NetworksBasicsFinal.ppt

transcript

Networking Basics

For : Level 1 – Networks and Computer Science DiplomaDeanship of Community Services and Continuous Education - Imam University

Based on : Cisco Networking Academy – Exploration 1

Instructor : Mahmoud Rabie

Grading 15 for Attendance and Participation 35 for the Take-Home Open-Book Exam 50 for the Final Exam

Topics Introduction to Networking Networking Fundamentals Networking Media Communicating over the Network Application Layer Functionality and

Protocols Ethernet and Link Layer

Addressing

Introduction to Networking

Objectives

Requirements for Internet Connection

Network Interface Card (NIC)

TCP/IP Description and Configuration

Testing Connectivity with Ping

Web Browser and Plug-Ins

Troubleshooting Internet Connections

Network Math ISA will be covered well, by Dr.

IP Addresses and Network Masks

Networking Fundamentals

Objectives

Data Networks

Networking Devices

Network Topology

Network Protocols

Local-area Networks (LANs)

Wide-area Networks (WANs)

Storage-Area Networks (SANS)

Virtual Private Networks (VPNs)

Importance of Bandwidth

Bandwidth Pipe Analogy

Bandwidth Highway Analogy

Bandwidth Measurements

Bandwidth Limitations

Using Layers to Analyze Problems

Using Layers to Describe Data Communication

OSI Model

OSI Layers

•Provides connectivity and path selection between two host

•Provides Logical address

•No error correction, best effort delivery.

OSI Layers

Peer-to-Peer Communication

TCP/IP Model

Networking Media

Objectives

Voltage

Resistance and Impedance

Current Flow

Circuits

Coaxial Cable

Shielded Twisted-Pair Cable (STP)

Unshielded Twisted Pair (UTP)

Single Mode Fiber

Multimode Fiber

Optical Media

Wireless LAN Standards

Internal Wireless NIC

Wireless USB Adapter

Modulation

Communicating over the Network

Network Structure Define the elements of communication

3 common elements of communication message source the channel message destination

Define a network data or information networks capable of carrying many

different types of communications

Network Structure Describe how messages are communicated

Data is sent across a network in small “chunks” called segments

Multiplexing

Network Structure Define the components of a network

Network components hardware software

Network Structure End Devices and their Role in the Network

End devices form interface with human network & communications network

Role of end devices: client server both client and server

Network Structure Identify the role of an intermediary

device in a data network and be able to contrast that role with the role of an end device Role of an intermediary device

provides connectivity and ensures data flows across network

Network Structure

Define network media and criteria for making a network media choice

Network media this is the channel over which a message travels

Network Types

Define Local Area Networks (LANs) - A network serving a home, building or

campus is considered a Local Area Network (LAN)

Network Types Define Wide Area Networks (WANs)

LANs separated by geographic distance are connected by a network known as a Wide Area Network (WAN)

Network Types

Define the Internet The internet is defined as a global mesh of interconnected networks

Network Types Describe network representation symbols

Function of Protocol in Network Communication

The importance of protocols and how they are used to facilitate communication over data networks

A protocol is a set of predetermined or formal rules

Explain network protocolsNetwork protocols are usedto allow devices to communicate successfully

Define different protocols and how they interact

Technology independent Protocols -Many diverse types of devices can communicate using the

same sets of protocols. This is because protocols specify network functionality, not the underlying technology to support this functionality.

Layers with TCP/IP and OSI Model

Explain the benefits of using a layered model– Benefits include

• assists in protocol design• fosters competition• changes in one layer do not affect other layers• provides a common language

Describe TCP/IP Model

Describe the Communication Process

Explain protocol data units (PDU) and encapsulation

Describe the process of sending and receiving messages

Explain protocol and reference models

A protocol model provides a

model that closely matches the structure of a particular

protocol suite.

A reference model provides a

common reference for maintaining consistency within all types of network protocols and services.

Define OSI

Compare OSI and TCP/IP model

Addressing and Naming Schemes

Explain how labels in encapsulation headers are used to manage communication in data networks

Describe examples of Ethernet MAC Addresses, IP Addresses, and TCP/UDP Port numbers

Explain how labels in encapsulation headers are used to manage communication in data networks

Application Layer Functionality and Protocols

Applications – The Interface Between Human and Data Networks

Explain the role of applications, services and protocols in converting communication to data that can be transferred across the data network

Define the separate roles applications, services and protocols play in transporting data through networks

Describe the role protocols play in networking and be able to identify several message properties that can be defined by a protocol

The Role of Protocols in Supporting Communication

Describe the roles of client and server processes in data networks

List common Application Layers services and protocols

Compare and contrast client server networking with peer-to-peer networking and peer-to-peer applications

Features, Operation, and Use of TCP/IP Application Layer Services

Describe the features of the DNS protocol and how this protocol supports DNS services

Describe the features of the HTTP protocol and how this protocol supports the delivery of web pages to the client

Features, Operation, and Use of TCP/IP Application Layer Services

Link Layer Addressing

MAC Addresses and ARP 32-bit IP address:

network-layer address used to get datagram to destination IP

subnet

MAC (or LAN or physical or Ethernet) address: used to get datagram from one interface to

another physically-connected interface (same network)

48 bit MAC address (for most LANs) burned in the adapter

LAN Addresses and ARPEach adapter on LAN has unique LAN address

Broadcast address= FF-FF-FF-FF-FF-FF

=adapter

1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

71-65-F7-2B-08-53

LAN(wired or

wireless)

•MAC address allocation administered by IEEE•Manufacturer buys portion of MAC address space (to assure uniqueness)

ARP: Address Resolution Protocol

Each IP node (Host, Router) on LAN has ARP table

ARP Table: IP/MAC address mappings for some LAN nodes

< IP address; MAC address; TTL>

TTL (Time To Live): time after which address mapping will be forgotten (typically 20 min)

Question: how to determineMAC address of Bknowing B’s IP address?

1A-2F-BB-76-09-AD

58-23-D7-FA-20-B0

0C-C4-11-6F-E3-98

237.196.7.23

237.196.7.78

237.196.7.14

237.196.7.88

ARP protocol: Same LAN A wants to send datagram to B, and B’s MAC address not in A’s ARP

table.

A broadcasts ARP query packet, containing B's IP address Dest. MAC address = FF-FF-FF-FF-FF-FF all machines on LAN receive ARP query

B receives ARP packet, replies to A with its (B's) MAC address frame sent to A’s MAC address (unicast)

A caches (saves) IP-to-MAC address pair in its ARP table until information becomes old (times out)

soft state: information that times out (goes away) unless refreshed

ARP is “plug-and-play”: nodes create their ARP tables without intervention from net administrator

Star topology Nowadays, star topology prevails (يسود) Connection choices: hub or switch

hub orswitch

Ethernet Frame Structure

Sending adapter encapsulates IP datagram (or other network layer protocol packet) in Ethernet frame

Preamble: 7 bytes with pattern 10101010 followed

by one byte with pattern 10101011 used to synchronize receiver, sender

clock rates

Ethernet Frame Structure – Cont.

Addresses: 6 bytes If adapter receives frame with matching destination

address, or with broadcast address (eg ARP packet), it passes data in frame to net-layer protocol

Otherwise, adapter discards frame

Type: indicates the higher layer protocol (mostly IP)

CRC: checked at receiver, if error is detected, the frame is simply dropped

Hubs are essentially physical-layer repeaters: bits coming from one link go out all

other links at the same rate no frame buffering Adapters not Hub detect collisions

Interconnecting with hubs Backbone hub interconnects LAN segments Extends max distance between nodes But individual segment collision domains

become one large collision domain

hubhub

Backbone hub

Switch Link layer device

stores and forwards Ethernet frames examines frame header and selectively

forwards frame based on MAC destination address

when frame is to be forwarded on segment, uses CSMA/CD to access segment

Transparent hosts are unaware of presence of switches

Plug-and-play, self-learning switches do not need to be configured

Forwarding

• How do determine onto which LAN segment to forward frame?• Looks like a routing problem...

hubhub

switch1

Self Learning

A switch has a switch table Entry in switch table:

(MAC Address, Interface, Time Stamp) stale entries in table dropped (TTL can be

60 min) Switch learns which hosts can be reached

through which interfaces when frame received, switch “learns”

location of sender: incoming LAN segment records sender/location pair in switch table

Filtering/ForwardingWhen switch receives a frame:

index switch table using MAC dest addressif entry found for destination

then{ if dest on segment from which frame arrived

then drop the frame else forward the frame on interface

indicated } else flood

forward on all but the interface on which the frame arrived

Switch ExampleSuppose C sends frame to D

• Switch receives frame from from C– notes in bridge table that C is on interface 1

– because D is not in table, switch forwards frame into interfaces 2 and 3

• Frame received by D

address interface

hub hub

switch

Switch ExampleSuppose D replies back with frame to C.

• Switch receives frame from from D– notes in bridge table that D is on interface 2

– because C is in table, switch forwards frame only to interface 1

• Frame received by C

hub hub

switch

address interface

ABEGCD

112312

Switch: Traffic Isolation Switch installation breaks subnet into LAN

segments Switch filters packets:

same-LAN-segment frames not usually forwarded onto other LAN segments

segments become separate collision domains

hub hub hub

switch

collision domain collision domain

collision domain

Switches: Dedicated Access Switch with many

interfaces Hosts have direct

connection to switch No collisions; full

duplex

Switching: A-to-A’ and B-to-B’ simultaneously, no collisions

switch

Switches vs. Routers Both store-and-forward devices

routers: network layer devices (examine network layer headers)

switches are link layer devices Routers maintain routing tables, implement routing algorithms Switches maintain switch tables, implement filtering, learning

algorithms

Switch

Summary Comparison

hubs routers switches

traffi c isolation

no yes yes

plug & play

optimal routing

NetworksBasicsFinal.ppt

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