Re: [Idr] draft-zhou-idr-bgp-srmpls-elp-06 - Adoption call (1/27/2023 to 2/10/2023) - extended to 3/3

[Ketan Talaulikar <[e-mail]>]

Hi Sue,

I support the adoption of this document since it attempts to address an
existing technical gap with the signaling of SR Policies.

However, I have a concern with the proposal using one of the 4 remaining
per-segment flags. There are multiple alternatives including using a new
sub-TLV of the Segment List sub-TLV to indicate the position or even the
use of a new Segment Type for indicating the placement of an EL.

I understand that there is an equivalent proposal for PCEP where the
authors introduced extended flags for the purpose of introducing the "E"
flag. Since the same might not be possible in BGP SR Policy SAFI encoding,
we should conserve the existing flags and instead go for an alternative
encoding proposal.

Thanks,
Ketan


On Wed, Mar 1, 2023 at 9:38 AM Susan Hares <[e-mail]> wrote:

> Greetings:
>
>
>
> The support for draft-zhou-idr-bgp-srmpls-elp-06 is positive, but light.
>
> I am extending the original call to 3/3 to see if we can obtain additional
> support.
>
>
>
> https://mailarchive.ietf.org/arch/msg/idr/vVpUpFP_0QqY4tzGAoeEyLM7Brc/
>
>
>
> The text of the initial call is included below.
>
>
>
> Cheerily, Sue
>
>
>
> ===========
>
> his adoption begins a two week WG Adoption call for
>
> draft-zhou-idr-bgp-srmpls-elp-06.txt
>
> https://datatracker.ietf.org/doc/draft-zhou-idr-bgp-srmpls-elp/
>
>
>
> The authors should respond to this message with
>
> Email that indicates whether they know of any IPR
>
> related to this draft.
>
>
>
> In your discussions please consider if this WG
>
> should approve an  extension to Segment flags defined in the
>
> draft-ietf-idr-segment-routing-te-policy-20.txt .
>
>
>
>
>
> The existing flags are the following
>
>
>
> 2.4.4.2.12.  Segment Flags
>
>
>
>    The Segment Types sub-TLVs described above may contain the following
>
>    flags in the "Flags" field defined in Section 6.8:
>
>
>
>     0 1 2 3 4 5 6 7
>
>    +-+-+-+-+-+-+-+-+
>
>    |V|A|S|B|       |
>
>    +-+-+-+-+-+-+-+-+
>
>
>
>    Figure 22: Segment Flags
>
>
>
> The changes proposed by this draft are the addition
>
> Of an "E" flag to those bits.
>
>
>
>
>
>     0 1 2 3 4 5 6 7
>
>
>
>    +-+-+-+-+-+-+-+-+
>
>
>
>    |V|A|S|B|E|     |
>
>
>
>    +-+-+-+-+-+-+-+-+
>
>
>
>
>
>
>
> E-Flag: This flag, when set, indicates that presence of < ELI, EL>
>
>
>
> label pairs which are inserted after this segment.  E-Flag is
>
>
>
> applicable to Segment Types A, C, D, E, F, G and H.  If E-Flag
>
>
>
> appears with Segment Types B, I, J and K, it MUST be ignored.
>
>
>
> Cheerily, Sue
>
>
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