All the different kinds of networks we use are powered by different internetwork equipment which perform specific functions in the architectural build-up of the network signals. Because of the complex nature of broadband networks, we will dissect the functions of different equipment used in telecommunications.
By Eng. Shingie Levison Muringi
Remember these equipment are manufactured by different vendors but they still function in similar manner due to the open standards incorporated by the Internet Society (ISOC) and its lesser boards such as the International Organization for Standardization (ISO).
Among the current popular network equipment vendors, Cisco Systems Inc, Huawei, Sony Ericson and Lucent Alcatel leads the pack. The beauty about the architecture behind the Internet itself is the interoperability which exists between these equipment from different vendors.
ROUTERS: The router operates at the Network layer of the OSI Model and is used to forward packets across network segments to reach a certain destination address. Do not be confused between a router and a bridge – a bridge simply forwards packets or frames based on their destination address from one connected network segment to another. A router can determine where a packet should be sent to given its final destination (IP address).
Usually, routers forward packets to other routers, but sometimes routers also forward to other pieces of network equipment. A router is usually used to connect a home computer to an “always-on” Internet connection through the home network. To appreciate what a router really does, run tracert to your favorite website and see how many steps (hops) are involved in getting from your computer to the web server in question. Eg: C.Windows> tracert www.facebook.com
BRIDGE: A bridge also operates at the Data Link layer (aka Layer 2) and is used to connect two (similar or dissimilar) physical network segments together, forming a larger inter-network. It can forward packets or reject them based on their destination (MAC) address. Note: The connected network segments must have same network ID like 192.168.10.0 with all the IP Addresses to be assigned coming from this network ID.
HUB: A hub, at the most basic level networking device, but considered “dumb” and operates at the Physical layer of the OSI model. A hub forwards all signals it receives to all connected network devices. Think of a hub as a “drunk” – when he speaks, he speaks to all around him, even if he really only means to speak with one person.
SWITCH: Because the hub is something of a “drunk,” it can be an inefficient (think about the excess traffic created) and unsecure device. Imagine if you wish to send sensitive credit card information over the network – do you really want every node to receive your electronic signal? To alleviate this, the switch was developed. A switch operates at the Data Link layer of the OSI model. It uses the MAC sub-layer to forward the relevant frames of information only to the intended recipient. Messages can still be broadcast, but this is only an option and not the normal condition. Unlike the “drunken” hub, the switch can speak softly to one person at a time or announce to the crowd. The Network+ exam tends to test you on this difference between a hub and switch, so keep it fresh in your mind.
GATEWAY: A gateway is any device that serves to interface with other networks using dissimilar protocols . For example, a gateway might interface between a home network and the Internet or between a NetBIOS network and an IPX/SPX network. A gateway operates in any of the seven OSI layers.
WAP: A Wireless Access Point is a device that allows wireless devices to access and to communicate with the network. It acts as a bridge between the wired, traditional network and other wireless devices. Alternatively, it can act as a bridge between wireless devices and another, linked WAP. It typically operates in the Network layer of the OSI model as a sort of router/bridge/switch combination. Note that most WAP devices direct traffic by MAC address, making them switched.
More Network Equipment and their functions to be covered in the next #TechExchange Episode.
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