[WinMac] UNSOLVED MYSTERIES: DHCP Dropout
Daniel L. Schwartz(expresso[at]snip.net)
<http://www.macwindows.com/NTunsolv.html#DHCPdropout>, and I have a few solutions below.
>>>>
DHCP Dropout DESCRIPTION: Macs connected to the NT DHCP server suddenly loose their IP identity. (The MacWindows Server Tips page has some related information regarding BOOTP.) Here are some description of the problem from readers, and some hints as well: Sept. 16, 1998 Scott Fraze "The person will be cruising along just fine then suddenly loose TCP/IP connectivity. The AppleTalk stuff will still work, so they can see the NT-based shares just fine, but any attempts to surf the web or retrieve email fail. This has happened on several different G3's. "The machines are running OS 8.1, with Farallon 100-base-T (PN996-TX) PCI NICs in them. When the machines refuse to browse the web, if you bring up the TCP/IP control panel .... the machine is set to DHCP lookup. Multiple reboots do not solve the problem, the only way I've been able to bring the machines back up is to switch over to the built-in 10 MB/sec ethernet for a day, then switch back." Sept. 19, 1998 Gary Swick I'm Gary Swick, the Systems Editor for The News Journal in Wilmington, Delaware. We're a Gannett newspaper with 160 Macs, 220 PCs and 20 NT servers. The NT boxes are both 3.51 and 4. We run both 10BaseT and 100BaseT, and also have DAVE on a few machines. A couple of things I'd like to comment on: Using DHCP, we've had no problems with the Macs connecting when the DHCP server was on NT 4.0. We learned from Gannett's corporate operations center that DHCP has problems with NT 3.51, where it won't release IP addresses correctly. We'd get an error message like "A device with hardware address 00 00 94 7C AC 68 is using the IP address 10.1.11.164." Moving DHCP to NT 4.0 solved this problem. Also, the older Farallon cards can't handle full-duplex at 100BaseT, so IP connections won't be completed. Several of our Macintosh applications use TCP/IP to connect to servers, and if we have a problem with one connecting, we've found that pinging a known address will force DHCP to give that Macintosh an IP address. Services For Macintosh is slow, much slower than Windows 95 to NT, or even DAVE to NT. If Microsoft doesn't fix the problems in the next Service Pack, we'll switch to DAVE and a total IP network. Sept. 17, 1998 John Wolf There are a couple things he needs to try: Has he set the Macs TCP/IP control panel to "Advanced" and then used the option button to set TCP/IP to "Always Load"? This is important when using DHCP. If you don't set it to always load the TCP/IP stack, the Mac will cancel its lease after about 30 seconds of inactivity, and try and grab a new lease the next time TCP/IP is required. This just waists time, and may likely be the culprit. You may want to pass along a similar problem that we have here and the solution. On occasion a Mac will lose IP connectivity. If you look in the TCP/IP control panel, it still shows an IP address as always, but only AppleTalk works. It turns out that out network switch caches the Ethernet address, IP address and AppleTalk address of each node on the network. Sometimes it just fritzes out and decides not to forward IP packets to that Mac again. The solution is to telnet into the switch and clear the cache. <<<<
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