Hardware Addressing and Frame Type Identification

The sending computer identifies the type of data stored inside the frame.
The sending computer also uses hardware address to identify the destination computer.

Specifying a Destination

The hardware interface detects the frames and extracts the data from it.
However, the data is sent to all the computers.
There needs to be a way to specify the exact destination computer.

Hardware Addressing

Each device has a hardware or physical address which is included in the transmitted frame.
So if the address matches, the frame is received.
Otherwise, it is ignored.

LAN Hardware AND Packet Filtering

The LAN interface does the following: 1. Adds hardware addresses and error detection codes to outgoing frames. 2. It obeys the CMSA/CD rules. 3. It analyzes the hardware address from incoming frames. 4. It also checks for error detection codes. 5. It may use dynamic-memory-access to copy data from the main memory. 6. It may use dynamic-memory-access to copy data to the main memory.

The frames which are not for the destination, are ignored.

Format of Hardware Address

It consists of numeric value and its size is selected for specific network technology.
The length is 1-6 bytes.

Assigning Hardware Address

There are 3 types of addresses.

Static

In this type, the manufacturer assigns a permanent hardware address to the interface and he is also responsible in keeping them unique.

Configurable

These addresses can be set up by the end user either electronically by using some software or manually by using switches or jumpers.

Dynamic

In this one, a new address is automatically assigned when the hardware turns on.

Broadcasting

There is a special broadcast address as well which is captured by all the stations.