Questions tagged [tcp]

For questions about Transmission Control Protocol (TCP), a transport protocol used to encapsulate data across a network for reliable communication.

18 questions with no upvoted or accepted answers
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Behaviour of TCP SACK

I will ask the question based on the following scenario. Assume I have to send 10 packets using TCP using a window size of 5. I send 1, 2 and receive ACK for them, I send 3 and the ACK is lost, I send ...
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351 views

Why is an empty TCP segment at right edge of receive window not acceptable?

The TCPv4 specification (RFC 793) classifies a received segment as unacceptable if it has zero length, a sequence number equal to RCV.NXT+RCV.WND while the receive window is not zero (second row in ...
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32 views

Packets lost with correct TCP sequence number. Is it possible?

I'm analysing some communication issues that we have between a server (SCADA) and remote terminal units (RTU) that we have in the field. The communications are IEC104 protocol which use TCP/IP. The ...
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346 views

Why SYN-RECEIVED sends reset on not acceptable ACK?

The tcp protocol actions on arriving segment vary. The set of choices includes: silently drop segment kill connection (i.e. enter CLOSED) send reset (and maybe kill connection) send dup/null ack (etc)...
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1answer
45 views

Which of TCP flags will use a timer, and what Timer will use?

When I study the TCP protocol life cycle, There are 3 stages: Establish Connection Data Transmission Connection Removal TCP have 6 Flag types: SYN, ACK, PSH, FIN, RST, URG. TCP has 4 Timer: ...
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37 views

How can I configure a Cisco router 4300 to allow internal server ip:80 to be accessed on public ip:4500

I have an internal web server on port 80. I need help commands maybe to configure port forwarding to access the server on my private network from a public IP Current running config interface ...
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0answers
26 views

TCP Payload vs Cellular Data Usage

I have a device that connects to the AWS via a LTE CAT1 modem. In the effort to reduce cellular data consumption, I put some monitoring code to keep track the amount of data usage at the TCP layer. ...
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294 views

AWS tunnel TCP retransmissions and DUP ACKs

I have a IPsec tunnel from my firewall towards AWS, the tunnel is up in both phases. If I run traffic sniffer in the firewall, I can see interesting traffic going through, but there are MANY TCP ...
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68 views

Processing received SACK information in case of reordering

I would like to understand how TCP receiver in established state should treat SACK information of out-of-order and fully within receive window segments, where rcv_nxt < seq_no < rvc_nxt + ...
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581 views

TCP: RST after ACK when limiter is in place

We are seeing TCP connections sporadically fail to establish, when a bandwidth limiter is placed on the network regardless of whether the limit is being hit. Below are links to some packet captures ...
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1k views

TCP retransmissions when we rapidly open multiple connections to the same host

We are experiencing a retransmission issue on some of our computers on our LAN, when connecting to external hosts. I first started trying to trace the issue when the npm typings install command was ...
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45 views

sending more datarate through less bandwidth

I was stimulating a program in ns2. The program consist of 4 nodes arranged as 1,2,3,4,5. Each of these nodes are connected with a 2 Mbps link, and I was sending data from node 1 to 5 through ...
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66 views

Broken session detection in mobile network

I'm interested in TCP connection between mobile unit which is connected over GPRS to server on public network. I need to keep open, so I will send periodically keep-alive packets for hold session. ...
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1answer
44 views

Is it valid to send consecutive tcp packets having overlapping data?

Assuming: TCP Window Size of client: 2000 bytes MSS (maximum segment size) of client: 1500 bytes Now server want to send 3000 bytes to client B1..B3000. Server sends: Packet-1: Contains B1..B1500 ...
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1answer
60 views

When the first bit reaches the host B, which bit is exit from the host A?

When the first bit reaches the host B, which bit is exit from the host A?
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40 views

Understanding TCP congestion control

Why is the congestion avoidance here [6,14] and [18,25]. Why not [6-10] and [18-22]? Other examples I have seen online suggest otherwise: For example here: https://www.researchgate.net/figure/TCP-...
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15 views

Whether every TCP segment of Data Transmission Stage have ACK flag and ack number?

In classic TCP lifecycle, there shows every TCP segment have a flag(SYN, ACK and so on). In 3-times handshake and 4-times wave-leave, there must be flag in every TCP segment, I can understand. But ...
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41 views

Will Eifel detection algorithm conflict PAWS?

From The Eifel Detection Algorithm for TCP: Given that timestamps are enabled for a connection, a TCP sender always stores the timestamp of the retransmit sent in the beginning of loss ...