Subject: [Softwires] Unclear text re port parameters in draft-ietf-softwire-map-dhcp-06

From: Tom Taylor <[email-masked]>
Date: Thu, 21 Nov 2013 20:54:02 -0500

The text describing client validation of OPTION_S46_PORTPARAMS in the 
second-last paragraph of Section 4.5 currently reads as follows:

    When receiving the Port Parameters option with an explicit PSID, the
    client MUST use this explicit PSID in configuring its MAP interface.
    If the conveyed IPv4 address is not 32 bit-long.  The formula for
    this check is "prefix4-len + ea-len = 32" and serves to ensure
    that the explicit PSID is only applied to configurations with a
    completely formed IPv4 address.

I don't think the sentence fragment "If the conveyed IPv4 address ..."
should be there. In the subsequent sentence, I believe the check must be:

     "prefix4-len + ea-len > 32"

Otherwise no port values are conveyed by the option. See Section 5.2 of 
the MAP document, particularly Figure 6 and associated text.

I would also add "shared and" before "completely formed" at the end of 
the paragraph.

Tom Taylor

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From: Tom Taylor <[email-masked]>
Date: Thu, 21 Nov 2013 21:00:16 -0500

Just realized that the option will be provided only if no EA bits were 
present in the BMR. Hence the test as it stands is correct. The sentence 
fragment still needs expansion or deletion. Wonder if we need text 
saying what to do if prefix4-len + ea-len > 32 and the option is also 
present?

Tom

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From: Wojciech Dec <[email-masked]>
Date: Fri, 22 Nov 2013 11:40:29 +0100

Seems like an editing error resulted in this dangling sentence. The
corresponding text in draft -04 read as shown below, and I suggest we
reinstate the "discard the option" behaviour:

   The MAP algorithm, as per Section 5.1
<http://tools.ietf.org/html/draft-ietf-softwire-map-dhcp-04#section-5.1>
[I-D.ietf-softwire-map
<http://tools.ietf.org/html/draft-ietf-softwire-map-dhcp-04#ref-I-D.ietf-softwire-map>],
allows
   the port-indexing algorithm to be parametrized in terms of an
   excluded port range (a-bits) and an explicit Port Set ID (PSID)
   value, which can be conveyed via the S46 Port Parameters Option .
   The following behaviour is expected when processing this option by
   MAP clients: A client receiving a S46 Port parameters Option in an
   OPTION_S46_BRULE or OPTION_S46_FRULE whose derived IPv4 address is
   not 32 bit-long MUST discard the option.  The formula for this check
   is "prefix4-len + ea-len == 32".  This is to ensure that the explicit
   PSID is only applied to configurations with a completely formed IPv4
   address.

On 22 November 2013 03:00, Tom Taylor <[email-masked]> wrote:

> fragment still needs expansion or deletion. Wonder if we need text saying
> what to do if prefix4-len + ea-len > 32 and the option is also present?
>
> Tom
>
> _______________________________________________
> Softwires mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/softwires
>

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From: Ole Troan <[email-masked]>
Date: Sun, 24 Nov 2013 20:10:02 +0100

Tom, Wojciech,

thanks, fixed.

Best regards,
Ole

On 22 Nov 2013, at 11:40 , Wojciech Dec <[email-masked]> wrote:

> Seems like an editing error resulted in this dangling sentence. The corresponding text in draft -04 read as shown below, and I suggest we reinstate the "discard the option" behaviour:
> 
>    The MAP algorithm, as per Section 5.1 [I-D.ietf-softwire-map
> ], allows
> Just realized that the option will be provided only if no EA bits were present in the BMR. Hence the test as it stands is correct. The sentence fragment still needs expansion or deletion. Wonder if we need text saying what to do if prefix4-len + ea-len > 32 and the option is also present?
> 
> Tom
>