8 votes
Accepted

Why only after 3-duplicate ACK retransmission takes place in TCP?

You're referring to 'Fast Retransmit' in the TCP Reno implementation. It is basically an assumption. RFC 2001, TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms ...
moogzy's user avatar
  • 854
6 votes

Relationship between TCP window size and TCP congestion control

The first thing to realize is that the TCP window size and the round-trip time (RTT) limit the throughput: no more than one window size per RTT can be transported. Essentially, with a large RTT (...
Zac67's user avatar
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6 votes

How is congestion avoided when using UDP?

UDP does not provide any congestion control, control of packet loss, duplication, reordering ... . All of this has to be implemented at the application level and each protocol might handle this ...
Steffen Ullrich's user avatar
5 votes
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BGP: Route congestion

In theory, the answer is yes, but based on your diagram and description, the practical answer is NO. The problem is you can control your outbound traffic, but you have little control over your ...
Ron Trunk's user avatar
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5 votes
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QoS shaper, shapes traffic without dropping packets?

How does my policy manage to shape traffic to the requested size without dropping packets? ... Tunnel traffic remains 10Mbps and still a few packets in queue but no drops… Your C-class FTP ...
Mike Pennington's user avatar
5 votes
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TCP Congestion Control, Sender window = minimum ( Congestion window, Receiver window)

The receive window is maintained by the receiver and indicates how much buffer space has to be receiving more segments (from any senders). So a sender would want to take that into account when setting ...
auspicious99's user avatar
4 votes
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What is congestion collapse?

To start off I'm going to first ask you to ignore queueing. Imagine that routers in the following text have no queues at all. It is possible to understand congestion without bringing queues into the ...
mere3ortal's user avatar
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4 votes
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What is the maximum value that a receiver can set in its advertising window

The Window Size field in each TCP header indicates the amount of empty space, in bytes, remaining in the receive buffer. The field is 16 bits in TCP, but with the Windows Scale option, values larger ...
MUSR's user avatar
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4 votes
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Why does throughput (consumed BW) increase when the packet error rate is increased in the TCP?

Errors in transmission are detected in TCP layer. The receiving TCP layer discards the damaged segment, forcing the sender to sent the segment again.
jcbermu's user avatar
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4 votes
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How is congestion avoided when using UDP?

In addition to Steffen's fine answer perhaps more direct replies: how applications can determine: How many UDP datagrams can be sent at once They can't. Neither IP nor UDP provide any mechanism to ...
Zac67's user avatar
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3 votes

When should TCP send a cumulative acknowledgement?

I recommend reading RFC 1122 "Requirements for Internet Hosts -- Communication Layers", section 4.2.3.2 "When to Send an ACK Segment", and follow up from there. https://www.rfc-...
jonathanjo's user avatar
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3 votes

TCP flow control active waiting

Why is an active waiting mechanism employed here, instead of having the receiver just notify the sender that its buffer is no longer full? To prevent a deadlock. Consider your scenario, where the ...
Ron Trunk's user avatar
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3 votes
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Latency between a churn and congestion event triggered in the TCP code

basically you are correct. packet losses are discovered either by 3 (or more) duplicate ACKs or by a retransmission timeout. The former should happen in about one RTT, provided that there are enough ...
Effie's user avatar
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3 votes

Does window size in tcp header include tcp header size?

No, the receive window refers to payload data only. It excludes any TCP headers. Case 2 is correct. Note that segment does include the TCP header. See RFC 793 for the TCP protocol standard.
Zac67's user avatar
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3 votes

Why does TCP sender drop rate 50% on lost-packets?

TCP adapts the receive window size when it detects congestion, ie. when packet loss occurs. There are several congestion algorithms, starting with the original Tahoe. An overview: https://en.wikipedia....
Zac67's user avatar
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2 votes
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TCP Traceroute with actual TCP session

It sounds like Scapy might be what you're looking for. Here's an example of how to change the TTL in a packet.
OzNetNerd's user avatar
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2 votes

Tuning TCP Reno parameters to reduce delay experienced by short flows of size 20KB ?

The above issue was resolved and I was able to reproduce the same figure. The authors specified that for TCP they were using 100 packets as the limit of buffer. And I was using 467 packets as buffer ...
akadam's user avatar
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2 votes

Can tcp throughput be equal to bandwidth?

This will be a really long answer, So here it goes. First things first the rate at which TCP will send the data is dependent on 3 things- application generating data, receive window, congestion window....
john 's user avatar
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2 votes
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The difference between simple ACK and ACK aggregation improvement in TCP

There is a mechanism that is called TCP delayed acknowledgment. It is used to improve network performance. You can find more info in google. Here is wiki page: https://en.wikipedia.org/wiki/...
Nuran Afrasiyabov's user avatar
2 votes
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LSA Weighted Fair Queuing Algorithm

In Cisco IOS: The order of removal from the fair queues is determined by the virtual time of the delivery of the last bit of each arriving packet. src: Cisco IOS Quality of Service Solutions ...
hertitu's user avatar
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2 votes

If we have Fast Retransmit does it mean we have Fast Recovery?

You should understand that there are a variety of TCP congestion control schemes, and "Reno" and "NewReno" are the ones which implement fast retransmit, but others do not because ...
Ron Maupin's user avatar
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2 votes
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WiFi signal drops and difficulty connecting... too many clients?

It sounds like you have channel contention. Increase the minimum data rate on all your APs to make the cell size smaller. You want to disable low speeds so clients can't connect if signal is marginal. ...
Ron Trunk's user avatar
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2 votes
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Ethernet Flow Control vs Quality of Service

QoS will apply policies to different traffic classes as it passes through the device, such as giving priority to certain traffic. But it does not signal to the transmitter to pause. Flow control ...
John K.'s user avatar
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2 votes
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congestion control

You didn't read the full sentence. Here it is from Data Communications and Networking 5th edition by Behrouz A. Forouzan Page 526: Acknowledgment Policy The acknowledgment policy imposed by the ...
Ron Trunk's user avatar
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2 votes

AIMD: Total number of packets sent

The dropped packet that is retransmitted becomes part of the second batch - it is not retransmitted separately.
Zac67's user avatar
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2 votes
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Initial TCP congestion window sizes

There is as you might imagine a lot of research on window sizes in general, and you will see there's a lot of research in specifically what are the recommendations for initial window size in TCP. The ...
jonathanjo's user avatar
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2 votes
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Response time of TCP congestion control

TCP congestion control is far too elaborate to look into detail here. For a start, check out https://en.wikipedia.org/wiki/TCP_congestion_control. Reaction to channel parameters can be as fast as RTT ...
Zac67's user avatar
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2 votes
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Routers and output buffers: Why can two devices interfere with each other and cause latency?

Are there output queues for information being transmitted from the internet to devices on a network? Your diagram shows switches, so I'll relate to that. According to your quote, output buffers ...
Zac67's user avatar
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