linux - Server sends TCP packets without receiving ACK from client -


i have ios chat app talking java xmpp chat server via tcp socket. server machine(machine 1) running redhat linux. moved chat server linux machine(machine 2) similar configuration except had more processors. way server works once receives particular data client(data1) sends 2 xml packets client(data2 , data3). looking @ packets in wireshark, see below consistent behavior in machine1. 

ios app          java server   syn      -->            <--   syn,ack   ack      --> tcp handshake ends here     data1     -->              <--    ack            <--    data2   ack      -->           <--    data3   ack      -->

but in machine2 works below.(not of time)

ios app          java server   syn      -->            <--   syn,ack   ack      --> tcp handshake ends here    data1     -->              <--    ack            <--    data2           <--    data3   ack      -->   ack      -->

as seen above ack 2 packets sent @ once client. why there such change in behavior. since app same in both cases have made server send data 3 without receiving ack data2. have verified of tcp socket related properties in these machines send buffer , tco_nodelay etc. these looks same. can if need behavior in machine1.

i ve noticed behavior seen when connect through wifi.


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