Re: [multipathtcp] Question on Data Sequence Mapping

[Rao Shoaib <[e-mail]>]

I think I have answered my questions. As long as the subflow-sequence 
number and Data sequence number in the DSS option are unchanged  things 
will work.

Rao



On 05/15/2017 05:39 PM, Rao Shoaib wrote:
> Hi,
>
> Section 3.3.1 of RFC 6824 says
>
> The data sequence mapping specifies a mapping from subflow sequence 
> space to data sequence space. This is expressed in terms of starting 
> sequence numbers for the subflow and the data level, and a length of 
> bytes for which this mapping is valid.
>
> <...>
>
> A mapping is fixed, in that the subflow sequence number is bound to 
> the data sequence number after the mapping has been processed. A 
> sender MUST NOT change this mapping after it has been declared;
>
> Does it mean that I can not map the data sequence to another (higher) 
> TCP sequence number on the same flow.
>
> The reason I am asking this is that if this is allowed  TCP and MPTCP 
> processing can be separated on the recv side. For example, TCP could 
> accept the packet but MPTCP could reject it. Since data level ack 
> would not be sent the peer would retransmit, possibly using the same 
> flow but with a different mapping so that TCP would accept the packet.
>
> Is this legal to do and if not than why ?
>
> Regards,
>
> Rao
>
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