The first response will be an ARP reply; no packet will be transmitted (apart from broadcasts) to any host without the sender knowing the ethernet MAC address of the recipient first. To find this, the sender does an ARP broadcast of a "who is 1.2.3.4?". The reply is then cached for later use.

If the ARP request is being received by the empeg's kernel, it'll be sending an ARP reply; ISTR it should be the same length as the request though.

To appear in emplode requires a TCP connection and quite a bit of network traffic - identifying player type, version, etc. You'd notice this! I'd try a simple ping first, which should be an ARP request, an ARP response, an ICMP request and and ICMP response.

Hugo