Tutorial&info,networks basics

Networking Basics For : Level 1 – Networks and Computer Science Diploma Deanship 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

TCP/IP Description and Configuration

Testing Connectivity with Ping

Troubleshooting Internet Connections

Network Math ISA will be covered well, by Dr. Baha

IP Addresses and Network Masks

Networking Fundamentals Objectives

Storage - Area Networks (SANS)

Virtual Private Networks (VPN s )

Using Layers to Analyze Problems

Using Layers to Describe Data Communication

OSI Layers Provides connectivity and path selection between two host Provides Logical address No error correction, best effort delivery.

Shielded Twisted-Pair Cable (STP)

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

Function of Protocol in Network Communication Explain network protocols Network protocols are used to allow devices to communicate successfully

Function of Protocol in Network Communication Define different protocols and how they interact

Function of Protocol in Network Communication 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

Layers with TCP/IP and OSI Model Describe TCP/IP Model

Layers with TCP/IP and OSI Model Describe the Communication Process

Layers with TCP/IP and OSI Model Explain protocol data units (PDU) and encapsulation

Layers with TCP/IP and OSI Model Describe the process of sending and receiving messages

Layers with TCP/IP and OSI Model 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.

Layers with TCP/IP and OSI Model Define OSI

Layers with TCP/IP and OSI Model Compare OSI and TCP/IP model

Addressing and Naming Schemes Explain how labels in encapsulation headers are used to manage communication in data networks

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

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

Applications – The Interface Between Human and Data Networks 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 Applications – The Interface Between Human and Data Networks

The Role of Protocols in Supporting Communication Describe the roles of client and server processes in data networks

The Role of Protocols in Supporting Communication List common Application Layers services and protocols

The Role of Protocols in Supporting Communication 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

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 ARP Each adapter on LAN has unique LAN address Broadcast address = FF-FF-FF-FF-FF-FF = adapter MAC address allocation administered by IEEE Manufacturer buys portion of MAC address space (to assure uniqueness) 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)

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) 1A-2F-BB-76-09-AD 58-23-D7-FA-20-B0 0C-C4-11-6F-E3-98 LAN 237.196.7.23 237.196.7.78 237.196.7.14 237.196.7.88 Question: how to determine MAC address of B knowing B’s IP address?

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 or switch

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 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 hub

Interconnecting with hubs Backbone hub interconnects LAN segments Extends max distance between nodes But individual segment collision domains become one large collision domain hub hub hub 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... 1 2 3 hub hub hub switch

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/Forwarding When switch receives a frame: index switch table using MAC dest address if 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 Example Suppose 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 A B E G C 1 1 2 3 1 hub hub hub switch A B C D E F G H I 1 2 3

Switch Example Suppose 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 address interface A B E G C D 1 1 2 3 1 2 hub hub hub switch A B C D E F G H I

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 collision domain collision domain collision domain hub hub hub switch

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 A A’ B B’ C C’

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

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