Re: [tsvwg] SCTP ABC
"Gorry (erg)" <gorry@erg.abdn.ac.uk> Thu, 24 June 2021 07:45 UTC
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From: "Gorry (erg)" <gorry@erg.abdn.ac.uk>
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Date: Thu, 24 Jun 2021 08:45:28 +0100
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To: Timo Völker <timo.voelker@fh-muenster.de>
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Subject: Re: [tsvwg] SCTP ABC
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See below: > On 23 Jun 2021, at 16:02, Timo Völker <timo.voelker@fh-muenster.de> wrote: > > Hi, > > SCTP (RFC4960) limits the increase of its cwnd in slow start to one PMTU (or PMDCS as named in the rfc4960-bis document) as stated in Section 7.2.1. This means the cwnd may be increased less when the receiver sends an ack on every second packet compared to on every packet. > > --- > Ex: > 1. A sender in slow start with PMTU=1200 sends two packets with 1000 byte of data each. > >> DATA(len=1000, tsn=1) >> DATA(len=1000, tsn=2) > > 2a. In case the receiver sends an ack on every packet, the sender receives two acks. > > < ACK(cum_tsn=1) > --> cwnd += 1000 > < ACK(cum_tsn=2) > --> cwnd += 1000 > > resulting in a cwnd increased by 2000 byte. > > 2b. In case the receiver sends an ack on every second packet, the sender receives one ack for both packets. > > < ACK(cum_tsn=2) > --> cwnd += 1200 > > resulting in a cwnd increased by only 1200 byte due to the PMTU limit. > --- > > TCP's Appropriate Byte Counting (ABC) specified in RFC3465 addresses that with the parameter L set to 2*SMSS. > > Adding a note for that in rfc4960-bis would help, I think. > > Timo What do others think? Are the SCTP implementors happy with this proposal? Gorry
- [tsvwg] SCTP ABC Timo Völker
- Re: [tsvwg] SCTP ABC Gorry (erg)
- Re: [tsvwg] SCTP ABC Michael Tuexen