Novell LINUX ENTERPRISE SERVER 10 SP2 - INSTALLATION AND ADMINISTRATION Installation Manual page 605

All built-in network cards and hotplug network cards (PCMCIA, USB, some PCI cards)
are detected and configured via hotplug. The system sees a network card in two different
ways: first as a physical device and second as an interface. The insertion or detection
of a device triggers a hotplug event. This hotplug event triggers the initialization of the
device with the script hwup. When the network card is initialized as a new network
interface, the kernel generates another hotplug event that triggers the setup of the inter-
face with ifup.
The kernel numbers interface names according to the temporal order of their registration.
The initialization sequence is decisive for the assignment of names. If one of several
network card fails, the numbering of all subsequently initialized cards is shifted. For
real hotpluggable cards, the order in which the devices are connected is what matters.
To achieve a flexible configuration, the configuration of the device (hardware) and the
interface has been separated and the mapping of configurations to devices and interfaces
is no longer managed on the basis of the interface names. The device configurations
are located in /etc/sysconfig/hardware/hwcfg-*. The interface configura-
tions are located in /etc/sysconfig/network/ifcfg-*. The names of the
configurations are assigned in such a way that they describe the devices and interfaces
with which they are associated. Because the former mapping of drivers to interface
name required static interface names, this mapping can no longer take place in /etc/
modprobe.conf. In the new concept, alias entries in this file would cause undesirable
side effects.
The configuration names—everything after hwcfg- or ifcfg-—can describe the
devices by means of the slot, a device-specific ID, or the interface name. For example,
the configuration name for a PCI card could be bus-pci-0000:02:01.0 (PCI
slot) or vpid-0x8086-0x1014-0x0549 (vendor and product ID). The name of
the associated interface could be bus-pci-0000:02:01.0 or
wlan-id-00:05:4e:42:31:7a (MAC address).
To assign a certain network configuration to any card of a certain type (of which only
one is inserted at a time) instead of a certain card, select less specific configuration
names. For example, bus-pcmcia would be used for all PCMCIA cards. On the
other hand, the names can be limited by a preceding interface type. For example,
wlan-bus-usb would be assigned to WLAN cards connected to a USB port.
The system always uses the configuration that best describes an interface or the device
providing the interface. The search for the most suitable configuration is handled by
Basic Networking 587