Re: [v6ops] draft-ietf-6man-grand : saving lookups

[Jen Linkova <[e-mail]>]

On Sun, Aug 9, 2020 at 7:40 PM Mark Smith <[e-mail]> wrote:
>> > Maybe the host should renew the NCE in the router periodically ?

>> I guess we can add to the very end of the Section 4.1.2 (the new text):
>> "A node MAY send unsolicited NAs for its preferred addresses
>> periodically to refresh the Neighbor Cache on the first hop routers."
>>
>> On the other hand it might pollute the router NC with entries for
>> addresses which the node has configured but is not going to use.

> Won't NUD probes keep those entries current in the routers' cache, even though hosts may not be actively using them?

No, why would it? By the definition, for STALE entries no attempts are
made to verify the neighbor reachability. So if the node has not been
receiving traffic for that address, the STALE entry would stay there
until the router cleans it up.
So if we recommend sending periodic unsolicited NAs it might
re-populate the router cache with unused addresses which have been
cleaned up.
As sending periodic NAs would make sense for the very specific
scenario - the was sleeping, has woken up and is going to send some
traffic it might be a bit tricky to give guidance on that. In all
other cases I do not see much benefits...
Strictly speaking nothing described in this draft is prohibited in
RFC4861 anyway. So hosts can send unsolicited NAs anyway ;)

> I've thought that something like GRAND + NUD is starting to approach an address registration protocol, or at least, makes the routers' cache the "active addresses on a link" database.

I'd say 'most active addresses' as we can not guarantee that
unsolicited NAs reach routers.

-- 
SY, Jen Linkova aka Furry