International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
HOST-TO-HOSTCONGESTION CONTROL
FOR TCP
1
2
M.V.L.Alekhya
P. Chakradhar
1
PG Student, Rama Chandra College of Engineering, Eluru, A.P., India
2
Associate Professor, Rama Chandra College of Engineering, Eluru, A.P., India
___________________________________________________________
ABSTRACT:
The Transmission Control Protocol
(TCP) carries most Internet traffic, so
performance of the Internet depends to a
great extent on how well TCP works.
Performance characteristics of a particular
version of TCP are defined by the
congestion control algorithm it employs.
This paper presents a survey of various
congestion control proposals that preserve
the original host-to-host idea of TCP—
namely, that neither sender nor receiver
relies on any explicit notification from the
network.
The proposed solutions focus on a
variety of problems, starting with the basic
problem of eliminating the phenomenon of
congestion collapse, and also include the
problems of effectively using the available
network resources in different types of
environments (wired, wireless, high-speed,
long-delay, etc.). In a shared, highly
distributed, and heterogeneous environment
such as the Internet, effective network use
depends not only on how well a single TCP
based application can utilize the network
capacity, but also on how well it cooperates
with other applications transmitting data
through the same network.
I.INTRODUCTION
To transfer data from one system to
other system in TCP, packet congestion
ISSN: 2231-5381
should be very less to send data packets
without any loss. So we are focusing on an
application to reduce the congestion that
occurs in TCP, by proposing congestion
avoidance algorithm by considering
congestion window as rate limiting factor
there by, the packet loss statistics is very
less or the packet loss can be eliminated
completely. Hence the object is to avoid the
packet loss while transferring data from a
system to another system by avoiding the
congestion in the network.
The Transmission Control Protocol
(TCP) carries most Internet traffic, so
performance of the Internet depends to a
great extent on how well TCP works.
Performance characteristics of a particular
version of TCP are defined by the
congestion control algorithm it employs.
This presents congestion control proposals
that preserve the original host-to-host idea of
TCP—namely, that neither sender nor
receiver relies on any explicit notification
from the network. The proposed solutions
focus on a variety of problems, starting with
the basic problem of eliminating the
phenomenon of congestion collapse, and
also include the problems of effectively
using the available network resources in
different types of environments (wired,
wireless, high-speed, long-delay, etc).
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
Currently we have as situation where
there is no Single congestion control
approach for TCP that can universally be
applied to all network environments. One of
the primary causes is a wide variety of
network environments and different (and
sometimes opposing) network owners’
views regarding which parameters should be
optimized. A number of the congestion
control algorithms. Moreover, the current
version of Linux kernel provides an API for
software developers to choose any one of
the supported algorithms for a particular
connection. However, there are not yet the
well-defined and broadly-accepted criteria to
serve as a good baseline for appropriately
selecting a congestion control algorithm.
Additionally, objective guidelines to select a
proper congestion control for a concrete
network environment are yet to be defined.
Loss-based and delay-based techniques are
used to estimate the congestion states in the
network and to detect packet loss quickly.
Sliding window based flow control is to
control the flow between the systems.
Sender buffers all the data before
transmission and then assigns sequence
numbers to all the buffered data bytes.The
buffered data are packetized into TCP
packets that includes the sequence number
of the first data byte.So,these packets are
transmitted by using the IP protocol between
the systems.If the congestion is high, packet
loss will be more. Thereby the receiver
system sends the rate limiting factor to the
sender.So,based on that factor the sender
may increase/reduce its factor value.
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II. Congestion Control in TCP
In connectionless networks, the role
of flow control is to modify the natural
sending rate of an application to match the
realities of network capacity, and to make
the data stream better behaved. This is done
by insisting that some assertions about the
data stream are always valid, for example,
that no more than 12kbtyes of data will be
outstanding (sent but unacknowledged) at
any given time. The test of a flow control
protocol is its effectiveness in making
network operation smoother as a result of
this modification . In a high speed network
with large delays, problems can arise from
two sources.
This introduces the problem of slow
start where a node slowly ramps up its rate
of transmission of packets over the network
until a comfortable rate can be established.
This is a problem because the average file
(approx 1 KB) would have been already
completed transmission before this ramping
up to a comfortable rate takes place. This
causes network inefficiencies, since the
file could have been transmitted much
quicker had this feedback-based TCP
Congestion Control not been employed.
Therefore this project seeks to design an
algorithm that can be implemented in a TCP
that can determine the optimal transmission
rate rapidly, eliminating the slow start
problem.
In the existing TCP system ,as the
transmission rate and receiving rate are not
considered ,the packet loss statistics will be
very high due to inconvenience of flow
control rate. The standard already requires
receivers to report the sequence number of
the last in-order delivered data packet each
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
time a packet is received though the
sequence number of the packet that it
received is not in order. So the sender can’t
detect the packet loss till the end of the
transmission.
Proposed System
The proposed system overcomes the
problems that occurred in existing system by
considering the rate limiting factor inorder
to avoid the congestion that occurs in the
network. The Host to Host congestion
control proposals that build a foundation for
all currently known host-to-host algorithms.
This foundation includes
The basic principle of probing the
available network resources
Loss-based
and
delay-based
techniques to estimate the congestion state
in the network.
Techniques to detect packet losses
quickly.
The objectives of the project are to avoid
the packet loss by reducing the congestion
that occurs during transmission of data in
the network.Increase of efficiency and
throughput of the original TCP Avoid
unnecessary assumption of crash of servers
by using RTO(Retransmission Time
Out).Determines Optimal transmission rate
rapidly, thereby eliminating slow start
problem
TCP standard specifies a sliding window
based flow control. This flow control has
several mechanisms. First, the sender
buffers all data before the transmission,
assigning a sequence number to each
buffered byte. Continuous blocks of the
buffered data are packetized into TCP
packets that include a sequence number of
the first data byte in the packet. Second, a
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portion (window) of the prepared packets is
transmitted to the receiver using the IP
protocol. As soon as the sender receives
delivery confirmation for at least one data
packet, it transmits a new portion of packets.
Finally, the sender holds responsibility for a
data block until the receiver explicitly
confirms delivery of the block. As a result,
the sender may eventually decide that a
particular unacknowledged data block has
been lost and start recovery procedures (e.g.,
retransmit one or several packets). To
acknowledge data delivery, the receiver
forms an ACK packet that carries one
sequence number and (optionally) several
pairs of sequence numbers.
In order to reduce the congestion that
occurs in TCP here we use proposed
congestion avoidance algorithm. In this
proposed system we consider congestion
window as rate limiting factor there by, the
packet loss statistics is very less or the
packet loss can be eliminated completely.
Wireless networks rely on the
uninterrupted availability of the wireless
medium to interconnect participating nodes.
However, the open nature of this medium
leaves it vulnerable to multiple security
threats. Anyone with a transceiver can
eavesdrop on wireless transmissions, inject
spurious messages, or jam legitimate ones.
While eavesdropping and message injection
can be prevented using cryptographic
methods, jamming attacks are much harder
to counter. They have been shown to
actualize severe Denial-of-Service (DoS)
attacks against wireless networks. In the
simplest form of jamming, the adversary
interferes with the reception of messages by
transmitting a continuous jamming signal, or
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
several short jamming pulses. Typically,
jamming attacks have been considered under
an external threat model, in which the
jammer is not part of the network. Under
this model, jamming strategies include the
continuous or random transmission of highpower interference signals. However,
adopting an “always-on” strategy has
several disadvantages. First, the adversary
has to expend a significant amount of energy
to jam frequency bands of interest. Second,
the continuous presence of unusually high
interference levels makes this type of attacks
easy to detect. Conventional anti-jamming
techniques rely extensively on spreadspectrum (SS) communications, or some
form of jamming evasion (e.g., slow
frequency hopping, or spatial retreats). SS
techniques provide bit-level protection by
spreading bits according to a secret pseudonoise (PN) code, known only to the
communicating parties. These methods can
only protect wireless transmissions under
the external threat model. Potential
disclosure of secrets due to node
compromise neutralizes the gains of SS.
Broadcast communications are particularly
vulnerable under an internal threat model
because all intended receivers must be aware
of the secrets used to protect transmissions.
Hence, the compromise of a single receiver
is sufficient to reveal relevant cryptographic
information. In this paper, we address the
problem of jamming under an internal threat
model. We consider a sophisticated
adversary who is aware of network secrets
and the implementation details of network
protocols at any layer in the network stack.
The adversary exploits his internal
knowledge for launching selective jamming
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attacks in which specific messages of “high
importance” are targeted. For example, a
jammer can target route-request/route-reply
messages at the routing layer to prevent
route
discovery,
or
target
TCP
acknowledgments in a TCP session to
severely degrade the throughput of an endto-end flow. To launch selective jamming
attacks, the adversary must be capable of
implementing a “classify-then-jam” strategy
before the completion of a wireless
transmission. Such strategy can be
actualized either by classifying transmitted
packets using protocol semantics, or by
decoding packets on the fly. In the latter
method, the jammer may decode the first
few bits of a packet for recovering useful
packet identifiers such as packet type,
source and destination address. After
classification, the adversary must induce a
sufficient number of bit errors so that the
packet cannot be recovered at the receiver.
Selective jamming requires an intimate
knowledge of the physical (PHY) layer, as
well as of the specifics of upper layers.
Real Time Packet Classification
Consider the generic communication
system depicted in Fig. At the PHY layer, a
packet m is encoded, interleaved, and
modulated before it is transmitted over the
wireless channel. At the receiver, the signal
is demodulated, deinterleaved, and decoded,
to recover the original packet m.
Selective Jamming Module
We illustrate the impact of
selective jamming attacks on the network
performance. Implement selective jamming
attacks in two multi-hop wireless network
scenarios. In the first scenario, the attacker
targeted a TCP connection established over
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
a multi-hop wireless route. In the second
scenario, the jammer targeted network-layer
control messages transmitted during the
route establishment process selective
jamming would be the encryption of
transmitted packets (including headers) with
a static key. However, for broadcast
communications, this static decryption key
must be known to all intended receivers and
hence, is susceptible to compromise. An
adversary in possession of the decryption
key can start decrypting as early as the
reception of the first cipher text block.
Strong Hiding Commitment Scheme
(SHCS)
We propose a strong hiding commitment
scheme (SHCS), which is based on
symmetric
cryptography.
Our
main
motivation is to satisfy the strong hiding
property while keeping the computation and
communication overhead to a minimum.
Cryptographic Puzzle Hiding Scheme
(CPHS)
We present a packet hiding scheme based on
cryptographic puzzles. The main idea behind
such puzzles is to force the recipient of a
puzzle execute a pre-defined set of
computations before he is able to extract a
secret of interest. The time required for
obtaining the solution of a puzzle depends
on its hardness and the computational ability
of the solver. The advantage of the puzzle
based scheme is that its security does not
rely on the PHY layer parameters. However,
it
has
higher
computation
and
communication overhead
s o u rc e
d e s tin a tion
w s n p a ck e t h id in g
co n n e c t S o u ce
co nn e c t D es tin a tio n
C h a n n e l E n c o d in g
in t e r le a v in g
pa cke t se nd
d e i n t e r le a v in g
c h a n n e l d e c o d in g
p a ck et h id in g / q u e u e
J a m m i n g a t t a c k a n a ly s is
Figure 1 Sequence Diagram
W SN jamming networks
`
Sour ce
connect
Destination
Channel Encoding
interleaving
De-interleaving
Pa cket Hiding/queue
Channel Decoding
Show results
Figure 2 Activity Diagram
IV. Results and Discussions
This paper advocates the concept of congestion
control that occurs in TCP .This introducesthe
technique of probing the network resources and
relying on packet loss to detect that the network limit
has been reached by sending the transmission and
receiving rate. Here we consider congestion window
as rate limiting factor, In case of server or client, not
in the position of sending or receiving files, RTO
(Retransmission Time Out) is developed to avoid
unnecessary assumption of crash of servers. Thus this
project provides an effective method for avoiding
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
congestion in the network and no packet loss occurs
during transmission.
A group of congestion control proposals that are
focused
on
environments
where
packets
are
frequently reordered. These proposals show that in
such environments, efficiency can be improved
significantly by delaying the control actions or by
Figure 6 Receiving Packets System Screen
undoing previously applied actions if reordering is
detected or by refining the network state estimation
REFERENCES
heuristic . we showed that basic host to-host
congestion control principles can solve not only the
direct congestion problem but also provide a simple
traffic prioritizing feature.
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Figure 3 Implemented System Screen Login Page
Figure 4 Packet conversion Screen Shot
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International Journal of Engineering Trends and Technology (IJETT) – Volume 6 Number 1- Dec 2013
[6] Z. Wang and J. Crowcroft, “Eliminating
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Authors Profile:
M.V.L. Alekhya is
pursuing
her
master’s Degree (M.
Tech)
from
Rama
Chandra College of
Engineering, Eluru. She completed
her
Graduation
Bapatla
(B.Tech)
Engineering
from
College,
Bapatla.
P. Chakradhar
is
working as Associate
Professor, in Rama
Chandra College of
Engineering, Eluru.
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