Network interconnect type: 1, the same type of local area network interconnection. 2. Different types of local area networks. 3. LAN will be associated with the main network. 4. Interconnect the local area network through the WAN (WAN). 5. LAN access external computer system.
Repeter (REPEATERS): The simplest local area extension device operates in the physical layer, that is, the bottom of the OSI. Different types of local area networks use hackers.
The function of the repeater: zoom in to zoom in or regenerates.
Repeats using the HUB structure can support Ethernet and tag ring networks with a large number of devices, but it does not support long-distance connections.
Bridge: Run in the data link layer.
Bridge function: function of the function of the current signal between the different network segments and the function of packet addressing signals within the link layer.
Multiple LAN Interconnection Techniques: Source Routing Brindge, Source Routing Brindge.
The source path algorithm is two advantages than the spanning Tree algorithm: 1, which can fully utilize all router capabilities. 2, the source path algorithm does not need to be treated in the style. Disadvantages of the source path algorithm: need to be added in the source station, and the calculation route is required when the network configuration is changed. Spanning Tree is sometimes also known as transparent bridge. Translation Bridge is a bridge that is coupled to Ethernet and marked ring network. There are not many coupons, the same type of network segment, the bridge is the best interconnected device. The bridge is mainly used for the same type of local area network interconnection. • Conversion bridge is used for different types of local area networks. • Packaging bridge is used in FKKI main network interconnection LAN.
Routers: Support for multiple link connections, with dynamic selection routing to balance the communication load of each router. The router runs on the network layer. There are three advantages over the ride sedan: 1, it can be filtered and routed according to the packet type. 2. It supports a network between the LAN segments When a link is corrupted, you can select other routes. 3. The router dynamically selects the route based on the network communication.
Three independent routing algorithms: 1, point-to-point protocol (PPP). 2, Routing Information Protocol (RIP). 3, the shortest path protocol (OSPF).
The PPP protocol only requires a router to operate with each other. The RIP protocol allows the route selection function, but always by the shortest route. The OSPF protocol overcomes the above disadvantages for large networks. The bridge is independent of the network layer protocol, while the router relies on the network layer protocol. Multi-protocol routers still cannot support data routes between two LANs of different network layer protocols because routers cannot convert different network layer protocols. Communication in Computer Integrated Manufacturing System (CIMS) is made up of various communication mechanisms, mainly local networks, point a point communication, venue bus, etc.
The characteristics of CIMS communication: 1, communication distance;
Characteristics of the CIMS network: 1, openness; 2, standardization; 3, real-time; 4, rich network services.
The network services are: (1) Venue service; (2) File transfer service; (3) Network file system (NFS); (4) E-mail E-mail; (5) Manufacturing Packet Specification (MMS). 5, adapt to the physical environment and geographical environment. Manufacturing protocol (Manufacturing Automation Protocol, MAP) Map can communicate various computers, medium-programming controllers, robots and smart devices. The MAP is based on the OSI basic reference model. MMS is an extremely important application layer protocol in the automated manufacturing environment. MMS (Manufacturing Message Specification) or (Manufacturing Message Service). The core of the MMS protocol is VMD (Virtual Manufacturing Devi (E); MMS control object is a unified vmd.mms mainly have eight categories of application features: context management, processing program transmission management, machining program running control, variable access, operator communication , VMD Support, Event Management, and Log Management. Site Bus: Refers to a digital serial communication between the primary automation device distributed in the production site and the higher level automation device in the control room. Link. Site bus is defined as two categories: H1, H2H1 bus is a point one point communication link, using a 20mA current loop system to transmit digital signals. H2 bus is a multipoint communication link, shielded twisted pair, coaxial cable or fiber There are more than 100 kHz with baseband transmission or carrier transmission carrier frequency. There are two protocols to be used in Internet, namely serial Line IP, SLIP, and Point-to-Point Protocol, PPP. PPP provides three features: (1) The method of framework can be clearly clear, and the beginning of the F-frame, the frame format also handles errors. (2) Link Control Protocol is used to start the line, test, and Select the functional negotiation and shutdown connection. (3) The negotiation method of the network layer optional function is independent of the network layer protocol used, so it can be applied to the NetWork Control Protocol, NCP) Public Switchphone Network ( Public Switch Telephone Network. Public Packet Data Network (Packet Switch Data Network) has become an important transmission system in a wide area network. Digital Pipe: That is, through the line between the user equipment and the transmission device.
Development of high-speed WAN four important solids: (1) For more than 20 years, the speed of computers has increased by millions of times, and the speed of the network is only several thousand times, the rate of solid and network has become a bottleneck. (2) End users not only require transmission of data, but also need to transmit multimedia information such as sound, images, and the application of network environments is increasing, so the network is required to have a wider frequency band. (3) The laying of a large number of optic cables solves the frequency width problem of the transmission medium, and the bottleneck is converted to the rate bandwidth of the switching system. (4) Promotion of US Government High Performance Calculation and Communication Program (HPCC), especially the current governments are stepping on planning national accommodation infrastructure. The difference between the high speed network and existing networks is to require only broadband and require low delay. Main technologies of high-speed network: Asynchronous Transfer mode (ATM) and Co-Fiber Network (SONET) Several high-speed WAN technology: Switch Multimegabit Data Service, SMDS, Frame Relay , Broadband Integrated Service Digitol Network, BISDN. SMDS features: high speed, no connection, wide area network technology; unit switching technology for public data networking services. Frame Relay: Simply provide a network-oriented, low-cost medium-sized public network that delivers data from A-A to a place. The main features of the frame relay: medium speed to high-speed data interface; standard rate is DSI, namely T1 rate; can be used for private network and public network; only transmit data; make variable length packets. Asynchronous trylnasfer mode, atm. The basic concept of ATM is to transmit all information in a small, fixed size packet called cell. Main Features of ATM: Support multimedia communication, including voice, video, and data; to allocate frequency bands on demand; low delay characteristics. ATM main characteristics: connection-oriented technology; use fixed length cells; each cell has an identifier as a flag; all kinds of information is processed, real-time communication can be ensured; no link to the link Wrong control; the link of the link-free link; the address is the concept of virtual channel and virtual path. BISDN is a high speed, asynchronous, time division transfer network, the same network provides various applications of data, voice, and video. Main Features of BISDN: is a broadband network, based on packet transmission; provide ATM-based transmission; support data voice and video integrated services; ATM provides cell-based interfaces; supports exchange and permanent point-to-point service. Three main features of broadband services: (1) Not all services require high transmission rates and broadband. (2) Some services have high bursts. (3) Requirements to networks are services that support various rates, support in burst, to consider the application and delay sensitivity of resurgery. Single transfer mode features: 1, all digital. 2, simple. 3, flexible.
