Re: [Teas] question on the topology filter draft

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<mailto: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.

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.

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

(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”?

Best regards,
Jie

/Loa
--

Loa Andersson                        email: loa@pi.nu<mailto:loa@pi.nu>
Senior MPLS Expert                          loa.pi.nu@gmail.com<mailto:loa.pi.nu@gmail.com>
Bronze Dragon Consulting             phone: +46 739 81 21 64

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