User`s guide

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TCP/IP Network Basics
TCP/IP Protocols
The Network Interface Layer
The lowest layer in the TCP/IP stack is the Network Interface Layer. The
primary responsibility of this layer is to define how a host device (computer,
instrument, etc.) connects to the network. The Network Interface Layer acts
as a host’s connection (interface) to the network. There are no TCP/IP
protocols associated with the Network Interface layer.
The Network Interface Layer is used to send and receive packets. At the
Network Interface Layer, a header that contains addressing information is
applied to each packet. A part of this header is the host
hardware address.
The hardware address must be unique to the device and does not change
during the life of the device.
The hardware address, also called the Media Access Control (MAC)
Address, Ethernet Address, Physical Address, or Network Interface Card
(NIC) Address, is a 12-digit hexadecimal address. A typical hardware
address is 00:30:D3:00:00:23, where the first six digits represent the
manufacturer of the device and the last six digits represent the serial
number assigned to the device.
As packets are sent through the network, each host on the network looks at
the packet to see if the packet is addressed to the host’s hardware address.
If not, the host ignores the packet.
NOTE
For a TCP/IP packet to be delivered to a device, the packet
must contain
the destination device’s hardware address.