Thanks Tim and Jonathan. I am reading RFC9119 just now to see if I can find anything useful.
I am reasonably confident that the wireless network itself is at least sending the multicast RA packets because Linux and Windows laptops and desktops on WiFi are having perfect reliability on IPv6 as far as I can tell. Reliability issues on my network at home appear limited to mobile devices - Android and iOS - and were greatly reduced by increasing the advertisement lifetimes. Sadly with the increased lifetime it is extremely difficult to replicate the fault on my network here; its happening once every few weeks at best. Since increasing advertisement lifetime helped so much I am very suspicious that the devices may simply be becoming 'deaf' to the multicast RAs some time after connecting in order to improve battery life. If they initially have poor signal then they may miss the RA and then if they become deaf to multicast they may never configure IPv6. I've adjusted the minimum rate controls to increase range on my network because this should also improve reliability of receiving the RA multicasts and I am hoping this may result in higher reliability. Ultimately it will be a few weeks before I know if it has helped. The 'devices are becoming deaf to multicast after some time' theory is born out of being able to replicate the fault with short RA lifetimes even on hard wired mobile devices (ie connecting my tablet using a USB C ethernet dongle). This theoretically removes Ubiquiti as being the cause in my opinion and suggests that there is something else going on here. On Thu, Jul 13, 2023 at 8:45 AM Tim Chown via uknof <[email protected]> wrote: > > 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 > > > >
