I guess the ILO itself could be bad, or the NIC built into it. Seems strange but anything could happen.
Just to eliminate the chance that it's something with the switch or some other network interference, maybe you could try plugging the server and the ILO into some isolated switch with nothing else plugged in (just some desktop level 4-port thing), or if you have a crossover cable, go directly from ILO to the server port. Then do your troubleshooting like ping tests, etc.
If even that bare bones attempt to ping the IP address on the ILO fails, then I'd be more concerned about the NIC on the ILO being bad, and then open a case with HP support. Until then, in my mind it's more likely for a bad cable, switch, IP conflict, etc. to be the cause, but sounds like you've eliminated most of those already.
Just to eliminate the chance that it's something with the switch or some other network interference, maybe you could try plugging the server and the ILO into some isolated switch with nothing else plugged in (just some desktop level 4-port thing), or if you have a crossover cable, go directly from ILO to the server port. Then do your troubleshooting like ping tests, etc.
If even that bare bones attempt to ping the IP address on the ILO fails, then I'd be more concerned about the NIC on the ILO being bad, and then open a case with HP support. Until then, in my mind it's more likely for a bad cable, switch, IP conflict, etc. to be the cause, but sounds like you've eliminated most of those already.
