Guide to Networking Essentials 8th Edition PDF

Guide to Networking Essentials 8th Edition Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Chapter 7...

Guide to Networking Essentials 8th Edition Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Chapter 7 Network Reference Models and Standards Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Objectives Describe the OSI and IEEE 802 networking models Summarize the IEEE 802 networking standards Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Introducing the OSI and IEEE 802 Networking Models The Open Systems Interconnection (OSI) reference model proposed by the International Organization for Standardization (ISO) provides a common framework for developers and students of networking to work with and learn from The OSI model is not specific to any protocol suite and can be applied to most networking protocols This model is a seven-layer organization of how data travels from place to place on any given network Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Role of a Reference Model (1 of 2) To see the value of a layered model outside the field of networking, look at an example of a letter being created, sent and delivered by the US Postal Service The letter has to be written The letter has to be placed in an envelope and addressed in the correct format The envelope has to be stamped The local post office in the destination town has to sort the letter correctly based one the zip code and get it on the right plan to the destination The post office in the destination town has to sort the letter correctly for the right part of town The local carrier has to deliver the letter to the correct house The recipient has to receive the letter, open it, and read it A layered approach to a complicated process reduces its complexity and turns it into a series of interconnected tasks Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Role of a Reference Model (2 of 2) Each task of the previous example can be handled separately without affecting the procedures of the other tasks. For example, in the step where the local carrier delivers the letter to the correct house: Let’s say he currently walks on his route, which takes a considerable amount of time He gets an “upgrade” to a delivery truck so that he can perform his task faster As you can see, one part of the process can change but the rest of the process remains unchanged Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Structure of the OSI Model (1 of 7) Figure 7-1 The seven layers of the OSI reference model Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Structure of the OSI Model (2 of 7) To comprehend how a network works as a whole, you need to understand: How each layer functions What networking components and devices operate at each layer How layers interact with one another Each layer in the OSI model has its own set of well-defined functions The functions of each layer communicate and interact with the layers immediately above and below it Example: The Transport layer works with the Network layer below it and the Session layer above it You were introduced to the TCP/IP model in previous chapters so the next slide will compare the two models Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Structure of the OSI Model (3 of 7) Figure 7-2 Comparing the OSI model and the TCP/IP model Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Structure of the OSI Model (4 of 7) Figure 7-3 Layers of the OSI model in the Ethernet0 Properties dialog box Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Structure of the OSI Model (5 of 7)  Each layer provides services to the next higher layer until the data reaches the Application layer  The Application layer has the job of providing services to user applications  Each layer on one computer behaves as though it were communicating with the same layer on the other computer  This behavior is known as peer communication between layers Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. Structure of the OSI Model (6 of 7) Protocol Stack Model Application Transport Internet Network Access Figure 7-4 Peer communication between OSI layers Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Structure of the OSI Model (7 of 7) On data’s way down the protocol stack (model): It’s data is divided into data units suitable for each layer Each unit, called protocol data units (PDU), is passed from one layer to another on its way up or down the protocol stack Some layers add their own formatting to the PDU, which is called a header (encapsulation) When data arrives at the receiving end, it is passed up the protocol stack: At each layer, software reads its PDU data and strips its header information (called deencapsulation) and passes the PDU to the next higher layer The packet leaves the Application layer in a format the receiving application can read Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Application Layer The Application layer (Layer 7) provides interfaces for applications to access network services Examples are file sharing, message handling, and database access Generally, components at the Application layer have both a client component and a server component Common protocols found at Layer 7 include HTTP, FTP, SMB/CIFS, TFTP, and SMTP Possible problems at this layer include missing or misconfigured client or server software and incompatible or obsolete commands used to communicate between a client and server Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Presentation Layer The Presentation layer (Layer 6) handles data formatting and translation For outgoing messages: It converts data into a format specified by the Application layer For incoming messages: It reverses the conversion if required by the receiving application A software component known as a “redirector” operates at this layer It intercepts requests for service from the computer, requests that can’t be handles locally are redirected across the network to a network resource that can handle the request Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Session Layer The Session layer (Layer 5) permits two computers to hold ongoing communications, called a “session”, so applications on either end of the session can exchange data for as long as the session lasts This layer handles communication setup ahead of data transfers and session teardown when the session ends Common network functions at this layer: Name lookup and user logon and logoff The Session layer also manages the mechanics of ongoing conversations such as identifying which side can transmit data when and for how long Checkpointing is performed at this layer, which is a synchronization process between two related streams of data Example: keeping the audio in sync with video Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Transport Layer (1 of 4) The Transport layer (Layer 4) manages data transfer from one application to another across a network It breaks long data streams down into smaller chunks called “segments” Segmenting data is important because every network technology has a maximum frame size called the maximum transmission unit (MTU) The Transport layer includes flow control and acknowledgements to ensure reliability This layer also handles resequencing segments into the original data on receipt The PDU at this layer is a segment UDP’s PDU is often called a “datagram” rather than a segment Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Transport Layer (2 of 4) Figure 7-5 The Transport layer breaks data into segments Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Transport Layer (3 of 4) Figure 7-6 The Transport-layer PDU: a segment Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Transport Layer (4 of 4) Some key fields in the Transport-layer header include: Source and destination port numbers Sequence and acknowledgement numbers Window size Problems that can occur at this layer include segments that are too large for the medium between source and destination networks This situation forces the Network layer to fragment the segments, which causes performance degradation Hackers can exploit TCP’s handshaking feature with a half-open SYN attack (discussed in Chapter 11) Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Layer (1 of 2) The Network layer (Layer 3) handles logical addressing, translates logical network addresses (IP addresses) into physical addresses, and performs best path selection and routing in an internetwork Access control is handled at this layer during the routing process The router consults a list of rules before forwarding an incoming packet to determine whether a packet meeting certain criteria should be permitted through Software components working at this layer include IP, ARP and ICMP Routers operate at this layer A switch with routing capabilities (called a “Layer 3 switch”), also works at the Network layer Problems that can occur at the Network layer often include: Incorrect IP addresses or subnet masks, incorrect router configuration, and router operation errors Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Network Layer (2 of 2) Figure 7-7 The Network-layer PDU: a packet Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Data Link Layer (1 of 3) The Data Link layer (Layer 2) works with frames and is the intermediary between the Network layer and Physical layer It defines how computers access the network medium (also called media access control) The MAC address is defined at this layer A layer 2 frame consists of both a header and a trailer component: The trailer component is labeled “FCS” (frame check sequence) and contains the CRC error-checking code The CRC value is recalculated on the receiving end If the sent and recalculated values agree, the assumption is that the data wasn’t altered during transmission The Data Link layer discards frames containing CRC and other frame errors Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Data Link Layer (2 of 3) Figure 7-8 The Data Link-layer PDU: a frame Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Data Link Layer (3 of 3) The Data Link header contains fields for source and destination addresses After receiving a frame from the Physical layer and verifying the destination MAC address and the CRC, the Data Link layer strips its header and trailer information from the frame It then sends the resulting packet up to the Network Layer for further processing The software component operating at this layer is in the NIC driver Hardware components that operate at this layer include NICs and switches Problems at this layer include collisions and invalid frames, which can be caused by collisions, poor network design, line noise, or NIC driver problems Another problem at this layer results from trying to use incompatible network technologies Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Physical Layer (1 of 2) The Physical layer (Layer 1) converts bits into signals for outgoing messages and signals into bits for incoming messages The type of signals generated depend on the medium: Wire media uses electrical pulses, fiber-optic uses light pulses and wireless media uses radio waves Details for creating a physical network connection are specified at this layer Example: the type of connectors used to attach the medium to the NIC Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Physical Layer (2 of 2) Encoding is representing 0s and 1s by a physical signal such as electrical voltage or a light pulse Encoding happens at the Physical layer Components at this layer include all the cable and connectors used on the medium, along with repeaters and hubs Problems occurring here are often related to: Incorrect media termination EMI or noise that scrambles the signals NICs and hubs that are misconfigured or malfunctioning Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Summary of the OSI Model (1 of 3) The OSI model is a helpful way to categorize and compartmentalize networking activities The OSI model helps explain how data is formatted and how it moves up and down the protocol stack and from computer to computer Table 7-2 on the following slides summarizes the actions occurring at each layer Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Summary of the OSI Model (2 of 3) Layer PDU Protocols/software Devices Function 7. Application Data HTTP, FTP, SMTP, Computers Provides programs with access to DHCP network services 6. Presentation Data Redirectors N/A Handles data representation to application and data conversions, ensures that data can be read by the receiving system, and handles encryption and decryption 5. Session Data DNS, authentication, N/A Establishes, maintains, and coordinates protocols communication between applications 4. Transport Segment TCP, UDP N/A Ensures reliable delivery of data, breaks data into segments, handles sequencing and acknowledgements, and provides flow control Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Summary of the OSI Model (3 of 3) Layer PDU Protocols/software Devices Function 3. Network Packet IP, ICMP, ARP Routers, firewalls, Handles packet routing, logical Layer 3 switches addressing, and access control through packet inspection 2. Data Link Frame Ethernet, token ring, Switches, NIC Provides physical device addressing, FDDI, NIC drivers device-to-device delivery of frames, media access control, and MAC addresses 1. Physical Bits N/A Network media, Manages hardware connections, hubs/repeaters, handles sending and receiving of connectors binary signals, and handles encoding of bits Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Networking Standards The Institute of Electrical and Electronics Engineers (IEEE) defined LAN standards to ensure that network interfaces and cabling from multiple manufacturers would be compatible This effort was called Project 802 to indicate the year (1980) and the month (Feb) of its inception IEEE 802 predates the OSI Model Most of the standards affect the elements from the lower two levels of the OSI Model The 802 specifications describes how NICs can access and transfer data across a variety of networking media and what’s involved in attaching, managing, and detaching these devices in a network Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Specifications (1 of 4) The IEEE numbers the collections of 802 documents starting with 802.1, 802.2, etc… When a technology is enhanced each enhancement is specified by letters after the number For example: 802.3 is the original Ethernet and 802.3u specifies 100BaseT Ethernet Table 7-3 on the following slides lists the major 802 categories The 802.3 and 802.11 are the most widely used technologies of Ethernet and Wi-Fi, as of this point Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Specifications (2 of 4) Standard Name Explanation 802.1 Internetworking Covers routing, bridging, and internetwork communication 802.2 Logical Link Control Covers error control and flow control over data frames (inactive) 802.3 Ethernet LAN Covers all forms of Ethernet media and interfaces, from 10 Mbps to 10 Gbps (10 Gigabit Ethernet) 802.4 Token Bus LAN Covers all forms of token bus media and interfaces (disbanded) 802.5 Token Ring LAN Covers all forms of token ring media and interfaces 802.6 Metropolitan Area Covers MAN technologies, addressing, and services (disbanded) Network 802.7 Broadband Technical Covers broadband networking media, interfaces, and other Advisory Group equipment (disbanded) 802.8 Fiber-Optic Technical Covers use of fiber-optic media and technologies for various Advisory Group network types (disbanded) Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Specifications (3 of 4) Standard Name Explanation 802.9 Integrated Voice/Data Covers integration of voice and data traffic over a single network Networks medium (disbanded) 802.10 Network Security Covers network access controls, encryption, certification, and other security topics (disbanded) 802.11 Wireless Networks Sets standards for wireless networking for many different broadcast frequencies 802.12 High-Speed Networking Covers a variety of 100 Mbps-plus technologies, including 100VG- AnyLAN (disbanded) 802.13 Unused 802.14 Cable Modems Specifies data transport over cable TV (disbanded) 802.15 Wireless PAN Covers standards for wireless personal area networks 802.16 Wireless MAN (WiMAX) Covers wireless metropolitan area networks Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Specifications (4 of 4) Standard Name Explanation 802.17 Resilient Packet Ring Covers emerging standards for very high-speed, ring-based LANs and MANs 802.18 Wireless Advisory Group A technical advisory group that monitors radio-based wireless standards 802.19 Coexistence Advisory A group that addresses issues of coexistence with current and Group developing standards 802.20 Mobile Broadband A group working to enable always-on, multivendor, mobile Wireless broadband wireless access 802.21 Media Independent A group working to enable handoff between wireless networks of Handoff the same or different types 802.22 Wireless Regional Area A group of working to bring broadband access to hard-to-reach Network low-population areas 802.23 Emergency Services A group working to facilitate civil authority communication Working Group systems Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  IEEE 802 Extensions to the OSI Reference Model (1 of 2) The two lowest layers of the OSI model define how computers attach to specific network media These layers also specify how more than one computer can access the network without causing interference with other computers on the network The IEEE 802 specification expanded the OSI model by separating the Data Link layer into these sublayers: Logical Link Control (LLC) sublayer controls data-link communication and defines the use of logical interface points used to communicate to the upper OSI layers Media Access Control (MAC) sublayer manages access to the physical medium and communicates with the Physical layer Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part. IEEE 802 Extensions to the OSI Reference Model (2 of 2) Figure 7-9 The IEEE 802 standard divides the OSI Data Link layer into two sublayers Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Chapter Summary (1 of 2) The OSI reference model and IEEE Project 802 define a frame of reference for networking and specify the operation of most networking technologies in current use The OSI reference model separates networking into seven layers, each with its own purposes and activities Following is a summary of the functions of each OSI Model layer: Application – Provides access to network resources Presentation – Handles data formatting and translation Session – Manages ongoing conversations between two computers Transport – Breaks long data streams into smaller chunks (segments) Network – Provides best path selection and IP addressing Data Link – Defines how computers access the media Physical – Converts bits into signals and defines media and connectors Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.  Chapter Summary (2 of 2) The IEEE 802 project defines a set of networking standards to ensure that network interfaces and cabling from multiple manufacturers would be compatible The IEEE 802.2 standard specifies a Logical Link Control (LLC) and Media Access Control (MAC) sublayer Greg Tomsho, Guide to Networking Essentials, 8th Edition. © 2020 Cengage. All Rights Reserved. May not be scanned, copied or duplicated, or posted to a publicly accessible website, in whole or in part.