Re: [spring] Usage of DoH vs SRH TLVs

Hi Joel,

> Clearly there are some pieces of information that are closely tied to the
SRH

IMHO anything that requires some action on the segment endpoints (for
example segment by segment performance measurement) is "closely tied to the
SRH".

Since processing of TLVs is subject to local configuration I would leave it
to the operator to choose which TLVs he wants to execute in the packets
(likely subject to his hardware capabilities). Making any artificial walls
would be more of an obstacle then help.

Cheers,
R.

On Wed, Feb 22, 2023 at 3:37 PM Joel Halpern <jmh@joelhalpern.com> wrote:

> The SPRING WG Chairs have noticed several recent discussions which wound
> around to the question of whether specific information belongs in a
> Destination Option Header (DOH) before the SHR, or belongs in an SRH TLV.
> Clearly there are some pieces of information that are closely tied to the
> SRH, such as SRH Authentication information, that belong in the SRH TLV.
> The question is discussed here is about information that while tied to the
> SRH hops is not tied to the SRH contents.
>
> There seem to be two obvious answers, but we'd like to hear the WG
> opinion, in particular to propose alternatives.
>
> One obvious alternative would seem to be simply not to allow any extension
> in the SRH that can be properly handled by a DoH, and does not depend upon
> information in the SRH other than potentially the current DA, which is in
> the IPv6 Destination Address field. This provides a clear decision process
> for the working group, but some folks have argued it is limiting or
> inefficient.
>
> The next obvious choice would seem to be to allow any extension that can
> be carried in a DOH to also be carried in an SRH TLV. This seems to lead to
> a large number of SRH TLV definitions, complicating implementations and
> adding limited value.  It should also be noted for this evaluation that RFC
> 8754 section 4.3.1.1 and section 4.3.1.1.1 make it clear that processing
> TLVs at an SRv6 Hop is optional and subject to local configuration.
>
> Does the working group have any suggestions or opinions?
>
> Thank you,
>
> Joel, Jim, and Bruno
>
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