RE: ND (NUD) on ISATAP links (fwd)

Here is a message, which I sent, that was bounced from the list.  Sorry to
those who are receiving this message for the second time.


---------- Forwarded message ----------
Date: Sun, 20 Oct 2002 14:56:37 -0700 (PDT)
From: Jason Goldschmidt <[email protected]>
To: "Karen E Nielsen (TED)" <[email protected]>
Cc: 'Vladislav Yasevich' <[email protected]>,
     "'[email protected]'" <[email protected]>, [email protected],
     'Fred L. Templin' <[email protected]>
Subject: RE: (ngtrans) ND (NUD) on ISATAP links

On Sun, 20 Oct 2002, Karen E Nielsen (TED) wrote:

> Hi All,
> 
> > 
> > The scalability problem you mention only happens when there are
> > very few routers serving a lot of hosts.  In that case, a 
> > particular router
> > is more likely to be picked as a next hop and NUD will be run 
> > after the
> > AdvReachableTime has expired. The consuption of resources on 
> > that ISATAP 
> > router will roughly equivalent to a normal IPv6 router in a similar 
> > configuration (+ the extra is a tunnel overhead) so I don't 
> > see a large 
> > problem with scalability.
> > 
> > 
> 
> 
> As I understand it, there are two sides to this question.
> 
> In the above, the resources that you speak about 
> are the resources needed at a particular ISATAP
> router in order to _participate_ in NUD
> performed by its ISATAP host (responding to NS's).

The scalability problem is rooted in the fact that each ISATAP
host will have to send a unicast NUD to the router (as opposed to
multi/broadcast in the case of a "normal IPv6 router).  Thus ISATAP hosts   
can not passively listen for NA's, they must initiate a unicast NUD every
AdvReachableTime.  As opposed to the "normal IPv6 router" case, more NS's
would actually be sent and processed by the ISATAP router.


> Another concern is the scalability issues in relation to the resources
> needed at the ISATAP router in order to _perform_ NUD on its ISATAP
> neighbours - Do we agree that this has been ruled out - i.e. that
> performing NUD only is going to be demanded of ISATAP hosts - or do we
> want a LAN-like IPv6 functionality on ISATAP routers ?

It seems that if NUD is to be implemented at all, the only place it could
happen is the at the host.

-Jason


> (As is (static address resolution) "ISATAP" NUD does not work on routers)
> 
> Karen
>