Ch. 3: Networking Devices

Seite 1

3.1.1 Network Adapters

Network Adapter: also known as network interface card (NIC), is a computer component that transmits and receives data over a network. Network adapters are architecture specific.

The network adapters tranceiver converts data into different modes.

Modems - Converts digital signals into analog sound signals. Modem is short for demodulator. Sends the sound signals across telephone wires. Demodulates analog data from a telephone network into digital PC data. Modulates digital data from the PC into analog data and transmits it on a telephone network.

Small form-factor pluggable (SFP) - Mainly used on switches and routers to modify the media type used by a port.

GBIC - Slightly larger than the SFP, but performs same function.

MAC Adresses: Media access control address.

An ethernet MAC address is 48-bit, 12 character number that uniquely identifies a network adapter. Burned in addresses. (Hard coded) MAC addresses are used so that devices can communicate with one another.

ARP - used to identify the MAC address of a device from a known IP address.

3.2.1 Network Devices

Hub: sometimes called a repeater.

multi-port device with multiple RJ45 connectors that multiple computers use for a connection.

work by repeating information across all ports.

when a computer connected to a hub sends a message, the message is duplicated and sent out through every other port in the hub.

use logical bus topology where info is sent to every device on a network.

use physical star topology where all connect to a central point.

Operates on Layer One of the OSI model because it only relays signals and doesn't examine them.

Bridge: used to reduce network traffic.

connects network segments together and, in this case, isolates electrical signals between hubs. This prevents unnecessary messages from propogating between hubs.

makes forwarding decisions.

decides which messages to forward to a hub, and which should be contained just to this hub.

makes decisions by building a forwarding database, which contains the MAC addresses of all devices on a network and the port that is used to reach each device.