NOTE: This Technical Q&A has been retired. Please see the Technical Q&As page for current documentation.

Technical Q&A NW08
MacTCP


Q: We use two versions of MacTCP in-house: 2.0.4 and 2.0.6. We are experiencing an annoying bug in both versions -- IP Pings do not work properly on a class- C address when the subnet mask is set to 255.255.255.192. All other packets work, and we can also make IP Pings work by changing the subnet mask to 255.255.255.128, but we can't operate with the subnet mask at this setting.

A: The problem you're observing may be caused by a known bug in MacTCP, which incorrectly assumes that certain host addresses are broadcast addresses, based on the address class and the subnet mask. To determine if this is the same bug, monitor the line to see if there's an ICMP redirect being sent. Since ICMP does not respond to a broadcast source address, the absence of redirects would indicate this is being caused by the same bug.

[May 01 1995]


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