Informational message DTCARP049I on Release 5.4.0

The following new informational message (DTCARP049I) was added to release 5.4.0 to indicate that TCP/IP received an ARP broadcast packet which could indicate that our IP address is already in use on the LAN:

 ...
 DTCARP049I An ARP packet was received on link linkname
            with our IP address ipaddr as the source
            address.  Possible configuration error.
 ...

This message is displayed because TCP/IP received an ARP packet whose source IP address matched the TCP/IP home address for the link that the packet came in on. Although this can indicate that someone else on the LAN thinks that it owns this IP address, this message will also be displayed if z/VM TCP/IP receives its own broadcast ARP request for its own IP address.

If you have OSA devices that are used by z/VM TCP/IP in Passthru mode (meaning they have been defined to TCP/IP as LCS devices in the TCP/IP configuration file), then TCP/IP will always issue a gratuitous ARP during device initialization for these devices. That may result in the DTCARP049I message being displayed when TCP/IP receives the gratuitous ARP request on the network. This message can be ignored for that case.