Cabletron Systems MMAC-5FNB, Networking Manual

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Overview of Networking
2-6 The Classification of Networks
Star
The star topology consists of a number of individual stations which communicate
through a common central point. Similar to the bus topology, star topology
network stations all share a single common interface. In place of a section of cable,
however, the common central point in star topology networks is often a
concentrator device, or “hub.” Each station connects to the hub through its own
physical interface, and many concentrators incorporate their own troubleshooting
and monitoring functions, allowing network managers to determine faulty
stations and remove them from the concentrator without disrupting the
remaining network. Unfortunately, a failure of the concentrator can lead to the
same disabling of the network that can occur in bus topologies.
Hybrid
Any network topology that incorporates elements of two or more of the
previously discussed topologies is a hybrid. For example, a tree that led down to a
series of buses (the ‘leaves’) would be a hybrid called a “tree of buses.” A ring
topology network with a series of concentrators acting as stations on the ring
would be called a “ring of stars.” As networks grow to encompass more and more
of a facility’s needs, topologies tend to hybridize in order to fulfill the individual
needs of workgroups and departments.
Network Technologies
While a topology describes the way a network is physically laid out, the network
technology defines how the devices that make up the network receive and
transmit information, deal with faults and problems, and control the actual
operation of the network. The technology of the network can be seen as the Rules
of Order that will be followed at the meeting. These concrete and binding rules
will determine who may speak, at what time, for how long, to whom, in what
language, and so on. The technology determines how problems are identified and
what methods may be used to resolve them. If arm wrestling is going to be
considered a valid means of breaking a deadlock between two sides in a vote, the
rules of order must clearly state that, as well as provide the rules for arm
wrestling.
There are several commonly-encountered technologies in networking. Among the
most common of the ‘client-server’ (non mainframe-terminals) technologies are
Ethernet, Token Ring, and the Fiber Distributed Data Interface (FDDI). These
network technologies and their operation are individually described in their own
chapters later in this document.