Components of ER Diagram

Entity-Relationship model gives the possibility to visually describe a database using the components of ER Diagram, entity relationship stencils, relationship symbols, work flow shapes. ER-diagram lets represent the data or entities, attributes of these entities and relationships between them, using standardized Crow’s Foot notation icons or Chen’s notation icons. An entity is an object of the real world, it can exist independently and has the instances which differ in attribute values (properties). The attributes give an unambiguous (uniquely) identification for the instance and are called the primary key, this key can be composite and combine several attributes. ConceptDraw PRO is a professional software available with Entity-Relationship Diagram (ERD) solution from Software Development area that lets create ERDs for various database systems, using Crow’s Foot and Chen’s notations. It is invaluable tool for software engineers and developers, it supports ODBC-compatible databases (Oracle, MySQL, MS Access, MS SQL, InterBase, Firebird and others).

Hybrid Network Topology

A network topology is the topological structure or the arrangement of different elements of computer network. There are several basic types of network topologies, such as star, ring, bus, mesh. But the most popular is a combination of two or more diverse basic network topologies, which is known as hybrid network topology. The examples of hybrid topology are: star-bus, star-ring topologies, etc. Each resulting hybrid topology has its own features, advantages and limitations of its components. Hybrid network topologies are more flexible, reliable, and have increased fault tolerance, the faults in them can be easily diagnosed and corrected, new nodes can be easily added. But at the same time hybrid topologies often are sufficiently expensive and difficult for managing. ConceptDraw PRO diagramming and vector drawing software supplied with the tools of Computer Network Diagrams solution from Computer and Networks area is perfect for schematic description various types of computer network topologies and easy designing Hybrid network topology diagrams.

Metropolitan area networks (MAN). Computer and Network Examples

A Metropolitan Area Network (MAN) is a great computer network located on the large geographical area or region. It is a network bigger than Local Area Network (LAN), but territorially smaller than Wide Area Network (WAN), its diameter usually ranges from 5 to 50 kilometers. MAN usually includes several buildings or even the whole city (metropolis). It is based on high data rate compounds using the fiber channels and other digital data transmission channels. MAN includes a lot of communicating devices, for its construction are used multiple routers, switches and hubs. MAN can combine together several Local Area Networks or Campus Area Networks located in different buildings within a city and provides the Internet connectivity for them. Solutions included to Computer and Networks Area for ConceptDraw Solution Park are the real godsend for those who want design Computer Network Diagrams, and among others the Metropolitan Area Network Diagrams. They offer the libraries with ready-to-use vector design elements, professional-looking examples, samples and templates.