(usagi-users 00731) Re: [Patch 2of2] IPv6 routers don't join/leave the all routers group

[Pekka Savola <pekkas@xxxxxxxxxx>]

On Wed, 29 Aug 2001, YOSHIFUJI Hideaki / [iso-2022-jp] 吉藤英明 wrote:
> > Forwarding switching per device is currently not implemented, control
> > has another meaning (sets isRouter on advertisements).
>
> If a node forwards, it should announce NA with is_router set, IMHO.

Consider a situation like:

       Internet
         eth0
          |
        router
      /       \
 eth1          eth2
  |             |
  |             |
clients       NFS server ---> NFS server's primary network connection

It's legal to set general packet forwarding on every interface
(you can't avoid that), but you may not want to enable IsRouter etc.  on
eth2 because the router acts as a "client" on that interface.

So this might not be as simple in "mixed host/router" environments.  Most
scenarios with this are a bit far-fetched, but at least in the future, I
believe more of these will arrive..

The extra check suggested would appear to be safe in this kind of scenario
though (as router - NFS server traffic should not go through ip6_forward
anyway, and you don't want clients being able to add a static route
towards NFS server's IPv6 address to point to eth1).

This would change the logical behaviour a bit though.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords