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...