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Ethernet switch vs. ethernet hub?

Discussion in 'Tech Talk' started by Packin' Heat, Oct 15, 2006.

  1. Packin' Heat

    Packin' Heat

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    are those two things one and the same?


    First off this is a wired network. I've got my cable modem receiving the internet. From there I go to a netgear RP614 router. From the router, I go to 2 desktops, 1 networked printer and my Vonage VoIP. All those things have taken up all Ethernet ports on the router. I need to add a second networked printer. So if I have this right, all I need to get is an Ethernet switch and plug it into my router and just like that I've more ports to expand. Kinda like a USB hub.

    ...is that right?
     
  2. ThreadKiller

    ThreadKiller Socialism Sucks

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    Techically speaking a hub and a switch aren't the same thing. But for all practical purposes they fullfil the same role. Switches are "smarter" than hubs and maintain full bandwidth at each port.

    I don't know the last time I saw a hub in a store so you're going to get a switch. :)

    Anyway, buy a switch, connect it to your router (being careful to observe which port on the switch is the "uplink" port) and then connect whatever toy you wish to the remaining switch ports.
     

  3. berniew

    berniew Liberty

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    The difference is in what are called 'collisions' a true switch will not cause collisions, a hub will.

    Or to put it another way a switch is a hub with 'traffic control'
     
  4. IndyGunFreak

    IndyGunFreak

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  5. Tennessee Slim

    Tennessee Slim Señor Member CLM

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    First short answer:
    Yes, you are correct (provided we’re talking about networkable printers).

    Second still short but slightly longer answer:
    Yes, but have you considered setting up a USB printer instead and using one of your existing PCs as a print server (which any 32 or 64-bit Microsloth OS will do natively)?

    First really long answer:
    This is a blatant oversimplification and there will be many exceptions to my analogies. That said, ...

    A hub is like a 4-way intersection with no control measures (stop signs, etc) or signposts. There’s nothing present to cause the traffic to slow down so it’s very fast. But neither is there anything to bestow right-of-way so there are lots of collisions between *ss-hauling data (in direct proportion to the volume of traffic). And with nothing indicating the most direct route, all traffic is ‘cloned’ at each hub intersection and identical traffic goes down each alternate road. This doesn’t affect the time the traffic that has chanced onto the most direct route requires to reach its destination but it does needlessly increase the volume of traffic over all the other routes.

    A switch is like the same intersection with a (slightly smart) traffic signal added. When there’s a conflict, it gives the right of way to traffic from one direction so collisions are avoided. And its primitive intelligence enables it to watch the passing traffic and learn, over time, which way its regular customers mean to be going. After the break-in period, for instance, it knows that the blue ’51 Studebaker with the gangster sidewalls means to turn left and it thereafter will direct it that way.

    A router is a like a switch with several extra management functions built in. For one thing, it can be taught in advance what will be the best route for reaching certain destinations, reducing ramp-up time (but increasing reliance on proper management). And it not only suggests certain routes, it also can forbid certain routes. But probably the biggest change is that it can see in the trunk of the passing cars and base its decisions, not only on their intended destination, but also on what they are carrying.

    The hub is the dumbest and least expensive to manufacture. The fact that it is the least capable also means it is the easiest to administer. From the standpoint of speed, it also could be the fastest of the three, depending on the volume of traffic. But it also could be the slowest, depending on the volume of traffic (but that would be an extreme case).

    The switch falls in the middle on most counts, to include cost of manufacture, level of administration required and speed of networking traffic. In terms of processing power, its administrative overhead is comparatively low so its collision avoidance campaign pays off at a relatively modest volume of traffic. Once this break-even point is reached, compared to the hub’s unmanaged traffic, the collision-free, switch-managed network becomes the faster of the two.

    The router is the opposite end of the spectrum from the hub. It costs the most to build, requires the most administration, and can have a significant impact of the speed of passing traffic while it thinks about where each one should go. The upside is that there are fewer wrong turns taken and – provided it’s properly managed – no one ever gets lost.

    As with all things IT, you should get by with the lowest functioning device that will perform the required tasks. Networking 60 PCs with a box full of 4-port hubs would not provide satisfactory results if all 60 users wanted to join in a network game of Age of Warcraft (too many collisions, and gamers a temperamental about low ping times). And if you had two subnets connected via a slow network connection (such as a low bandwith frame relay), routers would better preserve that connection's limited capacity by restricting its use to the traffic that was authorized to go to the opposite subnet.

    So it all comes down to your requirements, the compromises you can live with, and the resources you have available.

    IMO, with so few devices networked, you have no need for a router. A switch or even a hub would be adequate.

    Addendum meaningless to this conversation but thrown in anyway for the sake of argument:
    I presume you meant “print device” rather than “printer”. According to Mr. Bill, the hardware gizmo that you feed the paper to and which spits out your printed documents is a “print device”. A “printer” is the software hosted by a computer which, in turn, controls the hardware “print device”.

    So, in Microsloth parlance:

    Print device = HP Laserjet 4200
    Printer = driver :freak:
     
  6. Packin' Heat

    Packin' Heat

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    well I went ahead and grabbed a Netgear Ethernet switch for 29.99, stuck him in the back of the router and presto, everything worked with less than a second of thought. It would have been nicer to just have a router with more ports but it was cheaper to just get the switch as the router was relatively new and perfectly functional anyway.
     
  7. Cassius

    Cassius

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    Heh, not to nitpick you tech guys but as a tech guy myself, I must point out that the difference between switches/hubs is about more than just collisions.

    Switches offer "switched" traffic. Hubs do not.

    This means that any packet sent over a hub is broadcasted to all the ports on the hub, and any port has the capability of reading the packet. Computers are smart enough to read the target address of the packet and disregard it if it is not for them. However, you can place a network card into a special surveillance mode and see all the traffic broadcasted over a hub.

    With a switch, a packet sent from machine A to machine B goes DIRECTLY to the port machine B is on, and none of the other devices on the switch will ever have a chance to see the packet, much less read it.

    So it's more like a traffic light with separate turning lanes divided by concrete dividers where you can't see the other traffic crossing the intersection at the same time as you =)
     
  8. stooxie

    stooxie NRA Life Member

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    To answer your question, a hub copies all data to all ports. If something comes in on port 1, destined for port 4, ALL ports gets the data. Hubs share the bandwidth so if two nodes are talking at max speed there is nothing left for anyone else.

    Switches learn the hardware ethernet addresses (MAC address) of all the devices connected to it and store them in a table. When packets come in it inspects them to see where they are going. Then it sends them to the port that contains the destination address. Fast switches can provide "wire speed" switching to all ports. Most consumer switches have a finite backplane speed but it's usually fast enough. As someone else said, a switch eliminates the problems of collisions, as long as you use full duplex connections.

    -Stooxie