Computers on a network communicate in agreed-upon ways called
Protocols dictate which signals computers
use across cables or radio waves,
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
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
Although there are many different types of networks, they fall
into two general categories:
Because the SCO OpenServer 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 OpenServer protocol stacks that you can use with the SCO OpenServer
network adapter drivers for LAN communication include:
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.
The SCO TCP/IP stack can also be used with these
WAN communication drivers:
SCO TCP/IP (provided with some SCO OpenServer products)
SCO IPX/SPX® (provided with some SCO OpenServer products)
Microsoft® NetBEUI (provided with SCO Advanced File and Print Server)
other SCO OpenServer-compatible transport stacks
PPP (Point-to-Point Protocol)
SLIP (Serial Line Internet Protocol)
For an overview of SCO OpenServer protocol stack support, see
``Networking protocol stacks''.
Network drivers from other vendors
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003