Iva, David,
First of all, many many thanks for your replies. I tried to run this demo with both openSDA (PEMicro) and JTAG (using SEGGER, so I used the DB-9 connector on the TWR-SER2 card), but with both failed. I checked all jumpers suggested by Iva and David. Everything ok on TWR-K65 (except J32, which I removed it just when I ran the test using JTAG with SEGGER). But I did NOT find the following jumpers on TWR-SER2 (they are supposed to be of TWR-SER, considering Iva's email):
• TWR-SER - CLK_SEL 3-4
• TWR-SER - CLKIN-SEL 2-3 (processor clock is taken from PHY)
• TWR-SER - ETH-CONFIG J12 9-10 to select RMII communication mode
In terms of PC configuration, please see the following picture (David, I can't leave gateway IP 0. You meant empty as in the pic here attached, correct?). I connected the TWR-SER2 directly to my PC. The latter, was once connected to the company's LAN and, during another test, just to the TWR-SER2.

So, looking at David and Iva posts, I notice TWR-SER has been used, while I'm using TWR-SER2. Can this be the difference?
BUT I FOUND A "WEIRD" WORK-AROUND THAT MADE IT WORK!
But this is not supposed to be the right procedure provided by Freescale to run this demo. So, somewhere, there is something wrong. This is the procedure I followed in both released and debug modes:
a) Connect the ethernet cable to ETH port A of TWR-SER2 and run the demo. It does NOT reply to a "ping 192.168.2.102" command. I also tried lots of time to reset the board.
b) Connect the ethernet cable to ETH port B of TWR-SER2 and run the demo. It does NOT reply to a "ping 192.168.2.102" command. I also tried lots of time to reset the board.
c) Reconnect the ethernet cable to ETH port A of TWR-SER2 and run the demo. After different resets of the board (at the beginning it didn't work), it replies to a "ping 192.168.2.102" command. From now on it's working.
Any explanation about that?
Thanks so much for all your help, I really appreciate it.