Re: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy

Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com> Tue, 07 May 2019 11:40 UTC

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From: Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com>
Date: Tue, 7 May 2019 17:10:30 +0530
Message-ID: <CAHhGMfGRgdDTam97sb5dYZQHBLLHpTj85yJ7oL5w7wrB3+q3jA@mail.gmail.com>
To: "Ketan Talaulikar (ketant)" <ketant@cisco.com>
Cc: Chaitanya Varma <chaitanya.varma@ipinfusion.com>, "idr@ietf.org" <idr@ietf.org>
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Subject: Re: [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy
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Hi Ketan,



Thanks for the quick response.

Additionally, we have more queries as follows



*"Alternatively, a router (i.e., a BGP egress router) advertises SR*

*   Policies representing paths to itself.  In this case, it is possible*

*   to send the policy to each head-end over a BGP session to that head-*

*  end, without requiring any further propagation of the policy."*



How does an egress router advertise SR policies representing paths to
itself? Is it done through BGP configuration or any other trigger?
In the above case how ERO (SID-List) is calculated?


Regards

Gurusiddesh V N

On Wed, May 1, 2019 at 7:34 PM Ketan Talaulikar (ketant) <ketant@cisco.com>
wrote:

> Hi Chaitanya,
>
>
>
> Please check inline below.
>
>
>
> *From:* Idr <idr-bounces@ietf.org> *On Behalf Of *Chaitanya Varma
> *Sent:* 30 April 2019 13:34
> *To:* idr@ietf.org
> *Cc:* Gurusiddesh Nidasesi <gurusiddesh.nidasesi@ipinfusion.com>
> *Subject:* [Idr] Mail regarding draft-ietf-idr-segment-routing-te-policy
>
>
>
> Hi,
>
>
>
> I have couple of queries from the below draft.
>
>
>
> https://tools.ietf.org/html/draft-ietf-idr-segment-routing-te-policy-05
>
>
>
> *  “ Typically, a controller defines the set of policies and advertise*
>
> *   them to policy head-end routers (typically ingress routers).” *
>
>
>
> How do we communicate SR policies from controller? Is it through BGP-SR
> session or PCEP session.
>
> *[KT] This draft is all about using BGP for signalling SR Policies from a
> controller to the head-end routers. So yes (b) below.*
>
>
>
> a. If it is through PCEP session what happens if the PCC is non-headend?
>
> b. If it is through BGP-SR what is the role for PCEP between PCE and PCC?
>
> *[KT] PCEP is another flavour for instantiation of SR Policies. Yet
> another option is using netconf/yang or another method for provisioning.
> This draft is about using BGP and PCEP is not required.*
>
>
>
> *  “ Moreover, one or more route-target SHOULD be attached to the*
>
>
>
> *   advertisement” *How Route-target should be attached to a SR-NLRI
> update?
>
> *[KT] As Route Target Extended Communities attribute – ref sec 1 of the
> draft.*
>
>
>
> Is it done through local configuration or picked up based on some dynamic
> parameter?
>
> *[KT] It is done by the controller and may be done via local config –
> either along with the SR Policy or route policy or even dynamically based
> on the head-end address. This would be implementation specific.*
>
>
>
> *Thanks,*
>
> *Ketan*
>
>
>
> Appreciate if you can help here.
>
>
>
>
>
> Regards,
>
> Chaitanya
>
>
>
>
> ..
>


-- 
Thanks,
Gurusiddesh V N

-- 
.