I was successful in porting FreeRTOS on Pxa303 processor. Now I am trying to use the uip code(FreeRTOS/common/ethernet/uip) provided in the FreeRTOS download(v7.3.0). Is it possible to do so? If not, are there any alternatives to perform ethernet level communication?
There are lots of alternatives for Ethernet.
If you just want UDP then you can try FreeRTOS+UDP (http://www.freertos.org/udp). There is also lwIP and numerous commercial alternatives. However, if you have an Ethernet port and low bandwidth requirements then there is no reason my you could not use uIP. In all cases you will have to port the stack to the Ethernet drivers.