From Richard.Scheffenegger at netapp.com Thu Nov 22 10:20:28 2018 From: Richard.Scheffenegger at netapp.com (Scheffenegger, Richard) Date: Thu, 22 Nov 2018 10:20:23 +0000 Subject: RFC6675 Message-ID: Hi, Eric recently added a patch to Linux 4.18, to deliberately do SACK compression (withholding of dup-acks, to streamline the TCP processing on the receiver side). https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5d9f4262b7ea41ca9981cc790e37cca6e37c789e However, that mechanism assumes that RFC6675 - at least the condition when to transition into SACK Loss Recovery (based on FACK >= 2*MSS+1 byte over snd_una, rather than 3x dup ack) is implemented... I suspect, that as the Rescue Retransmission logic is missing (also in RFC6675), the LR trigger condition is also not implemented... Does anyone know if there exists a patch to have (full) RFC6675 compliance in the tcp stack? Best regards, Richard