Types of Network Devices
1. Hub
2. Switch
3. Router
4. Repeater
5. Network card
6. Bridge
7. Gateways
HUB
As its name implies, a hub is a center of activity. In more specific network terms, a hub, or concentrator, is a common wiring point for networks that are based around a star topology. Arcnet, 10base-T, and 10base-F, as well as many other proprietary network topologies, all rely on the use of hubs to connect different cable runs and to distribute data across the various segments of a network. Hubs basically act as a signal splitter. They take all of the signals they receive in through one port and redistribute it out through all ports.
Hub works on Physical Layer of OSI model.
SWITCH
A Switch is a devicethat provides a central connection point for cables from workstations, servers, and peripherals. In a star topology, twisted-pair wire is run from each workstation to a central switch/hub. Most switches are active, that is they electrically amplify the signal as it moves from one device to another. Switches no longer broadcast network packets as hubs did in the past, they memorize addressing of computers and send the information to the correct location directly. Switches are:
- Usually configured with 8, 12, or 24 RJ-45 ports
- Switch works on Data-Link Layer of OSI model.
- Often used in a star or star-wired ring topology
- Sold with specialized software for port management
- Usually installed in a standardized metal rack that also may store net DSL modems, bridges, or routers
Switches subdivide larger networks and prevent the unnecessary flow of network traffic from one segment to another, or in the case of cross-segment traffic, switches direct the frames only across the segments containing the source and destination hosts.
This ensures the integrity of our data; it does nothing to increase overall network speed. Switches help to ensure additional network access opportunities for attached devices (increasing speed and reducing traffic) by restricting data flows to local segments unless frames are destined for a host located on another segment. The switch examine the destination address and forward the requisite frames only across the destination segment, leaving all additional segments attached to that switch free from that particular broadcast and (theoretically) able to facilitate local-segment traffic. Rather than being a passive connection between multiple segments, the switch works to ensure that network traffic burdens the fewest number of segments POSSIBLE.
Difference between a hub and a switch
Hubs and switches are different types of network equipment that connect devices. They differ in the way that they pass on the network traffic that they receive. Switches differ in some ways. They can be of the store-and-forward type, storing each incoming packet in an internal buffer before forwarding it, or cut-through, beginning to forward packets already after their header is in and before the rest of the packet has been received. Hubs repeat everything they receive and can be used to extend the network. However, this can result in a lot of unnecessary traffic being sent to all devices on the network. Hubs pass on traffic to the network regardless of the intended destination.
In a small network (less than 30 users), a hub (or collection of hubs) can easily cope with the network traffic generated and is the ideal piece of equipment to use for connecting the users.
When the network gets larger (about 50 users), you may need to use a switch to divide the groups of hubs, to cut down the amount of unnecessary traffic being generated.
