Hi,
1) I think the evaluation board ports do the crossover function, so if you are connecting directly to a PC, then use a straight cable. I guess this is also consistent with your previous mail in which you said that when you used a straight cable, the led lights came up on both the IXP port and the pc network card.
I would advise you to forget the hub for now, just connect a straight cable between your src and dst linux pc's and IXP ports and see if the ipmm app works for you. Look at the rcv microcode source code and the corresponding debug output on the console to see how far packet reception works.
If you get that working, you can always figure out the exact hardware setup (whether through switch/hub etc) later.
I started off with just that. Two PCs connected to two IXP1200 ports using straight-thru cables. The yellow LEDs on the IXP1200 ports blink, the LINK LED on the IXP1200 (one of those eight LEDs in the middle) does not come on. When I run 'mii-diag' on the linux PCs, the tool says that the autonegotiated speed is 100baseT Full-Duplex. The tool also says that the link is not established. The LEDs on the ethernet card of the PCs also blink (and not remain solid as is the normal case). When I run ping from one of the PCs, there is no reply, there is no indication in the IXP1200's serial port of packets being received and the no. of carrier errors in the PC's interface increases. Then I connected an IXP1200 port to a 10/100Mbps hub using a crossover cable. Now the three LEDs on the IXP1200 (yellow and green LEDs on the port (which I think are FDX and Activity) and one of the eight LEDs in the middle) blink and the two LEDs on the hub port also blink (which I think is abnormal). Then I replaced the 10/100 Mbps hub with a 10Mbps only hub. Now the LINK LED (one of the eight LEDs in the middle) comes on. This is the only case when it came on (other than forcing the ethernet card on the linux PCs to 10 Mbps in step 1). Then I connected the PCs to the same hub and now the IPmm application works. I do not understand why the IXP1200 ports cannot work at 100 Mbps and without a hub in between. Magesh