Hubs How a Hub Works How a Hub Works Diagram When & Where to Use a Hub When & Where to Use a Hub Cost of a Hub
Bridges How a Bridge Works How a Bridge Works Diagram When & Where to Use a Bridge When & Where to Use a Bridge Cost of a Bridge Cost of a Bridge
Switches How a Switch Works How a Switch Works Diagram When & Where to Use a Switch When & Where to Use a Switch Cost of a Switch Cost of a Switch Avaya ERS 2550T-PWR 50-port network switch
Routers How a Router Works How a Router Works Diagram When & Where to Use a Router When & Where to Use a Router Cost of a Router Cost of a Router Dlink DIR Wireless N Router Cisco 2800 Series Integrated Service Router
Gateway How a Gateway Works How a Gateway Works Diagram When & Where to Use a Gateway When & Where to Use a Gateway Cost of a Gateway Cost of a Gateway Cisco 32U CME Base, CUE and Phone FL w/4BRI, 1VIC
Firewall How a Firewall Works How a Firewall Works Diagram When & Where to Use a Firewall When & Where to Use a Firewall Cost of a Firewall Cost of a Firewall Cisco ASA 5505 Series Adaptive Security Appliance
Wireless Access Point How a WPA Works How a WPA Works Diagram When & Where to Use a WPA When & Where to Use a WPA Cost of a WPA Cost of a WPA Cisco WAP 2000 Wireless G Cisco Aironet 1040 Series
How a Hub Works Sends data from one computer to all other computers on the network Low cost & low function machine Works at Layer 1 of OSI Can use Twisted Pair, Coaxial, or Fiber Connections Works as repeater to regeneration attenuated signals Sometimes referred to as a concentrator Ethernet hubs utilized bus network topology which utilizes Carrier Sense Multiple Access with Collision Detection (CDMA) in a physical star topology Utilizes Token Passing in a Token Ring Hub
Diagram of How A Hub Works Physical Star Topology of a Bus or Token Ring Network
When & Where A Hub Is Used A Hub is generally used in a small closed collision domain. A true hub works as a repeater but has evolved into a combination of repeater/bridge/switch. They represent a connection point for an Ethernet or ring network topology. They are utilized within the construction under the rule of network design. The rule is a design guideline for Ethernet computer networks covering the number of repeaters and segments on shared-access Ethernet backbones in a hybrid star-tree topology. It means that in a collision domain there should be at most 5 segments tied together with 4 repeaters, with 3 segments containing active terminals.
Cost Of A Hub The cost of a true hub is dependent on the number of ports and bandwidth. Prices vary from a few dollars upward to a hundred dollars. From
How a Bridge Works A Bridge separates two collision domains. It works at Layer 2 of the OSI model. It creates a table of known MAC addresses and blocks traffic to addresses that it knows is not located across the Bridge. The table is built dynamically as traffic attempts to pass from one collision domain to another. Generally combined today with switching and router functionality sometimes referred to as a B-router.
Diagram of How a Bridge Works
When & Where a Bridge is Used Network bridging describes the action taken by network equipment to allow two or more communication networks, or two or more network segments to create an aggregate network. Bridging is distinct from routing which allows the networks to communicate independently as separate networks. A network bridge is a network device that connects multiple network segments. There are four types of network-bridging technologies: simple bridging multiport bridging learning, or transparent bridging source route Source:
Cost of A Bridge Finding a true one function bridge is no longer available in the marketplace. The function has been added into a switch. Pricing varies on number of ports and bandwidth. Prices range from a few dollars to several hundred. From
How a Switch Works A network switch (sometimes known as a switching hub) is a computer networking device that is used to connect devices together on a computer network. A switch is considered more advanced than a hub because a switch will only send a message to the device that needs or requests it, rather than broadcasting the same message out of each of its ports. A switch is a multi-port network bridge that processes and forwards data at the data link layer (layer 2) of the OSI model. Some switches have additional features, including the ability to route packets. These switches are commonly known as layer-3 or multilayer switches. Switches exist for various types of networks including Fibre Channel, Asynchronous Transfer Mode, InfiniBand, Ethernet and others.
Diagram of How a Switch Works
When & Where a Switch is Used An Ethernet switch operates at the data link layer of the OSI model to create a separate collision domain for each switch port. With four computers (e.g., A, B, C and D) on four switch ports, any pair (e.g. A and B) can transfer data back and forth while the other pair (e.g. C and D) also do so simultaneously, and the two conversations will not interfere with one another. In full duplex mode, these pairs can also overlap (e.g. A transmits to B, simultaneously B to C, and so on). In the case of using a repeater hub, they would all share the bandwidth and run in half duplex, resulting in collisions which would require retransmissions.
Cost of A Switch Switches have replace the repeating hub and bridge in network design and the function of both are contained within the switch. Price varies from several thousands of dollars to just a few depending on number of ports, bandwidth and advanced function. From
How a Router Works A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node.
Diagram of How a Router Works
When & Where a Router is Used The most familiar type of routers are home and small office routers that simply pass data, such as web pages, , IM, and videos between the home computers and the Internet. An example of a router would be the owner's cable or DSL modem, which connects to the Internet through an ISP. More sophisticated routers, such as enterprise routers, connect large business or ISP networks up to the powerful core routers that forward data at high speed along the optical fiber lines of the Internet backbone. Though routers are typically dedicated hardware devices, use of software-based routers has grown increasingly common.
Cost of A Router Routers of various types and function are the backbone of most networks and the core of the Internet. Wireless Routers have become a staple of home and small office networks. Cost vary from several thousand to just a few dollars. From
How a Gateway Works Hardware node or software configuration designed for protocol conversion between disparate networks. Can be a proxy service or provide firewall security. Works at all layers of the OSI model.
Diagram of How a Gateway Works
When & Where a Gateway is Used Gateways, also called protocol converters, can operate at any network layer. The activities of a gateway are more complex than that of the router or switch as it communicates using more than one protocol. Source:
Cost of A Gateway Due to the function of network gateway hardware, the price of these devices range from several hundred of dollars upwards of thousands.
How a Firewall Works In computing, a firewall is a software or hardware-based network security system that controls the incoming and outgoing network traffic by analyzing the data packets and determining whether they should be allowed through or not, based on applied rule set. Firewalls can be defined in many ways according to your level of understanding. A firewall establishes a barrier between a trusted, secure internal network and another network (e.g., the Internet) that is not assumed to be secure and trusted. Many personal computer operating systems include software-based firewalls to protect against threats from the public Internet. Many routers that pass data between networks contain firewall components and, conversely, many firewalls can perform basic routing functions.
Diagram of How a Firewall Works
When & Where a Firewall is Used Types of Firewalls Packet filtering firewalls Packet filters act by inspecting the "packets" which are transferred between computers on the Internet. If a packet matches the packet filter's set of rules, the packet filter will drop the packet or reject it. Stateful filtering firewalls Perform the work of packet filters but operate up to layer 4 of the OSI model. Stateless filtering firewalls Require less memory, and can be faster for simple filters that require less time to filter than to look up a session. They may also be necessary for filtering stateless network protocols that have no concept of a session. However, they cannot make more complex decisions based on what stage communications between hosts have reached. Application level firewall The key benefit of application layer filtering is that it can "understand" certain applications and protocols such as File Transfer Protocol (FTP), Domain Name System (DNS), or Hypertext Transfer Protocol (HTTP). This is useful as it is able to detect if an unwanted protocol is attempting to bypass the firewall on an allowed port, or detect if a protocol is being abused in any harmful way. Source: )
Cost of A Firewall Firewall function can be achieved with software or hardware. Price vary depending on device, application and need.
How a Wireless Access Point Works A wireless access point (AP) is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. The AP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself.
Diagram of How a Wireless Access Point Works
When & Where a Wireless Access Point is Used Prior to wireless networks, setting up a computer network in a business, home or school often required running many cables through walls and ceilings in order to deliver network access to all of the network-enabled devices in the building. With the creation of the wireless Access Point (AP), network users are now able to add devices that access the network with few or no cables. An AP normally connects directly to a wired Ethernet connection and the AP then provides wireless connections using radio frequency links for other devices to utilize that wired connection. Most APs support the connection of multiple wireless devices to one wired connection. Modern APs are built to support a standard for sending and receiving data using, these radio frequencies. Those standards, and the frequencies they use are defined by the IEEE. Most APs use IEEE standards. Source: