--- Begin Message ---
Hi Alan,
You might want to have a read of RFC 9119 for interesting background on
multicast in general on WiFi, for which IPv6 neighbour discovery is one example.
Tim
> On 10 Jul 2023, at 18:07, Alan Goodman <[email protected]> wrote:
>
> TLDR: I provide network rentals and leases among other related
> services. I started providing IPv6 by default in 2019 ish and
> recently started noticing spotty connectivity on mobile devices only.
> Was wondering if anyone else has ran into this.
>
> Following recent chatter about IPv6 I thought I would ask here to see
> if anyone has experienced spotty IPv6 connectivity on Android devices
> or iOS devices recently? I started providing IPv6 connectivity in all
> of my networks back in 2019 ish. Recently I moved a bunch of internal
> stuff to IPv6 only and quickly started to understand that IPv6
> connectivity for mobile devices on my networks was not completely
> reliable. Apparently randomly I will find that my Android or iOS
> devices do not have IPv6 connectivity and upon checking will find that
> they do not have any IPv6 addresses.
>
> I've tested Android devices hard wired to the network and this is also
> impacted. Increasing advertisement lifetimes helped significantly
> however the problem is still occurring occasionally. The issue is
> also replicated with iOS devices. I've tried enabling IGMP snooping
> and Ubiquitis multicast enhancement which didnt appear to make any
> difference. I've not had any customer reports of issues; though this
> is expected since they are not reliant upon IPv6 working and failover
> mechanisms are generally robust at present.
>
> I believe that the issue may be occurring if a device has poor signal
> when it initially connects to the network. This is ultimately
> unavoidable because for example your device may associate with the
> network in your house as you approach from the road. Most of my
> networks are designed to have -70dbm or better signal in all areas
> with 50% overlap. Typically I disable lower PHY rates to ensure
> devices roam promptly and do not cling onto the signal when they have
> poor coverage (ie when leaving the coverage area). I believe that
> this may have something to do with devices becoming 'deaf' to
> broadcast traffic some time after they connect to the network.
>
> I monitor all of my networks including IPv6 using firebricks so the
> underlying connectivity is known to be good. Additionally various
> servers, Windows desktops, linux laptops, printers and other devices
> are connected both wirelessly and hard wired and I've not noticed any
> problems. Some of these devices are actively monitored with no
> significant issues detected.
>
> At a high level my networks consist of a PC based router, running
> linux, IPTables ISC Named, ISC DHCPD, RADVD and Wide DHCPv6c. Most of
> my networks run on the BT Business network and get a /56 static
> delegation via DHCPv6. I then carve this up into /64s with one
> assigned per VLAN. Network equipment wise most of my networks use
> Netgear managed switches and UniFi access points. Most stock is
> currently WiFi 5 or WiFi 6 era. Advertisement valid lifetime is set
> to 2592000 with preferred life time set to 604800.
>
> Any thoughts or anecdotal experience would be valued here. For what
> its worth my default check for whether I have working v6 connectivity
> is to load up www.loopsofzen.uk or refresh one of my internal v6 only
> pages.
>
> Alan
>
--- End Message ---
