Samanathon.com

An Introduction

Let me begin by introducing myself: You can call me the Angry Networker, and I’m a cynical network specialist who has spent too much time dealing with ridiculous network issues and wanting to punch way too many idiots for telling me that IT means sitting in a cubical answering phone calls ~ making 30 grand a year.

Gather Around Kids

I’ll begin with a story about some people who prefer hubs instead of switches.

OH MY GOD. Did I fall into a time warp back to the mid 90’s were 8-port hubs were gods gift to SOHO networks??? Because I think I did. A few years ago I worked at Staples for all of two weeks (and became the fastest mover of those crappy warranty plans in the Tri-State area!) and I kid you not, I was prepared to slap anyone who would come in looking for a hub. Later, out of college and into my first ‘real job’, I landed in a place where we managed hundreds of computers. One day while Ghosting computers, I was told the reason Ghosting 50 computers at once failed, is because I used a switch to connect them instead of a hub… I mean this was an actual fight, it was bad…

I know switches are new, shiny, strange and scary devices. What do you mean they don’t forward data to EVERY port, my God, what’s a packet?!?!

What’s The Difference?!

Alright, I’m going to get into why hubs are stupid. In all seriousness, hubs ACTUALLY are stupid. A hub is known as a multi-port repeater. It is designed to work on Layer 1 of the OSI model - the Physical layer, meaning it handles bits via electrical signals.

Regular repeaters work by accepting the incoming signals, cleaning them up (regenerating them, thus removing static/interference that may have built up) and pumping them out of the outgoing port. A hub does the same thing, but pumps the signal back out of every port that’s connected to a host. This causes a slew of problems. In half duplex mode you have the potential for collisions, where two computers send data at the same time - if only it caused some soft of melt down that would be cool to watch and maybe take a few idiots with it… To prevent collisions, half-duplex uses CSMA/CD, carrier sense multiple access/collision detection. When a collision is detected, it’ll send a signal to the hosts calling them fools, and telling them to count to an arbitrary random number and resend the data. Full-Duplex takes care of this; however, hubs with any amount of traffic will bottle neck tremendously.

A switch is different. A switch operates on Layer two of the OSI model, making decisions based on MAC addresses (yea your network card has a PHYSICAL address, a lot like your house, but the difference is, if I knew your house address I’d probably burn it down. Your phone number would be similar to a Logical address (IP)).

Switches work by ‘learning’ the MAC address attached to each port of the switch. It stores these addresses in a MAC table. When you connect a host and send data, the switch will remember which port the source MAC was on, and then check the table for the destination MAC, if it doesn’t find said MAC, if floods the packet to all ports except the original port the data came in on. When it learns these addresses, it allows hosts to talk to other hosts simultaneously via VCs, or virtual circuits.

An Example

So here is an example, 4 people standing together, person 1 is talking out loud to person 2, but persons 3 and 4 can hear. Asides from the obvious security risk, if 3 needs to talk to 4, he can’t because it’ll interrupt 1. That’s a hub. A switch would change the situation greatly: 1 would be whispering to 2 in their ear, and 3 can whisper to 4 at the same time. Get it? I hope so.

Now, with this information, how are you going to argue with me that a hub is better then a switch!? Ok, I asked repeatedly why we use hubs and not switches. Well I got a response once saying that “switches didn’t work”.

Impossible, a switch would never NOT work in the situation where you are using a hub. With some scrounging I found out they were using Managed switches. Great, you see the words managed and unmanaged - obviously managed HAS to be better… um, NO! Not for every situation. You see, with managed switches you have to do something very important with them… Manage them. They need to be configured, fooled around with, and stood up for dinner. If a simple network is your intension, unmanaged is the way to go.

Let’s Review

Hubs

• Stupid
• Flood incoming data to all ports/hosts
• Security risk
• Severe bottleneck on networks
• Collision possibilities
• Not more expensive then switches

Switches

• Creates virtual circuits between hosts
• No collisions (creates a collision domain)
• Fast hardware switching
• Not going to cause situations where a hub will be better ^[1]

That’s all I really have for today. I hope that through my incessant loss of hope for all humanity you can extrapolate some knowledge from this article and put it to good use.

Remember Kids: Just say NO to hubs.

^[1] Hubs will work better in these situations, making this article null and void:

• Paper weights
• Geek Bling
• Moderately dangerous projectiles
• Ant farms
• Dog toys
• Argument starters

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