Description
5-5
Ethernet
The job of a transceiver in chassis design is to provide a connection to a network
that has already been established. Once a network has an established repeater in
the chassis, the addition of chassis modules which allow Ethernet workstations to
connect to the chassis may begin. These connectivity modules may be added to
the chassis until the chassis has no more available module slots remaining or until
the single network has reached the theoretical maximum population for an
Ethernet network, 1,024 stations.
Cabletron Systems connectivity modules are denoted by the suffix MIM, which
stands for Media Interface Module. The MIM provides an interface between the
backplane of the chassis and the external media for which it is intended. The
name of each individual MIM also identifies the external media to which it is
intended to connect. For example, MIMs which are intended to provide a
backplane connection for Unshielded Twisted Pair media are called TPMIMs, for
T
wisted Pair Media Interface Module. Those MIMs which provide connections to
fiber optic cabling are called FOMIMs, for Fiber Optic Media Interface Module.
The Example configurations section of this document provides detailed tables
listing the product names, media connectivity, and connector style of each MIM.
Rules and Regulations
Ethernet has a large number of rules associated with it. There are the distance
rules, for one, and the maximum population, for another. The maximum
population (number of devices) on a single Ethernet network is 1,024. Usually,
long before we reach 1,024 devices, we have moved to a new Ethernet network.
How we do that is covered later.
Another maximum associated with Ethernet deals with the maximum number of
devices per segment of cabling. The original Ethernet media, thick and thin
coaxial cable, may each be tapped at multiple points to provide connections for
stations. Each tap must be a certain minimum distance away from other taps, to
keep them from interfering with each other.
And there are more rules. Each cable has a maximum number of places where it
may support a connection. Thick coaxial cable, for example, may have no more
than 100 taps. Thin coaxial cable, which is not shielded against interference as
well as thick coaxial cable, may have no more than 30 taps. UTP and fiber optics
have no taps, stations must be connected at each end of the cable.
But what about the 1,024 maximum number of devices? If the absolute maximum
you can have on any of these media is 100 (over thick coaxial cable), how can you
ever get to the maximum number? And, along the same lines, what use is a UTP
link if you can only network two devices? A total of two stations does not seem
like a very efficient LAN.
Summary of Contents for MMAC-5FNB
Page 1: ...Cabletron Systems Networking Guide MMAC FNB Solutions ...
Page 2: ......
Page 4: ...ii ...
Page 10: ...viii ...
Page 188: ...Expansion Ethernet 8 12 Port Assignment and Virtual LANs ...
Page 194: ...Expansion Token Ring 9 6 Port Assignment ...