This paper describes the uIP TCP/IP stack. The uIP TCPAP stack is an extremely small implementation of the TCP/IP protocol suite. We describe two small and portable TCP/IP implementations fulfilling the requirements needed for full host-to-host interoperability. Our TCP/IP implementations do not sacrifice any of TCP's mechanisms such as urgent data or congestion control. They support IP fragment reassembly and the number of multiple simultaneous connections is limited only by the available RAM. Despite being small and simple, our implementations do not require their peers to have complex, full-size stacks, but can communicate with peers running a similarly light-weight stack. In this paper I have constructed the input with retransmission, output processing units of a TCP/IP stack using verilog code and its performance is analyzed and synthesized using xilinx. © EuroJournals Publishing, Inc. 2008. © 2014 Elsevier B.V., All rights reserved.