Girish M G writes:
> James Carlson wrote:
> >      b. The interface dynamically uses the global value as long as the
> >     local value is not configured specifically for that interface.
> >     Once it's configured, the connection with the global value is
> >     severed.
> In the same way how 'ip_forwarding' ndd tunable is handled today, 
> right?.

Sort of ... the existing ip_forwarding mechanism is actually much
simpler in definition.  It's more like variant (a): when you set the
global variable, we go out and change all of the current interfaces to
match.  When you plumb a new interface, the interface inherits a
simple copy of the current global variable.

If you just use the global variable functions, everything works as it
did long ago.

> You can set it for all the interfaces using 'ndd' and control 
> per interface forwarding ability using 'ifconfig <inf> [-/+]router'.

Yes.

> Now the question is should we change 'ndd -get' output to display per 
> interface property just like how we do for 'ip_forwarding'. For 'ndd' 
> always meant global and there wasn't no per interface stuff. How much 
> effort we need to put on a tool (read 'ndd') which is eventually going 
> to die.

No; don't do that.  The only reason it is still there for
ip_forwarding is that someone long ago embellished the ndd
ip_forwarding flag to work per-interface within ndd.  There's no
reason at all to replicate that.

If we had added the IFF_ROUTER stuff _before_ the ndd flag had
mutated, we would never have done that.

> The larger issue is how do we handle things where we will have two tools 
> 'ndd' and 'ipadm' to begin with and people start using these tools 
> interchangeably.

Yes; I agree.  But keep it simple.  (And I think the ndd ip_forwarding
model, sans the unnecessary "intf:ip_forwarding" hack, is a good way
forward.)

-- 
James Carlson, Solaris Networking              <james.d.carlson at sun.com>
Sun Microsystems / 35 Network Drive        71.232W   Vox +1 781 442 2084
MS UBUR02-212 / Burlington MA 01803-2757   42.496N   Fax +1 781 442 1677

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