Compare Networking Hardware Flashcards
Network Interface Cards
Ethernet communications are established by either electrical signaling over copper twisted pair cable or pulses of light transmitted over fiber optic cable.
The majority of PC motherboards today have a built-in 1000BASE-T compatible adapter.You might use a NIC adapter card to support other types of Ethernet, such as fiber optic. You can also purchase cards with multiple ports of the same type
The multiple ports can be bonded to create a higher-speed link. Four Gigabit Ethernet ports could be bonded to give a nominal link speed of 4 Gbps.
MAC
Each Ethernet NIC port has a unique hardware/physical address, called the “media access control” (MAC) address. Each frame of Ethernet data identifies the source MAC address and destination MAC address in fields in a header.
A MAC address consists of 48 binary digits, making it six bytes in size. A MAC address is typically represented as 12 digits of hexadecimal. Hex is a numbering system often used to represent network addresses of different types.
The 12 digits of a MAC address might be written with colon or hyphen separators or no separators at all—for example, 00:60:8c:12:3a:bc or 00608c123abc .
Patch Panels
In most types of office cabling, the computer is connected to a wall port and—via cabling running through the walls—to a patch panel . The cables running through the walls are terminated to insulation displacement connector (IDC) punchdown blocks at the back of the panel.
The other side of the patch panel has prewired RJ45 ports. A patch cord is used to connect a port on the patch panel to a port on an Ethernet switch. This cabling design makes it easier to change how any given wall port location is connected to the network via switch ports.
Hub
A hub is a legacy network hardware device that was used to implement the 10BASE-T and 100BASE-T Ethernet cabling designs. This design is referred to as a “star topology” because each end system is cabled to a concentrator (the hub).
A hub has a number of ports—typically between four and 48—and each computer is cabled to one port. The circuitry in the hub repeats an incoming transmission from a computer attached to one port across all the other ports.
Each computer attached to a hub receives all the traffic sent by other connected devices. This is referred to as a “collision domain.”
Each computer will ignore any frames that do not match its MAC address. performance is reduced, as only one computer can send a frame at any one time. If two computers try to send at the same time, there is a collision, and they must wait for a random period before trying again.
The more computers there are, the more collisions. The computers contend for a share of the media bandwidth and all communications are half-duplex. Half-duplex means that the computer can send or receive, but not at the same time. here are no hubs that are compatible with Gigabit Ethernet. These limitations mean that almost all networks are now based on Ethernet switching.
Switches
Like a hub, an Ethernet switch provisions one port for each device that needs to connect to the network. Unlike a hub, an Ethernet switch can decode each frame and identify the source and destination MAC addresses. It can track which MAC source addresses are associated with each port. When it receives an incoming frame, the switch intelligently forwards it to the port that is a match for the destination MAC address.
Each computer has a full duplex connection to the network and can send and receive simultaneously at the full speed supported by the network cabling and NIC.
Unmanaged Switch
An unmanaged switch performs its function without requiring any sort of configuration. You just power it on and connect some hosts to it, and it establishes Ethernet connectivity between the network interfaces without any more intervention.
You might find unmanaged switches with four or eight ports used in small networks. There is an unmanaged four-port switch embedded in most of the SOHO router/modems supplied by Internet Service Providers (ISPs) to connect to their networks.
Managed Switch
Switches designed for larger LANs are managed switches . A managed switch will work as an unmanaged switch out-of-the-box, but an administrator can connect to it over a management port, configure security settings, and then choose options for the switch’s more advanced functionality. Most managed switches are designed to be bolted into standard network racks. A typical workgroup switch will come with 24 or 48 access ports for client PCs, servers, and printers. These switches have uplink ports allowing them to be connected to other switches.
An enterprise might also use modular switches. These provide a power supply and fast communications backplane to interconnect multiple switch units. This enables the provisioning of hundreds of access ports via a single compact appliance.
Configuring a managed switch can be performed over either a web or command line interface.
Power over Ethernet
Power over Ethernet (PoE) is a means of supplying electrical power from a switch port over ordinary data cabling to a powered device (PD), such as a voice over IP (VoIP) handset, camera, or wireless access point.PoE is defined in several IEEE standards
POE IEEE standards 802.3af
802.3af allows powered devices to draw up to about 13 W. Power is supplied as 350mA@48V and limited to 15.4 W, but the voltage drop over the maximum 100m (328 feet) of cable results in usable power of around 13 W.
POE IEEE standards 802.3at (PoE+)
allows powered devices to draw up to about 25 W, with a maximum current of 600 mA.
POE IEEE standards 802.3bt (PoE++ or 4PPoE)
supplies up to about 51 W (Type 3) or 73 W (Type 4) usable power
PoE-enabled switch
A PoE-enabled switch is referred to as endspan power sourcing equipment (PSE). When a device is connected to a port on a PoE switch, the switch goes through a detection phase to determine whether the device is PoE enabled. If so, it determines the device’s power consumption and sets an appropriate supply voltage level. If not, it does not supply power over the port and, therefore, does not damage non-PoE devices.
Powering these devices through a switch is more efficient than using a wall-socket AC adapter for each appliance. It also allows network management software to control the devices and apply energy saving schemes, such as making unused devices go into sleep states and power capping.
If the switch does not support PoE, a device called a “power injector “ (or “midspan”) can be used.
