Real-Time Considerations

The TCP/IP protocol stack for eRTOS has been configured such that IP fragmentation is enabled in the protocol stack by default, and payload sizes are limited to what can fit in a single Ethernet packet.

Optimized Buffer Sizes

The following table specifies the optimized buffer sizes that may be used in this release with send, sendto, recv, and recvfrom for an IP MTU of 1500 bytes:

Socket Type	Optimized Buffer Size (bytes)
SOCK_STREAM	1460
SOCK_DGRAM	1472

TCP/IP Default Parameters

• The default interval between TCP keep-alive probes is 75 seconds. The default maximum number of retransmissions without responses from the remote is 12.
• For a non-established connection, since there is no computed round trip time yet, the connection times out after 75 seconds or when 12x the default network round trip time has elapsed, whichever occurs first. Use socket option TCP_MAXRT to change the connection timeout for a socket.