Re: [Lsr] Rtgdir last call review of draft-ietf-lsr-isis-sr-vtn-mt-05

[Daniele Ceccarelli <[e-mail]>]

Hi Chongfeng,

Thanks for addressing my comments.
I would just suggest to add some text to the draft to explain the comment
below


*[Chongfeng] This is discussed in the scalability considerations section of
this draft. This mechanism is useful for network scenarios in which the
required number of VTN/NRP is small, the advantage is no protocol extension
is required (as reflected by the document type). For network scenarios
where the number of required VTN/NRP is large, more scalable solution would
be needed, which may result in further protocol extensions and
enhancements.*


BR
Daniele

On Wed, Nov 29, 2023 at 1:00 AM Chongfeng Xie <[e-mail]>
wrote:

>
> *Hi Daniele,*
>
> *Thanks a lot for your careful review and comments. Please see my replies
> inline [Chongfeng]:*
>
> -----Original Message-----
> From: Daniele Ceccarelli via Datatracker [mailto:[e-mail]]
> Sent: Friday, November 24, 2023 10:21 PM
> To: [e-mail]
> Cc: [e-mail]; [e-mail];
> [e-mail]
> Subject: Rtgdir last call review of draft-ietf-lsr-isis-sr-vtn-mt-05
>
> Reviewer: Daniele Ceccarelli
> Review result: Has Issues
>
> - General: The term and concept of Enhanced VPN is being discussed in TEAS
> as part of the WG last call. I suggest to follow that thread and align the
> draft with whatever output will be agreed.
>
> *[Chongfeng] Yes the terminology in this draft will align with the
> decision on terminology in in TEAS*
>

> - General: i would suggest to change the title into "Applicability" rather
> than using. Per my understanding this document describes how to use
> existing mechanisms to achieve something new (the status is correctly
> informational)
>
> *[Chongfeng] Agree, we can make this change in next revision.*
>

> - Abstract: "enhanced isolation". i checked if it was defined in the
> framework for Enhanced VPNs in TEAS, but i couldn't find a definition there
> nor in this draft. What does it mean?
>
> *[Chongfeng]* *We will align this description with the enhanced VPN
> framework draft.*
>
> - VTN: is this a new term to identify a set of existing items? E.g. an
> ACTN VN, NRP, a set of RSVP-TE tunnel, a topology built with flex
> algo...are they cases of VTN or the VTN is a different thing?
>
> *[Chongfeng] According to the recent discussion in TEAS, it is agreed to
> replace the term VTN with NRP.*
>
> - Intro: s/than that can be provided/than the ones that can be provided
>
> *[Chongfeng] OK.*
>
> - "Another possible approach is to create a set of point-to-point paths,
> each with a set of network resources reserved along the path, such paths
> are called Virtual Transport Path (VTP)". In what is this different from an
> ACTN VN member? See RFC 8453.
>
> *[Chongfeng] VN member as defined in RFC 8453 refers to "edge-to-edge
> link" exposed in the management plane, which is formed as end-to-end
> tunnels in the underlying networks. The term VTP refers to point-to-point
> underlay paths with network resource reserved along the path. So VTPs can
> be considered as one specific type of underlay tunnel with resource
> reservation. As we will replace VTN with NRP, we will consider whether the
> term VTP is still needed or not.*
>
> - Introduction: "In some network scenarios, the required number of VTNs
> could be small, and it is assumed that each VTN is associated with an
> independent topology and has a set of dedicated or shared network
> resources. This document describes a simplified mechanism to build SR based
> VTNs in those scenarios." I don't understand, is there the need for a
> specific mechanisms (different from existing ones) only for particular
> cases in which the number of VTNs is small (smaller than other scenarios)?
>
> *[Chongfeng] This is discussed in the scalability considerations section
> of this draft. This mechanism is useful for network scenarios in which the
> required number of VTN/NRP is small, the advantage is no protocol extension
> is required (as reflected by the document type). For network scenarios
> where the number of required VTN/NRP is large, more scalable solution would
> be needed, which may result in further protocol extensions and
> enhancements.*
>

 Section 3.1 "The usage of other TE attributes in topology-specific TLVs is
> for further study." The draft is pretty simple and small, can't the usage
> of other TE attributes be described here as well?
>
> *[Chongfeng]* *Yes the encoding of TE attributes in topology-specific
> TLVs is simple, while a more important thing is to find valid use case for
> them. The current VTN/NRP use case only makes use of the bandwidth
> attribute, other TE attributes are not in the scope. Thus this statement is
> considered OK for this document.*
>
> *Best regards*
> *Chongfeng*
>
>