RE: [dhcwg] Re: WG last call on draft-ietf-dhc-dhcpv6-opt-prefix-delegation-02.txt

[Pekka Savola <[e-mail]>]

On Mon, 24 Feb 2003, Vijayabhaskar A K wrote:
> > That is, the requesting router is in charge of all the prefixes until
> > they expire.  The robust requesting router implementation will perform
> > some sane refreshing of these bindings way before they expire, even
> > periodically.
> > 
> > Thus, I fail to see any reason why these values would have to be 
> > communicated from the delegator.
> 
> Yes, I agree that the it can refresh the bindings at any periodic
> intervals it want. But, what if the delegating router is dead
> and not responding at all? 

Then it will try again a bit later and succeed.

> Hence, dhcpv6 provides you with 
> two values: 
> T1 -> This is the time at which the requesting router starts 
> contacting the delegating router for the renewal of the lease...
> T2 -> If till the expiration of T2 it didn't get the response
> from the delegating router, it can contact any available
> dhcpv6 server to refresh its bindings.

Do you mean that similar T1 & T2 values are being used by DHCP base spec?  
In that case I guess it's ok, but otherwise, I still fail to see the 
usability.

> Ofcourse, the requesting router can generate these values itself.
> With DHCPv6 server sending T1 and T2 values, the requesting
> router dont need to recalculate the values again and again..
> Trust the DHCPv6 server, the values provided by it makes the
> requesting router to refresh its bindings well before the expiry..

Well, typically the conventional wisdom is *not* to trust any external 
parties to any extent greater than necessary :-)

> > Prefix delegation by DHCP is not meant to be 
> > all-purpose-zero-configuration tool for routers, I think.
> > 
> > This seems conflicting -- a fringe case which should not came up.
> > 
> > Better would be just require that the requesting router will get a 
> > delegation from all the ISP's for itself, and subnet accordingly.
> > 
> > If the following does not apply, it seems to me that there 
> > must be routers 
> > connected to the downstreaming interfaces -- which in turn 
> > could perform 
> > prefix delegation directly from the ISP, the first router acting as a 
> > relay.
> > 
> > Doesn't seem to be need for this..
> 
> Need not be. Simple case is Home networks, they dont afford to have
> individual routers for every ISPs. They may need multiple ISPs 
> for high availablity or some other reason. In this case, there will
> be only one border router with mutiple appliances/nodes in the 
> downstreaming interfaces, which may span in one or more links.
> In this case, it needs to unique IA_PD for every ISP.

Seems a bit far-fetched, IMO, but ok..

> > Regardless of that, I'm not sure how the requesting router would
> > discover more of these delegating routers -- how would they be
> > connected?  Which kind of infrastructure would typically be between
> > requesting router and multiple delegating routers?
> 
> I beleive there will be unique dialup connection with each ISPs.

.. as above, I've yet to see dial-up routers deployed which would have two 
dial-out adapters and phone jacks, but ok..

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings


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