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You can simply ask Mac OS X to request another DHCP address when it comes up with Self-assigned IP. The Self-assigned IP address is actually in a range that is
by calloc 15y ago
You can simply ask Mac OS X to request another DHCP address when it comes up with Self-assigned IP. The Self-assigned IP address is actually in a range that is specified in the RFC 3927 [1]. This is mainly done so that if it joins a network without a DHCP server it can still communicate with other hosts on the network, just not the outside.
Also, in my experience Apple's DHCP agent will re-request an IP address after having assigned itself a self-assigned IP address. This generally takes about a minute or so, in that time the DHCP server can then reply once again. I've never had issues with this at all.
[1] http://www.ietf.org/rfc/rfc3927.txt http://www.ietf.org/rfc/rfc3927.txt
- deleted 15y ago[deleted]
- ajross 15y agoWhen it joins a what now? There are no wifi networks without DHCP servers. At least there are none in the consumer electronics market to which zeroconf is targetted. Zeroconf is a historical mistake. It shouldn't be there any more; it does far more harm than good.
- wmf 15y agoI think the use case was ad-hoc wi-fi networks. But getting back to the original complaint, if not for zeroconf you'd have no IP address at all; I don't see how that's any better.
- redthrowaway 15y agoThe problem is that OSX's behaviour (and not, notably, Windows') is to try once then fail as a "good enough" solution. It may indeed keep trying, but it's a problem that Windows never runs into in the first place. I'll admit to having only a rudimentary knowledge of how wireless networks work, but it's better than 99% of users and I find OSX frustrating (in this regard). At the end of the day, the user doesn't care whether the router manufacturer isn't following the spec, or whether Apple's implementation is buggy. The simple fact is that it works on Windows but not on OSX, and that's a failure on Apple's part.
- calloc 15y agoThis behaviour is the same on Windows. If Windows doesn't receive a DHCP address is will assign one in the self-assigned range first. After about a minute or so it too will re-request an IP address from the DHCP server and if it receives one it will assign that to the interface. What Windows does do wrong is that it then also drops the self-assigned IP address which may already be in use for communication, this can cause issues with other hosts that are communicating with it over zeroconf.
- mikeash 15y agoCreate a WiFi network on one Mac, join it with another Mac. No DHCP server is running, but thanks to the self-assigned IP fallback, the two Macs can still communicate with each other. This can be tremendously useful.
- calloc 15y agoThis depends off course on how you create the wireless network. If you create one by routing another network such as using Network Sharing a DHCP server is set up since now it acts as a router. You are correct for Ad-Hoc networks.
- adavies42 15y agoThis dates back to long before wifi was widely available--the original use case was ad-hoc wired networks, where people with backgrounds in old-school AppleTalk-based Mac networking were expecting any two Macs with a cable between them to be able to talk to each other with no supporting infrastructure.
- lucian1900 15y agoI've had numerous issues on my university's network with the DHCP lease. They have a stupid VPN setup, so that may have helped fuck it up.