Introducing LANs

Question 1

Include any device that can send or receive data on the LAN. Sometimes hosts are also called endpoints. Those two terms are used interchangeably throughout the course.

Answer 1

Host

Question 2

Allow data to travel from one point to another in the network. Interconnections include these components:

Answer 2

Interconnections

Question 3

NICs translate the data that is produced by the device into a frame format that can be transmitted over the LAN. NICs connect a device to the LAN over copper cable, fiber-optic cable, or wireless communication.

Answer 3

Network Interface Cards (NICs)

Question 4

In traditional LANs, data was transmitted mostly over copper and fiber-optic cables. Modern LANs (even small home LANs) generally include a wireless LAN (WLAN).

Answer 4

Network media

Question 5

Like switches and routers, are responsible for data delivery between hosts.

Answer 5

Network devices

Question 6

Form the aggregation point for LANs. Ethernet switches operate at Layer 2 of the Open Systems Interconnection (OSI) model and provide intelligent distribution of frames within the LAN.

Answer 6

Ethernet switches

Question 7

Sometimes called gateways, provide a means to connect LAN segments and provide connectivity to the internet. Routers operate at Layer 3 of the OSI model.

Answer 7

Routers

Question 8

Provide wireless connectivity to LAN devices. APs operate at Layer 2 of the OSI model.

Answer 8

Access points (APs)

Question 9

Are rules that govern how data is transmitted between components of a network.

Answer 9

Protocols

Question 10

• Ethernet protocols (Institute of Electrical and Electronics Engineers [IEEE] 802.2 and IEEE 802.3)
• Internet Protocol (IP)
• Transmission Control Protocol (TCP)
• User Datagram Protocol (UDP)
• Address Resolution Protocol (ARP) for IP version 4 (IPv4) and Neighbor Discovery Protocol (NDP) for IP version 6 (IPv6)
• Common Internet File System (CIFS)
• Dynamic Host Configuration Protocol (DHCP)

Answer 10

LAN protocols

Question 11

When users are connected through a network, they can share files and even software applications. This capability makes data more easily available and promotes more-efficient collaboration on work projects.

Answer 11

Data and applications

Question 12

The resources that can be shared include input devices, such as cameras, and output devices, such as printers.

Answer 12

Resources

Question 13

If a resource is not available locally, the LAN can provide connectivity via a gateway to remote resources, such as the internet.

Answer 13

Communication path to other networks

Question 14

Network connection that is made by a single unbroken network cable. Ethernet cables and segments can span only a limited physical distance.

Answer 14

Segment

Question 15

Network connection that is made by a single unbroken network cable. Ethernet cables and segments can span only a limited physical distance. Because frames may collide with each other. A network collision occurs when two or more devices, connected by a shared medium, try to communicate at the same time.

Answer 15

Collision Domain

Question 16

Central processing units (CPUs), buses, and peripherals are consistently becoming faster and more powerful; therefore, they can send more data at higher rates through the network.

Answer 16

Increasingly powerful computer and network technologies

Question 17

Network traffic is now more common, as remote resources are used and are even necessary to carry out basic work.

Answer 17

Increasing volume of network traffic

Question 18

Software applications are becoming richer in their Functionality and are requiring more bandwidth to process. Applications such as desktop publishing, engineering design, video on demand (VoD), e-learning, and streaming video all require considerable processing power and speed. This richer functionality puts a large burden on networks to manage the transmission of their files and requires sharing of the applications among users.

Answer 18

High-bandwidth applications

Question 19

This increases frame throughput. Switches with one user device per port have microsegmented the network. In this type of configuration, each user receives access to the full bandwidth and does not have to contend with other users for available bandwidth. As a result, collisions do not occur.

Answer 19

Dedicated communication between devices

Question 20

Multiple simultaneous conversations can occur by forwarding-or switching-several packets at the same time, increasing network capacity by the number of conversations that are supported. For example, when frames are being forwarded between ports 1 and 2, another conversation can be happening between ports 5 and 6. This multiplication is possible because of input/output (I/O) buffers and fast internal transfer speeds between ports. A switch that can support all possible combinations of frame transfers between all ports simultaneously is said to offer wire-speed and nonblocking performance. Of course, this class of switch is relatively expensive.

Answer 20

Multiple simultaneous conversations

Question 21

After a connection is microsegmented, it has only two devices (the switch and the host). It is now possible to configure the ports so they can both receive and send data at the same time, which is called full-duplex communication. For example, point-to-point 100-Mbps connections have 100 Mbps of transmission capacity and 100 Mbps of receiving capacity, for an effective 200-Mbps capacity on a single connection. The configuration between half-duplex and full-duplex is automatically negotiated at the initial establishment of the link connection. Half-duplex means that there is transmission of data in just one direction at a time.

Answer 21

Full-duplex communication

Question 22

A LAN switch that has ports with different media rates can adapt to between rates, for example between 10, 100 and 1000 Mbps, 1 and 10 Gbps, 1, 10 and 25 Gbps, 40 Gbps and 100 Gbps. This adaptability allows bandwidth to be matched as needed. Without this ability, it is not possible to have different media-rate ports that are operating at the same time.

Answer 22

Media-rate adaptation

Question 23

Switches have high port densities: 24-, 32- and 48-port switches operate at speeds of 100 Mbps, 1 Gbps, 10 Gbps 25 Gbps, 40 Gbps and 100 Gbps. Large enterprise switches may support hundreds of ports.

Answer 23

High port density

Question 24

The ability to store more received frames before having to start dropping them is useful, particularly when there may be congested ports connected to servers or other heavily used parts of the network.

Answer 24

Large frame buffers

Question 25

Depending on the switch, it may be possible to support a range of bandwidths. Ports of 100 Mbps, 1Gbps, and 10 Gbps are expected, but 40- or 100-Gbps ports allow even more flexibility.

Answer 25

Port speed

Question 26

Having fast internal switching allows higher bandwidths: 100 Mbps, 1 Gbps, 10 Gbps, 25 Gbps, 40 Gbps and 100 Gbps.

Answer 26

Fast internal switching

Question 27

Switches provide high port density at a lower cost. For this reason, LAN switches can accommodate network designs that feature fewer users per segment. This feature, therefore, increases the average available bandwidth per user.

Answer 27

Low per-port cost

Question 28

which are fundamental to how an Ethernet switch works. An ASIC is a silicon microchip designed for a specific task (such as switching or routing packets), rather than being used for general-purpose processing such as a CPU.

Answer 28

application-specific integrated circuits (ASICs),