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Hubs

Are you planning to network your PCs? Here are some buying tips on one of the most crucial elements of a network: the hub

Managed hubs allow a network administrator to monitor and configure them from a remote location

A hub that supports the Simple Network Management Protocol allows a network manager to configure the hub from anywhere on the network

In data communications, a hub is the pivot of convergence where data arrives from one or more directions and is forwarded to in one or more directions. A hub usually includes a switch (in telecommunications, a switch is a network device that selects a path or circuit for sending a unit of data to its next destination) of some kind. The distinction seems to be that the hub is the point where data comes together and the switch is what determines how and where data is forwarded from the place where data comes together. A hub is a hardware device that acts as a central connecting point and joins lines in a star network configuration.

Who Needs Hubs?
There is a simple way to determine whether you need a hub on your LAN. If you are building a network with a star topology and have two or more machines, you need a hub. There is, however, an exception to this rule. If you are building a 10base-T network and you have only two machines, you can connect them to each other without using a hub.

Classification of Hubs
As you may have already guessed, hubs perform a crucial function for star topology networks. There are many different types of hubs, each offering specific features that allow you to provide varying levels of service.

Passive Hubs: Passive hubs, as the name suggests, are rather quiescent creatures. Hubs don’t enhance the performance of your LAN. They simply take all of the packets they receive on a single port and rebroadcast them across all ports. Passive hubs commonly have one 10base-2 port in addition to the RJ-45 connectors that connect each LAN device.

Active Hubs: Active hubs actually do something other than simply rebroadcast data. Generally, they have all of the features of passive hubs, with the added bonus of actually watching the data being sent out. Active hubs use a technology called store and forward where the hubs actually look at the data they are transmitting before sending it. Active hubs are more expensive than simple, passive hubs and can be purchased in many configurations with various numbers and port types.

Managed Hubs: Managed hubs allow a network administrator to monitor and configure them from a remote location. These smart hubs can be used to fine tune a network's efficiency, allow only certain kinds of traffic on the network, and much more. Using the Simple Network Management Protocol, or SNMP, they give administrators the power and flexibility to fix network problems quickly as they arise. Because of their advanced management features, they're usually a lot more expensive than other hubs.

Features to look for

Here is the list of key features to look for when buying a hub:

Auto-sensing or dual-speed 10/100: Hubs with these features can run at both 10 Mbps and 100 Mbps speeds simultaneously on each port, making them extremely flexible. Recommended for all types of networks, large and small, old and new, and especially networks that have both 10 Mbps and 100 Mbps hardware.

Stackable: Hubs with this option are the most expandable. They can be stacked together, and when stacked, they operate as a single hub, providing more tightly integrated performance over standard hubs when networks are in need of expansion.

SNMP: A hub that supports the Simple Network Management Protocol allows a network manager to configure the hub from anywhere on the network. SNMP can provide managers with network traffic levels, error summaries, and much more. A good number of the hubs above can be equipped to support SNMP. SNMP is best used on networks in buildings with lots of floors, or for LANs with fifty or more users. These hubs are recommended for large networks requiring traffic monitoring.

Standard 10BaseT or 100BaseT: A 10BaseT hub supports 10 Mbps speeds were as a 100BaseT supports 100 Mbps speeds. A standard 10 Mbps hub cannot be connected to a standard 100 Mbps hub unless a special device called a switch or an auto-sensing hub is used in between. Recommend standard 100 Mbps or 10 Mbps hubs for brand new networks that don't need immediate expansion. Remember that hubs run at half duplex. When you need full duplex communication, choose a switch.

Combined features: Some hubs combine two or more of the features above. A 10/100 auto-sensing hub might also be stackable, and it may even come with SNMP management. Some hubs may also come with the option of adding additional features later on; many hubs, for instance, have plug-in modules that can add SNMP or fiber features as the network becomes more complex. Combined-feature hubs like 10/100 auto-sensing stackable models offer the maximum in flexibility and expansion for both small and large networks. They're good for new networks just starting out, or existing networks that plan on expanding in the future.

Mahesh Rathod can be reached at rathodmp@hotmail.com

Things to remember when buying a hub

Hubs connect nodes of all kinds together: A standard hub, for example, might have workstations, file servers, print servers, hubs, and other nodes plugged into it with networking cables.

All hubs can be uplinked together: A hub that has an uplink port can be connected directly to a second hub with a regular straight-through network cable. If neither hub has an uplink port, a crossover cable can be used for uplinking.

Hubs decrease in performance as more users are added: If a hub supports a speed of 100 Mbps, and 5 users are connected to it, each users will receive only 20 Mpbs of available bandwidth. This is fine for hubs that only service a small number of users, but as more users or hubs are added to the network, a switch should be installed to improve performance.

To make things easy, try to use hubs that have enough ports to service all of the nodes of the network. If there are 5 users, the hub should have at least 8 ports to accommodate expansion needs. Like most things, though, hubs are expandable, so a customer can always add more hubs in the future.

Dlink 8 port 10/100Mbps - Rs 5200

Intel 8 port 10/100Mbps - Rs 6250

Edimax 8 port 10/100Mbps - Rs 2600

Ace 8 port 10Mbps - Rs 1700

Dlink 8 port 10Mbps - Rs 2100

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