A Wired Computer Network (LAN) is basically a combination of various Active and Passive Network Components. In this article, we explore the salient points on the important Active and Passive Components that are required for building a basic wired computer network.
Wired Computer Network – Architecture Diagram:
In the above diagram, let us assume that there are basically three departments in an organization that wants to have a LAN across all the departments – IT Department, Department 1, Department 2. So, if we are to plan for the network components department wise, for the IT department, we could plan for,
Router, Core switch
Edge Switches (if required)
UTP Patch panel, UTP Patch Cords
Fiber Patch Panel, Fiber Patch Cords
Cat 6/ Cat6A UTP cables
I/O Box with Face Plate, UTP Patch Cords
PVC Channel – Casing Caping/ Conduits
Fiber Cables (Single Mode or Multi Mode)
The components required in the other two departments would also be similar with the exception of router/ core switch being replaced by distribution/ edge switches.
The above mentioned network components can be broadly divided in to two categories – Active Components and Passive Components. Active Components are those devices which required to be supplied with external power (AC/DC/POE etc) in order to function. They also boost the power of the signals. Passive components do not require to be provided with any electrical power to work – They just plug on to active components and transmit/ carry the information (electrical / optical signals).
Active Network Components:
Network Switches are the basic components of an IP Network. All the network endpoints (like PC’s, Laptops, Printers, etc) connect to these switches. As the name goes, they switch (distribute) the data received from one node to any other node in the network. The network switches come in a variety of configurations, and the popular ones are mentioned below:
8 Port – 10/100/1000 Mbps
16 Port – 10/100/1000 Mbps
24 Port – 10/100/1000 Mbps
48 Port – 10/100/1000 Mbps
Network switches could also have 10/100 Mbps and POE/Non-POE Port combinations. They could also have variations in terms of functionalities – Manageable, Semi-Manageable and Unmanaged Switches. There are even 24/ 48 Port Optical Switches which connect as many optical connections in addition to the 2/4 ports of the optical connections that normal switches have.
The numbers (8, 16 etc.) in the above list refers to the number of Copper UTP Connectors the switch has, and the switches can connect to as many network devices. Each such port supports a maximum speed of 10(or)100 / 10(or)100(or)1000 Mbps depending on the end-point connecting to it (it can auto negotiate to the highest speed supported by the endpoint). Some ports support POE (Power over Ethernet) which is a technology to carry the power as well as data to the endpoints, so that the endpoints need not connect to a separate power source (In the case of Wireless Access Points, IP Phones etc).
Some network switches are of Un-managed type – You can just connect the computers to them, connect them to neighboring switches and extend the network, but beyond that function, not much functionalities/ management features are supported by them. The advantages of unmanaged switches are their cost – they are inexpensive.
Some network switches are of Semi-Managed type – They come with a web browser-based management interface, limited QoS configurations, VLAN configuration, 802.1x support and other such limited management features required for the management of the critical functionalities of the network. But these management features are limited to what is determined by the manufacturer. These switches are slightly more expensive than the unmanaged variety but less expensive than fully manageable switches.
Some network switches are Fully Manageable – They allow the configurations of VLAN’s per port, allow VLAN trunking, support web-based management functionalities, support SNMP/RMON protocols so that each port can be monitored by an SNMP based network management system, support RSTP (Rapid Spanning Tree Protocol) so that alternates cabling paths can be created for uplinking, support Link Aggregation so that couple of cables from individual ports can connect to the uplink switch with double the speed, support port mirroring for management/ call recording, support stacking and many other such useful features which help in maintaining a network.
Layer 3 Switches:
As the network becomes bigger and bigger, it becomes difficult to manage all the nodes using a single layer 2 network segment. One of the main problem with such unsegmented networks are broadcasts which can create performance bottlenecks on large networks. Another issue is the spreading of virus and botnets – with a segmented network, these remain mostly within their segments. That’s why VLAN’s are advocated on large networks which segment the network based on the location/ department/ application etc.
But the devices in one segment of the network would need to invariably communicate with the other segments – Especially in centralized networks where all the servers are designed to be in a common VLAN and the nodes communicating with them are from different VLAN’s. In such cases, there needs to be a Layer 3 network device that performs seamless Inter-VLAN routing without affecting the performance of the network – This is exactly the reason why Layer-3 switches are required. They are capable of performing both the Layer 2 Switching and Layer 3 Routing at Line Rate. They also allow to configure flexible network wide security policies and perform Layer 3 QoS functionalities which are critical in converged networks which carry a substantial amount of real-time traffic that require low latency.
Passive Network Components:
Structured Cabling has become quite common for inter-connecting the various active devices in an IP network. So the following passive components are commonly utilized in an IP Network for Structured Cabling:
- Cat 6 UTP (Un-shielded Twisted Pair) Copper Cables – These are the network cables that connect a PC/ endpoint to a network switch. Some times, they are also used to provide inter-connectivity between switches as long as the distance is not greater than 90 meters, which is the distance they support for transmitting data without using any repeater (repeater function is provided by using network switches).
- Cat 6 UTP Patch Cords – These are one meter/ 2 meter factory crimped cables with RJ-45 connectors installed at both ends. Actually, the Cat 6 Cables are not recommended to be directly terminated in either the network switch or the PC/endpoint. Only the patch cords terminate on both devices and connect to the Cat 6 Network cable through an I/O Box and UTP patch panel.
- Network Rack – Network Racks are either wall mounted or Floor Standing types depending upon their size. Common sizes of network racks range from 6U to 42U. All the network equipments are designed in multiples of 1U so as to be accommodated in to these racks with standard fittings. They generally have a width of 19”. The network racks come with a glass door, lock and key, fans required for cooling, trays, power supplies, cable managers and all other accessories.
- I/O Box and Face Plate: The I/O Box and Face Plate are kept near the computers and a UTP patch cord is used to connect the Face Plate with the network port in the PC. The Cat 6 UTP cable which comes from the switch terminates in to a permanent connection behind the I/O Box.
- UTP Patch Panel: The UTP Patch Panel is used for terminating all the Cat 6 Cables that come from various PC’s/endpoints in the network (Actually I/O Box) to the rack. These Cables are permanently connected behind the UTP Patch Panel and UTP Patch Cords connect from the respective ports in front to the network switches. This allows for flexible moves, adds and changes without disturbing the switch ports. All the ports in the patch panel are labelled for easy identification of which node they are connected to.
- Optical Fiber Cables: For carrying data over 90 meters, Optical Fiber Cables are used. These cables use light for transmission of data instead of the electrical signals used by the UTP cables. They can carry data for longer distances – even to a few kilo meters without having to repeat the signals in between. There are two types of cables – Single Mode (Used for higher bandwidth requirements for longer distances) and Multi Mode (Used for shorter distances). They connect directly to the Fiber Patch Panel at either end. Usually they come in multiples of 6 Cores – 6 Core, 12 Core, 24 Core being common. For each connection, two cores are used – one for transmit and another for receive.
- Fiber Patch Panel/ Patch Cords: The Optical Fiber Cables are terminated on either end using the Fiber Patch Panel, Pigtails and Coupler assembly. Actually each core of the Fiber Cable is spliced to fit in to the Fiber Patch Panel. A Fiber Patch Cord connects to the Patch Panel and the Fiber interface of the Network Switch. The Fiber interface is usually an SFP Port over which a Fiber Module is inserted (Mini-Gbic interface). This Fiber Module can connect to the fiber patch cord directly.
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Related Article: A basic Enterprise LAN Network – Architecture diagram & Components.
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