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RE : [DNA] Review of draft-yegin-dna-l2-hints-01.txt
Hello DNA folks
Sorry for late reactions,
1)What can be inferred from a couple of Bernard comments is that he is not having the same definition of a hint as we've had when writing the document.
A hint for us (Alper correct me if I am wrong) was an informational parameter carried along with a trigger received from L2. Such paramters being able to contain
For GPRS: such information as IP address, default gateway, DNS server, brought by the IPCP exchange when buildig up the PPP link resulting from the PDP context establishment
For 802.11: the SSID advertised by the AP the STA has associated with
Whereas a hint for Bernard seems rather to be an indication (possibly wrong) that should prompt the action of checking if change of configuration at IP layer is needed or has occurred. Bernard is this the way you define a hint? If it is then we are not talking about the same thing. Hints for you therefore rather seem to be fallible triggers
We should first all agree on these terminology issues i think before moving to other considerations.
> -----Message d'origine-----
> De : owner-dna@ecselists.eng.monash.edu.au
> [mailto:owner-dna@ecselists.eng.monash.edu.au] De la part de
> Bernard Aboba
> Envoyé : vendredi 2 juillet 2004 05:30
> À : Alper Yegin
> Cc : dna@eng.monash.edu.au
> Objet : RE: [DNA] Review of draft-yegin-dna-l2-hints-01.txt
>
>
> > The IP address configured as part of the L2 establishment is
> > considered as the hint in 3GPP2 and 3GPP. The document has a bug on
> > the IPv6CP part, but other than that is there more to hints
> for 3GPP*?
>
> I'm not sure that DNAv4 provides any value on 3GPP links.
> For example, these links provide an explicit indication of
> whether the IP address has changed, and so there is no
> optimization to be done. For example, these links don't
> support ARP, and there is no need to confirm reachability to
> the default gateway. So I'd say that DNAv4 is bypassed
> altogether on 3GPP.
>
> With respect to IPv6, there may be value... but the DNAv6 BCP
> needs to be clear about what that is.
>
> > I'm not sure what to identify as hints in 802.11. What do you think?
>
> One hint is the SSID and/or the BSSID.
>
> > As far as the DNA process is concerned, triggers are always
> reliable.
> > If L2 says it has changed its point of attachment, I don't
> think L3 is
> > going to argue against it.
>
> Without damping, on 802.11 it is possible for "link up" and
> "link down" indications to be sent 5-50 times a second. Were
> DNA to be triggered each time such an indication is received,
> a packet storm will result.
>
> Thus, treating these indications as "triggers" rather than
> "hints" can have serious consequences.
>
> > As for hints, they are 100% reliable for 3GPP and 3GPP2.
> And they are
> > non-existent for 802.11 (subject to change pending feedback).
>
> I agree that 3GPP and 3GPP2 indications are more reliable --
> to the point where there is no point doing DNAv4 at all,
> since there is no optimization to be achieved.
>
> > Actually this is the intent. The latter is left to the DNA solution
> > specification(s).
>
> Is the only objective of the document to provide a definition
> of "link up" for various technologies?
>
> > Please see my response to Greg on the reliability of
> triggers. Let us
> > know what you think.
>
> My experience is that 802.11 "triggers" are not reliable, but
> that other triggers can be very reliable (GPRS/3GPP).
>
> > What generates the L2 trigger is a L2 event.
> > What "happens" as a result of the trigger is the DNA
> processing. For
> > example, DNA process may initiate router discovery when it receives
> > the Link-up trigger.
>
> I'd suggest that this would not be wise in cases where the
> trigger itself is not reliable (802.11).
>
> > OK, I'd remove that as this "anticipation" concept falls
> outside the
> > scope of DNA.
>
> I think it does because there may not be anything that can be
> done with this information.
>
> > The text says "may", not "MUST" or "SHOULD". If DNAv4 has a
> reason to
> > ignore this trigger, it's fine I think.
>
> I don't think any of the DNA specifications make use of "link
> down", only "link up". So saying that they "may" be used is
> confusing, no?
>