RFC Errata
RFC 793, "Transmission Control Protocol", September 1981
Note: This RFC has been obsoleted by RFC 9293
Note: This RFC has been updated by RFC 1122, RFC 3168, RFC 6093, RFC 6528
Source of RFC: LegacyArea Assignment: tsv
See Also: RFC 793 w/ inline errata
Errata ID: 1564
Status: Verified
Type: Technical
Publication Format(s) : TEXT
Reported By: Constantin Hagemeier
Date Reported: 2008-10-11
Verifier Name: Wes Eddy
Date Verified: 2011-08-13
Section 3.7 says:
When the sender creates a segment and transmits it the sender advances SND.NXT. When the receiver accepts a segment it advances RCV.NXT and sends an acknowledgment. When the data sender receives an acknowledgment it advances SND.UNA. The extent to which the values of these variables differ is a measure of the delay in the communication. The amount by which the variables are advanced is the length of the data in the segment. Note that once in the ESTABLISHED state all segments must carry current acknowledgment information.
It should say:
When the sender creates a segment and transmits it the sender advances SND.NXT. When the receiver accepts a segment it advances RCV.NXT and sends an acknowledgment. When the data sender receives an acknowledgment it advances SND.UNA. The extent to which the values of these variables differ is a measure of the delay in the communication. The amount by which the variables are advanced is the length of the data and SYN or FIN flags in the segment. Note that once in the ESTABLISHED state all segments must carry current acknowledgment information.
Notes:
SYN and FIN are counted, too