How to get consistent names for USB ports...

[Rick Thomas <rbthomas@pobox.com>]

Given a machine that provides serial consoles for several other machines via usb-serial connections:

If the console server is rebooted the usb ports come up in a random order and it's impossible to tell which /dev/ttyUSB* device points to which client machine.

Is there some systemd/udev/whatever way to force repeatable naming for the /dev/ttyUSB* devices?  I'd be happy if I could get something like /dev/ttyUSB<pci-path> where <pci-path> is found by doing something like
    
> :~$ lspci | grep -i usb
> 00:1d.0 USB controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #1 (rev 03)
> 00:1d.1 USB controller: Intel Corporation 82801DB/DBL/DBM (ICH4/ICH4-L/ICH4-M) USB UHCI Controller #2 (rev 03)
> 00:1d.7 USB controller: Intel Corporation 82801DB/DBM (ICH4/ICH4-M) USB2 EHCI Controller (rev 03)
> :~$

Thanks for any help!
Rick

PS:  A pointer to some place that documents the correlation between things that show up under /sys/devices/ and attributes I can use to identify individual devices in a udev ".rules" file would be greatly appreciated!