Re: [SCTP] Minimum DATA Length possible

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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