360 Systems DigiCart/E - Manual (Page 18)

16
• Installing an Ethernet Audio Network
Network Interface Cards
Network interface cards, commonly referred to as NICs, are used to connect a PC to a network. The NIC
provides a physical connection between the networking cable and the computer's internal bus. Different
computers have different bus architectures; PCI bus master slots are most commonly found on 486/Pentium
PCs. NICs come in three basic varieties: 8-bit, 16-bit, and 32-bit. The larger the number of bits that can be
transferred to the NIC, the faster the NIC can transfer data to the network cable.
Many NIC adapters comply with Plug-n-Play specifications. On these systems, NICs are automatically
configured without user intervention, while on non-Plug-n-Play systems, configuration is done manually
through a setup program and/or DIP switches.
Cards are available to support almost all networking standards, including the latest Gigabit Ethernet
environment. Some switches have the capability to connect to the server with a Gigabit connection while
connecting to clients with 100BaseT Fast Ethernet.
Fast Ethernet NICs are often 10/100 capable, and will automatically set to the appropriate speed.
Teamed networking is another option, where a dedicated connection of two NICs to a single switch allows
data transfer at twice the speed, with failover to a single NIC in the event of a NIC failure. This is also
referred to as Load Balancing/Fault Tolerant operation.
Hubs/Repeaters
A Hub is a generic term that is used for a device that acts as a central gathering point for LAN cable
segments. The most basic types of hubs are devices that simply connect cables together and regenerate data
thereby passing data from one device to another. Any incoming signal is repeated out of all ports. These types
of hubs are referred to as concentrators or repeaters.
In larger physical designs, signal quality begins to deteriorate as segments exceed their maximum length.
Hubs used as repeaters can provide the signal amplification required to allow a segment to be extended a
greater distance.
A multi-port hub allows several point-to-point segments to be joined into one network. One end of each
point-to-point link is attached to the hub and the other is attached to the computer or DigiCart/E recorder.
Hubs are not used in this capacity in the Ethernet Audio Network as Switches (described below) offer
superior performance and do not cost significantly more.
A network of hubs/repeaters is termed a "shared Ethernet," meaning that all members of the network are
contending for transmission of data onto a single network (collision domain). This means that individual
members of a shared network will get a percentage of the available network bandwidth.
There are also hubs that provide additional functionality, including bridges which connect network segments
and routers which connect different types of both local and wide area networks. The functionality of these
types of hubs are highly specialized and closely related to the type of network they are used in. They are
typically installed in very large, complex networks.
Ethernet Switches
Ethernet switches are an expansion of the hub concept, except that they analyze traffic from the server and
only retransmit messages to the port that the recipient is connected to. They have two basic architectures: cut-
through and store-and-forward. In the past, cut-through switches were faster because they examined the
packet destination address only before forwarding it on to its destination segment. A store-and-forward
switch, on the other hand, accepts and analyzes the entire packet before forwarding it to its destination.