Planetarion Forums

madi · 9 Mar 2004, 14:10

i need a website with information about equipment

how a switch works and what is a hub etc

my cisco log in isnt valid since i left uni

Tomkat · 9 Mar 2004, 14:38

I think that the difference is that a hub just links computers together in a big group. So you can make a LAN out of them. But a switch groups them, and then has another socket for you to plug into a router, or server, so the group of computers on the LAN can then connect to the net.

I could be wrong, though.

madi · 9 Mar 2004, 14:48

i know what the difference is
but i want to teach someone at work and i am not very good at explaining so i want some pictures

Spearhead · 9 Mar 2004, 14:57

google ?

Tomkat · 9 Mar 2004, 14:58

Just draw a bunch of computers with lines all going into a circle, for the hub.

And do the same for the switch, but do another line going out of the ring, with "THE INTERNET" written on.

Marilyn Manson · 9 Mar 2004, 15:01

Quote:

Originally Posted by madi

but i want to teach someone at work

Why? Just fire them, surely?

Belgarath The Sorcerer · 9 Mar 2004, 15:07

Quote:

Originally Posted by Marilyn Manson

Why? Just fire them, surely?

This sure does get my vote!

Marilyn Manson · 9 Mar 2004, 15:10

Well If I'm in favour of it, and Belgy's in favour of it, then no more discussion of it is needed.

NEWSBOT3 · 9 Mar 2004, 15:15

one sec madi, let me see if i can steal my last semesters uni notes for you.

NEWSBOT3 · 9 Mar 2004, 15:29

ok, i will download them and upload them somewhere for you.

Deciduous · 9 Mar 2004, 15:37

Hands up anyone who puts 'excellent communication skills' on their CV and is blatantly lying

\o

Dead_Meat · 9 Mar 2004, 15:39

http://computer.howstuffworks.com/lan-switch1.htm

Intrepid00 · 9 Mar 2004, 15:45

Mark this site down, your going to need it later on.

http://www.learntosubnet.com/

NEWSBOT3 · 9 Mar 2004, 15:45

ok, uploaded, will pm url

Ragnarak · 9 Mar 2004, 16:01

erm i thought a hub sent data to all computers, regardless of whether they requested it or not, whereas a switch is more intelligent and just sends to the one that requested the data...

Deepflow · 9 Mar 2004, 16:03

i never did IT at school. I had to wait till i was 19.

NEWSBOT3 · 9 Mar 2004, 16:03

thats a very basic explanation, but life and routing is never simple.

meglamaniac · 9 Mar 2004, 16:22

Quote:

Originally Posted by Tomkat

Just draw a bunch of computers with lines all going into a circle, for the hub.

And do the same for the switch, but do another line going out of the ring, with "THE INTERNET" written on.

Someone has no idea what a switch is then.

The simplest diagram would just be to draw a packet coming in from one pc connected to a hub, followed by the packet being sent to every other connection to the hub.
Obviously for the switch, it only goes to it's intended destination connection (or any uplink/downlink channels if it can't find the intended destination directly - depends how complex you want this diagram!).

It can't be that much of a stretch of the imagination to come up with a few diagrams to show the differences in bandwidth efficiency and so on if you want to include that too...

Deciduous · 9 Mar 2004, 16:22

life, liberty, route of the loom

madi · 9 Mar 2004, 16:43

my understanding is that hubs broadcast and switches address

i was being lazy wanting to send a link to information rather than supplying it myself

Intrepid00 · 9 Mar 2004, 16:46

Quote:

Originally Posted by Ragnarak

erm i thought a hub sent data to all computers, regardless of whether they requested it or not, whereas a switch is more intelligent and just sends to the one that requested the data...

Yes, but they both send broadcasts to all ports. Then their is managed and unmanaged boxes.

meglamaniac · 9 Mar 2004, 16:55

Madi: FIIIIIINNNNNNNEEEEEEEEE
http://computer.howstuffworks.com/lan-switch.htm
You'll have to find your own one for hubs tho.

Intrepid00, switches only send to the port that the data needs to go to.
This is why switches cost more than hubs, because they don't share the bandwidth and hence are vastly more efficient (also they need various other gadgets in them like address lookup tables and so on).
If all 8 connections on an 8 port hub are transmitting at the same time, they get 1/8th of the available bandwidth each. On a switch, everyone gets the maximum bandwidth so long as the gear in the switch can keep up as it makes and breaks connections - a switch basicly makes a direct connection between the two ports currently communicating. As most (household) switches can only make one direct connection at once, the bottleneck is how fast the switch can make the connection, transmit the buffer contents, then break it and move on to the next.

Tomkat · 9 Mar 2004, 18:31

Quote:

Originally Posted by meglamaniac

Someone has no idea what a switch is then.

.

D'oh.

You wouldn't guess I'm applying to be an ICT teacher in September, would you ;(

Intrepid00 · 9 Mar 2004, 19:08

Quote:

Originally Posted by meglamaniac

Madi: FIIIIIINNNNNNNEEEEEEEEE
http://computer.howstuffworks.com/lan-switch.htm
You'll have to find your own one for hubs tho.

Intrepid00, switches only send to the port that the data needs to go to.
This is why switches cost more than hubs, because they don't share the bandwidth and hence are vastly more efficient (also they need various other gadgets in them like address lookup tables and so on).
If all 8 connections on an 8 port hub are transmitting at the same time, they get 1/8th of the available bandwidth each. On a switch, everyone gets the maximum bandwidth so long as the gear in the switch can keep up as it makes and breaks connections - a switch basicly makes a direct connection between the two ports currently communicating. As most (household) switches can only make one direct connection at once, the bottleneck is how fast the switch can make the connection, transmit the buffer contents, then break it and move on to the next.

You went through all that trouble to correct me when switches still send broadcasts to all ports. What a waste of typeing. BTW, when one computer on a hub talks all ports become in use and hence only the computer that intiated the traffic can send data through a hub. Not 1/8 of the bandwidth because all eight ports can't be transmitting at the same time on a hub.

Structural Integrity · 9 Mar 2004, 19:13

Why tell they guy what a switch and hub does? Why not give him one and tell him to put the connectors in the holes and everything will be fine?

skiddy · 9 Mar 2004, 19:35

Quote:

Originally Posted by Tomkat

D'oh.

You wouldn't guess I'm applying to be an ICT teacher in September, would you ;(

I wouldn't hire you, thats for sure.

Hubs broadcast, intended computer gets information.

Switches know where intended computer is and only send to that. They broadcast if it cannot be found.

Routers pass information between subnets/networks

B-Routers are special as they can route NetBEUI which is non-routable, but no one ever uses it anymore.

Repeaters boost signals.

Firewalls analyse and block malicious.

Modems modulate and demodulate.

Cables carry signals.

xBox's play games and DVD's/

Structural Integrity · 9 Mar 2004, 19:41

Quote:

Originally Posted by Tomkat

D'oh.

You wouldn't guess I'm applying to be an ICT teacher in September, would you ;(

And why again do people complain about how bad the educational system is?

Intrepid00 · 9 Mar 2004, 19:44

Quote:

Originally Posted by skiddy

I wouldn't hire you, thats for sure.

Hubs broadcast, intended computer gets information.

Switches know where intended computer is and only send to that. They broadcast if it cannot be found.

Routers pass information between subnets/networks

B-Routers are special as they can route NetBEUI which is non-routable, but no one ever uses it anymore.

Repeaters boost signals.

Firewalls analyse and block malicious.

Modems modulate and demodulate.

Cables carry signals.

xBox's play games and DVD's/

Here I thought Repeaters repeated a signal and amplifiers boosted.

skiddy · 9 Mar 2004, 19:46

The difference being only the method - not the result.

Amplifiers amplify thus letting signal go further before degredation.

Repeaters repeat, thus giving it another x meters before degredation.

Intrepid00 · 9 Mar 2004, 19:49

No, amplifiers amplify signal degradtion and noise. Repeaters repeat signal and remove degradtion.

skiddy · 9 Mar 2004, 19:51

Does the signal travel a shorter distance without either of them.

Yes?

Ta.

Deciduous · 9 Mar 2004, 20:10

As much as I want skiddy to be wrong, repeaters contain an amplifier. Noise isnt really an issue either on a digital network as the signal can be restored without a problem and retransmitted.

But if you want to be picky a repeater doesnt boost signals, an amplifier does.

Structural Integrity · 9 Mar 2004, 21:10

Quote:

Originally Posted by Deciduous

As much as I want skiddy to be wrong, repeaters contain an amplifier. Noise isnt really an issue either on a digital network as the signal can be restored without a problem and retransmitted.

It is a problem...
Peak sharpness degrades if the signal get lower and is amplified.
In school books transmission signals are often drawn as blocks with sharp edges. One block on top of the line for a "1", and one block below the line for a "0".
In reality 0 volts is a binary 0, and 5 volts for a 1.
Also the blocks as shown in text books are not sharp on the actual line.
Imagine you go from a 0 to a 1, from 0 volts to 5 volts. You need a bit of time to make that transition. So what you see in reality is more of a sine shape. No sharp edge but a smooth transition.

See here for a little diagram of what happens:
http://www.nvision1.com/images/refbks/vidbook/1_4.gif

Now, as you signal travels down the line, the 5 volts it started with, might be only 1 volt at the end.
Insert a bit of noise from whatever equipment is placed along the line or even the cable itself.

As your amplifier boosts your signal with a factor 5, it also boosts the natural noise with a factor 5. Along the way the nice sine was already influenced by natural noise, now you amplify the signal and the noise and put it down another line. At a certain point, the computer at the end can see no difference between noise and the actual signal. Making 1's of 0's, or vice versa.

Repeaters interpret the signal, put it through an binary circuit taking out any noise, and put it back on the line. You don't amplify the noise here, so the signal stays in tact.

You can increase the max voltage on the line to make the edges sharper and thus less influenced by noise. People who overclock their CPU or Graphics card sometimes increase the voltage. This does not make your CPU faster, but it makes the difference between 1,s and 0's clearer, because even in CPU the un-sharp edges of a signal and signal degration are a serious problem.
That's why CPU get hotter as they become faster. If they increase frequency, they can not compensate for the transition time before the next bit arrives. So, bit one comes along, with a high signal, then bit two, with a low signal, and then bit three ALREADY comes before the transition from one-to-two is done. They increase the voltage to make the edges sharper.

Marilyn Manson · 9 Mar 2004, 21:12

Geekathon 2004.

Structural Integrity · 9 Mar 2004, 21:16

Quote:

Originally Posted by Marilyn Manson

Geekathon 2004.

But geeks brought you the internet!

Intrepid00 · 9 Mar 2004, 21:17

Don't forget the Flux Capicator.

Stew · 9 Mar 2004, 21:22

He built a time machine, like one in the film I'd seen

meglamaniac · 9 Mar 2004, 21:22

Soap on a rope!
SOAP ON A ROPE!!

Oh, wait...

Marilyn Manson · 9 Mar 2004, 21:25

Quote:

Originally Posted by Structural Integrity

But geeks brought you the internet!

Al Gore is a geek?

Intrepid00 · 9 Mar 2004, 22:03

If voteing YES to give funds to the project is considering inventing, then yes.

Marilyn Manson · 9 Mar 2004, 22:08

No-one mentioned inventing.

Dante Hicks · 9 Mar 2004, 22:16

Quote:

Originally Posted by Marilyn Manson

Geekathon 2004.

Damn geeks with their knowing stuff and technical skills that will benefit them in the workplace. Damn them all the way to hell.

Marilyn Manson · 9 Mar 2004, 22:21

Quote:

Originally Posted by Dante Hicks

Damn them all the way to hell.

This thread is only mildly more interesting than a two-week seminar on modern plumbing methods. You just made it slightly less so.

Dead_Meat · 10 Mar 2004, 04:06

Damn my knowledge of broadband wireless access technologies and the job I have that takes me to exotic places and pays me to stay in expensive hotels around the world.

DAMN IT TO HELL

at0mic.c0w · 10 Mar 2004, 04:08

Quote:

Originally Posted by Dead_Meat

exotic places

u mean like teh outside ?

Dead_Meat · 10 Mar 2004, 04:13

Yes, this is why I drink so much in hotels. Purely to summon courage to venture outside in the morning and be subjected to sunlight

Evergreen · 10 Mar 2004, 06:23

Quote:

Originally Posted by Dead_Meat

Damn my knowledge of broadband wireless access technologies and the job I have that takes me to exotic places and pays me to stay in expensive hotels around the world.

DAMN IT TO HELL

Don't they also pay you to stay in boring places from tiem to time and occassionally less than civilized places where crime there makes crime at home look like boy scouts?