How to config Vyos to send RA with M bit

Greetings,

I am trying to build a LAN network with PVE, I have one VM for DHCPv6 server, and two VMs for DHCPv6 clients, and I also have one VM installed Vyos which is also getting its IPv6 from the DHCPv6 server.

So currently my clients are able to get their IPv6 addresses successfully, but they can’t ping each other. That’s why I spin a new VM and installed Vyos. Because from what I research, I will need

" Even if you intend to use DHCPv6 instead of SLAAC in your environment, you still need RA messages to function on the local LAN. The RAs provide the default gateway information to an end node and, with the M-bit, inform the nodes that the LAN uses stateful DHCPv6. DHCPv6 does not currently have an option to provide this information to the DHCPv6 client in the same way it is provided with DHCP for IPv4. Providing the default gateway as a DHCPv6 option was proposed, but never made it into the standards."

Here’re my configurations:

set interfaces ethernet eth0 address dhcpv6
set interfaces ethernet eth0 address “192.168.100.97/24”

set router-advert interface eth0 prefix fd74:5656:15e2:10::/64

But after the configuration took place, I still can’t ping. I did a packets capture on one client. And I can see the RA from Vyos, but there’s no M-bit

ICMPv6 Option (Prefix information : fd74:5656:15e2:10::/64)
Type: Prefix information (3)
Length: 4 (32 bytes)
Prefix Length: 64
Flag: 0xc0, On-link flag(L), Autonomous address-configuration flag(A)
1… … = On-link flag(L): Set
.1… … = Autonomous address-configuration flag(A): Set
…0. … = Router address flag(R): Not set
…0 0000 = Reserved: 0
Valid Lifetime: 2592000 (30 days)
Preferred Lifetime: 14400 (4 hours)
Reserved
Prefix: fd74:5656:15e2:10::

Is there any configuration I have missed? Thanks to any advices!

If the goal is to simply send the managed flag, that can be achieved with:

set service router-advert interface eth0 managed-flag

If you would like to get an address only from DHCPv6 and not SLAAC, that can be achieved with:

set service router-advert interface eth0 managed-flag
set service router-advert interface eth0 prefix fd74:5656:15e2:10::/64 no-autonomous-flag

Hope you find this helpful

2 Likes

Nice, Thank you very much, Richard! Let me try and see!

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