Capwap Mailing List: Re: CAPWAP IESG Review Comment T12

[Pat Calhoun (pacalhou) (pcalhoun]

I think 4/5 is odd, personally. However, I think I have a better idea,
and one that I think will be MUCH clearer. In order to help express the
idea, I will include the whole text for the AC Descriptor section. If
this format works for you, I will replicate it in another two areas in
the spec that I had updated due to another IESG review comment.

<text>
4.6.1.  AC Descriptor

   The AC Descriptor message element is used by the AC to communicate
   its current state.  The value contains the following fields.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |            Stations           |             Limit             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |          Active WTPs          |            Max WTPs           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |    Security   |  R-MAC Field  |   Reserved1   |  DTLS Policy  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                       AC Information...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type:   1 for AC Descriptor

   Length:   >= 12

   Stations:   The number of stations currently served by the AC

   Limit:   The maximum number of stations supported by the AC

   Active WTPs:   The number of WTPs currently attached to the AC

   Max WTPs:   The maximum number of WTPs supported by the AC

   Security:   A 8 bit mask specifying the authentication credential
      type supported by the AC.  The following values are supported (see
      Section 2.4.4):

      1 -  X.509 Certificate Based

      2 -  Pre-Shared Secret

   R-MAC Field:   The AC supports the optional Radio MAC Address field
      in the CAPWAP transport Header (see Section 4.3).

   Reserved:  A set of reserved bits for future use.  All
      implementations complying with this protocol MUST set to zero any
      bits that are reserved in the version of the protocol supported by
      that implementation.  Receivers MUST ignore all bits not defined
      for the version of the protocol they support.

   DTLS Policy:   The AC communicates its policy on the use of DTLS for
      the CAPWAP data channel.  The AC MAY communicate more than one
      supported option, represented by the bit field below.  The WTP
      MUST abide by one of the options communicated by AC.  The
      following bit field values are supported:

      1 -  Clear Text Data Channel Supported

      2 -  DTLS Enabled Data Channel Supported

   AC Information:   The AC Descriptor message element contains multiple
      AC Information sub-elements, and defines two sub-types, each of
      which MUST be present.  The AC Information sub-element has the
      following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                AC Information Vendor Identifier               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |      AC Information Type      |     AC Information Length     |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                     AC Information Data...
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      AC Information Vendor Identifier:   A 32-bit value containing the
         IANA assigned "SMI Network Management Private Enterprise Codes"

      AC Information Type:   Vendor specific encoding of AC information.
         The following values are supported.  Both the Hardware and
         Software Version sub-elements MUST be included in the AC
         Descriptor message element.

         4 - Hardware Version:   The AC's hardware version number.

         5 - Software Version:   The AC's Software (firmware) version
            number.

      AC Information Length:   Length of vendor specific encoding of AC
         information, with a maximum size of 1024.

      AC Information Data:   Vendor specific encoding of AC information.
</text> 

-----Original Message-----
From: Romascanu, Dan (Dan) [mailto:dromasca [at] avaya.com] 
Sent: Monday, June 16, 2008 11:14 AM
To: Pat Calhoun (pacalhou); capwap [at] frascone.com
Subject: Re: [Capwap] CAPWAP IESG Review Comment T12

I won't fight this to death but I still find it confusing. Writhing 4 in
a field which can be either 4 or 5 may confuse other as well. What about
4/5? 

Dan
 

> -----Original Message-----
> From: Pat Calhoun (pacalhou) [mailto:pcalhoun [at] cisco.com]
> Sent: Monday, June 16, 2008 6:40 PM
> To: capwap [at] frascone.com
> Subject: [Capwap] CAPWAP IESG Review Comment T12
> 
> All,
> 
> The following is the IESG Comment Review:
> 
>    T12 - Section 4.6.1 - in the AC Descriptor protocol diagram delete 
> =4 from the Type
>    filed (it can be 4 or 5 as I understand)
> 
> Actually, the reason why this is part of the diagram is because both 4

> and 5 MUST be included (as described in the field description). So in 
> order to make this much clearer, we have included this in the diagram.
> 
> PatC
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