Servers:
A server is a system (software and suitable computer hardware) that responds to requests across a computer network to provide, or help to provide, a network service.
Device Servers
Print Servers
Multiport Device Servers
Access Servers
Network Time Servers
Device Servers:
A device server is a specialized, network-based hardware device used to perform a
single or specialized set of server functions.
It is characterized by a minimal operating architecture that requires
no per seat network operating system license, and client access that is independent of any operating system or proprietary protocol.
In addition the device server is a
"closed box," delivering extreme ease of installation, minimal maintenance,
and can be managed by the client remotely via a Web browser.
Print Servers
Print servers allow printers to be shared by other users on the network.
Supporting either
parallel and/or serial interfaces, a print server accepts print jobs from any person on the network using supported protocols and manages those jobs on each appropriate printer.
It do
not contain a large amount of memory and printers simply store information in a queue.
When the desired printer becomes available, they allow the host to transmit the data to the appropriate printer port on the server.
Multiport Device Servers
Devices that are attached to a network through a multiport device server can be
shared between terminals and hosts at both the local site and throughout the network.
A single terminal may be connected to several hosts at the same time (in multiple concurrent sessions), and can switch between them.
Multiport device servers are also used to network devices that have only serial outputs.
Access Servers
While Ethernet is limited to a geographic area, remote users such as traveling sales people need access to networkbased resources.
Remote LAN access, or remote access, is a popular way to provide this connectivity.
Access servers use telephone services to link a user or office with an office network.
Dial-up remote access solutions such as ISDN or asynchronous dial introduce more flexibility.
Dial-up remote access offers both the remote office and the
remote user the economy and flexibility of
"pay as you go" telephone services.
ISDN is a special telephone service that offers three channels,
two 64 Kbps "B" channels for user data and a
"D" channel for setting up the connection.
With ISDN, the
B channels can be combined for double bandwidth or separated for different applications or users.
With asynchronous remote access, regular telephone lines are combined with modems and remote access servers to allow users and networks to dial anywhere in the world and have data access.
For the remote PC user, one can connect from any available telephone jack
(RJ45), including those in a hotel rooms or
on most airplanes.
Network Time Servers
A network time server is a server
specialized in the handling of timing information from sources such as satellites or
radio broadcasts and is capable of providing this timing data to its attached network.
Specialized protocols such as NTP or udp/time allow a time server to communicate to other network nodes ensuring that activities that must be coordinated according to their time of execution are synchronized correctly.
GPS satellites are one source of information that can allow global installations to achieve constant timing.
