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Don’t worry too much about all some of the terms like “Frame” for now, simply make a note of them, writing things down helps recollection later on.

The biggest draw back of using hubs is that they are not “intelligent” devices. When we speak of intelligence in a piece of networking gear we are referring to the ability to examine the parcel it receives  and determine how to best deliver this parcel of data.

A hub will flood all data received out of all ports. Devices receiving data which they know is not for them will dispose of the data.

Going back to our initial question, “What is a Network?” we answered it by saying that a network is a collection of devices that move parcels of information from A to B.

When you are driving you know a few things, you know where you started and where you are going. To get to your destination you will follow road signs which point towards your destination, without these signs you would not be able to find your way.

These road signs where placed there by someone at some point, every so often someone will come along and clean the signs, fix them up and make sure they are still pointing the direction they need to be pointing.

Your network devices operate in the same way a cross road, initially the cross roads have no signs so no one arriving at the cross roads would find any useful information until the person from the “authorities” comes along and puts up some signs for travellers to use.

So in the networking world what are these signs? These signs are entries in tables held by your networking devise full of addresses, remember an intelligent networking device has this list address that it has either been told about by you the administrator or has learnt dynamically from another networking device. The networking devices like switches and routers use this information to forward your parces of data correctly out of the right interfaces towards their intended destinations. By the way your P.C, your laptop, your tablet computer all have addresses with which they use to identify themselves to receive traffic and send traffic.

Instructor Led Cisco CCNA & CCNP Classroom and self paced study courses.

Intro to Networking

What is a network?

How would you answer this? What would you say if you were asked to explain “what is a network” in your job interview?

To put it simply a network is a collection of devices that move parcels of information from A to B.

Do not think of a network as any more complex than this statement and you will find that networking is a complete doddle, I promise.

Of course there will be those who will think that I am trying to down play the sometimes complex nature of networks, sure, yes networks can be complex but only in the sense that there may be many components involved, but If you take each individual component and examine it as a single standalone function or item then the whole will make more sense and will appear far less complex. Than before. It’s a case of study each tree to understand the forest.

Hubs and the physical layer, the very basics toe in the water time

In the beginning the way in which computers were connected to one another was very primitive compared indeed to today’s methods.

Image a long electrical wire like a clothes line with shorter lengths of wires hanging down, at the end of each of these hanging wires you would find that there was a computer attached. That’s it, that’s the way the earliest networks were put together, they were very simple and very crude, but since that was the only method to connect computers together that was fine.

At some point someone looked at this “clothes line” network and decided it was too messy having this long length of cable snaking around the building so they decided to get a cardboard box and stuff the cable into the box with holes in the box to run the cables down to the computers, so now instead of a network which resembles a centipede we now have a network which resembles a box with lots of wires coming out of it, like in the picture below.

This type of network is referred to as a “Star Topology”

If you were to remove the box you would see only the wires, it would resemble the picture below

So in effect the “clothes line” network and the “box” network are one and the same, the major difference is that the “box” is more than a box it has the ability to amplify any data it receives and repeat the data out to all connected computers, this box has a name, and it is called a hub.

Hubs are very simple devices, they were used to connect multiple machines in an office network. One machine has something to say it will parcel it up into a little package called a “Frame” places it onto the wire, and once on the wire all connected “live” computers will receive a copy of the “Frame” even if they are not the intended recipient

When I started Commsupport in the famous garden shed at the end of my garden on that cold January in 2007 many people used to call and ask how I could offer courses at such low prices when every other training company was charging thousands for the same course, well since that fateful January I have proved that a great course can be delivered despite the low cost much to the distress of my competitors.

With almost 4000 students having attended our courses, we have proved that I and my gang of elves at Commsupport have built a company which is a very hard act to beat let alone follow.
Some would say why didn’t I just tow the line and offer the same courses at the same prices and make a killing. The truth is I could have easily done that, but I have always been the sort of person that loves a good scrap and that’s exactly how we like to view ourselves, we’re the underdogs, friday night bar room brawlers, above all we want to be different from the legions of sharks out there. It is this view that has been the driving force behind the idea that we have to be the first to innovate new ideas and concepts, it really annoys the market but benefits our students.

The first, last and every moment in between my mind is occupied by the single thought of how to improve the experience that my students have with us. Ultimately it is you the student which puts the bread on our table and roof over our heads, this is a sentiment held by all of us at Commsupport, it’s only logical you get the best course possible, to date I think we have done damn good job.

1. BREAK/FIX tm We’re the first school in the country to make it part of every CCNA course to run continual break/fix sessions in the classroom after the labs (The 1st and the best), before Commsupport no other company did this, it has proved so popular that students come to us for that alone.

2. FREE TRAINING DAYS: We’re the first school in the country to offer free one day training sessions to help people to decide if networking was for them before parting with any money.

3. FULLY KITTED OUT LABS: We’re the first school in the country to offer 6 pieces of lab equipment per student on the CCNA courses.

4. LIVE ON-LINE INSTRUCTOR LED CLASSES We’re the first school in Europe to offer line on-line Webinars so that our students can keep as current as possible
5. CUSTOM MADE VIDEOS We’re the FIRST school in Europe to have custom made all of our own complete set of CCNA videos, we don’t cheat you by giving you “Free Videos” out the back of a cheap CCNA manual

6. FREE WORK EXPERIENCE IN OUR CLASSROOMS: We were the first school in the country to offer work experience in the way of the LABRAT so that anyone could gain experience in our classrooms as assistants.

7. UNLIMITED FREE RETRAINING: We were the first to offer complete free re-training with no time limit, no having to take exam first conditions, free re-training means free retraining without the strings attached. we do ask that you attend the whole of the original course

8. FULLY KITTED OUT LABS IN THE PROFESSIONAL COURSES: We were the first school in the country to offer a complete lab per student on the CCNP courses.

9. We’re the first school to offer all of the Advanced CCNA courses with one Lab per student, even though the kit cost an arm and a leg.

10. We’re the first school to RECORD all of our classes for the student to take away with them at the end of the course

As a CCNA candidate you must be familiar with the functions and configuration of trunk links.
In brief a trunk link is any connection between two switches where there is the need to carry traffic for multiple vlans.

When a switch sends traffic out of one of it’s switch ports belonging to a vlan across to another switch it must mark the frame as being a member of that originating vlan on the sending switch so that the receiving switch can determine into which vlan to place the frame.

In the CCNA there are various methods of trunk link configuration that you must know and understand.

The first method of trunk link configuration you must know for the CCNA is the mode known as dynamic desirable. In this mode the port will take it upon itself to negotiate with the peer connecting port to become a trunk link. This Protocol is known as DTP (Dynamic Trunking Protocol), in the CCNA the way in which DTP operates is expected.
Switch(config-if)#switchport mode dynamic auto

As a CCNA candidate you have to know that a port set to DTP (Default on many Cisco Switches) will always try to become a trunk, periodically the port set to Dynamic Desirable will send out a DTP frame, if it receives a DTP frame in return then at that point the two ports will become trunks.

The second method for port setting is known as Dynamic Auto, another topic that as a CCNA student you must know and experiment with. Unlike Dynamic Desirable, the Auto mode is in a passive state and will not issue DTP frames until it receives a DTP frame from an attached port, at which point the auto mode port will reply with it’s own DTP frame and the two ports will then become trunk links and carry all vlans by default.

Switch(config-if)#switchport mode dynamic auto
The third method which as a CCNA candidate you must be aware of is the generally preferred method and is called simply “Trunk”. In this particular mode the port is going to become a static trunk regardless how the other end is set.

Switch(config-if)#switchport mode trunk
When setting a port to “Trunk” many CCNA students believe that DTP is disabled, this is not the case, to disable DTP one must run an exclusive command under the interface prompt, his command is

Switch(config-if)#switchport nonegociate

It is advisable that all ports connecting switches together are set for static trunking and that DTP is turned off.
The point of turning off DTP is so that is no other Cisco device (By somebody wanting view your traffic) to is connected to your switch they will not inadvertently negotiate a trunk link, at which point all of your broadcast traffic from all vlans is visible

If you’re locked out of a router due to not knowing the password don’t worry you can easily get back into the router by changing the configuration register.

The configuration register (CR) is a 16bit number (2 Bytes) written into NVRAM that is used to tell the router where and how to boot, by default the CR is set to load the IOS from flash followed by getting the startup file from NVRAM.is whether to use the contents of NVRAM to load a router configuration.

The default setting for the configuration value on the Cisco router is 0x2102, this setting tells the router to boot normally, i.e take the IOS from Flash and find the Startup configuration from NVRAM.

Below is a table detailing the software configuration meanings
Bit Number Hex Meaning
• 00-03 0x0000-0x000F Boots Field Parameters:
• 0x0000 – Stays at the system bootstrap prompt.
• 0x0001 – Boots the first system image in onboard Flash memory (EPROM).
• 0x0002-0x000F- Specifies a default netboot filename. Enables boot system commands that override the default netboot filename.
• 06 0x0040 – Ignore NVRAM contents
• 07 0x0080 – Disable boot messages
• 08 0x0100 – Break disabled
• 10 0x0400 – IP broadcast with all zeros
• 5,11,12 0x0020, 0x0800, 0x1000 • Console line speed
• 13 0x2000 – Boots default ROM software if network boot fails
• 14 0x4000 – IP broadcasts do not have net numbers
• 15 0x8000 – Enables diagnostic messages
• Ignores NVRAM contents

Step 1: To view the current Configuration Register settings run the command ‘show version’
Here are the main steps to password recovery:

R1# show version | sec Conf
Configuration register is 0x2102

Step 2: Lets go through the steps to recover the router, first of all you need to have a console connection to the router since you will boot the router and during the initial first few moments of the routers boot cycle you will interrupt the boot sequence by performing a break, breaking the boot sequence will take the router into ROM monitor mode.

Your first step is to boot the router and perform a break. This is usually done by pressing the
Ctrl+Break key combination when using HyperTerminal or Alt+B with Tera Term while the router first reboots.

After you’ve performed a break, you should see something like this for a 1841 series router

%SYS-5-RELOAD: Reload requested by console. Reload Reason: Reload Command.
System Bootstrap, Version 12.4(13r)T, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2006 by cisco Systems, Inc.
PLD version 0x10
GIO ASIC version 0x127
c1841 platform with 131072 Kbytes of main memory
Main memory is configured to 64 bit mode with parity disabled
rommon 1 >

At this point, you will be at the rommon 1> prompt, which is called ROM monitor mode.

Step 2: Change the configuration register by using the config-register command. To turn on bit 6, use the configuration register value 0x2142. Remember that if you change the configuration register to 0x2142, the startup-config will be bypassed and the router will load into setup mode.

rommon 1 > confreg 0x2142

You must reset or power cycle for new config to take effect

rommon 2 > reset

Step 3: The router will reload and ask if you want to use setup mode (because no startup-config is used). Answer no to entering setup mode, press Enter to go into user mode, and then type enable to go into privileged mode.

Step 4: Now you’re past the point where you would need to enter the user-mode and privileged-mode
passwords in a router. Copy the startup-config file to the running-config file:

router# copy startup-config running-config

The configuration is now running in random access memory (RAM), and you’re in privileged
mode, meaning that you can now view and change the configuration. But you can’t view the
enable secret setting for the password since it is encrypted. To change the password, do this:

router# config t
router(conf)# enable secret cisco

Step 5: After you’re finished changing passwords, set the configuration register back to the default
value with the config-register command:

router(conf)# config-register 0x2102

Finally, save the new configuration with a copy running-config startup-config and reload the router.

If we had a pound every time we were asked “Why are you so cheap?” we could close our doors and retire.

We wish we could claim that we started the whole discounting revolution but that accolade has to go to the likes of Southwest airlines in America and Ryanair in the UK, they led the way. They showed the world that charging high prices did not necessarily justify the product, but by offering low prices they proved that compromises did not have to be made in safety or the quality of the aircraft which they operated
But how is it possible that Ryanair and Easyjet can fly you across Europe for £1. We like to call it “Economic Intelligence”.

We apply the same Economic Intelligence to our business, for example all Commsupport office staff other than instructors all work remotely to reduce unnecessary office overhead costs, we run an almost 99% paperless office and negotiate hard with all our suppliers down to the very last last penny on all of our purchases so that we can pass the savings onto our students. Like Tescos’ say “every little helps”, everything helps down to helping ourselves to the free pens at Barclays bank.

We also get asked “do you make any money?” or “how do you make money?”, our response is, we of course do make a profit otherwise why would we bother; as much as we love teaching we do have to live, air is free but not very filling.

We say don’t worry about how much money we make or how we make a profit the real concern ought to be whether we can deliver the product that we claim to be able to deliver. We have been in business since January 2007 and we have trained over 3000 students with a lot of repeat business, that is testament that quality training can be delivered at rock bottom prices, just see how many copy cat companies our concept has spawned to tell you it can be done.

The question you ought to really be asking is why other training companies feel the need to rip their customers off with high prices and low quality courses, poor material, poorly qualified instructors.

Come to our “Free one day training sessions” so you can try us out before you commit, see the real classes in action. If the likes of Ryanair and EasyJet can make a £30 million pound aircraft pay its way for a quid a flight why can’t we offer a course at the prices we do?