CCNA 3 Labs and Study Guide - BINARYBB.INFO – @jagalbraith

222 Switching Basics and Intermediate Routing CCNA 3 Labs and Study Guide
Vocabulary Exercise: Completion
Directions: Complete the paragraphs that follow by filling in appropriate words and phrases.
A hub is a Layer 1 device and is sometimes referred to as a LAN or Ethernet concentrator or a multiport
repeater.
Ethernet is fundamentally a shared or broadcast technology through which all users on a given LAN segment
compete for the same available bandwidth. If two or more devices try to transmit at the same time, a
collision occurs.
Bridges and switches operate at the data link layer of the Open System Interconnection (OSI) model.
These Layer 2 devices make forwarding decisions based on MAC addresses contained within the headers
of transmitted data frames.
Switches create a virtual circuit between two connected devices that want to communicate, which is a dedicated
communication path established between the two devices.
The implementation of a switch on the network is called microsegmentation, which creates a collision-free
environment for each device connected to the switch.
The disadvantage of Layer 2 devices is that they forward broadcast frames to all connected devices on the
network.
Routers operate at the network layer of the OSI model and will not forward broadcast frames unless
specifically programmed to do so. Therefore, routers reduce the size of both the collision domains and the
broadcast domains in a network.
CSMA/CD is Ethernet’s access control method. Originally Ethernet was a half-duplex technology, which
allows hosts to either transmit or receive at one time, but not both.
Full-duplex Ethernet significantly improves network performance without the expense of installing new
media and offers 100 percent of the bandwidth in both directions because it is a collision-free environment.
Frames sent by the two connected end nodes cannot collide, because the end nodes use two separate
circuits in the Category 3, 5, 5e, or 6 cable.
Nodes that are attached to hubs that share their connection to a switch port must operate in half-duplex
mode, because the end stations must be able to detect collisions.
Latency, or delay, is the time a frame or a packet takes to travel from the source station to the final destination.
The networking device that adds the most latency is a router.
A 64-byte frame is the smallest frame that allows CSMA/CD to operate properly, and a 1518-byte frame is
the largest.
The distance that a LAN can cover is limited due to attenuation, which means that the signal weakens as it
travels through the network.