Unable to get IPv6 of secondary link on Dual Lan Fail Over setup

Doomer

Occasional Visitor
I have 2 links connected on my AX68U, running in Dual Lan Fail Over setup and works fine on IPv4, but when the primary link is down, the router is unable to get and publish the IPv6 announced by secondary link.

Both links announce properly the IPv6 through PPP when using the primary link.

I suppose that the failure is related to one of the following topics:
- the router OS does not consider getting the IPv6 from secondary link
- the router tries to get IPv6 through PPP port of PPPoE credentials of primary link (the credentials of PPPoE for secondary link is different)

Please, how to solve this to get IPv6 when my first link is down?

Thanks a lot and regards
 

grogi

Occasional Visitor
Do you get dynamic prefix allocation? If you have a static prefix allocation, you should be able to hard-code the IPv6 configuration in one of the custom scripts after WAN is up.

But have in mind, it is a tricky business. With IPv6 there is no NAT - so each host going out to the Internet is using it's own IPv6 address, regardless which WAN the packet will go out. Hosts are not necessarily aware that your primary WAN (let's call it WAN1) went down, so they can send packets with source address set to the IP in the prefix delegated on WAN1. Even if WAN2 will route them (not certain, as the ISP might have firewall rules in place to prevent routing any packets outside of the delegated prefix), the packets coming back from the other side will follow the return path to the WAN1 and fail, as it is down.

For Dual IPv6 WAN you would need the router to immediately advertise to the hosts that the WAN has changed, and the hosts would need to immediately take that into account.
 
Last edited:

Ranger802004

Very Senior Member
Try issuing this command during failover...

Code:
service restart ra_dvd
 

Doomer

Occasional Visitor
Do you get dynamic prefix allocation? If you have a static prefix allocation, you should be able to hard-code the IPv6 configuration in one of the custom scripts after WAN is up.

But have in mind, it is a tricky business. With IPv6 there is no NAT - so each host going out to the Internet is using it's own IPv6 address, regardless which WAN the packet will go out. Hosts are not necessarily aware that your primary WAN (let's call it WAN1) went down, so they can send packets with source address set to the IP in the prefix delegated on WAN1. Even if WAN2 will route them (not certain, as the ISP might have firewall rules in place to prevent routing any packets outside of the delegated prefix), the packets coming back from the other side will follow the return path to the WAN1 and fail, as it is down.

For Dual IPv6 WAN you would need the router to immediately advertise to the hosts that the WAN has changed, and the hosts would need to immediately take that into account.
Yes, I use DHCP-PD, as the prefix of each ISP are different I dont think I can trick it to announce the same prefix in my router :/
 

Viktor Jaep

Very Senior Member

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