Re: High latency for IPv6 on netbsd-8

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

Thank you for your kindness in helping me.

* Robert Elz (kre%munnari.OZ.AU@localhost) wrote:
>   | Long message does not interest people. :-p
> 
> Often, true, but requiring going to look at an external web page will also
> discourage some people...    It is a trade off.
Personally, I opt external links for long screen dumps.

>   | inet6 2405:9800:b550:2939:8638:35ff:fe48:5720/128 flags 0x0
> 
> which is an extra host address on the same IPv6 subnet as the primary
> address, and which has vanished when the ping eventually works.

> Second, the route (to myself) for that odd /128 address goes away.
Not really, please look below, the screen dump while it is working.
The ipv6 address of /128 is still there. And most of the time it is there.
And this address is never changed.
% ping6 -c 3 -n www.netbsd.org

PING6(56=40+8+8 bytes) 2405:9800:b550:2939:f234:69d6:e0bf:8ebf --> 2001:470:a085:999::80
16 bytes from 2001:470:a085:999::80, icmp_seq=0 hlim=51 time=307.804 ms
16 bytes from 2001:470:a085:999::80, icmp_seq=1 hlim=51 time=317.245 ms
16 bytes from 2001:470:a085:999::80, icmp_seq=2 hlim=51 time=244.747 ms

--- www.netbsd.org ping6 statistics ---
3 packets transmitted, 3 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 244.747/289.932/317.245/39.415 ms
%
% ifconfig wm0
wm0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	capabilities=2bf80<TSO4,IP4CSUM_Rx,IP4CSUM_Tx,TCP4CSUM_Rx>
	capabilities=2bf80<TCP4CSUM_Tx,UDP4CSUM_Rx,UDP4CSUM_Tx,TCP6CSUM_Tx>
	capabilities=2bf80<UDP6CSUM_Tx>
	enabled=0
	ec_capabilities=7<VLAN_MTU,VLAN_HWTAGGING,JUMBO_MTU>
	ec_enabled=0
	address: 08:00:27:2b:32:26
	media: Ethernet autoselect (1000baseT full-duplex)
	status: active
	inet 192.168.1.104/24 broadcast 192.168.1.255 flags 0x0
	inet6 fe80::bbe5:5eaa:bbaf:950b%wm0/64 flags 0x0 scopeid 0x1
	inet6 2405:9800:b550:2939:f234:69d6:e0bf:8ebf/64 flags 0x0
	inet6 2405:9800:b550:2939:8638:35ff:fe48:5720/128 flags 0x0

> Oh, I see now that in your original message you said:
> 	Disabling NPF does not fix it.
> but it is not clear from than what you meant.   Did you test with NPF
> disabled from rc.conf and boot that way?  Or did you boot, and then
> later, when ping6 was not succeeding, turn off NPF ?
I tried both disabling NPF after boot and turn it off in /etc/rc.conf.
The results are the same.

> At this point you are probably going to need help from someone more
> familiar with the current NetBSD IPv6 code to figure out what might be
> happening, and where to look next.
Your kind advices are still highly appreciated.

> Oh, somehow I skipped that part.   One network is OK, I meant some
> other IPv6 host on that same LAN (the point was just to check that
> neighbour discovery was working - and I no longer suspect any
> issues there, so there is no need to bother with this, even if there
> is some other host with a v6 addr that is local that you could ping.)
All other machines on the same LAN are working pretty fine. All of them are running dhcp. But this netbsd host I tried both dhcp and static, but it doesn't fix the problem. I shall probably go back and try dhclient.

> if it has one (not all routers do) you could try ping6 to the IPv6
> (global) address of the router on theLAN that is connected to
> your host.   That address would start 2405:9800:b550:2939:
> (almost anything might come after that, including :1)
Pinging router's IPv6 address works fine.

> Oh, how many other hosts are on this LAN?   (Regardless of
> whether they support v6 or not.)   One possibility for the issue
> might be if the router thinks the LAN link is down when your
> host is down, and drops the announcement of the route from
> its upstream (closer to the centre of the net).   Then it could
> take some time for that to be reannounced after the link
> comes back up (when your host boots).
IMHO, it is unlikely. I have 8 machines on this LAN. All of them, except this netbsd host, work with IPv6 pretty fine and without any efforts.

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