Re: IPv6 VIPs and deprecated flag

On Thu, Jun 23, 2016 at 08:35:28PM +0200, Tore Anderson wrote:
> * Ryan O'Hara
> 
> > > On the other hand if the VIP is a /64 it is most likely the only
> > > address in the prefix (i.e., backup routers do not have global
> > > addresses configured at all) and thus the above consideration does
> > > not apply.  
> > 
> > That is interesting. Thanks for the information.
> 
> Oh and by the way, having a prefix length attached to a VIP is a
> totally non-standard Keepalived protocol extension which probably won't
> interoperate with any other VRRP implementaiton.
> 
> > On a related note, has anyone tried this with SLAAC? I've been
> > investigating some strange behavior with IPv6 SLAAC where keepalived
> > will initially bring up a VIP with /128 prefix and correctly set the
> > deprecated flag, but after a few minutes I see the keepalived netlink
> > reflector report the global IPv6 address and VIP are "added" (which
> > seems to correspond to the lifetime being refreshed). As this point
> > the IPv6 VIP loses the deprecated flag and the load balancer ceases to
> > work. Thoughts?
> 
> That sounds really weird, considering that the Keepalived address
> you're adding is not assigned using SLAAC. Must be a bug or some
> connection manager gone haywire, maybe? Unless you're configuring
> Keepalived with a VIP that's the exact same address as the node would
> self-assign from SLAAC, that is?

I agree -- it is weird. Not only does the 'deprecated' flag get
removed when the netlink reflector is triggered, but the 'nodad' flag
remains intact. I would've guessed it would lose them both. I'll look
into the connection manager (NetworkManager) side of things, but I am
certain that my deployment scripts disable NM -- which I've been doing
for years.

The VIP is definitely not the same address as the node would
self-assigned. FYI, I am using 4 VMs under libvirt in F23 with a
simple SLAAC setup for IPv6 address assignment. 

Ryan


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