Questions tagged [transport-protocol]

For questions about or in relation to the transport protocol or OSI layer 4. For instance the best-known transport protocol of TCP/IP is the Transmission Control Protocol (TCP).

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How does QUIC encrypt packets containing multiple CRYPTO frames?

TCP is slowly being replaced by QUIC and I'm implementing a component that looks at QUIC packets to extract the server name indication from initial packets. The code is working fine, assuming that: (1)...
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Can QUIC prevent DNS/NTP amplification for DDOS

According to Cloudflare's article dedicated to QUIC - subtitle Deflecting Reflection implies that QUIC may prevent tampering IP packets. Doest it meat that QUIC may kill DNS/NTP amplification for DDOS ...
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How does QUIC provide delivery guarantee?

I'm struggling to grasp how QUIC implements handshakes in contrast with 3 handshakes in TCP. I came across with this picture on Wikipedia. As QUIC uses UDP, I don't understand how the protocol ensures ...
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How is congestion avoided when using UDP?

I understand how TCP goes about this - through various methods such as Congestion Window (CWND), Sliding Window, Slow Start and Fast Recovery - it's basically built into the protocol. I understand ...
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What does it mean that telnet uses port 23? [closed]

On the IANA Transport Protocol Port number registry, you can see that telnet connects to port 23. However, telnet takes a port number as an argument. For example, you can access the HTML of google.com ...
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Why do QUIC packets require a sequence number? [closed]

This may be a silly question, but if in QUIC we maintain separate sliding windows for each stream, why is there a need for sequencing even below the stream level? It seems to me that an application ...
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Maximum throughput for the Selective-Repeat protocol [duplicate]

I am currently learning about the transport layer, especially reliable data transfer protocols, from Jim Kurose's book "Computer Networking: A Top-down Approach". I want to find the maximum ...
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UDP supports multicasting and broadcasting in transport layer or application layer?

We know that UDP does supports multicasting and broadcasting. My question is which layer "UDP supports multicasting and broadcasting"? Is it transport layer or application layer? We know ...
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Is transport layer MSS dependent on Ethernet MTU? [duplicate]

Ethernet has an MTU of 1500 bytes whereas IP has a maximum length of 65535 bytes. It might seem that the average TCP segment that is lesser than the IP maximum length or the Ethernet MTU has to be ...
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Which protocol enforces a transmission time limit?

I would like to use an internet protocol for communicating with people in which transmissions are necessarily under 0.1 seconds. Is there any example of a pre-existing internet protocol where, by ...
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Does socket address include transport protocol (http://)? [closed]

Let's say I have the following: http://ip_addr:port This is supposedly called the socket address (see sources below), but I can't find a conclusive answer anywhere if the transport protocol (http://) ...
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When using link state routing algorithm, does each router have a map of the other routers?

I think when using dijsktra algorithm, each router's shortest-path tree can be different. And in link-state routing, all routers have the same topology of the total network. Therefore, does each ...
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Acknowledgement, retransmission of layer2 is actually belongs to layer4?

I followed from this question understand that only transport layer responsible for acknowledgement. But I have read on book stop and wait, GBN, SR protocols uses acknowledgement, retransmission in ...
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What will be the sequence number consumed by FIN flag? [duplicate]

In the connection termination phase, suppose the FIN segment from the client-side contains data ranging from sequence no 100 to 200, So will the ACK no from the server start from 201 or 202? Will the ...
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RSVP warning: ID "data" is not configured

I am trying to follow this document: https://www.cisco.com/c/en/us/td/docs/ios/qos/configuration/guide/12_2sr/qos_12_2sr_book/config_rsvp.pdf to configure rsvp, using gns3, for Entering Senders or ...
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Where are 0 TCP/UDP ports banned?

It is well-known that, on most systems, using 0 for the UDP destination port or for the TCP source or destination ports is disallowed. Is this required by RFCs, or is this just common practice? If it'...
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What is the minimum MTU of IPv4 68 bytes or 576 bytes?

I read that 68 bytes is the minimum size of IPv4 datagram every device must be able to forward without further fragmentation. 576 bytes is the minimum size of IPv4 datagram every device has to be able ...
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Which one is right, UDP has 508 or 512 bytes payload limits?

We know the size guarantees the datagram won't be fragmented in IPv4 is maximum 576 bytes. But the size when use UDP header 8 bytes and if we take UDP payload 512 bytes and choose maximum header size ...
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Why loss of first Syn + Ack from the server will not establish a connection? [duplicate]

In TCP 3-way handshake, 3 segments will be sent (SYN, SYN ACK, ACK). What if loss of syn+ack from the server will not establish a connection? What if the third segment(ACK) is lost? Is the sender ...
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Why sender window or congestion window size becomes 2^n mss after nRTT in slow start mechanism?

I seen everywhere in slow start mechanism if initial sender size denoted by cwnd= 1mss , then after 1 RTT cwnd becomes = 2 mss, and after 2 RTT cwnd becomes = 4 mss and so on. My question is why ...
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Is really TCP takes 3*RTT time to make a connection?

TCP takes 3 RTT time I have read from one stack overflow answer to make a connection with server. We know that TCP takes triple (Syn, Syn/Ack, Ack) to make a connection by 3-way handshake with server....
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How is UDP used in multimedia system inspite of being connectionless

We know that UDP does not care about segment (packet) in-order and their arrival on the destination.Then how on YouTube or VoIP (skype) are we able to stream videos? If a packets is lost (doesn't ...
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Is it possible for TCP can accept out of order segments?

TCP is connection-oriented protocol whereas IP isn't connection-oriented protocol. Any packets before sending into transport layer sorted operation must have been done in network layer. That's why we ...
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Definition of a socket [duplicate]

I wanted to confirm whether the definition of a socket I've understood in a computer network context is true. A socket is file who is unique and named by local IP,Local port, Foreign IP and foreign ...
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Is there any research that tracks fragmentation and drop rates of UDP packets based on size?

I'm designing a P2P system. I need to decide an ideal packet size that maximizes the efficiency of my system. This answer claims a 508 bytes is the maximum safe size, but I believe larger packets ...
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What's the advantage of IPSec over TLS/DTLS? [closed]

What's the benefit of IPSec over TLS and DTLS ? If someone's goal is to assure authentication, integrity and confidentiality, can't he/she simply encrypt the content with the two last protocols (on ...
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Does UDP can be exposed to stateful analysis?

From protocol theory we know that TCP is stateful protocol. Different stateful packet filters do filtration based on connection state. I.e. it can distinguish responses and replies. It's obviously for ...
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Why large queueing delays are experienced as a packet arrival rate nears the link's capacity? [duplicate]

From the book "Computer Networks A top Down Approach": It says if hosts A and B both are sending at rate R/2 and router's outgoing link has a capacity of R. There will be delays experienced ...
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How to create an internet protocol like HTTPS? [closed]

If I want to create my own internet protocol, what should I do? How can I create it? Will people be able to use my protocol in their internet browsers? I asked this question in a simple Discord server ...
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How TCP sequence numbers work in bidirectional communication/sliding window?

I was trying to understand how TCP works (not in detail of course). I was surfing the web for easy-to-understand flow diagrams and a question arose and couldn't find a straight answer. Let's suppose ...
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1 answer
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100BaseTX Ethernet Idle code ("/I/") 4B/5B origin

While searching how the PHY LINK status is determined, I stumbled across this answer : In 100BaseTX Ethernet, link pulses aren't used, but instead, link status is detected and maintained via the ...
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What happens to the packets in the sender buffer when "eventually a timeout would be reached" for a **delayed ACK** in a AIMD TCP connection?

In a AIMD TCP connection, What happens to the packets in the sender buffer when "eventually a timeout would be reached" for a delayed ACK for a specific packet at the sender side? Suppose ...
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What would happen if TCP flow control is turned off hypothetically? [closed]

I understand that TCP flow control provides a way for the receiver to backpressure the sender. But what if we eliminated this from the protocol. Of course, the receiver would still ACK everything ...
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I have issue with MSS and window size [duplicate]

I made a short example because I have tried understanding the difference between MSS and window size in tcp header when we consider a sender and a receiver. So let's say sender and receiver use the ...
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Nature of TCP Timeouts

Are timeouts in TCPs inherently part of sequence numbers, or is it an entirely different component of a TCP packet? I understand that timeouts provide some level of reliabilty to a data stream, in ...
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Is the TCP Reno Fast Recovery algorithm really linear?

I'm reading through Computer Networking, 8th Edition by Kurose & Ross, and I came upon this figure(Figure 3.52 pictured below), which graphs the operation of TCP Tahoe & TCP Reno. The graph ...
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Does the destination port change during TCP three-way handshake?

I'm learning networking programming in C and there is a question bothers me a lot, does the destination port change during TCP three-way handshake? Let's say I have a cilent application running on ...
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2 answers
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How are Ports Exposed to the Network?

When you register some server's port, whether it be an application, web, or something else - where exactly is this port registered? I understand how ports work in that they are essentially signposts ...
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Do these 2 packets belong to the same tcp socket?

Let's say we have two packets A and B. A: Has source-IP S1 , destination-IP D1 , source-port SP1 , destination-port DP1 B: Has source-IP S2 , destination-IP D1 , source-port SP2 , destination-port DP1 ...
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What is "TIME_WAIT" connection in a TCP connection and what is it's purpose?

I am requesting a webpage running on local server port 8080 and was expecting one connection to be established between the server (port 8080) and client (random port). But one additional port is also ...
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Why is a UDP port scan more complex than TCP port scan?

When I scour SO, I saw that it's a bit complex to port scan a UDP port than a TCP port, why?
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What is the relation between software and hardware ports?

A port number is a 16-bit unsigned integer, thus ranging from 0 to 65535 https://en.wikipedia.org/wiki/Port_(computer_networking) And I think computers have small number of hardware interfaces(ports) ...
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Does the first TCP FIN packet (active close) goes with just only FIN bit set?

Suppose we have established TCP connection. The active close process assumes the FIN packet been sent to trigger TCP connection closing. But I can't figure out, is this first (active close) FIN packet ...
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Is there any other network protocol than tcp/udp that works with ports?

Do you know at least one protocol (any OSI layer) that, like tcp and udp, works with ports ? Thank you
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Why is delayed segment prevention (TIME_WAIT) in TCP only done for one side?

One of the reasons for TIME_WAIT is to prevent old packets/duplicates, coming in late, to screw up subsequent connections on the same (src ip, src port, dst ip, dst port) quadruplet. That makes sense, ...
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Does UDP do anything at all?

It's my understanding that TCP has logic for ensuring reliable communication, but UDP just naively sends information along the channel set up for it using IP and things in lower layers. Does UDP ...
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Congestion control in transport and network layers in TCP/IP

Why do we need congestion control in BOTH the transport layer and network layer in TCP/IP model. Cant we be good enough with control in just one of the layers only? And how do they differ?
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What will happen if a server receives a duplicate SYN for an existing connection?

If a server receives a fresh SYN packet for a connection that is already established, what should it do? I have already seen What will happen at server side if it received 2 SYN packet from the same ...
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Is this UDP diagram wrong?

I was just wondering if anyone can tell me why all UDP diagrams I have seen list a request from the server to the client as the first point of communication? Take a look at the following diagram for ...
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How do I properly serialize a network packet [closed]

So I'm currently writing a program that is essentially just a server and a client. The idea is that I want them to be able to communicate with one and other by sending packets back and forth. And I'm ...
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