Dear Dmitry,

04 Jul 21 13:51, you wrote to me:

 DP>>> For example - rerouting traffic via VPN to get thru RKN's DPI.
 DP>>> Real life scenario :)

 VS>> Why would you need NAT for that? Get a VPN/tunnel provider who
 VS>> offers a global /64 or /56 or even a /48, like HE does.

 DP> With he.net you'll loose access to local google caches and to local
 DP> CDNs. With ipv4 I can forward only blocked subnetworks via VPN, with
 DP> ipv6 and without NAT66 I can't do that.

Well, it's a valid point of course. The protocol designers are not required to forsee the acts of malicious morons breaking the Internet intentionally. But they could have provided for a simple failover mechanism.

OTOH, when I have to circumvent RKN, I prefer to start a new browser session where all traffic goes via a VPN. Yes, I lose access to local google caches and to local CDNs, but be it so.

 DP>>> Yeah, but you can have "host" part the same for several uplinks
 DP>>> and change prefix only on NPTv6 gateway. It's the best ipv6 can
 DP>>> offer for you, sorry.

 VS>> Too bad and a bit unexpected. There are/were rather complex
 VS>> things like Mobile IPv6 and HMIP, and they have not thought of a
 VS>> simple failover?

 DP> Mobile IPV6 is an operator controlled tool to keep your IPv6 address
 DP> intact. But you are asking for exactly the opposite solution - to
 DP> change your IPv6 address.

Not exactly "to change my IPv6 address", but rather provide some simple failover mechanism for multihomed IPv6 hosts. It has just come to my mind: if those multihomed hosts ran some kind of routing protocol (OSPFv3 or a simple equivalent thereof) there would be absolutely no problem selecting the working gateway.

 DP>>> It adds more complexity and cannot be implemented easily in
 DP>>> userland across multiple OSes.

 VS>> OK, let's start anew with a simple setup. If there are two
 VS>> routers in a home LAN advertising different global prefixes, and
 VS>> one of them goes offline, will IPv6 end hosts detect that and
 VS>> remove the corresponding addresses from their configuration?

 DP> Yes but you'll still have single routing table and timeout for client
 DP> to remove dead ipv6 address from interface and routing table is large
 DP> enough to be unacceptable for general use.

So, we need some simple routing protocol with keepalives, running both on end hosts and the router?

Victor Sudakov, VAS4-RIPE, VAS47-RIPN
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