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Difference between a Switch and a Hub?

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June 23, 2002 4:55:09 AM

I am setting up a network up at my house and was wondering what is the difference between a Switch and a Hub? Which should I buy amd why? Thanks for the help.

More about : difference switch hub

June 23, 2002 9:50:47 AM

I refer the honorable gentleman to the answer I gave a few moments ago in the networking section.

<b><font color=blue>~ What do you mean "It isn't working!"...Now where's my sonic screwdriver? ~ </font color=blue></b>
June 24, 2002 4:17:33 PM

Switch is smart, hub is dumb.

That is a nice <b><font color=green>Garbage Can</font color=green></b> you have there!
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June 24, 2002 9:46:28 PM

I would just get a switch. The price difference is not that big anyway.
June 24, 2002 10:38:13 PM

a switch will give you a longer possible cable range at each cable speed. for example, in my house, a switch can run 100 megabit cat-5 for the 200 foot cable to my cable modem, while a hub can only do 10 megabit that distance.

The *real* diff is that the switch will communicate only from source port to destination port during any one transfer. So if you have computers A, B, C, D, and uplink on a switch, packets can be sent from A to C and from B to uplink simultaneously without collisions. A hub simply reads an incoming packet and sends it to all the ports except the one it came in on, so switches help with heavy communication too. However, if you want to use any device to listen to ethernet traffic to debug the network, the switch will not work, you will need a hub, because a switch will not echo the traffic to the listening device's port. I guess this won't matter to you though, if you didn't know the difference you probably won't be using packet sniffers any time soon. ;) 

BTW the switch's behavior is automatic - you don't have to configure anything. Look for the words "auto sensing" and "10/100" when you shop. I'm happy with Linksys.

-- Monkeys? What does this .sig have to do with monkeys? --
June 25, 2002 10:48:41 AM

The limit for ethernet cable is 100 meters. Both hub and switch have the same limit. Within that limit a 100 megabit Hub and 100 megabit switch both will do 100 megabit. If you exceding the limit both will have trouble with it.

I get a Siemens 5 port 10/100 Ethernet Switch for $10 a few week ago. As I said the price difference of Hub and Switch is very small now and there is no reason to get a hub instead of a switch.
June 25, 2002 9:52:56 PM

hmm, seems that different sources are in dispute over this, or maybe technology improved since the material I read was printed. (got it from a networking book, would have to dig it out of its little grave to tell you which one, but I'll try if you want me to.)

I believe the specifics of what I read were that the card-to-hub/switch ranges were smaller than the hub/switch-to-hub/switch ranges, and that if you were doing hub-to-switch instead of hub-to-hub it had longer range. This was a couple years ago, though, so maybe I'm muddled.

-- Monkeys? What does this .sig have to do with monkeys? --
June 25, 2002 11:27:00 PM

Hub: If you have a 10 MBps hub and ten computers are on the hub (and all computers are accessing info at the same time), then each computer can only pull info at 1 MBps (10/10=1). Also, hubs are subject to collisions as somebody said above.
Switch: 10 Computers all accessing at same time on a 10 MBps switch, all computers still pull info at 10 MBps. If you have a really good switch, then you can run VLANS on the switch -- this way only certain ports can talk to other ports on the switch. you don;t need this unless you need this switch for a large network.
June 26, 2002 7:46:03 AM

Technology improves but standard does not change. I read it about the limit from serveral book. It is part of standard.
June 27, 2002 12:19:05 AM

Ok, I found where I got my information. Not from a networking manual, but from the Linksys user's guide for the product. It's for topology guidelines, maximum distances between X and Y component for 100Mbit networks.

What do you think, did Linksys just pull these out of thin air? I know "enough" about networking but I'm not an expert by any means, so tell me what you make of it.

It's on page 4:
ftp://ftp.linksys.com/pdf/ezxs55wv2ug.pdf

-- Monkeys? What does this .sig have to do with monkeys? --
June 27, 2002 3:55:41 PM

The Linksys user guide it state:

Each port on your Switch can connect to workstations, file servers, hubs, repeaters, bridges, routers or other switches. Connections to the switch require Category 5 UTP network cabling with RJ-45 tips, not to exceed 100 meters (328 feet) in length.

It did not state switch will give you a longer cable range.
June 28, 2002 12:25:38 AM

Neither will.

100M is the maximum recommended length for this <b>type of cable</b>. Every 100M you need a repeating device.

<b><font color=blue>~ What do you mean "It isn't working!"...Now where's my sonic screwdriver? ~ </font color=blue></b>
June 28, 2002 2:36:22 AM

Exactly, and the switch is a repeating device, and hubs are not.

The length recommendation is in the table on page four like I said. The table says:

-----From---------To---------Max.-Length-----
---Switch-----Switch/hub-----100 meters----
-----Hub----------Hub--------5 meters--------
-Switch/hub---Workstation----100 meters---

sorry if the table doesn't look great - doing it in text. : p

It also says that no more than 2 hubs in a row should be uplinked on a fast ethernet network, and if they are stacking hubs that must be stacked, to use a "stacking cable".

It also says hubs to not act as repeaters, and switches do, verifying by extension my original statement that switches have a longer distance from them to other devices, because you have 100 meters on either side, rather than a max. of 100 meters from one side, through, to the other, which explains where my thought that you can't go as far from hub to hub as from switch to switch came from.

Hub:
[X]----- wire A ----- HUB ----- wire B ----[Y]
for any X and Y the total wire distance cannot exceed 100m.

Switch:
[X]----- wire A --- SWITCH ---- wire B ----[Y]
for any X and Y the length of wire A cannot exceed 100m, and the length of wire B cannot exceed 100m.


-- Monkeys? What does this .sig have to do with monkeys? --
June 28, 2002 2:55:01 AM

Oh, and Upec, my cable modem does have a 100 megabit connect, or at least I hope it does because there's 250 feet of cable between me and it, plugged directly into it at the other end, and my autosensing switches both register 100 megabit full duplex. It's an RCA brand, don't know what model number. That info is all the way across the house and I have a big math exam tomorrow so I'll only look if you're really interested.


-- Monkeys? What does this .sig have to do with monkeys? --
June 28, 2002 3:10:54 AM

A hub, by definition, is a multi port repeater. It sends a signal, regardless of source and destination out all of it's ports. If there's a PC attached, it'll get the data hitting it's NIC.

<b><font color=blue>~ What do you mean "It isn't working!"...Now where's my sonic screwdriver? ~ </font color=blue></b>
June 28, 2002 3:12:13 AM

Quote:

Hub: If you have a 10 MBps hub and ten computers are on the hub (and all computers are accessing info at the same time), then each computer can only pull info at 1 MBps (10/10=1). Also, hubs are subject to collisions as somebody said above.

That's correct, except for the collisions - switches are also subject to them, but not as often.
Quote:

Switch: 10 Computers all accessing at same time on a 10 MBps switch, all computers still pull info at 10 MBps.

That's not entirely true. A switch "connects" two ports together who are communicating. If you have a 10 port switch, and it's a "perfect" switch, then five users can communicate with five other users and all get 100 megabit duplex. This would be a situation where ports are communicating as follows:
1 <--> 2
3 <--> 4
5 <--> 6
7 <--> 8
9 <--> 10

If the ports are communicating like this instead:
1 <--> 2
3 <--> 4
5 <--> 8
6 <--> 8
7 <--> 8
9 <--> 1

then ports 1, 2, and 9 get 50 megabit each, and ports 5, 6, 7, and 8 get 33 megabit each, and ports 3 and 4 get full 100 megabit. (also, 1, 2, and 9 can collide w/ each other, as can 5, 6, 7, 8, and no collisions on 3 or 4.)

-- Monkeys? What does this .sig have to do with monkeys? --
June 28, 2002 3:37:27 AM

Quote:

A hub, by definition, is a multi port repeater. It sends a signal, regardless of source and destination out all of it's ports.

Oh, we're talking about two different things... I meant repeater as in it amplifies and retransmits the signal. Repeater as another name for 'hub' is a different meaning, means it repeats the signal on all ports like you said.

ftp://ftp.linksys.com/pdf/ezxs55wv2ug.pdf

bottom left of page 4 by Acrobat's numbering, or bottom of page 2 by the manual's page numbers... (sory Upec, didn't notice the page number thing before, you looked at manual's page 4 I looked at Acrobat's page 4) but it says:
<i><b>
In Fast Ethernet networks, your 10/100 Switch acts as a repeater, regenerating data signals before passing them on to the next device. Hubs do not function as repeaters.
</b></i>

-- Monkeys? What does this .sig have to do with monkeys? --
June 28, 2002 10:11:35 PM

By hub, I mean each port takes the signal and repeats it. No more, no less.

Hubs are essentially dumb devices. They can be used as repeaters.

<b><font color=blue>~ What do you mean "It isn't working!"...Now where's my sonic screwdriver? ~ </font color=blue></b>
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