Topologies and Network Types
A topology defines how the devices are connected. A point-to-point topology has a single connection between two devices. In this topology, two devices can directly communicate without interference from other
devices. These types of connections are not common when many devices need to be connected together.
In a star topology, a central device has many point-to-point connections to other devices. Star topologies are used in environments where many devices need to be connected. When connecting devices together, you connect your computers to a hub or switch (the center of the star).
Star topologies have all networking devices connected to a central device
A bus topology uses a single connection or wire to connect all devices.
A bus topology has all devices connected to a central backbone cable with terminating
resistors on each end of the central backbone cable. This really is not used too much
anymore since one computer, connector, or cable segment can cause the entire network to go down.
In a ring topology, device one connects to device two, device two connects to device three, and so on to the last device, which connects back to device one. Ring topologies can be implemented with a single ring or a dual ring. Dual rings are typically used when you need redundancy.
Ring topologies have every device connected to exactly two other devices. As a good
example have your class stand up and hold hands to form a ring.
There are two types of meshed topologies: partial and full. In a partially meshed environment, every device is not connected to every other device. In a fully meshed environment, every device is connected to every other device.
Network Types
Networks come in a wide variety of types. The most common are LANs and WANs MANs, intranet and extranet VPNs.
The following sections provide a brief overview of each of these network types.
Local Area Networks
Local area networks (LANs) are used to connect networking devices that are in a very close geographic area, such as a floor of a building, a building itself, or a campus environment. In a LAN, you’ll find PCs, file servers, hubs, bridges, switches, routers,multilayer switches, voice gateways, firewalls, and other devices. The media types used in LANs include Ethernet, Fast Ethernet (FE), Gigabit Ethernet (GE)
Wide Area Networks
Wide area networks (WANs) are used to connect LANs together. Typically, WANs are used when the LANs that must be connected are separated by a large distance.Whereas a corporation provides its own infrastructure for a LAN, WANs are leasedfrom carrier networks, such as telephone companies.
Metropolitan Area Networks
A metropolitan area network (MAN) is a hybrid between a LAN and a WAN. Like a WAN, it connects two or more LANs in the same geographic area. A MAN, for example,might connect two different buildings or offices in the same city.
Virtual Private Networks
A virtual private network (VPN) is a special type of secured network. A VPN is used to provide a secure connection across a public network, such as an internet. Extranets typically use a VPN to provide a secure connection between a company and its known external users or offices. A VPN typically provides authentication, confidentiality, and integrity to create a secure connection between two sites or devices. Authentication is provided to validate the identities of the two peers. Confidentiality provides encryption of the data to keep it private from prying eyes. And integrity is used to ensure that thedata sent between the two devices or sites has not been tampered with.and extranet VPNs.
