Re: High latency for IPv6 on netbsd-8

[Robert Elz <kre%munnari.OZ.AU@localhost>]

    Date:        Sat, 28 Jul 2018 17:38:13 +0700
    From:        Gua Chung Lim <gua.chunglim%gmail.com@localhost>
    Message-ID:  <20180728103813.GA114%gmail.com@localhost>

  | I previously had rtsol in /etc/ifconfig.wm0 i.e.
  |
  | % cat /etc/ifconfig.wm0
  | up
  | !rtsol $int

Yes, rtsol was deleted, dhcpcd does that job now (Roy can probably supply
you with an incantation (the options to use) to cause it to expliciately send a
rtsol on that interface, that's something I have never tried ... where I have 
IPv6 I still have an old system, and where I run up to date code, there is no
IPv6 available (except tunnels, which is an entirely different beast) 
unfortunately.

  | But during boot, it complains as rtsol is obsolete, so I remove the second line.

Yes, unless you can get a dhcpcd command (the options to use) to replace it, 
that was the right thing to do.

  | Anyway, I saw "Waiting for DAD to complete..." right before router solicitation.
  | So I guess that DAD complete before RS.

Yes, it looks that way.

  | https://pastebin.com/udwFzp3N

That makes it clear that you are receiving the RA, and a default
route (and a route to your local IPv6 network) are being installed,
which should be all that is needed.

  | Sometimes I have to wait for 30 minutes.

That would be a little long for an RA interval from the router, but is
not totally absurd.   But it does not look like that is the issue anyway.

  | Immediately after boot, I can ping6 fe80::1. (I believe it's LL.)

Yes, it is, this indicates that your IPv6 stack, and hardware (the ethernet)
is all up and working.   If there is some other LL IPv6 on your net it might
be worth testing that one as well, to confirm that multicast is also working
(the router's MAC addr will have been in the RA that it sent, so no neighbour
discovery (IPv6 version of ARP) would be needed for that one, but for other
IPv6 addresses (except the host's of course) ND would be needed, and that
needs multicast to work (whereas for v4, ARP uses broadcast).

That's kind of a remote possibility as I can't think of any reason that 
multicast would fail near boot, and then magically just start working some
time later.

Actually, is that exactly what you are typing ( "ping6 fe80::1" ) ?

If so, there's no interface specified, and it might be using the one other
than where your default route goes, so try
	ping6 fe80::1%wm0
instead (if that is not what you already did).

  | Right after boot, where ping6 canonical name fails, ping6 global ipv6 address also fails.
  | So it should not be a DNS issue.

I agree.   Keep testing with addresses, rather than names, just to avoid any
possibility of that (or addresses in addition to names if you like.)

  | Adding this line to /etc/sysctl.conf and reboot doesn't fix the problem.

Yes, the output you showed on pastebin.com made it obvious my initial guess
was wrong, there is some other problem.

  |  ping6 LL works but ping6 the public ipv6 address or canonical name doesn't.

That suggests more a routing problem,   Can you show an actual ping6 command
failing?   And the IPv6 routing table, which you can get by

	netstat -r -n -f inet6
or
	route -n show -inet6

(just one of them will do ...)

There is no need to use pastebin.com - just including the output from one of
those in e-mail should work.

Oh, also include the output from
	ifconfig -a
as well, just in case something jumps out from that.

  | Both ping6 global address and canonical name fail.

If pinging the address fails (and you have the correct address) there's
no point also trying with the name, that just adds one extra layer of
indirection before doing the exact same ping (to the address) - it is
convenient for us humans though.

Last (after collecting the routing table, and ifconfig output while the
v6 address is not working correctly) wait until it "fixes itself" and do
those commands again (use the same method to get the v6 routing
table so it is possible to diff the two rationally...) and send that as well.

  | > ps: I hope you are on the list
  | I am on the list. :-)

Good.

kre