Re: [Dart] Gen-art LC review: draft-ietf-dart-dscp-rtp-07

Robert Sparks <rjsparks@nostrum.com> Tue, 14 October 2014 18:47 UTC

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Date: Tue, 14 Oct 2014 13:46:52 -0500
From: Robert Sparks <rjsparks@nostrum.com>
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To: "Black, David" <david.black@emc.com>, General Area Review Team <gen-art@ietf.org>, "draft-ietf-dart-dscp-rtp.all@tools.ietf.org" <draft-ietf-dart-dscp-rtp.all@tools.ietf.org>, "ietf@ietf.org" <ietf@ietf.org>, "dart@ietf.org" <dart@ietf.org>
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Subject: Re: [Dart] Gen-art LC review: draft-ietf-dart-dscp-rtp-07
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On 10/14/14 1:18 PM, Black, David wrote:
> Robert,
>
> Thanks for the review.
>
>> At the end of page 13, the sentence that starts "Transport protocol
>> support for multiple"... is very long and hard to parse. I suspect it
>> will be hard to translate. The action of changing the existing protocols
>> is implied rather than explicit in the current wording. "current
>> designs" is vague. I suggest this as a starting point: "Adding support
>> for multiple QoS-based traffic classes within a single network 5-tuple
>> to a transport protocol adds significant complexity compared to the
>> current protocol definitions. For congestion-controlled transport
>> protocols, network congestion information for each QoS-based traffic
>> class would have to be disambiguated to allow congestion control to be
>> managed separately for each such traffic class." Hopefully it can be
>> made even simpler.
> Indeed, that sentence is problematic.  I've edited the entire paragraph for
> clarity.  Here's the new text:
>
> When PHBs that enable reordering are mixed within a single network 5-tuple,
> the effect is to mix QoS-based traffic classes within the scope of a single
> transport protocol connection or association. As these QoS-based traffic
> classes receive different network QoS treatments, they use different pools
> of network resources and hence may exhibit different levels of congestion.
> The result for congestion-controlled protocols is that a separate instance
> of congestion control functionality is needed per QoS-based
> traffic class.  Current transport protocols support only a single instance
> of congestion control functionality for an entire connection or association;
> extending that support to multiple instances would add significant protocol
> complexity.  Traffic in different QoS-based classes may use different paths
> through the network; this complicates path integrity checking in connection-
> or association-based protocols, as those paths may fail independently.
That's great. Thanks!
>
>> In the first paragraph of 5.2, would "Such reordering may lead to
>> unneeded retransmission, and spurious emission of retransmission control
>> signals (such as NACK) in reliable delivery protocols (see Section 5.1)"
>> work?
> Yes, and I've removed "emission of" from that proposed text.
Ack
>
> Thanks,
> --David
>
>
>> -----Original Message-----
>> From: Robert Sparks [mailto:rjsparks@nostrum.com]
>> Sent: Tuesday, October 14, 2014 11:50 AM
>> To: General Area Review Team; draft-ietf-dart-dscp-rtp.all@tools.ietf.org;
>> ietf@ietf.org; dart@ietf.org
>> Subject: Gen-art LC review: draft-ietf-dart-dscp-rtp-07
>>
>> I am the assigned Gen-ART reviewer for this draft. For background on
>> Gen-ART, please see the FAQ at
>>
>> <http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>;.
>>
>> Please resolve these comments along with any other Last Call comments
>> you may receive.
>>
>> Document: draft-ietf-dart-dscp-rtp-07
>> Reviewer: Robert Sparks
>> Review Date: 14-Oct-2014
>> IETF LC End Date: 14-Oct-2014
>> IESG Telechat date: not yet scheduled for a telechat
>>
>> Summary: Ready with nits
>>
>> These are very small nits to consider. Please feel free to leave the
>> existing text alone if these suggestions don't help.
>>
>> At the end of page 13, the sentence that starts "Transport protocol
>> support for multiple"... is very long and hard to parse. I suspect it
>> will be hard to translate. The action of changing the existing protocols
>> is implied rather than explicit in the current wording. "current
>> designs" is vague. I suggest this as a starting point: "Adding support
>> for multiple QoS-based traffic classes within a single network 5-tuple
>> to a transport protocol adds significant complexity compared to the
>> current protocol definitions. For congestion-controlled transport
>> protocols, network congestion information for each QoS-based traffic
>> class would have to be disambiguated to allow congestion control to be
>> managed separately for each such traffic class." Hopefully it can be
>> made even simpler.
>>
>> In the first paragraph of 5.2, would "Such reordering may lead to
>> unneeded retransmission, and spurious emission of retransmission control
>> signals (such as NACK) in reliable delivery protocols (see Section 5.1)"
>> work?
>>
>>