IPV6 openwrt router to route a subnet . how to advertise subnet to wan interface

I have TWO openwrt routers. Router1 is connected to the internet gets nicely an ipv6 GUA and on Router 1 Lanside (call it network1) all the clients get nicely ipv6 addresses from a delegated subnet.

One of the clients in network 1 is Router2.
That router has its WAN side connected to Router 1

Router2 gets an ipv6 address from router 1 plus and ipv4 NAT address
On router2 i setup an ipv6 tunnel to he networks.
so now on the LAN side of router 2 i get ipv6 addresses from HE networks. (call it network2)
All works well i can ping nodes from network 1 to network 2 and a trace shows they go via the internet to get to eachother.

Next i created a ULA network with 2 64 subnets 1 i assign to network1 nodes
and subnet 2 to network 2 nodes

if i set up a manual route from network 1 to network 2
like fex
sudo ip -6 route add fd67:123:123::2 via fd67:123:123:1::100 metric 5068

i can ping to the ULA addresses from subnet 1 to subnet 2 and vice versa and traceroute shows nicely all goes directly via router 2

Now what i want is that the router 2 advertises the ULA subnet 2 to network 1
so i do not have to manually add the route .

But the router 2 does not seem to advertise this ULA subnet to network 1

how can this be done ?

With static routes.

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i can put static routes in router 2.
for router 2 that is not needed. because it knows both networks
i can put it in router 1. which means all trafic goes via router 1 to router 2 and then to subnet 2 .

I want all traffic to go directly to subnet 2 from subnet 1 not via router 1.

whatever route i put static in router 2 i do not see router2 advertising any route info to the wan only rdnss and prefix

Then add static routes to all the hosts of the network1.

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I want it to go automatic. is it not supposed to go automatic with ipv6 and router advertisement ?
i know i can do it manually, as i showed in the original post, but that is not what i want.

Maybe it can be done, but I have never seen it in practice, especially in OpenWrt.


would i be able to deliver the subnet route info (so not in the form of default gateway) via dhcp to the clients ? have not looked into that possibility as i have not tought of that way yet. since i am delivering the ULA addresses with dhcp anyway. and dont know if that is supported then with windows and debian clients.

the idea is to have all on autonfigure but have the ULA addresses fixed and in the local dns so its easy to get to stuff and not depending on a internet connection

plus, since i have actually 2 different ipv6 networks this way to keep local traffic local over the router2

i might have found how to do it the dhcp way. Will explore that first. Still find it strange that the whole router info advertisement only would work with default gateways and not with subnets behind a router. sounds not thought thru if that is the case which i find hard to believe.

Still.. its only a few weeks i decided to dive into ipv6, i still have a lot to learn, that's why i made this setup in the first place.

Routing Configuration Over DHCPv6 - ISC