RFC Errata
RFC 5681, "TCP Congestion Control", September 2009
Note: This RFC has been updated by RFC 9438
Source of RFC: tcpm (wit)See Also: RFC 5681 w/ inline errata
Errata ID: 5458
Status: Verified
Type: Editorial
Publication Format(s) : TEXT
Reported By: James McCauley
Date Reported: 2018-08-12
Verifier Name: Mirja Kühlewind
Date Verified: 2018-08-13
Section 2 says:
DUPLICATE ACKNOWLEDGMENT: An acknowledgment is considered a "duplicate" in the following algorithms when (a) the receiver of the ACK has outstanding data, (b) the incoming acknowledgment carries no data, (c) the SYN and FIN bits are both off, (d) the acknowledgment number is equal to the greatest acknowledgment received on the given connection (TCP.UNA from [RFC793]) and (e) the advertised window in the incoming acknowledgment equals the advertised window in the last incoming acknowledgment.
It should say:
DUPLICATE ACKNOWLEDGMENT: An acknowledgment is considered a "duplicate" in the following algorithms when (a) the receiver of the ACK has outstanding data, (b) the incoming acknowledgment carries no data, (c) the SYN and FIN bits are both off, (d) the acknowledgment number is equal to the greatest acknowledgment received on the given connection (SND.UNA from [RFC793]) and (e) the advertised window in the incoming acknowledgment equals the advertised window in the last incoming acknowledgment.
Notes:
There is no such thing as TCP.UNA in RFC793. The boundary between acknowledged and unacknowledged sent data is SND.UNA.