CCNA (Cisco Certified Network Associate)

1. CCNA (Cisco Certified Network Associate) By SyedMunawer Hassan (Assistant Engineer)

2. What is Network

3. Categories of Networks • Local Area Network (LAN) • Metropolitan Area Network (MAN) • Wide Area Network (WAN)

4. Local Area Network • Privately owned networks within a single building or campus of up to few kilometers in size. • LAN has own Hardware for communication i.e. no service provider is involved.

5. Metropolitan Area Network (MAN) • Is basically bigger version of LAN and normally use similar technology. • It may be a means of connecting a number of LANs into a larger network. • A MAN is wholly owned by a service provider or a public company.

6. Wide Area Network (WAN) • Provides a long distance transmission of data, voice , image and video information over a large geographical area.

7. Basic Components of Network • Network Interface Card • NIC Converts digital data into a form that is acceptable by the media (i.e. Electrical / Optical / Radiowave) • Hub / Switch • Used to connect different networked devices • Media (Wired / Wireless) • Provide a way of commuication. It can be wired (Guided) or wireless (Unguided)

8. NIC Selection Criteria • Type of media • Bandwidth • Communication type (Full / Half Duplex) • Interface (USB/ISA/PCI etc)

9. Repeater • Is a device which receives signal regenerates it amplifies it and then pass to other station.

10. HUB • A hub is a multiport repeater. • It makes network scaleabale (i.e. more devices can be connect to network) • It has single Broadcast and single collision domain. • In order to cop up collision CSMA/CD (Carrier Sense for Multiple Access / Collision Detection

11. Data Sending Techniques • Broadcast : send data to all • Multicast : Send data to sepecific group • Unicast : Send data to single node / computer

12. Bridge • A bridge is used to devided collision domain. • It connects two or more network segments • It is software based • Each port of a bridge is a single collision domain. • It is a slow device which can connect only up to 16 network segments.

13. Switch • A hardware based modified form of bridge. • Contains an IC (ASIC application specific IC) for switching functions. • Supports Unicast,Multicast and Broadcast. • Each port is a single collision domain • It has 1 broadcast domain.

14. Functions of Switch • Address Learning • Static • Dynamic • Forward / Filter Decision • Loop Avoidance

15. MAC Address • Broadcast MAC FFFF.FFFF.FFFF.FFFF

16. Firewall • A firewall is a part of a computer system or network that is designed to block unauthorized access while permitting authorized communications. It is a device or set of devices that is configured to permit or deny network transmissions based upon a set of rules and other criteria. • Firewalls can be implemented in either hardware or software, or a combination of both. Firewalls are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which inspects each message and blocks those that do not meet the specified security criteria.

17. Firewall Techniques • There are several types of firewall techniques: • Packet filter: Packet filtering inspects each packet passing through the network and accepts or rejects it based on user-defined rules. Although difficult to configure, it is fairly effective and mostly transparent to its users. It is susceptible to IP spoofing. • Application gateway: Applies security mechanisms to specific applications, such as FTP and Telnet servers. This is very effective, but can impose a performance degradation. • Circuit-level gateway: Applies security mechanisms when a TCP or UDP connection is established. Once the connection has been made, packets can flow between the hosts without further checking. • Proxy server: Intercepts all messages entering and leaving the network. The proxy server effectively hides the true network addresses.

18. Router • Each port of a router is a single Broadcast domain.

19. NMS • HP Openview • Cisco Works • Solar Wind • OP Manager • Rmon • Net Scout

20. Introduction of OSI Model • ISO International Standard Organization Established in 1947 Multinational body dedicated to worldwide agreement Standard of international level Covers all aspects of network communications • It is Open System Interconnection MODELAllow two different Machines to connect without change in hardware and softwareIt is model for understanding and designing a network architecture 

21. The Model • Layered framework Designed for communication across all types of computer system 7 separate but related layer Each defines segment of process of moving information across network.

22. Why we need OSI Model • To allow different types of network hardware and software to communicate with each other • Avoidable duplication of equipment resources • To breaks network communication into smaller, simpler parts that are easy to develop • To facilitates standardization of network components to allow multiple – vendor development and support

23. 1. Physical Layer • Physical characteristics of interfaces and medium. • Representation of bits. • Physical topology. • Line configuration. • Data rate. • Synchronization of bits. • Transmission mode.

24. 2. Data Link Layer • Framing. • Physical addressing. • Flow control. • Error control. • Access control.

25. 3. Network Layer • Logical addressing. • Routing.

26. 4. Transport Layer • Service-point addressing. • Segmentation and reassembly. • Connection control. • Flow control. • Error control.

27. 5. Session Layer • Dialog control. • Synchronization.

28. 6. Presentation Layer • Translation. • Encryption. • Compression.

29. 7. Application Layer • Network virtual terminal. • File transfer, access, and management. • Mail services. • Directory services.

30. Summary • The International Standards Organization created a model called the Open Systems Interconnection, which allows diverse systems to communicate.  • The seven-layer OSI model provides guidelines for the development of universally compatible networking protocols.  • The physical layer coordinates the functions required to transmit a bit stream over a physical medium.  • The data link layer is responsible for delivering data units from one station to the next without errors.  • The network layer is responsible for the source-to-destination delivery of a packet across multiple network links.  • The transport layer is responsible for the process-to-process delivery of the entire message.  • The session layer establishes, maintains, and synchronizes the interactions between communicating devices.  • The presentation layer ensures interoperability between communicating devices through transformation of data into a mutually agreed upon format.  • The Application Layer Enable user, (human or software) to access the network and Provides user interface and support for services (email, Remote file access, shared database management system).

31. How to connect a Switch to computer • Step 1 create a Hyper terminal session by setting default values. • Set communication attributes.

32. Types of Switch • Switches can be classified into • Unmanaged (Layer 2 ) Switch • Managed (Layer 2 / Layer 3 ) Switch

33. Operation Modes of Switch/Router • Following are the modes of Switch • User mode (>) • Privileged mode (#) • Global Configuration Mode (config) # • Interface Configuration Mode (config-if)# • Line Configuration Mode (config-line)#