Advance Networking Module 1 - 8

Command Line Interface

CLI means

Rollover Cable

Old Console Cable

User EXEC Mode

router>

User Mode

User EXEC mode is also called what?

Privileged EXEC Mode

router#

Global Configuration

router(config)#

running-config

the current, active configuration file on the device

startup-config

the configuration file that will be loaded upon restart of the device

MD5 configuration

a cryptographic hash algorithm that generates a 128 bits string value from any length string

Trailer - Packet - Header

Ethernet Frame

Frame Check Sequence

FCS meaning

7 byte (56 bit)

Length of Preamble

Preamble

Allows devices to synchronize their receiver clocks

Start Frame Delimiter

SFD meaning

1 byte (8 bit)

SFD length

SFD

marks the end of the preamble, and the beginning of the rest of the frame

Destination and Source

indicates the devices sending and receiving the frame

Destination and Source

consists of the destination and source MAC Adress

6 byte (48 bit) address of the physical device

length of destination and source

2 byte (16 bit)

Type length

Type or Length

a value of 1500 or less in this field indicates the length of the encapsulated packets

Type or Length

a value of 1356 or greater in this field indicates the _____ of the encapsulated packet and the _____ is determined via another method

FCS

detects corrupted data by running “CRC” algorithm over the received data

MAC Address

Also known as burned in address (BIA)

MAC Address

is globally unique

MAC Address

the first 3 bytes are QUI which is assigned to the company making the device

MAC Address

written as 12 hexadecimal characters

Mac Address for Windows

5C-23-5A-24-2B-3D

Mac Address for Cisco devices

0011.5ccc.5c00

Mac Address for LINUX and IOS

5C:23:5A:24:2B:3D

Address Resolution Protocol

ARP meaning

ARP

is used to discover the layer 2 address (MAC address) of a known layer 3

ARP Request

sent by the device that wants to know the mac address of the other device

ARP Reply

which is sent to inform the requesting the device of the mac address

ARP request is broadcast

sent to all host on the network

ARP request is Unicast

sent only to one host

Ping

a network utility that is used to test reachability

Router Interfaces

have the shutdown command applied by default- will be in the administratively down/down state by default

Switch Interfaces

do not have the shutdown command applied by default- will be in up/up state if connected to another device

Half Duplex

the device cannot send and receive data at the same time. if its receiving a frame, it must wait before sending a frame. device attached to a hub

Full Duplex

the device can send and receive data at the same time. it does not have to wait. device attached to a switch

Carrier Sense Multiple Access with Collision Detection

CSMA/CD meaning

CSMA/CD

in a collision does occur, the device sends a jamming signal to inform the other devices that a collision happened. the process repeats

Speed / Duplex Autonegotation

interfaces advertise their capabilities to the neighboring device, and they negotiate the best speed and duplex settings they are both capable of

Speed

the switch will try to sense the speed that the other device is operating at

Runts

frames that are smaller than the maximum frame size (64 bytes)

Giants

frames that are larger than the maximum frame size (1518 bytes)

CRC

frames that failed the CRC check

Frames

frames that have an incorrect format (due to an error)

Input errors

total of various counters, such as the above four

Output errors

frames the switch tried to send, but failed due to error

Networking Models

categorize and provide a structure for networking protocols and standards

Protocols

are a set of rules defining how network devices and software should work

Protocols

also refer to logical rules about how the devices should communicate, not physical standards

Open System Interconnection Model

OSI Model meaning

Application Layer

• this layer is closest to the end user

• interacts with software applications

Present Layer

• to translate between application and network formats

• it needs to be translated into a different format to be sent over the network

Session Layer

• establishes, manages, and terminates connections between the local application and the remote application

• controls dialogues between communication hosts

Transport Layer

• segments and reassembles data for communications between end hosts

• provide host to host

• break large pieces of data into smaller segments that can be more easily sent over network and are less likely to cause transmission problems if errors occurs

Network Layer

• provides connectivity between end hosts on different networks

• provides logical addressing

Data Link Layer

• provides node to node connectivity and data transfer

• defines how data is formatted for transmission over a physical medium

• detects and corrects physical errors

Physical Layer

• defines physical characteristics of the medium used to transfer data between devices

• digital bits are converted into an electrical signal

Computer Network

is a digital telecommunications network that allows nodes to share resources

• Router

• Switch

• Firewall

• Server

• Client

Devices in Computer Network

Client

is a device that accesses a service made available by a server

Server

is a device that provides functions or services for clients

Switches

• have many network interfaces/ports for end hosts (usually 24+)

• provide connectivity to hosts within the same LAN

• do not provide connectivity between LAN over the internet

Routers

• have fewer interfaces than switches

• used to provide connectivity between LANS

• used to send data over the internet

Firewalls

• monitors and control network traffix based on configured rules

• can be placed “inside” or “outside” the network

Firewall

also known as “Next Generation Firewalls: when they include more modern and advanced filtering capabilites

• Network Firewalls

• Host-based Firewalls

Types of Firewalls

Network firewall

are hardware devices that filter traffic between netwrok

host based firewall

are software applications that filter traffic entering and exiting a host machine like a PC

RJ - 45 (Register Jack)

also called 8 pin 8 collector

Ethernet

is a collection of network protocols/standars

Ethernet

is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN), wide area network (WAN)

Institute of electrical and electronic engineers

IEEE means

Unshielded Twisted Pair

UTP meaning

UTP

the wire that is twisted together protects against EMI

Electromagnetic Interference

EMI meaning

Auto MDIX

allows devices to automatically detect which pins their neighbor is transmitting data on and then adjust which pins they use to transmit and receive data

Small Form Factor Pluggable

SFP Transceiver meaning

• single mode

• multi mode

Types of Fiber Optic Connections

Multimode Fiber

allows multiple angles (modes) of light waves to enter the fiberglass core

Multimode Fiber

allows longer cables than UTP

core diameter is wider

singlemode fiber

light enters at ## from a laser based transmitter

UTP

lower cost than fiber optic

Fiber optic

higher cost than UTP

UTP

shorter maximum distance than fiber optic (100m)

Fiber Optic

longer maximum distance

UTP

can be vulnerable to EMI

fiber optic

no vulnerability to emi

UTP

emit (leak) a faint a signal outside of the cable which can be copied (security risk)

fiber optic

does not emit any signal outside of the cable

Networking models

categorize and provide a structure for networking protocols and standards

Protocols

are set of rules defining how network devices and software should work

protocols

also refer to logical rules about how devices should communicate, not physical standards

Open System Interconnection

OSI meaning

OSI model

a conceptual model that categorizes and standardizes the different functions in a network

Application Layer

• closest to the end user

• interacts with software applications

• http and https