The CME requires that TCP packets contain only complete SBE messages. Otherwise, fragmented messages go to additional processing, leading to latency degradation, and finally, the CME can terminate the session with the
ExceededMaxNoOfSplitMsgsQueued (29) error code. To reduce the probability of SBE message fragmentation across multiple TCP packets, one can apply the following options:
maxPacketSizeparameter. This parameter represents the maximum number of bytes written to the socket's send buffer together. The reduction of this value reduces the probability of fragmentation. This parameter's default value equals the CME's MTU (
1420) and should work in most cases. However, it makes sense to try different values to find an optimal one. Additionally, please note that the OnixS::CME::iLink3::Session::messageGrouping setting contradicts the usage of batch sending, so you should not use it together.
1420) and make sure that there are no routers on the way with different MTU sizes. Usually, MSS is set automatically based on minimum MTU and MSS announced by hosts during the TCP three-way handshake. But, if necessary, one can configure it at the system level via the network interface.
The fragmentation can appear on the TCP level due to the TCP protocol's nature (stream protocol) since it is unaware of the message size and sends just bytes. Therefore, in case of any overflow issues on the TCP connection, the TCP level can send a part of the outgoing message.