages, 7 figure
Analytical Model of TCP Relentless Congestion Control
We introduce a model of the Relentless Congestion Control proposed by Matt
Mathis. Relentless Congestion Control (RCC) is a modification of the AIMD
(Additive Increase Multiplicative Decrease) congestion control which consists
in decreasing the TCP congestion window by the number of lost segments instead
of halving it. Despite some on-going discussions at the ICCRG IRTF-group, this
congestion control has, to the best of our knowledge, never been modeled. In
this paper, we provide an analytical model of this novel congestion control and
propose an implementation of RCC for the commonly-used network simulator ns-2.
We also improve RCC with the addition of a loss retransmission detection scheme
(based on SACK+) to prevent RTO caused by a loss of a retransmission and called
this new version RCC+. The proposed models describe both the original RCC
algorithm and RCC+ improvement and would allow to better assess the impact of
this new congestion control scheme over the network traffic.Comment: Extended version of the one presented at 6th International Workshop
on Verification and Evaluation of Computer and Communication Systems (Vecos
2012
TCP-Aware Backpressure Routing and Scheduling
In this work, we explore the performance of backpressure routing and
scheduling for TCP flows over wireless networks. TCP and backpressure are not
compatible due to a mismatch between the congestion control mechanism of TCP
and the queue size based routing and scheduling of the backpressure framework.
We propose a TCP-aware backpressure routing and scheduling that takes into
account the behavior of TCP flows. TCP-aware backpressure (i) provides
throughput optimality guarantees in the Lyapunov optimization framework, (ii)
gracefully combines TCP and backpressure without making any changes to the TCP
protocol, (iii) improves the throughput of TCP flows significantly, and (iv)
provides fairness across competing TCP flows
- …