Re: [Idr] WG LC draft-ietf-idr-flowspec-path-redirect-10.txt [11/17/2019 to 12/2/2019]

Sue,

> On Nov 18, 2019, at 12:41 AM, Susan Hares <shares@ndzh.com> wrote:
> 
> This begins a 2 week WG Last call on draft-idr-flowspec-path-redirect-10.txt from [11/17/2019 to 12/2/2019]. 
>  
> You can obtain the draft at:
>  
> https://datatracker.ietf.org/doc/draft-ietf-idr-flowspec-path-redirect/
>  
> Consider in your review whether this draft: 
>  
> 1)      Is compatible with draft-ietf-rfc5575bis-17.txt? 

Yes.  (Close enough.)  The current version of the draft is implementable.

> 2)      Whether the draft is useful for deployments of flow specification

It can be useful.

> 3)      Is this technology ready for deployment? 
> 4)      Is the write-up of this technology in draft-ietf-idr-flowspec-path-redirect clearly written and ready for publication? 

Ready with minor issues, IMO:

Procedure-wise, there needs to be a bit more text covering cases about interactions with other traffic actions.  This was a known headache for similar drafts such as redirect-to-ip.  In particular, interaction with redirect-to-ip and redirect-to-vrf is needed.

The text "A single flowspec rule MUST NOT have more as one indirection-id per S-ID.  On a flowspec client the indirection-id with lowest S-ID MUST be imposed first for any given flowspec entry."  There's no procedure for what happens in error handling when you do have more than one of the same S-ID.  The text about the case for S-ID of 0 is also a bit ambiguous.  It feels like it's reading "there is no sequence", but what do you do when you then have ones that do?

A few IANA issues:
I see the type registry is currently registered with IANA (code point 0x09).  However, the sub-type registry is not established for some reason?
The ID-Type field likely needs its own IANA registry.  Values 1-5 are defined in this draft.

The flags field (one octet) currently has 3 bits reserved.  In the past, we've not done a registry for such cases (c.f. graceful restart) until we need to start carving out those reserved bits for future extensions.  I leave it to the chairs' opinion whether we want this a priori or not.

>  
> Thank you for considering this draft. 
>  
> Cheerily, Susan Hares 
>  
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