Computers on a network communicate in agreed-upon ways called
``protocols''.
Protocols dictate which signals computers
use across cables, how they tell one another that they have
received information, and how they exchange information.
Protocols are more accurately termed protocol
``stacks'' or protocol
``suites''. These terms reflect the fact
that the communications functions are complex and are usually
divided into independent layers or levels.
A stack is a collection of protocol layers which implement
network communication.
The protocol associated with each layer communicates only with the
layers immediately above and below it, and assumes the support
of underlying layers.
Lower layers are closer to the hardware;
higher layers are closer to the user. The number of layers and
tasks that each layer performs depends on which stack you
are using.
Although there are many different types of networks, they fall
into two general categories:
A LAN (Local Area Network)
connects computers that are in the same office
or in adjacent buildings. All the computers on a LAN are
connected to a single cable or hub, unless they use a gateway or bridge.
A computer on a LAN can communicate directly with
any other computer on that LAN.
A WAN (Wide Area Network)
connects computers over long distances using serial
lines and sometimes satellite connections. Computers on a
WAN can be several hundred feet apart or on the
other side of the world from each other.
Sometimes messages must go through additional computers
(called ``gateways'', ``routers'', or ``bridges'')
to reach their destination.
Because the SCO network adapter drivers provide a standard
way for networking hardware and software to communicate,
you can easily configure different protocol stacks for use
on the same machine.
The SCO protocol stacks that you can use with the SCO
network adapter drivers for LAN communication include:
SCO TCP/IP (provided with some SCO OpenServer products)
SCO IPX/SPX® (provided with some SCO OpenServer products)
Microsoft® NetBEUI (provided with
Microsoft LAN Manager for SCO Systems)
other SCO-compatible transport stacks
The SCO TCP/IP stack can also be used with these
WAN communication drivers: