Ethernet Devices - .: Advanced Linux Networking :.

Wednesday, November 22, 2006

Ethernet Devices

Ethernet is the most common type of local network hardware in 2002, and it seems likely to retain that status for some time. (Wireless technologies, discussed shortly, are becoming popular in some environments, but they lag behind Ethernet and several other wired technologies in terms of speed.) From the point of view of an OS, the problem with Ethernet's popularity is that it's spawned literally hundreds, if not thousands, of specific Ethernet cards.

Fortunately, most Ethernet cards use one of just a few chipsets, so Linux can support the vast majority of Ethernet cards with about 60 drivers. These drivers are split across two submenus: the Ethernet (10 or 100 Mbit) and Ethernet (1000 Mbit) menus. By far the most drivers appear in the first menu, which as the name implies covers 10 and 100Mbps devices. (The most popular type of Ethernet in 2002 is 100Mbps, although 1000Mbps, or gigabit Ethernet, is gaining in popularity, and 10 gigabit Ethernet is being developed.)

In addition to three common Ethernet speeds, there are several different types of Ethernet cabling: coaxial (used only with some forms of 10Mbps Ethernet), twisted-pair (used by some types of 10Mbps, all types of 100Mbps, and some forms of gigabit Ethernet), and fiber-optic (used by some forms of gigabit Ethernet). Twisted-pair cabling supports distances of up to 100 meters (m) between devices (one of which is normally a central hub or switch), and fiber-optic cabling permits distances of up to 5 kilometers (km) between devices.

The organization of the 10 or 100Mbps driver menu is less than perfect. The menu begins with listings for several popular or once-popular devices from 3Com, SMC, Racal-Interlan, and a few other companies; proceeds with a grouping of Industry Standard Architecture (ISA) bus cards; continues with a grouping of Extended ISA (EISA), VESA Local Bus (VLB), and Peripheral Component Interconnect (PCI) cards; and concludes with a grouping of parallel-to-Ethernet adapters. You may need to search for your card in two or three places because of this organization.

A few Ethernet devices aren't activated through drivers in the Network Device Support menu or its submenus. Specifically, PC Card devices have their own drivers, as described shortly, and USB-to-Ethernet adapters are activated in the USB Support menu. To use a USB device, you must activate Support for USB; either UHCI Support or OHCI Support, depending upon which type of controller your motherboard uses; and an appropriate USB network driver option, such as USB ADMtek Pegasus-Based Ethernet Device Support.

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