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

[Gurusiddesh Nidasesi <[e-mail]>]

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) <[e-mail]>
wrote:

> Hi Chaitanya,
>
>
>
> Please check inline below.
>
>
>
> *From:* Idr <[e-mail]> *On Behalf Of *Chaitanya Varma
> *Sent:* 30 April 2019 13:34
> *To:* [e-mail]
> *Cc:* Gurusiddesh Nidasesi <[e-mail]>
> *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

-- 
.