Subject: [PANRG] Flow labels in draft-irtf-panrg-what-not-to-do-02

From: Tom Herbert <[email-masked]>
Date: Mon, 1 Apr 2019 05:31:13 +0200

Hello,

>From the draft wrt IPv6 flow label:

"Before methods are widely deployed to use this method, there could be
no incentive for an endpoint to set the field."

At this point, the majority of IPv6 packets in the Internet should
have properly set non-zero flow labels. Non-zero flow label is set by
default for Linux since 2014. iOS was setting it before that, and I
believe Windows started setting flow labels not long after Linux. This
is one of the few things we were able to turn on in the
Internet without causing any major problems and it has zero negative
performance impact. The impetus is on network devices to start using
the information.

e.g. a tcpdump unconnected UDP from my Linux host:

20:12:06.099837 IP6 (flowlabel 0x1b95a, hlim 64, next-header Options
(0) payload length: 56) 3333::1 > 1113:1:0:0:8000::: HBH (opt_type
0xde: len=20) 58669 > 7777: [udp sum ok] UDP, length 24

Tom