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Chapter 1

Internetworking

known as an aggregate rate, which translates, "You're supposed to get"
100 percent efficiency. No guarantees in networking as in life.

Full-duplex Ethernet can be used in three situations:

With a connection from a switch to a host

With a connection from a switch to a switch

With a connection from a host to a host using a crossover cable

Full-duplex Ethernet requires a point-to-point connection when only two

nodes are present.

Now, if it's capable of all that speed, why wouldn't it deliver? Well, when

a full-duplex Ethernet port is powered on, it first connects to the remote end,
and then negotiates with the other end of the FastEthernet link. This is called
an auto-detect mechanism. This mechanism first decides on the exchange
capability, which means it checks to see if it can run at 10 or 100Mbps. It
then checks to see if it can run full duplex, and if it can't, it will run half
duplex.

Remember that half-duplex Ethernet shares a collision domain and provides

a lower effective throughput than full-duplex Ethernet, which typically has a

private collision domain and a higher effective throughput.

Ethernet at the Data Link Layer

Ethernet at the Data Link layer is responsible for Ethernet addressing, com-
monly referred to as hardware addressing or MAC addressing. Ethernet is
also responsible for framing packets received from the Network layer and
preparing them for transmission on the local network through the Ether-
net contention media access method. There are four different types of Ethernet
frames available:

Ethernet_II

IEEE 802.3

IEEE 802.2

SNAP

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