IPv6 BGP & kernel 4.19

[Frederik Kriewitz]

On Sat, Nov 30, 2019 at 12:26 PM Benedikt Neuffer
<benedikt.neuffer at kit.edu> wrote:
> as far as I see one need some traffic to reproduce the issue. Without
> traffic I haven't seen the issue.

Yes, we saw this behaviour too using the buster kernel. It seems to be
traffic and/or neighbours related.
Forwarding itself seems to work but neighbour discovery stops working
(that's why multicast based OSPF sessions are not affected).
In this state the kernel doesn't generate any neighbor solicitation
packets (not visible using tcpdump). Once the neighbour cache times
out IPv6 connectivity is broken.

We don't know if this might be NIC related yet. We're seeing it happen
with Intel X710 NICs (With all offloading features disabled). Which
NICs are you using?
Resetting the NIC using ethtool -r $INTERFACE seems to have fixed it
once for us. The problem fixes itself after ~ 90 to 110 minutes too
until it appears again.