In TCP,
segment1---client-to-server----x(dropped)
seg1(ACK+somedata)<-----------server-to-client
segment2---------->client-to-server
seg2(ack+somedata)<-----------server-to-client
Retransmitted Segment1------> client-to-server
Now can retransmitted segment1 ack for seg2? Or seg2 will be acked by seperate message from client?
Related
client tcp_syn_retries=2,server,tcp_synack_retries=5,In the Wireshark, which packet number is the first synack retransmitted packet,client syn retransmitte and server acksyn retransmittedat the same time?
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How does tcp protocol (of an established connection) respond to a package with an ack number higher than the largest sequence number sent. That is, the other party tells that it has received bytes that the other end of the connection have not sent.
How does tcp protocol respond to that?
Segment 1 is sent at t0.
Ack for segment 1 is received at t5.
Ack for segment 1 is recieved at t7.
Which Ack should I use to calculate Re-transmission Timeout?
I have a question on how TCP_ACK works when the original packet are fragmented.
For example, original packet size is 1,500*N bytes and MTU is 1,500. Then, the packet will be frgmented into (approximately) N packets.
In this case, how does the receiver sends TCP_ACK to the sender?
I checked with wireshark, it seems that the receiver sends TCP_ACK for every two fragmented packet. Is it right?
Could you give me some refereces for this or explanation?
Thanks.
IP layer on the receiver stack reassembles all the IP fragments into a single TCP segment before handing the packet over to TCP. Under normal conditions, TCP should send only one ACK for the entire TCP segment. The ACK # would be the next expected SEQ # as usual.
Why does the TCP three-way handshake bump the sequence number when acking during the initial handshake? How is that better than just leaving the acknowledgement number equal to the sequence number?
The connection is established with
Client sends SYN,A
Server responds with SYN-ACK,A+1,B
Client confirms with ACK,B+1
How is that better than
Client sends SYN,A
Server responds with SYN-ACK,A,B
Client confirms with ACK,B
That's because the ACK field means this when the ACK flag is set:
Acknowledgment number (32 bits) – if the ACK flag is set then the value of this field is the next sequence number that the receiver is expecting.
If it is not set to (inital sequence number+1), it would be inconsistently mean both ack'ing the SYN (both SYN and ACK flags must be set in this packet) and saying it is expecting that sequence number again (i.e. hasn't received it).