Schematic for a Networking Hub and Switch

[BharatNT2IE]

Hello,

I am trying to find out the schematic for at Networking hub and switch, to better understand collision and broadcast and duplex logic.

I was re-visiting the ethernet cabling ( straight through ,cross over etc etc) . I mentioned that (1,2) are used for Transmitting and (3,6) are used for receiving then why in half duplex can a station not send and receive at the same time unless , i have attached of what is my understanding of HUB . Is this schematic correct.Please kindly take a look at the attachment.

Is so can anyone share the schematic (basic) for a switch.

Thanks
Bharat C P

 

[MacGyverS2000]

A schematic will not help you understand what is basically happening in the firmware of the router... collision handling, broadcast messaging, etc. are all firmware level items.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[BharatNT2IE]

I am trying to understand the full and half duplex logic. So i am trying to understand the consequence of each logic at the Physical layer. Basically i am trying to understand PHY layer.

In short i am trying to learn, the consequence of each and every action. When i plug in a cable what happens

a) To the router processor. ( How will the router or switch detect it which part of the IOS is engaged...etc)
b) How does it detect the speed ( How will it figure it out, obviously it need to use the physical cable to determine it, but what mechanisms the switch/router using to detect the speed.)

Thanks
Bharat C P

 

[Skogsgurra]

Dan is perfectly right.

A schematic diagram doesn't tell you anything. Only that there are some wires that connect some IC:s.

What happens inside those IC:s, which are mostly processors with firmware that handles all the tasks you are mentioning, is not revealed by any schematic diagram. A rough parallel is a city map. That city map tells you where buildings, parks, railway stations, streets etcetera are. But it doesn't describe what all the people in the city are doing, how they move or for what purpose. Yes, the parallel is rough, but I couldn't find a better one all of a sudden.

You need to study the documents that describe what each layer does. The physical layer is the least complicated and I think that you need to understand the overall structure first. I'm afraid that you need to work hard to "delearn" what you think that you know. The better you get rid of those thoughts, the better you will eventually understand what really happens.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[BharatNT2IE]

Gunnar, i agree with you "to work hard to "delearn" what you think that you know", there are lot of things one needs to delearn, because if we do something long enough one's alertness/inquisitiveness subsides and the biggest impediment is an illusion that we understand.( until it comes back to haunt us...)

But on the question I believe the i made a hash of it.

I was afraid i used the word "schematic" a bit too liberally. By "schematic" i meant just a simple circuit representation to represent what a hub looks like the circuits.

In Ethernet ( not to patronize) there are 2 pairs (1,2) for Tx and (3,6) for Rx. Before in my mind a hub was just a device where i conveniently thought Hub is a single bus and that is why it is one collision domain and one broadcast domain. After revisiting the topic this idea cropped up, if (1,2) are used for Tx and (3.6) are used for Rx, then why cannot a station send and receive at the same time , after going back to the drawing board i came to a "vague" conclusion of what a physical bus might be like, but then again, i might be wrong, and i might open another can of worms.

If we take WiFi (at least the radio aspect , even more specific till 802.11n) , stations cannot send and recieve at the same there , they are all part of a collision domain, that is because they are sharing the bandwidth (or to put it in the most rudimentary form they are sharing the air).

So the gist of it , trying to see how the physical connections are? why one station cannnot send and receive at the same time? I hope you i made myself clear. I have appended a document in my original post, please let me know if i am going in the right direction.

Thanks
Bharat C P

P.S. Gunnar, i think Physical layer is the toughest subject, they have to be so meticulous in order for the baseline to be good, and then there are a lot of factors in the design to consider.

 

[IRstuff]

"b) How does it detect the speed ( How will it figure it out, obviously it need to use the physical cable to determine it, but what mechanisms the switch/router using to detect the speed.) "

This one is easy; it's called negotiation, which is exactly what dialup faxes do as well. You should do more research; there's tons of information on the web:

http://en.wikipedia.org/wiki/Autonegotiation

The article also explains how the router figures out that something is hooked up to it

TTFN
faq731-376

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[VEBill]

An example: Connectors, the 'magic' chip, and some boring power supply.

 

[VEBill]

I think you need to find the data sheet and application notes for an Ethernet Switch IC.

 

[MacGyverS2000]

if (1,2) are used for Tx and (3.6) are used for Rx, then why cannot a station send and receive at the same time

What makes you think they can't transmit and receive at the same time? That's the entire point of using separate pairs for Tx/Rx, full-duplex communications.

And wi-fi has no issues with full-duplex comms, either. There are somewhat different issues to worry about when it comes to RF comms, but there isn't a problem.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[IRstuff]

The collisions have more to do with different nodes competing for the same time slot.

TTFN
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