Tuesday 17 November 2009

Apple Time Capsule steals IP addresses, but that's OK really

Found one minor oddity with my new Apple Time Capsule.  If you have an ARP monitoring program running (such as arpwatch, or any FreeBSD server) you may notice that the Time Capsule's MAC address periodically appears to steal the IP address of one or more Mac Snow Leopard clients.  Odd as it may seem, this is by design.

The Time Capsule runs a Sleep Proxy service, part of the multicast DNS (mDNS) service involved in Apple's Bonjour protocol, which helps Macs to find each other.  When one of your Macs goes to sleep, the Sleep Proxy occupies its IP address, like keeping someone's chair warm for them.  It doesn't appear to cause any problems here, and presumably it all helps to allow sleeping Mac machines to continue to offer file sharing services, if you've allowed that in your Energy Saver preferences.

It's possibly worth sticking the Time Capsule on AppleCare warranty cover if you can, as there have been reports of PSU capacitor failures after 18 months, and it's hard to know whether that issue has been fixed yet.  AppleCare doesn't cover Time Capsule by itself, but you can add it free of charge to the AppleCare policy of a covered Mac.

Generally, the Apple Time Capsule seems like an impressive device, thoughtfully designed as usual.  It's small, fast, quiet, and frugal with power (the hard drive spins down when idle).   And of course it's very shiny, though as a backup device, you probably want to hide it somewhere so that if someone steals your computers, they don't also steal your backup device.

Offering a 4-port Gigabit Ethernet switch, a dual-band WiFi access point (including an optional guest network), and offering optional PPPoE and firewalling, it's very flexible.  You can use it for straight NAS file sharing and/or as a Time Machine (managed backups) server for a network of Apple Mac machines running Leopard or later.  Time Machine really works well, and you can go into the backups from another Mac if you know the password.  All in all, a nice bit of design.

Update (Jan 2010).  The SMB/CIFS server in the Time Capsule seems a bit buggy.  You can mount shares from Ubuntu 9.10 Linux using "mount -t smbfs //server/share /media/fred" but no files show up.  Apparently this has been reported, so maybe a future update will fix it.

Update (April 2010).  Following a firmware update (easily installed via the Mac management app), the SMB service now seems to work from Ubuntu Linux 9.10 and FreeBSD Unix 7.2.   I haven't used it for serious production yet but it looks OK, with the caveat that your first mount request sometimes times out and fails if the Time Capsule drive had been idle for long enough to spin down.  I guess energy saving is all about compromises, and the system will run cooler and last longer if it spins down.

Update (July 2010).  The Samba server in the current firmware (7.5.1) still seems very buggy.  Tried a mixture of clients (Windows XP, Windows 7, FreeBSD Samba, MAC Samba) will consistently poor results.  So whilst I can recommend the Time Capsule for Apple clients, I can't recommend it for Windows clients.

Update (December 2010).  I've just installed firmware 7.5.2 on the Time Capsule, and also on my Airport Express.  I expect this will finally cure the Samba problems, as I successfully tested a pre-release of 7.5.2.  Other enhancements appear to include improved IPV6 support (also for in the Airport Express).

1 comment:

  1. Thanks for this entry Martin ! I've been suspecting several different things when I looked on Wireshark the duplicate IP address warning ! All good ! Cheers.


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