[180727] in North American Network Operators' Group
RE: Android (lack of) support for DHCPv6
daemon@ATHENA.MIT.EDU (Tony Hain)
Wed Jun 10 03:16:26 2015
X-Original-To: nanog@nanog.org
From: "Tony Hain" <alh-ietf@tndh.net>
To: "'Lorenzo Colitti'" <lorenzo@colitti.com>
In-Reply-To: <CAKGbBmm7r=f95zDoHvAzH53XVDOc1oUxY6bnfciG5u+B0m-C3A@mail.gmail.com>
Date: Wed, 10 Jun 2015 00:14:12 -0700
X-SA-Exim-Mail-From: alh-ietf@tndh.net
Cc: 'NANOG' <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
From: Lorenzo Colitti [mailto:lorenzo@colitti.com]=20
Sent: Tuesday, June 09, 2015 11:47 PM
To: Tony Hain
Cc: Mikael Abrahamsson; Chris Adams; NANOG
Subject: Re: Android (lack of) support for DHCPv6
On Wed, Jun 10, 2015 at 3:38 PM, Tony Hain <alh-ietf@tndh.net> wrote:I =
claim that there is a platform bug, because there is never a reason to
ignore the WiFi RA. Use the other flag to set a preference if that is
needed, but ignoring the RA just breaks things in unexpected ways. LC =
has
did a hand-wave that the "ignore RA" flag is needed for battery life, =
but
beyond that we appear to be stuck in a world where Clueless OEMs believe =
in
breaking one network when another might exist.
This is not how current Android works. Each network can run IPv4, IPv6 =
or both independently of any other network. If you can reproduce this on =
a device running current Android (preferably a Nexus device), please =
file a bug.
=20
There is indeed an issue with OEMs dropping RAs when the screen is off. =
Because it is the OEM that provides the wifi firmware and not Android, =
it's not really fair to say it's an Android bug. FWIW, recent Nexus =
devices do not have that bug.
My Nexus tablet does not have a Cell interface, and T-Mobile has stopped =
releasing updates for my phone, so I can't test that. For the issue I =
saw in the past, there was no screen-off event. All I had to do was =
enable the IPv6 APN, and given that I live on the edge of the service =
area the link would drop at some point shortly after. At that point the =
expected behavior is that IPv6 would still work via wifi, but no. While =
it still has an address, and can talk to anything on the wire, it has no =
router because that was removed and the RA is being ignored.=20
I agree the OEM's are likely the problem here, but the platform should =
not allow them to create an invalid network state. Doing so only insures =
that they will pick the wrong options and break the network =
unnecessarily.
Tony
