Re: High latency for IPv6 on netbsd-8

[Gua Chung Lim <gua.chunglim%gmail.com@localhost>]

Thanks for your kind responses.

> You'll get better information either by trawling syslog, or by adding
> `logfile /var/log/dhcpcd.log` to dhcpcd.conf.
% cat /var/log/dhcpcd.log
https://pastebin.com/VyJ5BXQc

> Is the DHCP server in the router?
Yes, it is. It's basically a home network.
(At work I use FreeBSD.)

> Since I'm guessing you have a switched LAN
Yes I do.

> tcpdump -s 2000 -w DUMP-FILE -i wm0
It gave me a binary log. But how to read it?

> ping6 -n 2001:3c8:9007:1::21 (munnari.oz.au - one of its addresses)
I shall ping6 between 3:00-4:00pm GMT.
But note that ping6 while it is unable, it maybe only a short term.
I cannot estimate, sometimes 5 minutes or sometimes 30 minutes.
After that period ping6 becomes enable without any notification.
So I'm not sure whether at the time you check, it is enable or not.

> I could also try a ping6 from here to your host if I know more or less
> exactly what time to do it (when your host has just rebooted and things
> are not working as they should).
Do you mean pinging my router or my host? My host sits behind NAT.
Or shall I forward the port from router to my host?
(I remember when I was using 6bone, anyone can ping6 me behind LAN without port forwarding.)
Anyway my host is 2405:9800:b550:2939:f234:69d6:e0bf:8ebf/64
or 2405:9800:b550:2939:8638:35ff:fe48:5720/128 and
my router is 2405:9800:b550:2939:8ee1:17ff:fe1f:d1c7.

> You can also look at "netstat -s" output, before, during, and after, a ping6
> that is failing, and see which numbers are growing - and let us know

Before ping6, which will fail) ...
# netstat -s
https://pastebin.com/6K8s2QWi

During ping6, which fails ...
# netstat -s
https://pastebin.com/AKFbrmYk

During ping6, which works ...
# netstat -s
https://pastebin.com/kH7mc1ZB

After ping6, which already worked ...
# netstat -s
https://pastebin.com/uvbbQDsq

> So one of the changes in dhcpcd-7 was the default location of some 
> files, including the secret file which generates the SLAAC stable 
> private address. If you didn't change the location using postinstall(8) 
> before running dhcpcd it will have generated a new secret (and duid) 
> file which would result in different addresses being defined on the 
> interface. This could be an issue as well.
It seems likely. Please tell me the old and new file locations.

> You can add `nodhcp6` to dhcpcd.conf to disable DHCP6 entirely.
I have done it.
% tail -n 2 /etc/dhcpcd.conf
logfile /var/log/dhcpcd.log
nodhcp6
Now ping6 is usable even if DHCP6 is disabled entirely.

> the  NetBSD 7 host in question (when it was running NetBSD 7) was using
> dhclient and rtsol (and kernel IPv6 addr autoconf)

> Since dhcpcd was not being used previously there would have been no
> old files to worry about, it would all be new.
No, it was using dhcpdc and rtsol on -7.
I haven't used dhclient for long, probably -5.

Thank you,

-- 
Gua Chung Lim
 
"UNIX is basically a simple operating system,
but you have to be a genius to understand the simplicity."
-- Dennis M. Ritchie