Connectivity is My Touchdown

A year and three months into my Networking Specialist program and I've begun to foresee a new challenge. I can no longer easily explain what it is that I'm doing to friends and family to justify why I just jumped up in exuberance from my computer desk. "Yes!" I'll suddenly burst out loud, "Yes, yes, yes!." Maybe a couple fist pumps or a victorious robot dance will make an appearance....by now you've formed the proper mental image. Why is getting two computers to communicate so damn exciting for me!?

What I've found most intriguing is the new methods of explaining these complex network configurations to those around me; those who don't share the same nauseous levels of enthusiasm for networking connectivity that I do. Yesterday I found myself presented with a question I was asked in response to my newly performed robotic dance. "What did you just do?" After four hours of working on a CCNA network lab, setting up protocols, VLANs, and troubleshooting a very tricky NAT problem, I finally got PC A to ping an ISP while using PAT to go from a private IP address to a public one. As one can imagine, I received a blank stare, but sometimes I just get so enthusiastic about teaching it that I just have to try explain it to the layman.

"Well, remember what I told you about everything needing an IP address? Kinda like how everyone needs a unique phone number?"
"Well some of those IP addresses are private, that everyone can use in their own home networks and they don't work when trying to contact other computers beyond this house."
"Why not?"
"Well ..."

This is where it gets tricky. Going into intense details about port address translation and private/public IP addressing just isn't going to cut it. I also think being able to explain something complicated (even when simplifying it down) is a great way to see if I actually know what I'm talking about as well. It's like creating an analogy about networking. Plus it gives my friends and family a chance to see what all this fuss is about.

"Well...imagine in this house your parents are here. You call them Mom and Dad. When you call them those names they respond right?"
"Well if we were in a crowd of people and you needed to call to them and just yelled Mom or Dad more than the two might respond to that name.
"Well think of the internet as the crowd of people. Your parents are the computers. And there are rules set up on the net that don't allow you to yell out "Mom or Dad" in public. You'd have to use something more unique like their first or last name. All 'NAT' does is change their names when they are inside the house from Mom/Dad to their unique names when we leave the house. So nobody gets confused.
"Oh I get it!"

At this point we all jump up and down and everyone gets so intrigued about networking they all run off and set up their own networking labs. Okay, so it doesn't go exactly like that, but it's always fun for me to explain the things that I just spent several hours meticulously calculating over in an easily digestible way. Besides, when it comes down to it one day, I may have to explain it in such a manner to convince an Exec the justification for a shiny new piece of equipment.

"Well, see Sir, this prevents us from losing five million dollars in the event that this doohickey here breaks..."

So in the spirit of analogically speaking, I've been asked why exactly is it so exciting to have one computer 'ping' another. The best way I can explain it is it's like a football game to me. You try and try to get set up and make the right moves. Things go wrong, but you keep trying to figure out how to get passed the other team, and then finally you make it to the other side; Touchdown! Time to show them your new robot dance. I see connecting computers like that. The challenge of figuring out the network and connecting one side to the other. In the end, that glorious moment when it's all configured just right and you get that connection reply from your ping request. In my mind the crowd... goes.... wild and I just can't stop doing that robot dance! So you see...connectivity is my Touchdown.


How to: Used Router Not Saving Configuration Changes

If you've purchased a used router for your home Cisco lab there is a chance that no matter what changes you make to your starting-config (after running the router#copy run start command) when the router is reset it does not seem to save anything you do.  This is most likely due to running of password recovery on the router. Resale companies, in preparation of wiping the routers clean, need reset the router to a factory state and need to run password recovery to get around the pre-existing security settings. While this is great, so that you don't have to, many times they forget to change the configuration register settings back to a mode that will allow the router to boot from your changed config. Just follow these steps and you should be back in action in no time.

1) First things first. Run a router#show version . Press space bar to get to the bottom of the readout. What we are looking for is "Configuration register is 0x2142". Each number has a specific purpose but the key number we are looking to change here is the 4. The 4 in this instance tells the router to 'Ignore the contents of Non-Volatile RAM'. And no NVRM equals no custom configuration.

2) Next we are going to change the 4 to a 0 to allow contents from NVRAM to be loaded when the router is turned on. Simply go to router#configure terminal. Once in configuration mode type (may vary on different routers) Router(config)#config-register 0x2102.

3)To test this we can now run a router#show version again and you should see now at the bottom that configuration 0x2102 will take on the routers next reload. Before doing this go ahead and change the hostname and maybe add a logging synchronous so it's obvious that our new starting config has been loaded. Now save the config by typing router#copy run start.

4) Finally restart the router by entering router#reload.

And that's that. You should now be able to load your saved config file from the NVRAM allowing you to save your work when the router is reset.  


It's Alive! Investing in a CCNA Home Lab

So after coming down from the rush that was attending Cisco Live, and getting my first Cisco certification (CCENT), I decided it was time to invest in a home lab to help me on the next step. I had saved up some of my money for the journey to Florida, and received some from my loving and supporting family. (Thanks Mom!) Well it turned out that most everything was provided for us in Florida so in the end, I came home without really spending much. After being completely inspired by the Cisco Engineers and the sheer scale of equipment at the Rosen Centre, I determined to take my networking proficiency to the next level. I thought to myself, what a better way to reinvest an already amazing Cisco experience than by taking the money I had saved up for Cisco Live and start building a home networking lab. I could have easily spent it on things that may have not posed as a legitimate self investment...like pizza.
Universal 19" tray for adding gear

It's not entirely complete yet. I have a few things still heading this way by mail, but one already obvious plus is just the experience of shopping around for all the equipment I'll need. I started out telling myself that I'll get three routers and three switches, but that quickly turned into "well what kind will I need that will help me pass my CCNA?" This forced me to do research on equipment IOS, CCNA v2, and future usability of the gear that I planned to buy. From here I began to learn some of the advantages of certain routers over others. Just this learning experience alone is amazing. Shopping around for physical equipment, learning what modules you'll need and ordering them, and all while trying to use services like eBay to get the best deals possible, make building this lab a whole other educational process in itself. I love it, down to the WIC-2T modules I ordered, and finding a company that sells custom 1ft 26pin smart serial crossover cables so I can easily connect my routers in a serial connection setup. I'm taking the money that was just meant as spending money while I was out of town and turning it into a valuable educational tool. Just think I could have spent it on pizz.......but where was I?

So what makes up the lab?:

1 x Cisco Catalyst 3548 48 port switch (already owned, oldie but goody)
1 x Cisco Catalyst 2950 24 port switch
1 x Cisco WS- 3550  24 port PoE switch (bought for 'Power over Ethernet' capabilities)

2 x 2611xm routers
1 x 2621xm router (not shown)

3 x Cisco WIC-2T 2-port Serial Card WAN Card
3 x Smart Serial to Smart Serial DCE to DTE Crossover Cables (1ft)

1 x 19" Rack Stand
1 x 19" rack-able power strip
1 x 19" Universal Rack Tray (for attaching Hub and AP)

1 x 4 port Hub (already owned; for packet sniffing)
1 x Wireless Access Point (already owned)

All of this purchased lurking eBay for the best deals possible. It's actually amazing how good of deals you can find if you're patient. Now I'm finding myself becoming obsessed with proper cable management. Like playing a game of Tetris in front of your server rack.

Getting to go to something as awesome as Cisco Live really opened my eyes and made me want to try even harder and to achieve more. I couldn't think of a better way to help me do that then by started my own lab at home. It's nice to have simulators that help us do lab work at home, but actually having my own set of routers and switches to play with in front of me is totally awesome!  I'll always say that learning from multiple sources can never be a bad thing, and I'm glad I am able to take one great experience and invest it into another. Still, I kind of wish I had some pizza though.