Subject: [Capwap] Proposed Resolution for issue 221

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Wed, 22 Nov 2006 09:58:26 -0800

All,

As discussed in San Diego, issue 221 is included in this e-mail. The
issue raised is that while encryption of the data channel is possible
using DTLS, there is currently no way to signal from the AC to the WTP
what its policy is. This proposed resolution allows the AC to
communicate its policy. Note that the WTP does not get a say in whether
DTLS will be required or not. The DTLS policy field, introduced in the
AC Descriptor, is a bit field, and therefore it is possible for the AC
to communicate a range of possible connection types.

4.5.1  AC Descriptor

   The AC payload message element is used by the AC to communicate it's
   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  |Wireless Field |  DTLS Policy  |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
[...]

   DTLS Policy:   The AC communicates its policy on whether the use of
      DTLS is mandatory for all CAPWAP data packets.  The WTP MUST abide
      by the AC's policy.  The following values are supported:

      0 -  Clear Text Data Channel Supported
      1 -  DTLS Enabled Data Channel Supported

Pat Calhoun
CTO, Wireless Networking Business Unit
Cisco Systems
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From: "Bob O'Hara (boohara)" <[email-masked]>
Date: Wed, 22 Nov 2006 12:50:08 -0800

Pat,

On this issue, shouldn't the text describing the DTLS Policy bit field
refer to bit positions and not "values"?  Perhaps I am mistaken about
the use of this field.  Is it the intent to provide the WTP with all of
the policies allowable by the AC, or to provide it with one policy that
it must use?

 -Bob
 
-----Original Message-----
From: Pat Calhoun (pacalhou) 
Sent: Wednesday, November 22, 2006 9:58 AM
To: [email-masked]
Subject: [Capwap] Proposed Resolution for issue 221

All,

4.5.1  AC Descriptor

      0                   1                   2                   3

Pat Calhoun

---

From: "Pat Calhoun (pacalhou)" <[email-masked]>
Date: Wed, 22 Nov 2006 14:14:07 -0800

Thanks Bob. Note sure what happened because I though I had cleaned that
up. The text should have read:

   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

Pat Calhoun

> From: Bob O'Hara (boohara) 
> Sent: Wednesday, November 22, 2006 12:50 PM
> To: Pat Calhoun (pacalhou); [email-masked]
> Subject: RE: [Capwap] Proposed Resolution for issue 221
> 
> Pat,
> 
> On this issue, shouldn't the text describing the DTLS Policy 
> bit field refer to bit positions and not "values"?  Perhaps I 
> am mistaken about the use of this field.  Is it the intent to 
> provide the WTP with all of the policies allowable by the AC, 
> or to provide it with one policy that it must use?
> 
>  -Bob
>  
> As discussed in San Diego, issue 221 is included in this 
> e-mail. The issue raised is that while encryption of the data 
> channel is possible using DTLS, there is currently no way to 
> signal from the AC to the WTP what its policy is. This 
> proposed resolution allows the AC to communicate its policy. 
> Note that the WTP does not get a say in whether DTLS will be 
> required or not. The DTLS policy field, introduced in the AC 
> Descriptor, is a bit field, and therefore it is possible for 
> the AC to communicate a range of possible connection types.
> 
> 4.5.1  AC Descriptor
>