REPLY: 2:5020/545 60dbd819   
   MSGID: 2:5005/49 60e14ba9   
   CHRS: CP866 2   
   TZUTC: 0700   
   TID: hpt/fbsd 1.9.0-cur 2019-12-05   
   Dear Alexey,   
      
   30 Jun 21 05:24, you wrote to me:   
      
    VS>>>> I know that my home router can advertise multiple global IPv6   
    VS>>>> prefixes into the LAN, but how will LAN hosts failover to the   
    VS>>>> backup gateway if the primary ISP fails? They will have IPv6   
    VS>>>> addresses from both blocks, which should they choose for their   
    VS>>>> outgoing src address?   
    AV>>> This is the preferred mode of operation, but it has (only) two   
    AV>>> disadvantages: 1. All hosts in the LAN must be able to do the   
    AV>>> switching|balancing on thy own (that means, run Linux; the   
    AV>>> BSD-style networking stack, like the one used in Windoze, has   
    AV>>> very limited functionality). 2. This may require some manual   
    AV>>> configuration on every of them. Not really a problem, but may   
    AV>>> be boring.   
    VS>> This is not feasible because most of those LAN hosts are   
    VS>> smartphones, smart TVs, vacuum cleaners, cameras and other IoT   
    VS>> devices.   
      
    AV> Most of these devices have Linux kernel, but crippled userspace.   
      
    VS>>>> With two IPv4 ISPs and NAT, the setup is rather trivial,   
    VS>>>> outgoing connections will work via either of the ISPs because   
    VS>>>> the hosts needn't be aware of the failure, and their src   
    VS>>>> private IP is always the same. Can anyone enlighten me?   
    AV>>> This is second option, but you'd lose the main advantage of   
    AV>>> IPv6: the use of publicly routed addresses.   
    VS>> Indeed. I don't like the idea of using NAT in IPv6 even if I   
    VS>> could. So what's the solution?   
      
    AV> For dumb devices, especially portable, I'd suggest using NPT.   
      
   How well does NPT (being stateless) work with FTP, SIP and other protocols   
   which embed addresses into payload?   
      
    AV> Fully   
    AV> functional computers may be connected to some other VLANs (two at once   
    AV> in your case) and configured to use real addresses.   
      
   Speaking of those fully functional computers in the LAN, do you mean the setup   
   when there is a script pinging some outside hosts/interfaces and modifying the   
   IPv6 routing table, or something more advanced and interesting?   
      
   Victor Sudakov, VAS4-RIPE, VAS47-RIPN   
   --- GoldED+/BSD 1.1.5-b20170303-b20170303   
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