I Have downloaded the ethernet code from code bundle.zip it is working properly but iam unable to trace the IP address of the board.So please any one help me to identify the IP address of the evaluation board of LPC2378
Have you read this document: http://www.keil.com/mcb2300/mcb2300_quickstart.pdf
Do you have a DHCP server? If you have, then you should be able to check in the DHCP server what IP the board got.
If you haven't, then the document suggests how to set a fixed IP in the board.
There are also other methods to find a board, if you know the hardware addresss (MAC) of the board. Something for you to consider googling for.