Re: nd6_storelladdr: sdl_alen == 0, dst=...

["Jonathan A. Kollasch" <jakllsch%kollasch.net@localhost>]

On Fri, May 28, 2010 at 05:55:16PM -0500, David Young wrote:
> Messages such as these are showing up occasionally in my system log,
> 
> May 28 10:46:24 elmendorf /netbsd: nd6_storelladdr: sdl_alen == 0, 
> dst=2002:40c6:ff01:0002:0217:f2ff:fe4c:5f29, if=wm1
> May 28 10:49:17 elmendorf /netbsd: nd6_storelladdr: sdl_alen == 0, 
> dst=2002:40c6:ff01:0002:0217:f2ff:fe4c:5f29, if=wm1
> 
> and their appearance seems to be connected with brief periods of IPv6
> unreachability---ssh sessions hang, and ping6 gets no reply.
> 
> Does this look familiar to anyone?  Anyone understand the cause?

They do look familiar.  I've seen them for years.

I've just determined that one cause of such messages is the existence of
a route to a prefix that specifies it is on-link, and the default
interface (ndp -I) is different from the interface in for that prefix.

In other words, this message appears when the kernel should have done
a Neighbor Solicitation, but decided not to.

        Jonathan Kollasch