ACTIVE NETWORK DEVICES

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:

Architecture Diagram - Active and Passive Components in an IP Network
Architecture Diagram – Active and Passive Components in an IP Network

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,

Network rack,

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:

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.