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I can see that some ACK packet without PSH flag sends data as well. I have thought that ACK packet will always have len=0, but I see packets with ACK flag only and len=1380.

asked 06 Jan '15, 08:07

Otas's gravatar image

accept rate: 0%

converted to question 06 Jan '15, 08:46

grahamb's gravatar image

grahamb ♦

Its called as piggybacking,Piggybacking is a bi-directional data transmission technique. It makes the most of the sent data frames from receiver to emitter, adding the confirmation that the data frame sent by the sender was received successfully (ACK acknowledge). This practically means, that instead of sending an acknowledgement in an individual frame it is piggy-backed on the data frame

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answered 06 Jan '15, 08:41

kishan%20pandey's gravatar image

kishan pandey
accept rate: 28%

Hello Kishan,

thank you for lightning response. Fully clarified.



(06 Jan '15, 10:58) Otas

After the SYN packet, every single packet will have the ACK bit set, so data packets are also ACK packets.

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answered 06 Jan '15, 10:10

Jim%20Aragon's gravatar image

Jim Aragon
accept rate: 24%

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question asked: 06 Jan '15, 08:07

question was seen: 6,093 times

last updated: 06 Jan '15, 12:34

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