Ethernet NICs

Modern Ethernet NICs are cheap and available in many different flavors. I strongly recommend not relying on the cheapest NICs for production applications, because of the limitations of the chipsets used. A sufficient onboard buffer is also essential for TCP performance.

Note that similar to Cisco router interfaces, the adapters need configuration in terms of speed, duplex settings, and maximum transfer unit (MTU). All the necessary parameters can be set with the UNIX ifconfig command, available on virtually all UNIX platforms.

On Linux systems, the ifconfig tool has evolved into the ip utility (which is part of the iproute2 package). Consult the ifconfig manual pages and the iproute2-HOWTO for details. We will also use this utility for alias and VLAN configuration. I am well aware that iproute2 has superseded many Linux tools such as ifconfig and route, but these are available on all UNIX systems (whereas iproute2 is specific to Linux only).

Autonegotiation of speed and duplex settings has not proven reliable under many circumstances (IEEE 802.3U). The MAC address of some adapters can be changed with a user-space utility provided either by the vendor or the open-source community. This is not possible for all types of NICs. In the worst case, you can use a DOS boot disk with the appropriate utilities. Most vendors also provide firmware upgrades for their products.

I strongly suggest reading the hardware compatibility notes of your OS releases to ensure proper operation of hardware VLAN support, multicasting, and special features. I also recommend using the same brand of adapters throughout your topology. This makes replacements and driver deployment much easier and does not require kernel recompilation.