Re: [spring] 6MAN WGLC: draft-ietf-6man-sids

[Gyan Mishra <[e-mail]>]

Hi Suresh

Responses in-line

On Thu, Sep 29, 2022 at 4:12 PM Suresh Krishnan <[e-mail]>
wrote:

> Hi Gyan,
>   Thanks for your comments. Please find responses inline.
>
> On Sep 28, 2022, at 11:06 PM, Gyan Mishra <[e-mail]> wrote:
>
>
> I support publication of the draft.
>
> I have reviewed the draft and have some comments.
>
> As the C-SID draft had been adopted by Spring I don’t see a need for
> section 4.2 as is not relevant.
>
> Section 4 talks about C-SID which is vague as it should be referencing the
> two different vendor solutions below:
>
>
> Good point. I have a queued up change from early in the WGLC to update the
> reference to draft-ietf-spring-srv6-srh-compression which is the spring WG
> draft and that would obviate the need to add vendor specific solutions.
>

    Gyan> Perfect

>
>
> Brief description of each flavor and operation I think is important for
> the draft.
>
> 1. Cisco uSID micro sid - Next function- Shift by 16 bits and forward at
> each node endpoint processing.
> The 128 bit DA is a  uSID carrier can have up to 6 16 bit uSIDs encoded
> into the DA for steering up to 6 nodes without SRH.  If desirable to steer
> to more then 6 nodes an SRH is required along with SR Policy with Segment
> list.
>
> 2. Huawei G-SID - Replace function - Copies G-SID from SRH to DA address
> at each node endpoint processing.  G-SID operation requires SRH present.
>
> Most all deployments of SRV6 are done using ULA addressing RFC 4193.  Even
> across the internet the internal P nodes in a carrier network can use RFC
> 4193 as along as the eBGP peering points use next hop self which avoids
> requiring next hop eBGP subnet accessibility.  That being said subnets or
> even aggregate summary of the carrier network does not need to be
> advertised outside of the carrier networks domain.
>
> This draft proposed an IANA allocation /16 for the GUA address for the
> SRv6 block B:N deployment out of which the SRv6 locators are allocated.
>
> I understand the reasoning behind it to avoid advertisement of the
> locators outside of the domain.
>
> The IANA allocation does not mention that the block should be made non
> internet routable  like a ULA.
>
>
> Yes. The IANA allocation itself will not have such properties as the
> registry does not have a way to request it.
>
>
> https://www.iana.org/assignments/ipv6-address-space/ipv6-address-space.xhtml
>
> But we can certainly add an entry to
> https://www.iana.org/assignments/iana-ipv6-special-registry/iana-ipv6-special-registry.xhtml to
> mention this is in fact the case.
>

   Gyan> Excellent

I also see that the discussion about using ULA instead of a specific prefix
> has progressed on and I have a view that is very similar to what Brian C.
> and Michael R. had expressed.
>

    Gyan> Understood and Agreed

>
> Regards
> Suresh
>
> --

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*Gyan Mishra*

*Network Solutions A**rchitect *

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