Re: [Pce] Association Source in draft-ietf-pce-segment-routing-policy-cp-01

[Cyril Margaria <[e-mail]>]

Hi Mike

On Fri, 6 Nov 2020 at 14:09, Mike Koldychev (mkoldych) <[e-mail]>
wrote:

> Hi Dhruv,
>
> -----Original Message-----
> From: Dhruv Dhody <[e-mail]>
> Sent: Friday, November 6, 2020 8:27 AM
> To: Mike Koldychev (mkoldych) <mkoldych=[e-mail]>
> Cc: Dhruv Dhody <[e-mail]>; pce-chairs <[e-mail]>;
> [e-mail]; [e-mail]; Cyril
> Margaria <[e-mail]>; Stone, Andrew (Nokia - CA/Ottawa) <
> [e-mail]>
> Subject: Re: [Pce] Association Source in
> draft-ietf-pce-segment-routing-policy-cp-01
>
> Hi Mike,
>
> On Fri, Nov 6, 2020 at 5:08 PM Mike Koldychev (mkoldych) <mkoldych=
> [e-mail]> wrote:
> >
> > Hi Dhruv,
> >
> > I don't think it's valid to dismiss race conditions in the protocol
> because they are "rare". If they can happen at all means that
> implementations need to have extra logic to handle these race conditions.
> >
>
> Doesn't this "extra" logic exist anyway, as you must make sure there is
> only one SR policy association with a given set of SR Policy parameters
> under normal operations.
>
> [MK] If the PCC allocates the Association Source/ID, then it's always
> going to choose a unique value, so there will never be any collision. So
> no, this "extra" logic won't exist if we go with my proposal.
>

[MC] that's assuming that the PCE always sends 0, and not the previously
returned value, at that point why bother using or tracking association ?

<cut>

>
>
> BTW, what are your thoughts on the operator-configured association in the
> previous email? Not viable?
>
> [MK] You could set AssocExtID=Color, but I’m not sure what you would set
> Source to? Can we just set it to 0.0.0.0/0::0 and be done? Isn't that
> also a "special value"?
>

AssocExtID=Color, endpoint

Source should be a valid IP address, 0.0.0.0 looks OK, but I am rusty on
that.
0 is reserved, 0xFFFF is all assocation, 1 works as a fixed number not in a
reserved range.


>
> > All of this can be avoided if we just allow Source/ID to be 0 in PCInit
> messages. Is that really such a big change?
> >
>
> No, but the WG worked on RFC 8697 to make sure all the associations can be
> handled in a common way as much as possible. When deviating from that, IMHO
> a higher bar should be met. The WG should ponder if it is met here based on
> the scenario described above, that's all.
>
> [MK] I fully understand, but the value of 0 is reserved in that RFC. Can
> each application use 0/0.0.0.0/0::0 for its own purpose? Is that
> allowed/forbidden in the RFC?
>

 <cut>