Subject: [Capwap] New issues: readability/ease of use/lack of specification

From: "Bob O'Hara (boohara)" <[email-masked]>
Date: Tue, 23 May 2006 10:36:13 -0700

The -01 draft is a significant improvement over the -00 draft.  However,
I find it very difficult to easily find some information in the
document.  Following are some editorial and technical comments.

1. Please include a table of message element type values for the base
CAPWAP message elements in section 4.4.

2. Please include a table of message element type values for the 802.11
binding-specific elements in section 11.10.

3. Please describe how the binding-specific message element type values
are derived.  It appears that the 802.11 type values begin arbitrarily
at 1024.  Are the values for this field to be IANA controlled, or are
they able to be identified deterministically?

4. Please identify in which messages the nine additional message
elements in section 11.10 may appear, since they are not listed in the
table in section 11.9.3.

5. In 11.7, the Message Type Value for the two 802.11-specific messages
is given.  However, I don't see anywhere that describes how these values
were determined.  Please add a description of the derivation of the
message type values.

6. 11.8 says there are no 802.11-specific data message bindings.  I
think that the data packet containing an 802.11-encapsulated frame
should go here, along with its complete description.

 -Bob

Bob O'Hara
Cisco Systems - WNBU

Phone:  +1 408 853 5513
Mobile: +1 408 218 4025
 
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From: "Dorothy Stanley" <[email-masked]>
Date: Thu, 25 May 2006 10:32:53 -0700

Hi Bob,

Glad that you found the -01 draft a significant improvement. Proposed
resolutions to Issue 124 are inline below.

Thanks,

Dorothy

> CAPWAP message elements in section 4.4.

Proposed Resolution: Insert a tablet at the end of Section 4.4, just prior
to
4.4.1

The following CAPWAP protocol message elements are defined:
[Include the list - the 01 elements, plus changes due to issue resolution,
with type values]

> binding-specific elements in section 11.10.

Proposed resolution:  Insert a table in Section 10.10, just
prior to 11.10.1

The follwoing IEEE 802.11 specific message elements are defined:
[Include the list - the -01 values, plus any changes per issue resolution,
with type values]

> they able to be identified deterministically?

The resolution of Issue 91 (Duplicate message element values)
renumbered the CAPWAP message elements to begin with 1, and
The IEEE 802.11 message element values to begin with 1024.
The next wireless type would begin at 2048. The
definition of values is to be done in the CAPWAP document(s).

Proposed resolution: At the end of section 4.4, prior
to the table being added by comment #1 above, change from

   Where Type (16 bit) identifies the character of the information
   carried in the Value field and Length (16 bits) indicates the number
   of bytes in the Value field.

to

   Where Type (16 bit) identifies the character of the information
   carried in the Value field and Length (16 bits) indicates the number
   of bytes in the Value field. Type field values are allocated as follows:

                               Usage
Type Values

         CAPWAP Protocol Message Elements                1-1023
         IEEE 802.11 Message Elements                         1024-2047
         Reserved for Future Use                                      2048 -
65024

and delete text describing IANA allocation of message element values.

> elements in section 11.10 may appear, since they are not listed in the

The table in 11.9.3 lists the message elements that may be included in
the various configuration related messages.

Section 11.7.1 includes the message elements which can be included in the
IEEE 802.11 WLAN Config Request message:
IEEE 802.11 Add WLAN
IEEE 802.11 Delete WLAN
IEEE 802.11 Update WLAN
IEEE 802.11 Information Element

Section 11.7.2 lists the message elements that may be included in
the IEEE 802.11 WLAN Config Response:
IEEE 802.11 Assigned WTP BSSID

Section 11.9.1 lists the message elements that may be included in the
Mobile Config Request message:
IEEE 802.11 Mobile
IEEE 802.11 Mobile Session Key
Station QOS Profile

Section 11.9.2 lists the message elements that may be included
in the WTP Event Request message:
IEEE 802.11 MIC Countermeasures
IEEE 802.11 Statistics
IEEE 802.11 Radio Fail Alarm Indication

Between all of these sections, each message element is included in
at least one message. There is  one message element listed in the
section 11.9.3 table that is not defined:
IEEE 802.11 WTP Mode and Type. This seems to be CAPWAP
level information rather than 802.11 specific.

Proposed change:
Delete the IEEE 802.11 WTP Mode and Type row in the 11.9.3 table

> were determined.  Please add a description of the derivation of the

Please see the description in section 4.3.1.1 (extracted below). Is this
sufficient, or
is additional description required?

The Message Type field is comprised of an IANA Enterprise
   Number and a message type value field.  The first two byte contain
   the IANA Enterprise Number (for example, the IEEE 802.11 IANA
   Enterprise number is 13277), and the second two bytes contain the
   Message Type value.  The message type field can be expressed as:

   Message Type = IANA Enterprise Number * 256 + Message Type Value

> should go here, along with its complete description.

There is some descriptive text in Section 11.4, Transport
Specific Bindings, which describes the patload encapsulation.

Is this text sufficient? If not, what addtional information is needed?
Perhaps a figure should be added to this section?

-Bob