MacTCP: When It Initializes (2/95)


My office has a network of several Macintosh computers which run TCP/IP.

I am unable to consistently use Ping to find out the IP address of a particular Macintosh. If I start up one Macintosh without loading any software, then "ping" it from a second Macintosh, I will not get a response from the first Macintosh.

If I start up a Macintosh and run a TCP/IP application, like Gopher or NewsWatcher, then "ping" it from a second Macintosh, I will get a response from the first Macintosh and can obtain the IP address.

Why does this happen?

Traditionally, Apple's MacTCP driver was not initialized at startup. Instead, it loaded into memory and waited for the first MacTCP application to be launched before initializing. If you "ping" a Macintosh before it loads the MacTCP driver, you would not get a response.

MacTCP was designed so a user could change its parameters before launching a MacTCP application and not be required to reboot the Macintosh to use the new parameters.

With System 7.5, MacTCP does not initialize at startup as described above. Confusion might arise if the TCP/IP Connection for Macintosh product is installed which include SNMP agents. With SNMP present, the MacTCP driver is initialized at startup, and you can "ping" this Macintosh without other MacTCP applications being started.

Article Change History:
10 Feb 1995 - Added SNMP information and corrected System 7.5 information.
20 Dec 1994 - Noted that TCP is active at system start under System 7.5.

Support Information Services
Published Date: Feb 19, 2012