IPv6 Neighbor Discovery broken between Switches ?

RouterOS General
1

I am not sure what’s going on exactly to be honest.

I described the Issue on Proxmox Forums (https://forum.proxmox.com/threads/proxmox-ve-detected-as-an-ipv6-router-and-neighbor-discovery-not-working.162272/) since this appears to be somewhat Related to Proxmox VE.

However, also on my Ubuntu Desktop Machine, trying to list IPv6 Neighbors only lists those that are Physically connected to the Switch in one Room. PLUS for whatever Reason the main Router IPv6 Address. But nothing else from the Server Room.

The Issue seems to occur MOSTLY on Proxmox VE even after some custom Settings were applied to the Linux Network Bridge.

Basically trying to add an IPv6 Static Route fails, even if I can pin the Host, I can curl its HTTPS Port, etc.
It’s “just” NOT registered as a Nexthop for whatever Reason, which is why Static Routes cannot be added:

ip -6 route add 2XXX:XXXX:XXXX:AAAA::/64 via 2XXX:XXXX:XXXX:0001:0000:0000:000A:000B metric 256
RTNETLINK answers: No route to host

The “Quick Fix” would be to manually associate the Host to the Linux Bridge:

ip -6 route add 2XXX:XXXX:XXXX:0001:0000:0000:000A:000B dev vmbr0

And then it’s possible to add the Static Route:

ip -6 route add 2XXX:XXXX:XXXX:AAAA::/64 via 2XXX:XXXX:XXXX:0001:0000:0000:000A:000B metric 256

But why is it that somewhere along the Route between the 2 Rooms (and 2 Mikrotik Switches: on one End Mikrotik CRS309-1G-8S+IN, on the other End Mikrotik CRS317-1G-16S+RM) Network Discovery Protocol seems to break Down (EXCEPT the Main OPNSense Router IPv6 Address) ?

I previously had IGMP Snooping enabled on all Switches. Now I tried to disable it on all Switches but I cannot say if it’s worse or doing nothing at all.

Is there some “hidden” Setting that I need to configure in order for this to work ? “ND” IPv6 Setting seems “sane”.

Thanks :smiley:

IPv6 Ping work not as expected
2

Proxmox and RouterOS 7.17 may have issues:
http://forum.mikrotik.com/t/ipv6-ping-work-not-as-expected/181977/1
http://forum.mikrotik.com/t/chr-downgrade-on-v7/181975/1
https://forum.mikrotik.com/viewtopic.php?t=213941&hilit=Proxmox&start=300#p1125309

3

Thanks.

I also upgraded from 7.17 to 7.17.2 but the Issue persists :frowning:.

The linked Threads don’t really seem to offer any Solution though …

V7.17.2 [stable] is released!
4

I don’t have a solution but noted Proxmox was popping up in topics recently while 7.17 added bugs and features.
If your situation and time permits, downgrading RouterOS may or may not help isolate the issue.
Polling others for downgrade advice may be worthwhile before experimenting.
A forum topic had Proxmox and SR-IOV driver comparability discussed.
IMO search function on this forum is worthwhile learning well.

5

SRIOV is a whole other Discussion which also depends on Motherboard/BIOS Support etc :confused: .

For now, my Workaround is to add a Nexthop Host manually on the Bridge (Repository: https://github.com/luckylinux/networking-config/blob/main/etc/networking-general/functions.sh#L61) if the

ip -6 route add/replace

fails, then add again the route via the newly configured Gateway.

Proof of Concept worked so far, and I managed to reconfigure that Host that didn’t want to play along.

There are surely plenty of Edge Cases I didn’t consider thus far though :frowning: .