Midterm (Funding Networking Systems)

Shell

The user interface that allows users to request specific tasks from the computer.

• These requests can be made either through the CLI and GUI interface

• Surrounds it all

• Command line interface that lets you with the kernel

Kernel

Communicates between the hardware and manages how hardware resources are used to meet software requirements

• Inside the shell

• Provides only the functions you absolutely need

Hardware

The physical part of a computer including underlying electronics

• Inside the kernel

Graphic User Interface (GUI)

Allows the user to interact with the system using an environment of graphical icons, menus, windows

• User-friendly

• Needs less knowledge to use

• Windows, mac, Linux, etc.

What is the purpose of the OS?

Everyday computer = for everyday things

• Mouse, keyboard, etc.

CLI-based network  Command prompt stuff

• Only keyboard = input

Console Port

Big one on the back

• Used to access a device in order to provide maintenance

  • Such as performing the initial configurations

Secure Shell (SSH)

Establishes a remote CLI connection to a device, through virtual interface

• Using puTTY(don’t have to install/can have it on thumb drive) or tera term

• All data flowing = encrypted

Telnet

(Lets not to) Insecure remote CLI connection to a device

Terminal Emulation Programs

Used to connect to a network device by either a console port or by SSH/Telnet connection

• puTTY

  • More complicated

  • More options

  • Harder to use.

  • Can save things

• Tera term

  • Easier to use

  • Less options

  • Limited history kept

What are the two Command Modes?

User EXEC Mode (>)

• Allows access to only a limited number of basic monitoring commands

• Identified by the CLI prompt that ends with > symbols

Privileged EXEC Mode (#)

• Allows access to all commands and features

• Identified by the CLI prompt that ends with the # symbol

What are the configuration mode and sub configuration modes?

Global Configuration Mode:(Switch(config))

• Global settings

• Host settings

Line configuration made:(Switch(config-line))

• SSH, Telnet, AUX

• Configurating specific settings

Interface configuration mode: (Switch(config-if))

• Used to configure switch port or router interface

• Must be in global to go to this one

  • Switch(config)#interface vlan 1

How do you navigate between IOS modes?

Privileged EXEC Mode: (Switch> enable  Switch#)

• To move from EXEC mode to privilege EXEC mode, use the enabled command.

Global Configuration Mode: (Switch(config)#  Switch(config)#exit  Switch#)

• To move in and out of global configuration mode, use the configure terminal command. To return to privilege EXEC mode, use the exit command.

• Switch#configure terminal

• Switch#conf t

Line Configuration Mode: (Switch(config)#line console 0  Switch(Config-line)#exit  Switch(config)#)

• To move in and out of line configuration mode, use the line command followed by the management line type. To return to global configuration mode, use the exit command

• Switch(config)# line console 0

  • Have to be in global mode to get to line

What is the basic IOS command structure?

Prompt

Command

Space

• NEED!!

Keyword/Argument – All the stuff at the end

Ping – sonar  ping out there for it to return

What is the syntax?

A command might require one or more arguments

• Boldface

• Italics

• [X]

• {X} (Required)

• Etc.

Pattern or format that must be used when entering a command

Boldface = is a keyword  ping, traceroute, etc

If a command is complex with multiple arguments, you may see it represented

Some Basic Device Configurations

Device name

• First configuration command on any device should be to five it a unique hostname

  • Default = switch

  • Switch# configure terminal (conf t) Switch(config)# hostname Sw-Floor-1

    • Starts with a letter, has no spaces, Less than 64 characters

      • Known as cabob

  • To undo = no hostname

Password Guidelines

• Security concern = weak password (we use cisco or class)

• More than 8 characters in length

• Combination of upper and lowercase letters, numbers, special characters, etc.

• Avoid same passwords for all device

• No common words

Configure passwords

• Securing user EXEC mode access: (Slides 32-34)!!!!

  • First enter line console configuration mode using the line console 0 command in global configuration mode.

  • Next, specify the user EXEC mode password using the password password command.

  • Finally, enable user EXEC access using the login command.

• Securing privileged EXEC mode access:

  • First enter global configuration mode.

  • Next, use the enable secret password command

VTY ()

• SSH and Telnet

• Use VTY instead of console 0

  • VTY 0 15  16 lines

• Password path = same as before

Encrypted password

• service password-encrypted

• show running-config

Banner Messages:

• motd —> Message of the day

• Good place to put a warning so that people know they are not allowed to hack in

It goes user —> privilege exec —> configure terminal —> line (line console 0) or interface (interface vlan 1) —> so on

Startup-config

This is the saved configuration file that is stored in NVRAM. It contains all the commands that will be used by the device upon startup or reboot. Flash does not lose its contents when the device is powered off.

• Start up boots into the running

Running-config

This is stored in Random Access Memory (RAM). It reflects the current configuration. Modifying a running configuration affects the operation of a Cisco device immediately. RAM is volatile memory. It loses all of its content when the device is powered off or restarted.

• To save changes made to the running configuration to the startup configuration file, use the copy running-config startup-config privileged EXEC mode command

• At enable

  • show running conf

  • show startup conf

Alter Configuration

If changes made to the running config do not have the desired effect and the running-config has not yet been saved, you can restore the device to its previous configuration. To do this you can:

• Remove the changed commands individually.

• Reload the device using the reload command in privilege EXEC mode. Note: This will cause the device to briefly go offline, leading to network downtime.

If the undesired changes were saved to the startup-config, it may be necessary to clear all the configurations using the erase startup-config command in privilege EXEC mode.

• After erasing the startup-config, reload the device to clear the running-config file from RAM.

• If not already there it will refresh and start over

• IMPORTANT!!!! —> enable# erase startup-config

IP Addresses

The use of IP addresses is the primary means of enabling devices to locate one another and establish end-to-end communication on the internet.

The structure of an IPv4 address is called dotted decimal notation and is represented by four decimal numbers between 0 and 255.

• Means you can have 256 values (255.255.255.0  not special | subnet mask)

• The ones = network portion 11111111.11111111.111111111.00000000

• Host portion = zeros 11111111.11111111.111111111.00000000

• Default gateway = address of the router

• When IPv6 catches on = every device will have their address (crazy)!!

• Must happen!!  Can not repeat the IPv4 but we are running out of numbers since there are so many devices

An IPv4 subnet mask is a 32-bit value that differentiates the network portion of the address from the host portion. Coupled with the IPv4 address, the subnet mask determines to which subnet the device is a member.

The default gateway address is the IP address of the router that the host will use to access remote networks, including the internet.

DNS – Domain network service

What does DNS stand for?

Domain Network Service

Switch Virtual interface configuration

To access the switch remotely, an IP address and a subnet mask must be configured on the SVI.

To configure an SVI on a switch:

• Enter the interface vlan 1 command in global configuration mode.

• Next assign an IPv4 address using the ip address ip-address subnet-mask command.

• Finally, enable the virtual interface using the no shutdown command

What are the three elements of any communication?

Source

Destinations

Receiver/Transmitter

Rule Establishment

Individuals must use established rules or agreements to govern the conversation

Need to follow rules to know that the other is trying to get across

• Python is not C++

Protocols must account for the following requirements:

• An identified sender and receiver

• Common language and grammar

• Speed and timing of delivery

  • Can understand little Spanish till they speak super fast

  • Order of words are also important

• Confirmations or acknowledgement requirements

Message Encoding

Encoding is the process of converting information into another acceptable form for transmission

Decoding reverses this process to interpret the information

Words —> electronics frequency —> wave/ radio frequency —> speaker transfers back to the pressure of words

Message formatting and encapsulation

When a message is sent, it must use a specific format or structure

Message formats depend on the type of message and the channel that is used to deliver the message

Message Size

Encoding between hosts must be in a appropriate format for the medium

• Messages sent across the network are converted to bits

  • Can’t just send a 4G across email

• The bits are encoded into a pattern of light, sound, or electrical impulses

• The destination host must decode the signals to interpret the message

Message Timing

Flow control – manages the rate of data transmission and speed it can be delivered

Response timeout – Manages how long a device waits when it does not hear a reply from the destination

Access method – Determines when someone can send a message

• “Collisions” – When more than one device send traffic at the same time and the messages become corrupt

  • Not as big o a problem today, still happens though

  • Some protocols are proactive

Flow Control

Manages the rate of data transmission and speed it can be delivered

Response Timeout

Manages how long a device waits when it does not hear a reply from the destination

Access Method

Determines when someone can send a message

• “Collisions” – When more than one device send traffic at the same time and the messages become corrupt

  • Not as big o a problem today, still happens though

  • Some protocols are proactive

Message Delivery Options

Only three out there:

• Unicast – One to one (two people talking)

• Multicast – One to many (professor to class)

• Broadcast – One to all (whole world could see)

  • Not an option in IPv6  only in IPv4

    • Since there are way too many addresses to send to

    • Way less IPv4 networks out there

    • Idea of the anycast  anyone everywhere on IPv6

Unicast

One to one

Multicast

One to many

Broardcast

One to all

What are the one or many functions of protocols?

Addressing

Reliability

Flow Control

Sequencing

• Need a order to the madness

Error detection

• Check it so that you know it made it or not

Application Interface

What does HTTP stand for?

Hypertext Transfer protocol

Hypertext Transfer protocol (HTTP)

Defines content and format

What does TCP stand for?

Transmission Control Protocol

Transmission Control Protocol (TCP)

Makes sure things go where they are supposed to actually go

• Guaranteed delivery

• Manages flow control

What doe IP stand for?

Internet Protocol

Internet Protocol (IP)

Delivers messages globally from the sender to receiver

• Routers to router to router….

Ethernet

LAN

Network Protocol Suites

Protocols must be able to work with other protocols

Protocol suite:

• A group of inter-related protocols necessary to perform a communication function

Evolution of Protocol Suites

Internet Protocol Suite or TCP/IP

• Most Common used

Open system interconnection (OSI) protocols

Apple talk

• Don’t play well with others

Novell NetWare

What are some TCP/IP protocol examples?

KNOW :

• Application (http)

• Transport (TCP)

• Internet (IP)

• Network Access (Ethernet)

KNOW :

• Application layer

• Transport layer

• Internet layer

• Network Access layer

An open standard protocol suite that is freely available to the public and can be used by any vendor

A standards-based protocol suite that is endorsed by the networking industry and approved by a standards organization to ensure interoperability

What is the order of the OSI layers?

Network access:

• Physical

• Data Link

Internet:

• Network

Transport:

• Transport

Application:

• Session

• Presentation

• Application

Layer 1 - Physical Layer

Means to activates

Wires and ports

• Fiber optics, etc.

Bits

Layer 2 - Data Link

Frames over a common media

MAC address to MAC address

• Changes at every single hop

• Goes to a switch —> router —> switch = changed every time

  • Source = current device

  • Destination = Next device

Switches —> Layer 2 devices

• Layer 3 are more like router so don’t count

Frame

Level 3 - Network

Like a router

Exchanges individual pieces of data over the network

Local address/IP

• Does not change from step to step to step (guides it)

  • From my computer to whatever website used

Packets

Layer 4 - Transport

Encoding into TCP packet

Segments

Layer 5 - Session

Manage data exchange of browser

Layer 6 - Presentation

Make it look pretty

Layer 7 - Application

Process to process communications

Data

Segmenting Messages

Process of breaking up messages into smaller units

• Multiplexing

Allows us to send more than just one message at a time but splitting messages into smaller chunks

• My message piece then his and at the end of the rod the message is put back into original message

Sending multiple signals on same wire

Multiplexing

The process of taking multiplestreams of segmented data and interleaving them together

What are the 2 primary benefits of segmenting messages?

Increases speed – Large amounts of data can be sent over the network without tying up a communications link

Increases efficiency – Only segments which fail to reach the destination need to be retransmitted, not the entire data stream

• Now we can all use same wire

Sequencing

The order than we send the segmented information out

• Puts the data back together

• Numbers it so that it knows the order it need to be

TCP is responsible for sequencing the individual segments

UDP = Shoots it out and if you get it…great… if not well LOL

Protocol Data Unit (PDU)

Encapsulation is the process where protocols add their information to the data

• At each stage of the process, a PDU has a different name to reflect its new function

• No universal naming

• PDU passing: (Top to bottom = data encapsulation)

  • Data (Originates at the application/here) (top)

  • Segment (Look at slides if here posts)

  • Packet

  • Frame

  • Bits (At the bottom)

Network layer source and destination addresses

Responsible for delivering the IP (logical address) from original source to the final destination

• Source = me —> IP address

• Destination = where we want it to go  Google 8.8.8.8

Data link layer source and destination addresses

(Mas address —> computer to computer) Responsible for delivering the data link frame from one network interface card (NIC) to another NIC on the same network

• NIC = each is unique

What are the two IP addresses the are contained in IP packets?

Source IP address

• The IP address of the sending device, original source of the packet

Destination IP address

• The IP address of the receiving device, final destination of the packet

What does NIC stand for?

Network Interface Card

Network Interface Card (NIC)

Connects a device to the network

• Physical address = MAC address

Physical Connection

Before any network communications can occur, a physical connection to a local network must be established.

• Not connected = AIR GAP —> not physical connection

This connection could be wired or wireless, depending on the setup of the network.

• This generally applies whether you are considering a corporate office or a home.

• A Network Interface Card (NIC) connects a device to the network.

  • Physical address = Mac address

• Some devices may have just one NIC, while others may have multiple NICs (Wired and/or Wireless, for example).

• Not all physical connections offer the same level of performance.

  • Copper Vs. fiber optic = fiber is faster

    • Wired (ethernet) is faster than wireless (cloud)

      • Since so many people are trying to connect to the same wireless location

Physical layer

PDU = Bits

Transports bits across the network media

• Wires carry electronic pulses  Zeros or ones  Voltage or no voltages (voltages can vary)

Accepts a complete frame from the Data Link Layer and encodes it as a series of signals that are transmitted to the local media

• This is the last step in the encapsulation process.

• The next device in the path to the destination receives the bits and re-encapsulates the frame, then decides what to do with it

What are the three functional areas of the physical layer standards?

Physical Components

• Wire

  • Need them to match or they won’t connect

• RJ-45

Encoding

• Preparation for transmission

• Need a common language

• On physical wire = voltages

• Radio = Frequencies

• Lazers, etc.

Signaling

• How are we actually going to run it

• What are the actual voltages going to be used

What are the physical Layer characteristics?

Physical components

Encoding

Signaling

Bandwidth

Bandwidth Terminology

Encoding

Encoding converts the stream of bits into a format recognizable by the next device in the network path.

• This ‘coding’ provides predictable patterns that can be recognized by the next device.

• Examples of encoding methods include Manchester (shown in the figure), 4B/5B, and 8B/10B

• Devices also have to decode due to resistance and such

Signaling

The signaling method is how the bit values, “1” and “0” are represented on the physical medium.

• The method of signaling will vary based on the type of medium being used

• Square waves  on, off, on, off, etc.

Bandwidth

Bandwidth is the capacity at which a medium can carry data.

Digital bandwidth measures the amount of data that can flow from one place to another in a given amount of time; how many bits can be transmitted in a second.

• B = Byte —> b = bit!!!! (8b =1B)

• Physical media properties, current technologies, and the laws of physics play a role in determining available bandwidth

  • Bandwidth goes off of little b

    • Although it is getting faster and big B is 8 times faster

• Maximum capacity it can carry data

• SLIDE 11 = ALL bps, Kbps, Mbps, Gbps, Tbps

Bandwidth Terminology

Analog = voice travel

• Digital = opposite of analog

  • Digital = more latency  slower than analog

Latency

• Amount of time, including delays, for data to travel from one given point to another

Throughput

• The measure of the transfer of bits across the media over a given period of time

  • What is actually going through

    • Bandwidth is the max that can go through (Not same thing!!)

Goodput

• The measure of usable data transferred over a given period of time

• Goodput = Throughput - traffic overhead

Latency

Amount of time, including delays, for data to travel from one given point to another

Throughput

The measure of the transfer of bits across the media over a given period of time

• What is actually going through

  • Bandwidth is the max that can go through (Not same thing!!)

What is the most common type of cabling?

Copper cabling

Attentuation

The longer the electrical signals have to travel, the weaker they get

• Electrons have resistance —> Further they go the slower they go due to lost of heat

• Insulators are like throwing a ball into water

What does EMI stand for?

Electromagnetic Interference

What does RFI stand for?

Radio Frequency Interference

What does UTP stand for?

Unshielded Twisted Pair

Unshielded Twisted Pair (UTP)

Most common networking media!!!

Terminated with RJ-45 connectors

• Interconnects hosts with intermediary network devices

What are the key characteristics of UTP?

1. The outer jacket protects the copper wires from physical damage.

• Keeps it organized

2. Twisted pairs protect the signal from interference.

3. Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair.

• Twisted to eliminate crosstalk!!

What does STP stand for?

Shielded Twisted Pair

Shielded Twisted Pair (STP)

Better noise protection than UTP

More expensive than UTP  More copper

Harder to install than UTP

Terminated with RJ-45 connectors

Interconnects hosts with intermediary network devices

What are the key characteristics of STP?

1. The outer jacket protects the copper wires from physical damage

2. Braided or foil shield provides EMI/RFI protection

3. Foil shield for each pair of wires provides EMI/RFI protection

4. Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair

What are the properties of UTP cabling?

UTP has four pairs of color-coded copper wires twisted together and encased in a flexible plastic sheath. No shielding is used. UTP relies on the following properties to limit crosstalk:

• Cancellation - Each wire in a pair of wires uses opposite polarity. One wire is negative, the other wire is positive. They are twisted together and the magnetic fields effectively cancel each other and outside EMI/RFI.

  • One is negative while the other is positive to = zero

• Variation in twists per foot in each wire - Each wire is twisted a different amount, which helps prevent crosstalk amongst the wires in the cable

Color order of wires?

White strip green

green

white strip orange

blue

white strip blue

orange

white strip brown

brown

What are the properties of Fiber-Optic Cabling

Not as common as UTP because of the expense involved

• Ideal for some networking scenarios

• Transmits data over longer distances at higher bandwidth than any other networking media

  • Good for long distance

  • Different cities

• Less susceptible to attenuation, and completely immune to EMI/RFI

• Made of flexible, extremely thin strands of very pure glass (single mode)

  • Plastic strands for multimode (LEDs)

• Uses a laser or LED to encode bits as pulses of light

• The fiber-optic cable acts as a wave guide to transmit light between the two ends with minimal signal loss

Single-Mode Fiber

Very small core

Uses very expensive lasers

Long-Distance applications

Single, straight path for light

Multimode Fiber

Larger core

Uses less expensive LEDs

LEDs transmit at different angles

• Light kinds of bounces around

• Degrades since it bounces

Up to 10 Gbps over 550 meters

Dispersion

Refers to the spreading out of a light pulse over time.

• Increased dispersion means increased loss of signal strength. MMF has greater dispersion than SMF, with the maximum cable distance for MMF is 550 meters

• Multimode has more dispersion than single-mode

What four types of industry used Fiber-optic cabling?

1. Enterprise Networks - Used for backbone cabling applications and interconnecting infrastructure devices

2. Fiber-to-the-Home (FTTH) - Used to provide always-on broadband services to homes and small businesses

3. Long-Haul Networks - Used by service providers to connect countries and cities

4. Submarine Cable Networks - Used to provide reliable high-speed, high-capacity solutions capable of surviving in harsh undersea environments at up to transoceanic distances.

• Bundles of single modes (across the ocean)

Fiber vs. Copper

Optical fiber is primarily used as backbone cabling for high-traffic, point-to-point connections between data distribution facilities and for the interconnection of buildings in multi-building campuses

• Glass is an insulator

Properties of Wireless Media

It carries electromagnetic signals representing binary digits using radio or microwave frequencies. This provides the greatest mobility option. Wireless connection numbers continue to increase.

• Some people use WIFI extended

• We use microwave or radio wave frequency = wireless

  • China product can see your browser history is you use their product

• Should use VPN (NORD VPN)

• WIFI pineapple can be use to decrypt peoples stuff

Limitations of Wireless Media

Coverage area

Interference

Security

Shared Medium

Coverage area (Limitation of wireless)

Effective coverage can be significantly impacted by the physical characteristics of the deployment location.

• Only goes a certain distance

• 5G = faster, less distance

• 2.5G = slower, more distance

• Hertz = cycles per second (Hz)

• 5GHz = 5000 cycles per second

• More information but weaker (more speed though)

Interference (Limitation of wireless)

Wireless is susceptible to interference and can be disrupted by many common devices.

• Any type of AC current will cause problems

• A louder signal comes and covers it up

• Someone is whispering and the person next to them is yelling

Security (Limitation of wireless)

Wireless communication coverage requires no access to a physical strand of media, so anyone can gain access to the transmission.

• Walking dragon —> finding free WIFI’s and hacking into them

• Need VPN

Shared Medium (Limitation of wireless)

WLANs operate in half-duplex, which means only one device can send or receive at a time.

• Many users accessing the WLAN simultaneously results in reduced bandwidth for each user

• Half-duplex = deals with directionality of signal, can’t send and receive at the same time

• Full-duplex = can send and receive data at the same time

WI-FI

IEEE 802.11

Wireless LAN (WLAN) Technology

Bluetooth

IEEE 802.15

Wireless Personal Area Network (WPAN) standard

WiMAX

IEEE 802.16

Uses a point-to-multipoint topology to provide broadband wireless access