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24-port NWay Ethernet Switch User’s Guide
86 Switch Management and Operating Concepts
products from the same vendor) may communicate in completely
different ways. As long as peers can communicate and
interoperate, this has no impact on the functioning of the
network.
The communication between layers within a given protocol stack
can be both different from a second stack and proprietary, but
communication between peers on the same OSI layer is open and
consistent.
A brief description of the most commonly used functional layers
is helpful to understand the scope of how protocol layering works.
Layer 1
This is referred to as the physical layer. It handles the electrical
connections and signaling required to make a physical link from
one point in the network to another. It is on this layer that the
unique Media Access Control (MAC) address is defined.
Layer 2
This layer, commonly called the switching layer, allows end
station addressing and the establishment of connections between
them.
Layer 2 switching forwards packets based on the unique MAC
address of each end station and offers high-performance,
dedicated-bandwidth of Fast or Gigibit Ethernet within the
network.
Layer 2 does not ordinarily extend beyond the intranet. To
connect to the Internet usually requires a router and a modem or
other device to connect to an Internet Service Provider’s WAN.
These are Layer 3 functions.