Capwap Mailing List: Re: IESG Review Comment T24

[Margaret Wasserman (margaret]

I'm personally not wild about changing the packet formats at this  
point, but there does appear to be a technical justification for this  
change...

Are there actually systems on which you wouldn't know the packet size  
at this layer, though?  Or is this just a theoretical technical  
justification?

Margaret



On Jun 16, 2008, at 11:35 AM, Pat Calhoun (pacalhou) wrote:

> All,
>
> Here is the IESG Review Comment:
>
>    T24 - Sections 4.6.27, 4.6.28 - should not these two messages  
> include
> length of the
>    Value fields?
>
> Originally, this was not included, because it could be inferred.
> However, I can imagine a software architecture where the packet  
> size is
> not known when the message elements are parsed. So I have added them:
>
> <text>
> 4.6.27.  Image Data
> [...]
>
>    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
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |   Data Type   |      Data Length      |        Data ....
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> [...]
>
>    Data: Length of data field, with a maximum size of 1024.
>
>    Data:   The Image Data field contains up to 1024 characters.  If  
> the
>       block being sent is the last one, the Opcode is set to 2.   
> The AC
>       MAY opt to abort the data transfer by setting the Opcode to 5.
>       When the Opcode is 5, the Value field has a zero length.
>
> 4.6.28.  Image Identifier
> [...]
>    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
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |                       Vendor Identifier                       |
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>   |         Value Length          |           Data...
>
>   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
> [...]
>
>    Data: Length of data field, with a maximum size of 65535.
>
>    Data:   A variable length UTF-8 encoded string containing the
> firmware
>       identifier to be run on the WTP.
> </text>
>
> PatC
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