Table Of Content

CCNA Study Guide v2.62 – Aaron Balchunas 1 ___________________________________________ Cisco CCNA Study Guide v2.62 © 2012 ________________________________________________ Aaron Balchunas CCNA Study Guide v2.62 – Aaron Balchunas 2 Table of Contents Part I – General Networking Concepts Section 1 Introduction to Networking Section 2 OSI Reference Model Section 3 Ethernet Technologies Section 4 Hubs vs. Switches vs. Routers Section 5 STP Section 6 IPv4 Addressing and Subnetting Section 7 TCP and UDP Section 8 IPv6 Addressing Section 9 Introduction to 802.11 Wireless Part II – The Cisco IOS Section 10 Router Components Section 11 Introduction to the Cisco IOS Section 12 Advanced IOS Functions Part III - Routing Section 13 The Routing Table Section 14 Static vs. Dynamic Routing Section 15 Classful vs. Classless Routing Section 16 Configuring Static Routes Section 17 RIPv1 & RIPv2 Section 18 IGRP Section 19 EIGRP Section 20 OSPF Part IV – VLANs, Access-Lists, and Services Section 21 VLANs and VTP Section 22 Access-Lists Section 23 DNS and DHCP Part V - WANs Section 24 Basic WAN Concepts Section 25 PPP Section 26 Frame-Relay Section 27 NAT * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 3 ________________________________________________ Part I General Networking Concepts ________________________________________________ * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 4 Section 1 - Introduction to Networks - What is a Network? Α network is simply defined as something that connects things together for a specific purpose. The term network is used in a variety of contexts, including telephone, television, computer, or even people networks. A computer network connects two or more devices together to share a nearly limitless range of information and services, including: • Documents • Email and messaging • Websites • Databases • Music • Printers and faxes • Telephony and videoconferencing Protocols are rules that govern how devices communicate and share information across a network. Examples of protocols include: • IP – Internet Protocol • HTTP - Hyper Text Transfer Protocol • SMTP – Simple Mail Transfer Protocol Multiple protocols often work together to facilitate end-to-end network communication, forming protocol suites or stacks. Protocols are covered in great detail in other guides. Network reference models were developed to allow products from different manufacturers to interoperate on a network. A network reference model serves as a blueprint, detailing standards for how protocol communication should occur. The Open Systems Interconnect (OSI) and Department of Defense (DoD) models are the most widely recognized reference models. Both are covered in great detail in another guide. * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 5 Basic Network Types Network types are often defined by function or size. The two most common categories of networks are: • LANs (Local Area Networks) • WANs (Wide Area Networks) A LAN is generally a high-speed network that covers a small geographic area, usually contained within a single building or campus. A LAN is usually under the administrative control of a single organization. Ethernet is the most common LAN technology. A WAN can be defined one of two ways. The book definition of a WAN is a network that spans large geographical locations, usually to connect multiple LANs. This is a general definition, and not always accurate. A more practical definition of a WAN is a network that traverses a public or commercial carrier, using one of several WAN technologies. A WAN is often under the administrative control of several organizations (or providers), and does not necessarily need to span large geographical distances. A MAN (Metropolitan Area Network) is another category of network, though the term is not prevalently used. A MAN is defined as a network that connects LAN’s across a city-wide geographic area. An internetwork is a general term describing multiple networks connected together. The Internet is the largest and most well-known internetwork. Some networks are categorized by their function, as opposed to their size. A SAN (Storage Area Network) provides systems with high-speed, lossless access to high-capacity storage devices. A VPN (Virtual Private Network) allows for information to be securely sent across a public or unsecure network, such as the Internet. Common uses of a VPN are to connect branch offices or remote users to a main office. * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 6 Network Architectures A host refers to any device that is connected to a network. A host can also be defined as any device assigned a network address. A host can serve one or more functions: • A host can request data, often referred to as a client. • A host can provide data, often referred to as a server. • A host can both request and provide data, often referred to as a peer. Because of these varying functions, multiple network architectures have been developed, including: • Peer-to-Peer • Client/Server • Mainframe/Terminal In a basic peer-to-peer architecture, all hosts on the network can both request and provide data and services. For example, two Windows XP workstations configured to share files would be considered a peer-to-peer network. Peer-to-peer networks are very simple to configure, yet this architecture presents several challenges. Data is difficult to manage and back-up, as it is spread across multiple devices. Security is equally problematic, as user accounts and permissions much be configured individually on each host. In a client/server architecture, hosts are assigned specific roles. Clients request data and services stored on servers. An example of a client/server network would be Windows XP workstations accessing files off of a Windows 2003 server. There are several advantages to the client/server architecture. Data and services are now centrally located on one or more servers, consolidating the management and security of that data. As a result, client/server networks can scale far larger than peer-to-peer networks. One key disadvantage of the client/server architecture is that the server can present a single point of failure. This can be mitigated by adding redundancy at the server layer. * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 7 Network Architectures (continued) In a mainframe/terminal architecture, a single device (the mainframe) stores all data and services for the network. This provides the same advantages as a client/server architecture – centralized management and security of data. Additionally, the mainframe performs all processing functions for the dumb terminals that connect to the mainframe. The dumb terminals perform no processing whatsoever, but serve only as input and output devices into the mainframe. In simpler terms, the mainframe handles all thinking for the dumb terminals. A dumb terminal typically consists of only a keyboard/mouse, a display, and an interface card into the network. The traditional mainframe architecture is less prevalent now than in the early history of networking. However, the similar thin-client architecture has gained rapid popularity. A thin-client can be implemented as either a hardware device, or software running on top of another operating system (such as Windows or Linux). Like dumb terminals, thin-clients require a centralized system to perform all (or most) processing functions. User sessions are spawned and managed completely within the server system. Hardware thin-clients are generally inexpensive, with a small footprint and low power consumption. For environments with a large number of client devices, the thin-client architecture provides high scalability, with a lower total cost of ownership. The two most common thin-client protocols are: • RDP (Remote Desktop Protocol) – developed by Microsoft • ICA (Independent Computer Architecture) – developed by Citrix * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 8 Section 2 - OSI Reference Model - Network Reference Models A computer network connects two or more devices together to share information and services. Multiple networks connected together form an internetwork. Internetworking present challenges - interoperating between products from different manufacturers requires consistent standards. Network reference models were developed to address these challenges. A network reference model serves as a blueprint, detailing how communication between network devices should occur. The two most recognized network reference models are: • The Open Systems Interconnection (OSI) model • The Department of Defense (DoD) model Without the framework that network models provide, all network hardware and software would have been proprietary. Organizations would have been locked into a single vendor’s equipment, and global networks like the Internet would have been impractical, if not impossible. Network models are organized into layers, with each layer representing a specific networking function. These functions are controlled by protocols, which are rules that govern end-to-end communication between devices. Protocols on one layer will interact with protocols on the layer above and below it, forming a protocol suite or stack. The TCP/IP suite is the most prevalent protocol suite, and is the foundation of the Internet. A network model is not a physical entity – there is no OSI device. Manufacturers do not always strictly adhere to a reference model’s blueprint, and thus not every protocol fits perfectly within a single layer. Some protocols can function across multiple layers. * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 9 OSI Reference Model The Open Systems Interconnection (OSI) model was developed by the International Organization for Standardization (ISO), and formalized in 1984. It provided the first framework governing how information should be sent across a network. The OSI model consists of seven layers, each corresponding to a specific network function: 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data-link 1 Physical Note that the bottom layer is Layer 1. Various mnemonics make it easier to remember the order of the OSI model’s layers: 7 Application All Away 6 Presentation People Pizza 5 Session Seem Sausage 4 Transport To Throw 3 Network Need Not 2 Data-link Data Do 1 Physical Processing Please ISO further developed an entire protocol suite based on the OSI model; however, the OSI protocol suite was never widely implemented. The OSI model itself is now somewhat deprecated – modern protocol suites, such as the TCP/IP suite, are difficult to fit cleanly within the OSI model’s seven layers. This is especially true of the upper three layers. The bottom (or lower) four layers are more clearly defined, and terminology from those layers is still prevalently used. Many protocols and devices are described by which lower layer they operate at. * * * All original material copyright © 2013 by Aaron Balchunas ( CCNA Study Guide v2.62 – Aaron Balchunas 1 0 OSI Model - The Upper Layers The top three layers of the OSI model are often referred to as the upper layers: • Layer-7 - Application layer • Layer-6 - Presentation layer • Layer-5 - Session layer Protocols that operate at these layers manage application-level functions, and are generally implemented in software. The function of the upper layers of the OSI model can be difficult to visualize. Upper layer protocols do not always fit perfectly within a layer, and often function across multiple layers. OSI Model - The Application Layer The Application layer (Layer-7) provides the interface between the user application and the network. A web browser and an email client are examples of user applications. The user application itself does not reside at the Application layer - the protocol does. The user interacts with the application, which in turn interacts with the application protocol. Examples of Application layer protocols include: • FTP, via an FTP client • HTTP, via a web browser • POP3 and SMTP, via an email client • Telnet The Application layer provides a variety of functions: • Identifies communication partners • Determines resource availability • Synchronizes communication The Application layer interacts with the Presentation layer below it. As it is the top-most layer, it does not interact with any layers above it. (Reference: http://docwiki.cisco.com/wiki/Internetworking_Basics) * * * All original material copyright © 2013 by Aaron Balchunas (