Network Topologies, Wireless Networks, and Devices Explained
Network Topologies and Wireless Basics
Physical Star and Logical Bus: A network can have a physical star topology but behave as a logical bus. In a logical bus, devices send signals across the network, and all devices receive them, regardless of their physical location. Messages contain information specifying the intended recipient; other devices ignore the message.
Basic Service Set (BSS) in Wireless Networks: A BSS consists of fixed and mobile stations, optionally including an access point (AP). An ad hoc network is a BSS without an AP, while an infrastructure network is a BSS with an AP.
802.11 LAN Frame Types
- Management Frames: Used for initial communication between stations and access points.
- Control Frames: Used to control access to the channel and for acknowledgment.
- Data Frames: Used to carry data and control information.
Bluetooth Technology
Bluetooth is a wireless LAN technology connecting devices in a small area. A Bluetooth network is called a picorred. Several picorredes form a scatter network. A picorred consists of one primary and up to seven secondary devices, using the IEEE 802.15 protocol.
Bluetooth Picorredes
A picorred can have up to eight stations, one primary and the rest secondary. Secondary stations synchronize with the primary. Communication can be one-to-one or one-to-many. Picorredes can combine to form a scatter network. A secondary station in one picorred can act as a primary in another.
Network Devices
Bridges
A bridge operates at both the physical and link layers. It regenerates signals and verifies MAC addresses. A bridge connects two network segments using the same protocol. It maintains a table relating addresses to ports. Transparent bridges forward and filter frames and can use the spanning tree algorithm to prevent loops.
Switches
A switch interconnects network segments, moving data based on the destination MAC address. Unlike hubs, a switch learns MAC addresses, allowing direct communication between ports.
Routers
A router routes packets based on logical addresses, typically connecting LANs and WANs. It uses a routing table, updated by dynamic routing protocols, to make routing decisions.
Intranets
An intranet is a private network using Internet technology to securely share information within an organization, preventing external access.
ATM Networks
Virtual Paths (VP) and Virtual Circuits (VC)
A virtual path (VP) provides a connection between switches. Networks are based on virtual circuits (VC). Cells belonging to the same message follow the same virtual circuit, maintaining their order until reaching their destination.