In message <[email protected]>
Acee Lindem writes:
 
> On Oct 10, 2011, at 5:18 PM, Curtis Villamizar wrote:
>  
> >=20
> > In message <[email protected]>
> > Acee Lindem writes:
> >=20
> >=20
> > On Oct 9, 2011, at 8:41 PM, Fred Baker wrote:
> >=20
> >>>=20
> >>> On Oct 9, 2011, at 8:01 PM, Acee Lindem wrote:
> >>>=20
> >>>> Since OSPFv3 also uses a 4 byte router ID, our implementation will
> >>>> use the same algorithm for picking a router ID as OSPFv2.
> >>>=20
> >>> which is to say "any old thing it wants, quite often an IPv4 =
> address"?
> >>=20
> >>=20
> >> Correct, it uses the best or only configured IPv4 address in the
> >> context (aka, virtual router). Of course, we'd want to use something
> >> else for true auto-configuration.
> >>=20
> >> Thanks,
> >> Acee=20
> >=20
> >=20
> > And on an IPv6 only homenet with no configured addresses it does what?
>  
> Our Ericsson SmartEdge routers were never meant to be deployed in the =
> home or to support complete auto-configuration - I was just responding =
> to Fred's query as to what OSPFv3 implementations do today.=20
> If there is no IPv4 address available and no OSPFv3 Router-ID is =
> explicitly configured, we'll log an error and shut the OSPFv3 instance =
> down until such time as an IPv4 address or explicit router-id are =
> configured.
> A new draft is required for OSPFv3 auto-configuration.=20
> Thanks,
> Acee
>  
> >=20
> > Curtis


Acee,

I'll have to confess that my most recent employer's equipement was
also not intended for the home.  :-)

I'm sure you saw the suggestions I made in another response.  The fix
for autoconfig may be to pick a random number and create an OSPF
extension to advertise the detection of a collision on a given
router-id, then respond to the collision.  Any device using autoconfig
would have to support this extension.  If colliding with a router that
did not support the extension, that other router would do nothing, but
the autoconfig router would pick a new router-id.

The point is you can't make a unique 32 bit number out of a 48 bit
number or a 64 bit number or an 80 bit number (for a /48).  So you
might as well accept low probability of collision and define a way to
fix the situation.

The absolute worst case is a stomped on LSA that an old router doesn't
update until maxage expires.  That would be bad so maybe we need to
figure out what a legacy OSPF router would do on such a collision
where it got from a neighbor something it did not send as its own LSA.
Hopefully it would readvertise the right stuff and try to withdraw the
bad stuff.  The autoconfig router would just pick a new router-id.

It all sounds fine except maybe the backwards compatibility with no
changes.  Your the OSPF expert so ...

Curtis
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