Re: [v6ops] RFC7084

[Owen DeLong <[e-mail]>]

On Dec 11, 2013, at 2:21 AM, Alexandru Petrescu <[e-mail]> wrote:

> Le 11/12/2013 11:08, Erik Kline a écrit :
>>> Am I the only to read this as maybe a hint towards necessity of
>>> creation of a new flag akin to M/O but specific to IA_PD? I.e. it
>>> would be allow a Router to see whether it may be able to
>>> specifically request a Delegated Prefix even when it would
>>> self-configure its address by other means than DHCP.
>> 
>> I'm not sure I understand how's that materially different/better
>> than a node just trying to request a PD if it wants one, and coping
>> with the response (whatever it may be), like it does today.
> 
> Well, as you suggest below, it may save some bytes on the wire, i.e.
> would not send the expensive Solicit if the preceding RA said no PD
> available.

I hardly think that an RS packet could legitimately be called “expensive”.

It’s a relatively small multicast datagram.

> I suppose this is the same reason of presence of other flags in the RA,
> like the H (HMIPv6) and P (PMIPv6).

As near as I can tell, those flags are for capabilities that are:

	1.	unlikely to be present on the majority of networks
	2.	would be much more difficult/expensive to negotiate without
		information in the RA.

The P flag isn’t alone in the RA, it’s also accompanied by a MAP option
in the RA that provides information about the MAP.

Owen