Hangout 06 June 2019

• IPv6 Fragment reviews which need testing:
  • Eliminate KAME circular queues: D16847.
  • Drop packets with overlapping fragments: D16850.

• IPv6 modernization project: Wiki Page
  • Julius proposed importing OpenBSD fragmentation regression test cases (see D17376). thj@ is working on it.
    • Drop from list: need to be re-written.
  • RFC 7112 D16851.
    • Just updated. Tom will mercilessly harass jtl@ until he reviews it.
  • IP6 IDs (and IP IDs, maybe?): may use an insecure algorithm. Ideally, switch to some sort of per-host-pair hash?
    • What do OpenBSD/NetBSD do?
      • tuexen: OpenBSD does skip32. We use a linear congruential algorithm. NetBSD uses the same algorithm we do.
    • See paper.
    • Perhaps, a small cache would be sufficient?
      • RFC 7739 provides three different options to consider.
  • Absent a compelling application that needs this, put any changes on hold.

• jtl@ to send patch to Richard for burst mitigation in the default stack. An idea is in D19047.
  • Still need to do.

• D18811: standardize on snd_recover (vs. sack_newdata). Reviewer: tuexen@, lstewart@.
  • @tuexen will review again.

• D18624: RFC 6675 support. Actual functionality in D18985.
  • Helps when HW LRO is enabled.
  • Also, this enables a PRR patch (based on Lars work). D18892. Needs review.

• CUBIC: Only invoking NewReno after_idle, not resetting ssthreash, not resetting epoch time: D18982, D18954, and D19118. Including another issue, this will be discussed at the IETF.
  • lstewart@ is the best person to review this.

• D19000 deal with a bug that the 1 byte occupied in the sequence number space by SYN segments results in a cwnd increase when acked. This bug exists only on the server side. tuexen@ and Richard are working on it.

• Richard is working on burst mitigation. An initial version (WIP) is available as D19047.

• tun/tap interfaces: should we see outgoing packets in tcpdump?
  • Currently inconsistent. In general, yes, these should be visible.
  • There was a re-write of tun/tap interfaces in the meantime. tuexen@ will re-evaluate.

• Items for future discussion (based on BSDCan discussions):
  • Revisit how we maintain multiple TCP stacks
  • Revisit CC API
  • Talk about further network modularity (as requested by Juniper)

• hps@ gives update on D20080.
  • markj@ reviewing.

• hps@ asks about D19622.
  • Feedback: because fragments are not tied to arrival interface, it doesn't make sense to drop fragments.
  • jtl@ to summarize conversation in review. Hopefully, we can have a real-time conversation on the call in 2 weeks.

• tuexen@ committed D20372.

• Richard reports NetApp is testing DC-TCP.

Scheduled for 20 June, 14:00 UTC.