Information Technology Blog (Archive)

1. The router performs Power-On Self Test (POST) to discover the hardware components and verify that all components work properly. 2. The router copies a bootstrap program from ROM into RAM and run the bootstrap program. 3. The bootstrap program decides which IOS image to load into RAM based on the low-order four bits in configuration register:             0 = use ROMmon OS             1 = load first IOS file in flash             2-F = a) try each boot system command in startup config in order until one works                      b) if none of the boot system command works load first IOS file in flash 4. If the bootstrap program has loaded IOS, IOS finds configuration file (typically startup config in NVRAM) and loads it into RAM as running-config. If startup config cannot be located in NVRAM, enter setup mode. 5. If no IOS file is found in fla...

I got inspired by this post so I thought I want to share. I don't own this.  8 TIPS TO BECOME A RELEVANT NETWORK ENGINEER Over the last few years I've had the opportunity to work with many great engineers and I've also had the displeasure of working with many not so great engineers. I worked a contract at the Sprint World Headquarters in Kansas City where I was in a room with 8 to 10 extremely skilled network engineers who may or may not have been CCIEs and/or JNCIEs. These were the kind of engineers that literally spoke routing protocols as a first language, throwing around the more advanced concepts without thinking about it, much like a book worm uses big words all the time, wondering why everyone else "doesn't get it." These were the engineers who never spoke of their certifications because their extreme skill spoke for itself. Network technologies radiated from their pores and you never once questioned their judgement, their knowledge, or their certificat...

As I prepare for CCNA, I had the opportunity to really get into the bottom of things. Today, I finally settled it with Native VLAN. During my Cisco Networking Academy days, we had to do our skill-based exam for CCNA 3 (LAN Switching and Wireless) which lasted 10 hours because of a problem with Native VLAN. I even made a post about it. But that was the end of it, we made a mistake and we learned to never configure Native VLAN on the trunk link of the switch connected to the router configured for router-on-a-stick. We just moved on, we did not even bother to research why is that a problem. Even our instructor did not enlighten us with the issue. But it's been bugging me since that day. Why? WHY? Now I have the answers. First, let me review the problem: I applied the command switchport trunk native vlan 88 on the trunk link of S2. This trunk link is connected to R1 which is configured for router-on-a-stick. The Native VLAN in LAB1 domain is VLAN 88. When I ping S1's management i...

After reading on different CCNA concepts, I thought I wanted to assess myself by building a network where almost all the concepts I learned will come and work altogether, a simulation lab which will test my familiarity with different Cisco CLI commands. I began by thinking, What do I want my network to do? What technologies I want to use to enable those functions? Then I started building the topology and I came up with this: These are the CCNA concepts used in this lab: VLANS and VTP Inter-VLAN WAN IP Routing NAT/PAT ACL I did this lab in Packet Tracer and lucky I was able to finish it. My approach was focus on one portion and list out what I need to accomplish on that portion of the network, like, for the Local Area Network, hosts on the same subnets should be able to communicate with each other and so on.  I thought others might want to try this so I made a documentation which comes along with a  Packet Tracer file with the topology already set up...

If you are studying for CCNA, it is not enough that you know how to configure Cisco routers using the CLI, you also have to learn how to use Cisco SDM (Security Device Manager) as stated in the exam objectives: Configure, verify and troubleshoot DHCP and DNS operation on a router (using both  the CLI and SDM) Access and utilize the router to set basic parameters.(including: CLI/SDM) Configure and apply ACLs based on network filtering requirements using SDM and CLI Configure and apply an ACL to limit telnet and SSH access to the router using SDM and CLI Configure NAT for given network requirements using SDM and CLI Another reason for learning how to use SDM, as quoted from CCNA ICND1 Official Cert Guide (3rd Ed) : Routers that are built specifically for consumers as Internet access routers ship from the factory with DHCP client services enabled on the Internet-facing interface, DHCP server functions enabled on the local interface, and PAT functions enabled. ...

I've been trying many things with the enabled connection between my virtual router in GNS3 and my own laptop (through the Microsoft Loopback Adapter). First I tried SSH then Telnet and now I've tried to set up a tftp server which I got here  and execute this simple command: R1#copy running-config tftp Here's the output--Sweet! Next on my list is to try the new Cisco Configuration Professional and SDM :)

GNS3 is freakin amazing! I was just reading some stuff on the website (gns3.net) and I am really curious about how to connect hosts in my topology. First I learned about using the Microsoft loopback adapter which is really a complicated task. Then I read that there's a simpler way if you are just gonna use the host for Ping and traceroute. It is through vpcs (Virtual PC Simulator). I connected 2 hosts and I configured the ip address of each host using vpcs. Then I configured the ip address of interface of the router in GNS3. Finally I tried pinging the remote host from the other host, the pings were successful (as seen from the image below). It was amazing! And vpcs can even save the configuration, which is really handy. Thanks to this tutorial . I am going to try more complicated topology now that I know how to use hosts in my network.

Today I am officially starting my CCNA Certification self-review. This is really what I want to achieve for now, and then have a long-term career in networking. I will not totally give up programming though, I will from time to time try to program (I love Java and VB .Net!). I will be using one book for reference: CCNA Study Guide by Todd Lammle and video series: CBT Nuggets CCNA Certification Package by Jeremy Cioara and with the help of Packet Tracer and GNS3 for hands-on lab. I hope I have everything I need to get me prepared for the exam. Good luck to me! I hope I can achieve my dreams! To CCNA, Cheers! :)

It's been 6 months since I last posted about our senior project entitled Zigbee-based Water Level Monitoring and Data Acquisition System. I finally managed to get the paper done to make it available for reading online. This is a brief discussion of the system. View on Google Docs Our project caught the attention of the Public Safety Office of the city and they were interested in adapting the system for flood monitoring of the city.

 Previous Post : SP Update 2.5: GUI Zigbee-based Water Level Monitoring and Data Acquisition System is complete. It has already been deployed in a river.  The alarm device is operational and being controlled by the GUI according to the processed data. The people of Brgy. Dinaga can be warned from impending flood risks. I had fun doing this project and I am lucky to be given the opportunity to do such a great project along with my group mates. I learned a lot during this whole experience. Defense will be on Saturday, March 7. Wish us luck! MAGIS!!! As an added feature to the system, the application can connect to Twitter.com and post the data online. Visit the twitter account @zwlmonitoring

Previous Post: SP Update 2.0 The GUI was developed using Visual Basic 2010 Express. This was the first time I made a Visual Basic application and thanks to many tutorials on the internet about VB .NET, I was able to build this. The GUI shows the status of the Zigbee network, and the water level being monitored. Basically, it sends a signal (a byte) on the serial port which is transmitted through the Zigbee network. When the mote receives this signal, the Arduino performs analogRead() and then sends the data back to the serial port. The application continuously listens for incoming data from the serial port. The raw data is converted to actual measurements based on the calibration of the sensor. Other functionality of the application: 1. Save the data to SQL server database 2. Plot the last 15 (most recent) data on the graph for the two motes. 3. Display the last 30 (most recent) data on the table for the two motes. 4. Set the time interval of data acquisition. 5. Set the serial port a...

Previous post: SP Update 1.5 The stackable headers have arrived from E-Gizmo and finally we were able to test Zigbee wireless communication!!! First we followed this tutorial from Sparfkun in assembling the shield. Then we uploaded our sketch to Arduino to send ADC readings of the sensor  to the gateway and computer. We also programmed the XBees to communicate in Star Topology network. Below is the package of our "mote". We have here the sensor, sensor signal amplification ciruit, the stacked Arduino, and XBee shield with the XBee. The tube from the sensor goes to a drum filled with water. To test the circuit, we tried to remove then place water to the drum, observe and take note of the readings. We observed that for every 5cm increase, the ADC readings increase 1 bit. For full testing, we are going to deploy this project on a real river. We have below the gateway which receives the data from the mote. I made a Visual Basic application which sends a string through the serial...

Original circuit from HAMRADIOINDIA. The circuit there uses two temperature sensors and 3 seven segment displays because of decimal point in the output (e.g. 25.6 Celsius). I modified the circuit and simplified it by removing the spare sensor and using only two display. The reason is when I simulated it in Proteus, the output is somehow wrong. I don't know if the output is right on actual but since I want to make sure with the actual circuit, I followed my schematic that gives the right output on simulation. I did not program the microcontroller. The HEX is from the site and the code is available there. Motor circuit from NERDKITS . Great explanation of the basic principle of motors. THERMOMETER:   Digital Thermometer using PIC16F877A microcontroller. The circuit uses LM35 as its temperature sensor, and displays the temperature (0-99 Celsius) using the two 7 segment display.  Input voltage: 9-12V DC then it is regulated to 5V DC connected to...

Previous post: SP Update 1.0 1/16/11 - Finally, the materials have arrived. It was a dream come true for us that finally after so many mishaps that happened, we got our hands on these precious little things. I've submitted the order to Sparkfun.com and a shipping confirmation has been sent from Sparkfun last 1/3/11. We are expecting that it will arrive after 3 days. But 4 days had passed and no news about our package.  Tracking the order, we discovered that it arrived here in the Philippines on 1/06/11. But for some clearance issues, it has been delayed and after 5 days of being delayed, we decided to call FedEx to verify. We have been told that we are going to pay an additional PHP5,000 for the taxes before we can receive our package which is almost 50% of the amount ($276). It was our 2nd time to do online shipping and we did not know about this whole tax thing! It was insane! But because we are so delayed in our project, we have no choice but to pay them the amount to finally ge...