RL-TCPnet TCP reception problem

Ok

My old platform (with 8 bits Atmel CPU ) receive the packet in one time.

So why with this configuration,
#define TCP_MTU 1460 /* TCP default max. transfer unit */
#define TCP_DEF_MSS 1460 /* TCP default max. segment size option */
I receive always first 536 bytes.
Why 2 packets, It is bad for the performance I think

Ok

My old platform (with 8 bits Atmel CPU ) receive the packet in one time.

So why with this configuration,
#define TCP_MTU 1460 /* TCP default max. transfer unit */
#define TCP_DEF_MSS 1460 /* TCP default max. segment size option */
I receive always first 536 bytes.
Why 2 packets, It is bad for the performance I think

Check the function: tcp_max_dsize

... that the PC actually sent it as a single packet?

Yes
I sent only one packet but If I check with an sniffer I see the 2 packets.

tcp_max_dsize return 1460

How do you send it?
How do you know that it is actually sent as just one single packet?

"I check with an sniffer I see the 2 packets."

What "sniffer"?
Where are you "sniffing"?

Are there any other devices (routers, etc) between the PC and your ARM target?

How do you send it?

With the Win32 Socket send function :

int send(
  __in  SOCKET s,
  __in  const char *buf,
  __in  int len,
  __in  int flags
);

What "sniffer"?
Where are you "sniffing"?

It is the Microsoft Network Monitor program running on the PC which send the TCP packet.

Are there any other devices (routers, etc) between the PC and your ARM target?

All are connected to an switch but I try with the pc connected directly to the ARM target and it is the same thing

And does that give you any guarantee that it will send only a single packet?

"It is the Microsoft Network Monitor program running on the PC which send the TCP packet."

Well, if that tells you that there were two packets, then I guess you'd better believe it!

I know there is 2 packets and I want to know why.

If I send an packet smaller than the Maximum Transfer Unit (MTU), normally I will be able to receive it in one packet.

Maybe there is something to configure in the TCP opening connection, but I find nothing

It's the PC that decided to send two packets, so this is a PC question - it has nothing to do with Keil or their libraries!

I don't think so, because with the same PC, same application, same send socket function, but Atmel 8 bits target, Only one packet is sent

"same PC, same application, same send socket function, but Atmel 8 bits target, Only one packet is sent"

Are you sure that only 1 packet is sent?

What does your sniffer say?

My sniffer says one packet with 1022 bytes

What version of RL-ARM are you using?

The latest (4.10) has a 'solved problem' stating:

Added: MSS option (maximum segment size) to SYN packet for outgoing TCP connections. Because this option was missing, PC used reduced segment size of 536 bytes in communication.

Go here for source of info:

http://www.keil.com/update/whatsnew.asp?p=RL-ARM&v=4.10

Aaaaah it seems be the problem.....thank you

Is it possible to have the patch to solve the problem ?

If you have an active license, then you can get the update via:

www.keil.com/.../4.10