Chương 2: Mạng Ethernet 2. Giới thiệu về mạng Ethernet. Kết nối mạng cục bộ Ethernet. Chia sẻ trong môi trường Mạng cục bộ.
Quá trình phân phối gói tin từ host to host thông qua switch 1 Cơ bản về mạng What Is a Network? A network is a connected collection of devices that can communicate with each other. Networks carry data in many kinds of environments, including homes, small businesses, and large enterprises. Common Physical Components of a Network Interpreting a Network Diagram Resource-Sharing Functions and Benefits Data and applications Resources Network storage Network User Applications E-mail (Outlook, POP3, Yahoo, and so on) Web browser (IE, Firefox, and so on) Instant messaging (Yahoo IM, Microsoft Messenger, and so on) Collaboration (Whiteboard, Netmeeting, WebEx, and so on) Databases (file servers) Impact of User Applications on the Network Batch applications FTP, TFTP, inventory updates No direct human interaction Bandwidth important, but not critical Interactive applications Inventory inquiries, database updates. Human-to-machine interaction.
Because a human is waiting for a response, response time is important but not critical, unless the wait becomes excessive. Real-time applications VoIP, video Human-to-human interaction End-to-end latency critical Characteristics of a Network Speed Cost Security Availability Scalability Reliability Topology Physical Topology Categories Logical Topologies Bus Topology All devices receive the signal. Star Topology Transmission through a central point. Single point of failure.
Extended-Star Topology More resilient than star topology. Ring Topology Signals travel around ring. Single point of failure. Dual-Ring Topology Signals travel in opposite directions.
More resilient than single ring. Full-Mesh Topology Highly fault-tolerant Expensive to implement Partial-Mesh Topology Trade-off between fault tolerance and cost Connection to the Internet Local Area Network LAN Components Computers PCs Servers Interconnections NICs Media Network devices Hubs Switches Routers Protocols Ethernet IP ARP DHCP Functions of a LAN Data and applications Share resources Provide communication path to other networks LAN Sizes 2. Giới thiệu về mạng Ethernet. a) IEEE STANDARDS: In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication among equipment from a variety of manufacturers.
Project 802 does not seek to replace any part of the OSI or the Internet model. Instead, it is a way of specifying functions of the physical layer and the data link layer of major LAN protocols. Giới thiệu về mạng Ethernet. The IEEE has subdivided the data link layer into two sublayers: logical link control (LLC) and media access control (MAC).
IEEE has also created several physical layer standards for different LAN protocols. Giới thiệu về mạng Ethernet. The relationship of the 802 Standard to the traditional OSI model 26 2. Giới thiệu về mạng Ethernet.
Giới thiệu về mạng Ethernet. Data Link Layer: 1)Logical Link Control (LLC) : In IEEE Project 802, flow control, error control, and part of the framing duties are collected into one sublayer called the logical link control. The LLC provides one single data link control protocol for all IEEE LANs. A single LLC protocol can provide interconncctivity between different LANs because it makes the MAC sublayer transparent.
The purpose of the LLC is to provide flow and error control for the upper layer protocols that actually demand these 28 services 2. Giới thiệu về mạng Ethernet. 2)Media Access Control (MAC): 802. Giới thiệu về mạng Ethernet.
IEEE Project 802 has created a sublayer called media access control that defines the specific access method for each LAN. For example, it defines CSMA/CD as the media access method for Ethernet LANs and the token passing method for Token Ring and Token Bus LANs. In contrast to the LLC sublayer, the MAC sublayer contains a number of distinct modules; each defines the access method and the framing format specific to the corresponding LAN protocol. 30 MAC Address Components 2.
Giới thiệu về mạng Ethernet. Giới thiệu về mạng Ethernet. Physical Layer: The physical layer is dependent on the implementation and type of physical media used. IEEE defines detailed specifications for each LAN implementation.
Giới thiệu về mạng Ethernet. b) Ethernet: The original Ethernet was created in 1976 at Xerox's Palo Alto Research Center (PARC). Since then, it has gone through four generations: Standard Ethemet (10 Mbps), Fast Ethemet (100 Mbps), Gigabit Ethemet (1 Gbps), and Ten Gigabit Ethemet (10 Gbps). Giới thiệu về mạng Ethernet.
Ethernet Evolution CSMA/CD Ethernet Frame Structure Communicating Within the LAN 2. Giới thiệu về mạng Ethernet. Ethernet evolution through four generations 39 2. Giới thiệu về mạng Ethernet.
Giới thiệu về mạng Ethernet. MAC Sublayer : -Frame Format : 41 2. Giới thiệu về mạng Ethernet. MAC Sublayer : -Frame Length : 42 2.
Giới thiệu về mạng Ethernet. MAC Sublayer : -Addressing : Each station on an Ethernet network (such as a PC, workstation, or printer) has its own network interface card (NIC). The NIC fits inside the station and provides the station with a 6-byte physical address. Example of an Ethernet address in hexadecimal notation: 43 2.
Giới thiệu về mạng Ethernet. Unicast, Multicast, and Broadcast Addresses: A source address is always a unicast address-the frame comes from only one station. The destination address, however, can be unicast, multicast, or broadcast. Unicast and multicast addresses 44 2.
Giới thiệu về mạng Ethernet. - Access Method: CSMA/CD 45 2. Giới thiệu về mạng Ethernet. Giới thiệu về mạng Ethernet.
Encoding in a Standard Ethernet implementation: 47 2. Giới thiệu về mạng Ethernet. 2) Fast Ethernet The goals of Fast Ethemet can be summarized: Upgrade the data rate to 100 Mbps. Make it compatible with Standard Ethernet.
Keep the same 48-bit address. Keep the same frame format. Keep the same minimum and maximum frame lengths. Giới thiệu về mạng Ethernet.
MAC Sublayer -Autonegotiation: is a new feature added to Fast Ethemet. Autonegotiation allows two devices to negotiate the mode or data rate of operation - Autonegotiation was designed particularly for the following purposes: 49 2. Giới thiệu về mạng Ethernet. To allow incompatible devices to connect to one another.
To allow one device to have multiple capabilities. To allow a station to check a hub's capabilities.