307N Midterm

Five Layers of the TCP-IP Model

Application, Transport, Network, Data Link, Physical

What are transport layer messages encapsulated in?

Segments

What are segments encapsulated in?

Packets

What are packets encapsulated in?

Frames

Encapsulation

The process by which data is packaged and sent between devices

IP Address

A 32-bit address used to identify devices

DHCP

Dynamic Host Configuration Protocol; used by a router to automatically configure connected devices with an IP address

ipconfig command

Used to find the IP address of each port on a computer

ipconfig /all command

Used to find the IP address and MAC address of each port on a computer

ping command

Used to send a packet to another device; checks if data can be transmitted successfully between two devices

ICMP

Internet Control Message Protocol; used for performing network diagnostics in ping commands

Switch

A device that is used to connect many end devices together and move frames between devices

Three Functions of a Switch

Forwarding and Filtering Decisions, Address Learning, and Loop Avoidance

MAC Address

A 48-bit address displayed in hexadecimal that is used as a unique identifier for a physical port

Subnet Mask

Determines the number of bits in the network ID that will be reserved for the subnet portion

Subnet ID

The combination of a network ID and the subnet mask into an abbreviated IP address (i.e. 192.168.0.0 /16)

Default Gateway

A special subnet ID assigned to a router port that is the forwarding address for networks/subnets

APIPA

Automatic Private IP Addressing; an IP assigning protocol that is used by PCs when DHCP fails

Unicast Address

An IP/MAC address that only forwards packets to one host

Broadcast Address

An IP/MAC address that forwards packets to all hosts on a subnet

Broadcasting/Flooding

The act of forwarding a packet to every device on a subnet

Broadcast Address of the subnet 192.168.10.0 /24

192.168.10.255

Straight-Through Cable

A copper cable used to connect end devices to switches

Cross-Over Cable

A copper cable that is used to connect switches to other switches

Console Cable

A special cable that is used to connect a PC to a switch or router with the purpose of configuring the device’s settings

Three Layers of the Campus Topology

Access, Distribution, and Core

MAC Address Table

A list of MAC addresses learned by a switch as frames are filtered through it

How do switches learn MAC addresses?

Switches learn MAC addresses by interacting with other devices. It associates a MAC address with the port that the frame is forwarded through

ARP

Address Resolution Protocol; correlates IP addresses and MAC addresses

How long do MAC addresses remain in the MAC address table?

5 minutes

What happens when a switch tries to add a MAC address to a full table?

The oldest MAC address will be removed from the table.

Auto-Negotiation

The process by which two switches determine default transmission parameters (i.e. duplex mode, speed)

Access Mode

Only allows for the transmission of data over one VLAN on a port

Trunk Mode

Allows for data to travel across multiple VLANs over one port

ROM

Read-Only Memory; a nonvolatile type of memory that cannot be written over and will be saved even if the system shuts down

RAM

Random Access Memory; a volatile memory type that is used as temporary storage for an OS

NVRAM

Non-Volatile RAM (will hold data even if the memory’s power is cut)

Running Configuration

The configuration settings for a device at any given point in time

Startup Configuration

The configuration settings for a device when the system boots

STP

Spanning Tree Protocol; prevents switches from entering logical loops in a network

STP Forwarding State

Allows a port to send and receive data normally

STP Blocking State

Turns all user traffic away, essentially disables the port

Broadcast Storm

Occurs when a frame loops around a network indefinitely

MAC Table Insecurity

When multiple ports of the same switch are associated with the same MAC address

Multiple Frame Transmission

When multiple copies of the same frame arrives at a destination

STP Convergence

How switches recognize a change in the LAN’s topology and how they react to that by changing port STP states

Root Switch

The switch in a network that is chosen as the starting point for STP based on its priority number

Bridge ID

A unique eight-byte value assigned to each switch

Two parts to a Bridge ID

2 byte priority and a 6 byte MAC address

BID Priority Number

Determines which switch will be the root

Hello BPDU

Sent by switches to communicate with one another

Etherchannel

Multiple physical links between two switches working together to form one logical link

Synonyms for Etherchannels

PortChannel and Channel Group

Two Main Concepts for Network Design

Scalability and Redundancy

Scalability

Creating a topology that can be upgraded without major complications

Redundancy

Having physical loops over a network in case a connection fails

Failure Domain

The affected area of a network if a connection fails

Network Time Protocol (NTP)

Synchronizes the time-of-day clock on all devices in a network

Basic Service Set (BSS)

Defined by the wireless access point and the devices connected to that access point

Extended Service Set (ESS)

Composed of multiple BSS’s

Wireless Access Point (WAP)

A device used to wirelessly connect to devices; essentially a wireless switch

Basic Service Set Identifier (BSSID)

The MAC address of the WAP

Service Set ID (SSID)

A string of text that humans can read to identify a WAP

802.11 Frame

The type of frame that is used for wireless transmissions