Re: [Sigtran] [SCTP] Minimum DATA Length possible

  Hi Michael
   
  Thanks for the response.
   
  
  
  Please clarify about the minimum value of L. 
  I think it should be 1. Which means that SCTP should not allow the zero byte data in the DATA chunk.
   
  Thanks & Regards,
  Ashwani Kathuria
  FSS India.
    
Michael Tuexen <[email protected]> wrote:

  Hi,

I'm sending the answer also to TSVWG, where the SCTP related things 
are discussed now...
draft-ietf-tsvwg-2960bis-02 should be changed to state

A DATA chunk with a user data field of length L will have Length set 
to (16 + L)
(indicating 16+L bytes).

I consider this editorial.

Best regards
Michael

On Jul 19, 2006, at 12:35 PM, ash kat wrote:

> Hi All
>
> What is the minimum possible length of user DATA which can be sent 
> by SCTP DATA chunk?
>
> ------------------------------
> 1. As per Section 3.3.1 of
> draft-ietf-tsvwg-2960bis-02
> ------------------------------
> " Length: 16 bits (unsigned integer)
> This field indicates the length of the DATA chunk in bytes from
> the beginning of the type field to the end of the user data 
> field
> excluding any padding. A DATA chunk with no user data field 
> will
> have Length set to 16 (indicating 16 bytes)."
>
> This indicate that user data of length zero can be sent by setting 
> "length" field in the DATA chunk to 16, which is the DATA chunk 
> header length. It means no user data in the DATA chunk.
>
> However as per
> ------------------------------
> Section 3.3.10.9 of
> draft-ietf-tsvwg-2960bis-02
> ------------------------------
>
> " 3.3.10.9. No User Data (9)
> Cause of error
> ---------------
> No User Data: This error cause is returned to the originator of a
> DATA chunk if a received DATA chunk has no user data. "
>
> So my point is that -
> If the length field in the DATA chunk Header will be of 16 bytes 
> then there will be no user data in the DATA chunk and when there 
> will be no user data in the DATA chunk the SCTP will returm error.
> So why it is allowed by SCTP to send DATA chunk with no user data 
> when it is not accepted by the peer SCTP.
>
> Thanks & Regards,
> --Ashwani Kathuria
> FSS India
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