Re: [Dots] Mirja Kühlewind's Discuss on draft-ietf-dots-data-channel-28: (with DISCUSS and COMMENT)

<mohamed.boucadair@orange.com> Thu, 02 May 2019 11:54 UTC

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Re-,

Please see inline. 

Cheers,
Med

> -----Message d'origine-----
> De : Mirja Kühlewind via Datatracker [mailto:noreply@ietf.org]
> Envoyé : jeudi 2 mai 2019 13:25
> À : The IESG
> Cc : draft-ietf-dots-data-channel@ietf.org; Roman Danyliw; dots-
> chairs@ietf.org; rdd@cert.org; dots@ietf.org
> Objet : Mirja Kühlewind's Discuss on draft-ietf-dots-data-channel-28: (with
> DISCUSS and COMMENT)
> 
> Mirja Kühlewind has entered the following ballot position for
> draft-ietf-dots-data-channel-28: Discuss
> 
> When responding, please keep the subject line intact and reply to all
> email addresses included in the To and CC lines. (Feel free to cut this
> introductory paragraph, however.)
> 
> 
> Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html
> for more information about IESG DISCUSS and COMMENT positions.
> 
> 
> The document, along with other ballot positions, can be found here:
> https://datatracker.ietf.org/doc/draft-ietf-dots-data-channel/
> 
> 
> 
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
> 
> I support Suresh's discuss that the process of how it is indicated if a 1 or
> 2
> byte mask is used is not clear. However, I would additionally like to discuss
> why this bit mask is needed at all. The TCP flags field in RFC8519 is already
> defined as bits. Storing these bits in a signal 8 bit field and applying a
> matching operation is implementation specific only and doesn't require any
> changes to the YANG model.

[Med] The motivation is similar to the one for the IPv4 flags:  

   Nevertheless,
   the use of 'flags' is problematic since it does not allow to define a
   bitmask.  For example, setting other bits not covered by the 'flags'
   filtering clause in a packet will allow that packet to get through
   (because it won't match the ACE).  

The use of bitmask will also ease inter-working witg BGP flowspec.

> 
> I would also quickly like to discuss the use of keep-alives as described in
> Section 3.1: "While the communication to the DOTS server is
>    quiescent, the DOTS client MAY probe the server to ensure it has
>    maintained cryptographic state.  Such probes can also keep alive
>    firewall and/or NAT bindings.  A TLS heartbeat [RFC6520] verifies
>    that the DOTS server still has TLS state by returning a TLS message."
> I understood that multiple requests can and should be send in the same
> connection, however, I would expect that those requests are send basically
> right after each other, such as a look-up and then change of the config. I
> don't see a need to keep up the connection for a long time otherwise.
> Especially any action performed are (other than in the signal channel case)
> not
> time critical. Therefore I would rather recommend to close and reopen
> connections and not recommend to use keep-alives at all.

[Med] The activity of the DOTS client may be used to track/detect stale entries:

   Also, DOTS servers
   may track the inactivity timeout of DOTS clients to detect stale
   entries.


> 
> 
> ----------------------------------------------------------------------
> COMMENT:
> ----------------------------------------------------------------------
> 
> Editorial comment: As alias 

[Med] The grouping "target" is defined in the data-channel, and reused in the signal channel. The name cannot be reused because it is a key of the aliases in data-channel and a node in the signal-channel. 

and migration-scope 

[Med] I guess you meant "mitigation-scope". There is no such item in the data channel. Please note that "ietf-data:target" is called in the signal-channel under mitigation-scope. 

(in the signal channel
> document) have the same fields, wouldn't it make sense to only definite it
> once
> somewhere?
>