Re: [Pce] [PCE]: Draft-ietf-pce-sid-algo: Prefer Intra vs Inter-domain

Hi Marcel, PSF,

Speaking as a WG participant...

Note that we do have a metric type "T=20: Domain Count metric (number of
domains crossed)."; we can simply use this metric type, asking the PCE to
optimize based on this which should lead to preferring intra-domain paths.
See https://www.rfc-editor.org/rfc/rfc8685.html#section-3.5

Thanks!
Dhruv

On Tue, Sep 19, 2023 at 9:04 AM <peng.shaofu@zte.com.cn> wrote:

>
> Hi Marcel,
>
>
> May it be a local policy of PCE ?
>
> For a given <ingress PE, egress PE> that belongs to the same domain, it
> may be
>
> the default policy for PCE to calculate a candidate path intra domain.
>
> Otherwise, it may bring unnecessary complexity. For example, for a real
> inter-domain
>
> path requirement of <ingress PE, egress PE> that belongs to the different
> domain,
>
> the intention is to split the path calculation requirements into multiple
> domains, e.g,
>
> <ingress PE, ABR1> for domain 1, <ABR1, ABR2> for domain 2, etc. Now, in
> this case,
>
> does <ingress PE, ABR1> itself again get a inter-domain path ? In theory,
> yes. But in
>
> reality, it doesn't make sense.
>
>
> Regards,
>
> PSF
>
>
> Original
> *From: *MarcelReuter(External) <marcel.reuter.external@telefonica.com>
> *To: *pce@ietf.org <pce@ietf.org>;
> *Date: *2023年09月15日 16:25
> *Subject: **[Pce] [PCE]: Draft-ietf-pce-sid-algo: Prefer Intra vs
> Inter-domain*
> _______________________________________________
> Pce mailing list
> Pce@ietf.org
> https://www.ietf.org/mailman/listinfo/pce
>
> Aloha,
>
> Dear colleagues,
>
>
>
> I have a question regarding the PCE with SR Flex-algo and multiple IGP
> domains.
>
>
>
> In my understanding in each IGP Domain the Flex-Algo is calculated
> independently of each other domain.
>
> The PCE should have the view of all IGP domains, including IGP metrics and
> delay metrics.
>
>
>
> So if the PCE calculate a path and ingress and egress PE are in the same
> IGP domain,
>
> It would be preferable to choose an IGP intra domain vs using another IGP
> as transit.
>
> Or at least have the possibility to choose or prefer an Intra-Domain path
> (with a flag maybe?)
>
>
>
> Reason:
>
> Especially in mobile operator RAN networks, there could be bandwidth
> limitations in RAN IGP domains, but still a lower delay path.
>
>
>
> What’s your opinion about this?
>
>
>
> Thanks
>
> Marcel
>
>
>
>
>
>
>
>
>
>
>
>
>
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