Re: [lwip-users] handling packets with equal sequence number

[Thomas Richter (TCD - DE/Dresden)]

Hi Kieran,

based on your answers is it right, that each byte in the data stream
occurs only once?
Even if a blocking state (equals Receive Not Ready at one side off wire)
and after then a retransmission occurs then the IP stack gives me (in
lwIP the callback function registered with tcp_recv()) each byte in data
stream only once?

In my example:

For instance the following frames are sent by :
- Frame 1 with some data of length 100 bytes, e.g. AABBCCDD..YYZZ
- Frame 2 consists of data of Frame 1 (100 bytes) + new data (50 bytes)
= 150 bytes, e.g. AABBCCDD..YYZZ001122..

The data of frame 1 will be received and of the frame 2 the data "frame
2 - frame 1" (here: "001122...") is given?

Sorry, if I have some understanding problems with this topic.

Thanks for all.

Best regards
Thomas


Am 30.03.2011 17:08, schrieb Kieran Mansley:
> On 30 Mar 2011, at 15:59, Thomas Richter (TCD - DE/Dresden) wrote:
>
>> Ok the data stream is correctly ordered. But how my application can the
>> information that the frames have the same sequence number?
> It won't need to.  lwIP will give it each byte exactly once, even if there 
> are duplicates on the wire.
>
>> Is there any possibility to get this information in lwIP?
> No.
>
>> Or have I analyze all my data to prevent double data?
> No.  The whole point of TCP is that it does this for your application.
>
> Kieran
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>
>

-- 
Mit freundlichen Grüßen / Kind regards

Thomas Richter
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