Re: [Teas] question on the topology filter draft

Jie,

Please see inline [prefixed Pavan]

Regards,
-Pavan

On Thu, Nov 11, 2021 at 12:11 PM Dongjie (Jimmy) <jie.dong@huawei.com>
wrote:

> Hi Pavan,
>
>
>
> Please fine some comments about topology filter and its usage inline:
>
>
>
> *From:* Teas [mailto:teas-bounces@ietf.org] *On Behalf Of *Vishnu Pavan
> Beeram
> *Sent:* Wednesday, November 10, 2021 8:23 PM
> *To:* Loa Andersson <loa@pi.nu>
> *Cc:* TEAS WG <teas@ietf.org>
> *Subject:* Re: [Teas] question on the topology filter draft
>
>
>
> Loa,
>
>
>
> Please see inline (prefixed VPB)
>
>
>
> Regards,
>
> -Pavan
>
>
>
>
>
> On Tue, Nov 9, 2021 at 11:57 AM Loa Andersson <loa@pi.nu> wrote:
>
> WG, Pavan, authors,
>
> I was cut off at the end of the queue in the wg discussion. I had a
> fairly simple question,
>
> Where the topology filter(s) defined
>
>
>
> [VPB] The term “topology filter” is being introduced in
> draft-bestbar-teas-yang-topology-filter (not aware of any other document
> where it is defined). As per this data model draft, a “topology filter” is
> a data construct that can be applied on either a native topology or a
> customized topology to produce a filtered set of topological elements. The
> native or customized topology referred to here is a TE aware topology
> [RFC8795].
>
>
>
> [Jie] Since the term “topology filter” is newly introduced in this YANG
> model draft, it would be useful to state in the document “who” is the
> consumer of this information. More specifically, who will use the topology
> filter in path or route computation.
>
>
>

[Pavan] The consumer depends on the use-case; The to-be-added use-case
section is expected to  have sufficient details to address this.

> and what benefits do we get from
> using them?
>
>
>
> [VPB] There are a couple of use-cases that are being targeted with this
> construct.
>
>
>
> (a) Specification of topology related constraints for TE path computation
> (any setup type):
> A few examples:
> - Compute a path within a specific topology
> - Compute a path within the topology associated with a specific IGP domain
> - Compute a path within the topology learnt from a specific TE Information
> Source
> - Compute a path within the topology defined by the application of one or
> more topology-filters
> ** Say, a topology with elements that are learnt via ISIS Level-2 and
> include resource-affinity red
> ** Or, a topology with elements associated with ISIS Flex-Algo 128 and do
> not include resource-affinity blue
>
>
>
> [Jie]  In the last case, why use Flex-Algo with an additional rule of
> include-affinity blue? The include rule can be defined as part of the
> Flex-Algo.
>
>
[Pavan] Good question (was expecting someone to ask this; brownie points
are in order)! Yes, you could always place as many constraints as you want
in your Flex-Algo definition (FAD). But we are talking about TE path
computation profiles here -- the number of TE path computation profiles
used in a network need not be "limited" by the number of FADs deployed in
it. When a Flex-Algo ID is passed in as part of the computation profile of
an SR path to a path compute engine, an implementation may merge the
constraints in the associated FAD with "other" specified constraints and
then come up with an appropriate path (the SIDs of the Flex-Algorithm are
used where applicable to compress the resultant path).

>
>
> And what does “resource-affinity” mean in a topology filter?
>

Resource Affinity == Admin group ([RFC3630
<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc3630__;!!NEt6yMaO-gk!Wf63bNr9BsYF3NyuMHU51LlImOftv9m46EjW6Sl_v-ePYK0WjHXlEnRjb6z3fYS2$>],
[RFC5329
<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc5329__;!!NEt6yMaO-gk!Wf63bNr9BsYF3NyuMHU51LlImOftv9m46EjW6Sl_v-ePYK0WjHXlEnRjb9gfGNqM$>],
[RFC5305
<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc5305__;!!NEt6yMaO-gk!Wf63bNr9BsYF3NyuMHU51LlImOftv9m46EjW6Sl_v-ePYK0WjHXlEnRjb33V9PD-$>]
and [RFC7308
<https://urldefense.com/v3/__https://datatracker.ietf.org/doc/html/rfc7308__;!!NEt6yMaO-gk!Wf63bNr9BsYF3NyuMHU51LlImOftv9m46EjW6Sl_v-ePYK0WjHXlEnRjb01y_A-E$>
]).

>
>
> (b) Specification of filter-topology associated with a Network Resource
> Partition
>
>
>
> [Jie] Topology-filter and filter-topology sounds confusing to me. How
> about simply say “specification of the topology associated with a Network
> Resource Partition”?
>
>
>

[Pavan] Ok. I was specifying a use-case using a term that is currently
specified in draft-ietf-teas-ietf-network-slices-05; We will address
terminology policing comments (if any) after the use-case section is
published in the draft.

> Best regards,
>
> Jie
>
>
> /Loa
> --
>
> Loa Andersson                        email: loa@pi.nu
> Senior MPLS Expert                          loa.pi.nu@gmail.com
> Bronze Dragon Consulting             phone: +46 739 81 21 64
>
> _______________________________________________
> Teas mailing list
> Teas@ietf.org
> https://www.ietf.org/mailman/listinfo/teas
>
>