Problem about Bus Topology

[Digimon]

Can i use any methods to install bus topology except using coaxial cable, T-shaped plug and terminator? Can i use CAT5e to install the bus topology?

If i use coaxial cable to install bus topology veritably, how can i connect the end of the bus network to the switch with LAN RJ45 ports for going to the internet?

[chrisbliss18]

Ahh... Tricky question. When I first read the question, I thought, "nope, that's the way you make a bus topology network", but I was wrong. Technically, a series of computers all connected to a hub using CAT5 cable is using bus topology. The reason for this is simple. In a bus-based network design, all the systems on that network are connected to a shared communication "line". When a device sends data on this shard communication line, all the other devices receive that data, but only the machine that the data is intended for will pay attention to the data sent. This is exactly what a hub does. In essence, the hub is doing the same thing as that single cable that all the machines connected to with t-connectors. A hub is nothing more than a repeater; data comes in on one port and the hub repeats this data to all the other ports. So, technically, a network consisting of nothing more than hubs is a bus topology network.

In order to truely have the functioning behavior of a star topology network, you would have to use a switch, which only sends data to the intended recipient rather than repeating it to every device.

As for whether or not it is possible to attach a network using coax to a network using CAT5, you can. You will need to get an intermediary of sorts. This intermediary will have the ability to connect to both the coax-based network and the CAT5-based network. This device can then act as a gateway between the two different networks.

[Digimon]

many people said bus network is not popular now when i asked them. so i have ignored this question already. but is the situation you said still apperared in favour?

i have another doubtful question too. people said using switch rather than hub because hub will broadcast the data to all pc, but why is hub still sold in the market? is it has any advantages?

also, do u have any information about the intermediary of sorts , the converter between coax and cat5?

thanks!

[chrisbliss18]

Bus networks are very inefficient. In order to ensure successful data transmission, each machine must monitor the network and wait for just the right moment to send the data. Then it must monitor what is occuring during the data send in order to see if there was a data collision. If there was a data collision, then it needs to decide how to resend the data. As you can see, very inefficient.

Switches have built-in logic circuitry that acts as a traffic controller. Essentially, it can tell all the traffic to stop and allow one port to send data through to the other port. This is why the devices are called switches; they switch where the data goes depending on where it is supposed to go, similar to how railroad switches connect different sections of track. Some switches are so "intelligent" that they can allow multiple ports to send at the same time. In other words, if port 1 wants to send data to the machine at port 5 and a machine on port 3 wants to send data to port 2, these switches can allow for both of those data transmissions to occur simultaniously. As you can see, switching technology was a giant step forward in the efficiency of networks. It takes the burden off of the individual machines and puts it on a single devices.

Something else that I haven't mentioned is that the bandwidth across a hub is shared whereas the bandwidth across a switch is dedicated. In other words, if you have a hub with 4 100Mbit devices attached, each device will, at best, be able to send and receive data at approximately 25Mbit/s. A switch on the other hand, because of the way switching works, allows for the full bandwidth to be used for each connection each time data is sent.

You say that hubs are still on the market, but they are in much more diminished numbers than they were a few years ago. The only advantage that hubs had over switches was that they were inexpensive by comparison. Switches have steadily gone down in price, down to a point where hubs aren't necessary since the switches are cheap enough to allow home owners to purchase them. As a result, it's hard to find a variety of hubs in stores anymore.

Since you are still asking about how to connect an older network to a broadband connection, I'll take that to mean that you currently have a bus network and want to connect all these machines to the internet using your broadband connection. As I said before, this is possible, but I do not recommend doing it. The primary reason that I don't recommend it is because it could prove to be quite a challenge to set everything up properly. It would also provide no end to all sorts of technical problems that would be hard to troubleshoot since I wouldn't think that too many people would have experience working with such a setup.

My recommendation would be to upgrade the network. Get a switch with enough ports to handle all the machines in the network (I don't know large the network is, so more than one may be necessary), run CAT5 to each machine, and replace the network cards if needed. I understand that my recommendation could be quite expensive depending on the size of your network, but it is the only way to ensure that the network is as stable and robust as possible.

As for what to use as an intermediary, I would think that devices exist to bridge such networks, but they may be quite expensive now since there can't be much demand for them anymore. You may be able to find such a device on eBay though. If you can't find a device to do it for you, add a CAT5 network card to one of the machines and bridge the two network devices. Depending on what operating system that machine is running, this could be easy or hard to do.