Originally Posted By: RFC2131 section 4.1
The 'xid' field is used by the client to match incoming DHCP messages with pending requests. A DHCP client MUST choose 'xid's in such a way as to minimize the chance of using an 'xid' identical to one used by another client. For example, a client may choose a different, random initial 'xid' each time the client is rebooted

Unfortunately there is a bug in 3.00 alpha 11, Receiver Edition only, such that it doesn't do this -- it doesn't adequately randomise the xid on boot, so two Receiver Edition car-players on the same network both get the same xid, and thus any attempt by the DHCP server to assign an IP address to either one of them, is actioned by both, so both get the same IP address. Which is bad.

There are some workarounds:
  • Give static IP addresses to Receiver Edition car-players. Note that you can't switch a car-player from DHCP to static while Receiver Edition is on it; you need to temporarily reinstate the Standard Edition.
  • Partition the network somehow, so that broadcast packets don't reach both players; this is likely to need features that domestic switches don't have.
  • Whenever you're powering-on a Receiver Edition car-player, temporarily unplug the others from the network.
  • Using the serial port, Ctrl-C and restart the player on all the units (or, technically, all but one). When the player restarts, it will pick a new random xid and thenceforth[1] be capable of obtaining a unique address.

This bug was probably my fault, sorry frown

Peter

[1] Tanstaafl is right, using a word that the BBS hasn't seen before is harder than you'd think.