Re: [quicwg/base-drafts] Reorganize ACK section (#2197)
janaiyengar <notifications@github.com> Sat, 05 January 2019 01:21 UTC
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Subject: Re: [quicwg/base-drafts] Reorganize ACK section (#2197)
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janaiyengar commented on this pull request. Looks good, a few comments, mostly minor. One note: ACK Ranges and ECN Counters are not fields, they are composed of fields. I would refrain from calling them fields. > @@ -2841,23 +2841,24 @@ needing acknowledgement are received. The sender can use the receiver's Strategies and implications of the frequency of generating acknowledgments are discussed in more detail in {{QUIC-RECOVERY}}. -To limit ACK Blocks to those that have not yet been received by the sender, the -receiver SHOULD track which ACK frames have been acknowledged by its peer. Once -an ACK frame has been acknowledged, the packets it acknowledges SHOULD NOT be -acknowledged again. +To limit the ranges of acknowledged packet numbers to those that have not yet +been received by the sender, the receiver SHOULD track which ACK frames have +been acknowledged by its peer. Once an ACK frame has been acknowledged, the +packets it acknowledges SHOULD NOT be acknowledged again. This is now fixed in #2245. > Because ACK frames are not sent in response to ACK-only packets, a receiver that is only sending ACK frames will only receive acknowledgements for its packets if the sender includes them in packets with non-ACK frames. A sender SHOULD bundle ACK frames with other frames when possible. To limit receiver state or the size of ACK frames, a receiver MAY limit the -number of ACK Blocks it sends. A receiver can do this even without receiving -acknowledgment of its ACK frames, with the knowledge this could cause the sender -to unnecessarily retransmit some data. Standard QUIC {{QUIC-RECOVERY}} -algorithms declare packets lost after sufficiently newer packets are -acknowledged. Therefore, the receiver SHOULD repeatedly acknowledge newly -received packets in preference to packets received in the past. +number of ACK Range fields it sends. A receiver can do this even without ```suggestion number of ACK Ranges it sends. A receiver can do this even without ``` > -The ACK frame uses the least significant bit (that is, type 0x03) to indicate -ECN feedback and report receipt of QUIC packets with associated ECN codepoints -of ECT(0), ECT(1), or CE in the packet's IP header. + +### ACK Ranges Section {#ack-ranges-section} ```suggestion ### ACK Ranges {#ack-ranges-section} ``` > -The ACK frame uses the least significant bit (that is, type 0x03) to indicate -ECN feedback and report receipt of QUIC packets with associated ECN codepoints -of ECT(0), ECT(1), or CE in the packet's IP header. + +### ACK Ranges Section {#ack-ranges-section} + +The ACK Range Section consists of alternating Gap and ACK Range fields in ```suggestion The ACK Ranges consists of alternating Gap and ACK Range fields in ``` > -The ACK frame uses the least significant bit (that is, type 0x03) to indicate -ECN feedback and report receipt of QUIC packets with associated ECN codepoints -of ECT(0), ECT(1), or CE in the packet's IP header. + +### ACK Ranges Section {#ack-ranges-section} + +The ACK Range Section consists of alternating Gap and ACK Range fields in +descending packet number order. The First Ack Range field is followed by a +variable number of alternating Gap and ACK Range fields. The number of Gap and This sentence ("The First Ack Range ...") can probably go. > -The ACK frame uses the least significant bit (that is, type 0x03) to indicate -ECN feedback and report receipt of QUIC packets with associated ECN codepoints -of ECT(0), ECT(1), or CE in the packet's IP header. + +### ACK Ranges Section {#ack-ranges-section} + +The ACK Range Section consists of alternating Gap and ACK Range fields in +descending packet number order. The First Ack Range field is followed by a +variable number of alternating Gap and ACK Range fields. The number of Gap and +ACK Range fields is determined by the ACK Range Count field; one of each field +is present for each value in the ACK Range Count field. + +The ACK Ranges field is structured as follows: ```suggestion ACK Ranges are structured as follows: ``` > number of acknowledged packets that precede the largest packet number in that -block. A value of zero indicates that only the largest packet number is -acknowledged. Larger ACK Block values indicate a larger range, with +range. A value of zero indicates that only the largest packet number is +acknowledged. Larger ACK range values indicate a larger range, with ```suggestion acknowledged. Larger ACK Range values indicate a larger range, with ``` > ~~~ -The range of packets that are acknowledged by the ACK Block include the range -from the smallest packet number to the largest, inclusive. +The packets that are acknowledged by the ACK Range include the range from the +smallest packet number to the largest, inclusive. Suggestion: "An ACK Range acknowledges all packet numbers between the smallest packet number and the largest, inclusive." > -: Contains one or more blocks of packet numbers which have been successfully - received, see {{ack-block-section}}. +: A variable-length integer indicating the number of contiguous packets + preceding the Largest Acknowledged that are being acknowledged. I think some more text about parsing this needs to be moved up. How about adding something like: "The smallest value in this range is determined by the formula: ~~~ smallest = Largest Acknowledged - First ACK Range ~~~ The First ACK range acknowledges all packet numbers between the smallest and the Largest Acknowledged, inclusive." > -The largest value for the First ACK Block is determined by the Largest -Acknowledged field; the largest for Additional ACK Blocks is determined by -cumulatively subtracting the size of all preceding ACK Blocks and Gaps. +The largest packet number value for the First ACK Range is determined by the +Largest Acknowledged field; the largest value for subsequent ACK Range fields is Remove this first part about First ACK Range. Start the sentence with: "The largest value for an ACK Range is determined by ..." > The value of the Gap field establishes the largest packet number value for the -ACK Block that follows the gap using the following formula: +ACK Range that follows the gap using the following formula: ```suggestion subsequent ACK Range, using the following formula: ``` > ~~~ largest = previous_smallest - gap - 2 ~~~ -If the calculated value for largest or smallest packet number for any ACK Block +If the calculated value for largest or smallest packet number for any ACK Range ```suggestion If any of these computed packet numbers ``` > is negative, an endpoint MUST generate a connection error of type FRAME_ENCODING_ERROR indicating an error in an ACK frame. -The fields in the ACK Block Section are: - -First ACK Block: - -: A variable-length integer indicating the number of contiguous packets - preceding the Largest Acknowledged that are being acknowledged. +The fields that form the ACK Ranges field are: ```suggestion The fields that form the ACK Ranges are: ``` > is negative, an endpoint MUST generate a connection error of type FRAME_ENCODING_ERROR indicating an error in an ACK frame. -The fields in the ACK Block Section are: - -First ACK Block: - -: A variable-length integer indicating the number of contiguous packets - preceding the Largest Acknowledged that are being acknowledged. +The fields that form the ACK Ranges field are: This should be moved above, to before the entire description of how ACK ranges are to be parsed. Probably to the top of {{ack-range-section}}. > @@ -4310,6 +4317,8 @@ section consists of 3 ECN counters as shown below. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~~~ +The fields that form the ECN Counters field are: ```suggestion The fields that form the ECN Counters are: ``` -- You are receiving this because you are subscribed to this thread. Reply to this email directly or view it on GitHub: https://github.com/quicwg/base-drafts/pull/2197#pullrequestreview-189574193
- Re: [quicwg/base-drafts] Reorganize ACK section (… Christian Huitema
- [quicwg/base-drafts] Reorganize ACK section (#219… Martin Thomson
- Re: [quicwg/base-drafts] Reorganize ACK section (… ekr
- Re: [quicwg/base-drafts] Reorganize ACK section (… Martin Thomson
- Re: [quicwg/base-drafts] Reorganize ACK section (… ianswett
- Re: [quicwg/base-drafts] Reorganize ACK section (… MikkelFJ
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… Martin Thomson
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… janaiyengar
- Re: [quicwg/base-drafts] Reorganize ACK section (… Martin Thomson