Hello People.. Welcome to GURUKULA!!!
Have you ever thought that how the protocols that are required for the effective delivery of the messages from one place to anpther place take place in a real time internet..... This video explains about the concept called PROTOCOL LAYERING, where you can learn the way how the protocols are layered in such a way..
Simple examples are also used to make the concepts clean nd clear.
This video will help you to learn:
What is protocol layering in networks, OSI Model in Computer Networks, Layers of OSI Model, OSI Model, OSI Internet Module, OSI Layers and their Functions, Examples of OSI Models, 7 layers of OSI Models, Principles of Protocol Layering, Why layering the Protocols,
Thanks for Watching, Keep Supporting and Keep Sharing...
Hello People.. Welcome to GURUKULA!!!
Have you ever thought that how the protocols that are required for the effective delivery of the messages from one place to anpther place take place in a real time internet..... This video explains about the concept called PROTOCOL LAYERING, where you can learn the way how the protocols are layered in such a way..
Simple examples are also used to make the concepts clean nd clear.
This video will help you to learn:
What is protocol layering in networks, OSI Model in Computer Networks, Layers of OSI Model, OSI Model, OSI Internet Module, OSI Layers and their Functions, Examples of OSI Models, 7 layers of OSI Models, Principles of Protocol Layering, Why layering the Protocols,
Thanks for Watching, Keep Supporting and Keep Sharing...
UNIT IV TRANSPORT LAYER 9
Introduction – Transport Layer Protocols – Services – Port Numbers – User Datagram Protocol – Transmission Control Protocol – SCTP.
High level overview of CoAP or Constrained Application Protocol. CoAP is a HTTP like protocol suitable for constrained environment like IoT. CoAP uses HTTP like request response model, status code etc.
RTOS-MicroC/OS-II
It is a priority-based real-time multitasking operating system kernel for microprocessors, written mainly in the C programming language.It is intended for use in embedded systems.
This presentation outlines the core functions of TCP - Transmission Control Protocol.
These comprise TCP Connection Control, TCP Flow Control, TCP Error Control, TCP Congestion Control, TCP Options and TCP Timers.
TCP/IP is the Internet core protocol that provides reliable, connection-oriented and stream-based communication service. Most of Internet traffic is carried in TCP connections, so scalability and reliability are crucial for a stable network on a global scale.
UNIT IV TRANSPORT LAYER 9
Introduction – Transport Layer Protocols – Services – Port Numbers – User Datagram Protocol – Transmission Control Protocol – SCTP.
High level overview of CoAP or Constrained Application Protocol. CoAP is a HTTP like protocol suitable for constrained environment like IoT. CoAP uses HTTP like request response model, status code etc.
RTOS-MicroC/OS-II
It is a priority-based real-time multitasking operating system kernel for microprocessors, written mainly in the C programming language.It is intended for use in embedded systems.
This presentation outlines the core functions of TCP - Transmission Control Protocol.
These comprise TCP Connection Control, TCP Flow Control, TCP Error Control, TCP Congestion Control, TCP Options and TCP Timers.
TCP/IP is the Internet core protocol that provides reliable, connection-oriented and stream-based communication service. Most of Internet traffic is carried in TCP connections, so scalability and reliability are crucial for a stable network on a global scale.
Examine common application performance problems hiding in plain sight. See how you can quickly remove the noise, pinpoint root cause and fix these problems once and for all. Watch the webinar replay: http://rvbd.ly/1QGxMBs
In a world of business that has increasingly become more and more distributed, and with our relationship with data having changed, we need to begin expanding the way we look at innovation in IT from solely focusing on the data center, to considering the requirements, challenges and costs associated with the edge. This presentation focuses on extending data center investments to all remote sites, and new opportunities to connect IT with today's business requirements through a Software-Defined Edge.
XPDS13: On Paravirualizing TCP - Congestion Control on Xen VMs - Luwei Cheng,...The Linux Foundation
While datacenters are increasingly adopting VMs to provide elastic cloud services, they still rely on traditional TCP for congestion control. In this talk, I will first show that VM scheduling delays can heavily contaminate RTTs sensed by VM senders, preventing TCP from correctly learning the physical network condition. Focusing on the incast problem, which is commonly seen in large-scale distributed data processing such as MapReduce and web search, I find that the solutions that have been developed for *physical* clusters fall short in a Xen *virtual* cluster. Second, I will provide a concrete understanding of the problem, and reveal that the situations that when the sending VM is preempted versus when the receiving VM is preempted, are different. Third, I will introduce my recent attempts on paravirtualizing TCP to overcome the negative effect caused by VM scheduling delays.
The dynamic nature of SaaS applications can slow performance due to the distance between the cloud and users. Riverbed accelerates the delivery of SaaS applications by up to 33x. Join us for this session to find out how you can accelerate applications and manage the delivery of business-critical data and content from your SaaS provider overcoming application latency, control quality of service, remove loss of visibility and bandwidth constraints. http://rvbd.ly/2hpKls6
Computer networks have experienced an explosive growth over the past few years and with
that growth have come severe congestion problems. For example, it is now common to see
internet gateways drop 10% of the incoming packets because of local buffer overflows.
Our investigation of some of these problems has shown that much of the cause lies in
transport protocol implementations (
not
in the protocols themselves): The ‘obvious’ ways
to implement a window-based transport protocol can result in exactly the wrong behavior
in response to network congestion. We give examples of ‘wrong’ behavior and describe
some simple algorithms that can be used to make right things happen. The algorithms are
rooted in the idea of achieving network stability by forcing the transport connection to obey
a ‘packet conservation’ principle. We show how the algorithms derive from this principle
and what effect they have on traffic over congested networks.
In October of ’86, the Internet had the first of what became a series of ‘congestion col-
lapses’. During this period, the data throughput from LBL to UC Berkeley (sites separated
by 400 yards and two IMP hops) dropped from 32 Kbps to 40 bps. We were fascinated by
this sudden factor-of-thousand drop in bandwidth and embarked on an investigation of why
things had gotten so bad. In particular, we wondered if the 4.3
BSD
(Berkeley U
NIX
)
TCP
was mis-behaving or if it could be tuned to work better under abysmal network conditions.
The answer to both of these questions was “yes”.
1.Wireless Communication System_Wireless communication is a broad term that i...JeyaPerumal1
Wireless communication involves the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors.
Wireless communication is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices.
Features of Wireless Communication
The evolution of wireless technology has brought many advancements with its effective features.
The transmitted distance can be anywhere between a few meters (for example, a television's remote control) and thousands of kilometers (for example, radio communication).
Wireless communication can be used for cellular telephony, wireless access to the internet, wireless home networking, and so on.
Multi-cluster Kubernetes Networking- Patterns, Projects and GuidelinesSanjeev Rampal
Talk presented at Kubernetes Community Day, New York, May 2024.
Technical summary of Multi-Cluster Kubernetes Networking architectures with focus on 4 key topics.
1) Key patterns for Multi-cluster architectures
2) Architectural comparison of several OSS/ CNCF projects to address these patterns
3) Evolution trends for the APIs of these projects
4) Some design recommendations & guidelines for adopting/ deploying these solutions.
This 7-second Brain Wave Ritual Attracts Money To You.!nirahealhty
Discover the power of a simple 7-second brain wave ritual that can attract wealth and abundance into your life. By tapping into specific brain frequencies, this technique helps you manifest financial success effortlessly. Ready to transform your financial future? Try this powerful ritual and start attracting money today!
ER(Entity Relationship) Diagram for online shopping - TAEHimani415946
https://bit.ly/3KACoyV
The ER diagram for the project is the foundation for the building of the database of the project. The properties, datatypes, and attributes are defined by the ER diagram.
1. Computer Networks: TCP 1
TCPTCP
Congestion ControlCongestion Control
Lecture material taken from
“Computer Networks A Systems Approach”,
Third Ed.,Peterson and Davie,
Morgan Kaufmann, 2003.
2. Computer Networks: TCP 2
TCP Congestion ControlTCP Congestion Control
• Essential strategy :: The TCP host sends
packets into the network without a reservation
and then the host reacts to observable events.
• Originally TCP assumed FIFO queuing.
• Basic idea :: each source determines how
much capacity is available to a given flow in the
network.
• ACKs are used to ‘pace’ the transmission of
packets such that TCP is “self-clocking”.
3. Computer Networks: TCP 3
AIMDAIMD
(Additive Increase / Multiplicative(Additive Increase / Multiplicative
Decrease)Decrease)
• CongestionWindow (cwnd) is a variable held by
the TCP source for each connection.
• cwnd is set based on the perceived level of
congestion. The Host receives implicit (packet
drop) or explicit (packet mark) indications of
internal congestion.
MaxWindow :: min (CongestionWindow , AdvertisedWindow)
EffectiveWindow = MaxWindow – (LastByteSent -LastByteAcked)
4. Computer Networks: TCP 4
Additive IncreaseAdditive Increase
• Additive Increase is a reaction to perceived
available capacity.
• Linear Increase basic idea:: For each “cwnd’s
worth” of packets sent, increase cwnd by 1
packet.
• In practice, cwnd is incremented fractionally for
each arriving ACK.
increment = MSS x (MSS /cwnd)
cwnd = cwnd + increment
5. Computer Networks: TCP 5
Figure 6.8 Additive IncreaseFigure 6.8 Additive Increase
Source Destination
Add one packet
each RTT
6. Computer Networks: TCP 6
Multiplicative DecreaseMultiplicative Decrease
* The key assumption is that a dropped packet and the
resultant timeout are due to congestion at a router or
a switch.
Multiplicate Decrease:: TCP reacts to a timeout by
halving cwnd.
• Although cwnd is defined in bytes, the literature often
discusses congestion control in terms of packets (or
more formally in MSS == Maximum Segment Size).
• cwnd is not allowed below the size of a single packet.
7. Computer Networks: TCP 7
AIMDAIMD
(Additive Increase / Multiplicative(Additive Increase / Multiplicative
Decrease)Decrease)
• It has been shown that AIMD is a necessary
condition for TCP congestion control to be stable.
• Because the simple CC mechanism involves
timeouts that cause retransmissions, it is important
that hosts have an accurate timeout mechanism.
• Timeouts set as a function of average RTT and
standard deviation of RTT.
• However, TCP hosts only sample round-trip time
once per RTT using coarse-grained clock.
9. Computer Networks: TCP 9
Slow StartSlow Start
• Linear additive increase takes too long to
ramp up a new TCP connection from cold
start.
• Beginning with TCP Tahoe, the slow start
mechanism was added to provide an initial
exponential increase in the size of cwnd.
Remember mechanism by: slow start
prevents a slow start. Moreover, slow start
is slower than sending a full advertised
window’s worth of packets all at once.
10. Computer Networks: TCP 10
SloSloww StartStart
• The source starts with cwnd = 1.
• Every time an ACK arrives, cwnd is
incremented.
cwnd is effectively doubled per RTT “epoch”.
• Two slow start situations:
At the very beginning of a connection {cold start}.
When the connection goes dead waiting for a
timeout to occur (i.e, the advertized window goes
to zero!)
12. Computer Networks: TCP 12
Slow StartSlow Start
• However, in the second case the source
has more information. The current value
of cwnd can be saved as a congestion
threshold.
• This is also known as the “slow start
threshold” ssthresh.
13. Computer Networks: TCP 13
Figure 6.11 Behavior of TCPFigure 6.11 Behavior of TCP
Congestion ControlCongestion Control
60
20
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Time (seconds)
70
30
40
50
10
14. Computer Networks: TCP 14
Fast RetransmitFast Retransmit
• Coarse timeouts remained a problem, and Fast
retransmit was added with TCP Tahoe.
• Since the receiver responds every time a packet
arrives, this implies the sender will see duplicate
ACKs.
Basic Idea:: use duplicate ACKs to signal lost packet.
Fast Retransmit
Upon receipt of three duplicate ACKs, the TCP Sender
retransmits the lost packet.
15. Computer Networks: TCP 15
Fast RetransmitFast Retransmit
• Generally, fast retransmit eliminates about half
the coarse-grain timeouts.
• This yields roughly a 20% improvement in
throughput.
• Note – fast retransmit does not eliminate all
the timeouts due to small window sizes at the
source.
16. Computer Networks: TCP 16
Figure 6.12 Fast RetransmitFigure 6.12 Fast Retransmit
Packet 1
Packet 2
Packet 3
Packet 4
Packet 5
Packet 6
Retransmit
packet 3
ACK 1
ACK 2
ACK 2
ACK 2
ACK 6
ACK 2
Sender Receiver
Fast Retransmit
Based on three
duplicate ACKs
19. Computer Networks: TCP 19
Fast RecoveryFast Recovery
• Fast recovery was added with TCP Reno.
• Basic idea:: When fast retransmit detects
three duplicate ACKs, start the recovery
process from congestion avoidance region
and use ACKs in the pipe to pace the
sending of packets.
Fast Recovery
After Fast Retransmit, half cwnd and commence
recovery from this point using linear additive increase
‘primed’ by left over ACKs in pipe.
20. Computer Networks: TCP 20
ModifiedModified Slow StartSlow Start
• With fast recovery, slow start only
occurs:
–At cold start
–After a coarse-grain timeout
• This is the difference between
TCP Tahoe and TCP Reno!!
22. Computer Networks: TCP 22
Adaptive RetransmissionsAdaptive Retransmissions
RTT:: Round Trip Time between a pair of
hosts on the Internet.
• How to set the TimeOut value?
– The timeout value is set as a function of
the expected RTT.
– Consequences of a bad choice?
23. Computer Networks: TCP 23
Original AlgorithmOriginal Algorithm
• Keep a running average of RTT and
compute TimeOut as a function of this
RTT.
– Send packet and keep timestamp ts .
– When ACK arrives, record timestamp ta .
SampleRTT = ta - ts
24. Computer Networks: TCP 24
Original AlgorithmOriginal Algorithm
Compute a weighted average:
EstimatedRTT =EstimatedRTT = αα xx EstimatedRTT +EstimatedRTT +
((1-1- αα) x SampleRTT) x SampleRTT
Original TCP spec: αα in range (0.8,0.9)in range (0.8,0.9)
TimeOut = 2 xTimeOut = 2 x EstimatedRTTEstimatedRTT
25. Computer Networks: TCP 25
Karn/Partidge AlgorithmKarn/Partidge Algorithm
An obvious flaw in the original algorithm:
Whenever there is a retransmission it is
impossible to know whether to associate
the ACK with the original packet or the
retransmitted packet.
26. Computer Networks: TCP 26
Figure 5.10Figure 5.10
Associating the ACK?Associating the ACK?
Sender Receiver
Original transmission
ACK
Retransmission
Sender Receiver
Original transmission
ACK
Retransmission
(a) (b)
27. Computer Networks: TCP 27
Karn/Partidge AlgorithmKarn/Partidge Algorithm
1. Do not measure SampleRTTSampleRTT when
sending packet more than once.
2. For each retransmission, set TimeOutTimeOut
to double the last TimeOutTimeOut.
{ Note – this is a form of exponential
backoff based on the believe that the
lost packet is due to congestion.}
28. Computer Networks: TCP 28
Jaconson/Karels AlgorithmJaconson/Karels Algorithm
The problem with the original algorithm is that it did not
take into account the variance of SampleRTT.
Difference = SampleRTT – EstimatedRTTDifference = SampleRTT – EstimatedRTT
EstimatedRTT = EstimatedRTT +EstimatedRTT = EstimatedRTT +
((δδ x Difference)x Difference)
Deviation =Deviation = δδ (|Difference| - Deviation)(|Difference| - Deviation)
where δδ is a fraction between 0 and 1.
29. Computer Networks: TCP 29
Jaconson/Karels AlgorithmJaconson/Karels Algorithm
TCP computes timeout using both the mean
and variance of RTT
TimeOut =TimeOut = µµ x EstimatedRTTx EstimatedRTT
++ ΦΦ x Deviationx Deviation
where based on experience µ = 1µ = 1 and ΦΦ = 4= 4.
