Here is an old but great video about how the Internet works. I actually watched this 7+ years ago when I was in High School, but is still a good video to teach you the basics about packets and routers. Enjoy!
Thanks Erik Zandboer for digging up this classic video.
I love the Gap chart that Aaron Paxson made and I think it is a perfect visual representation of what is going on with his helpdesk tickets.
The problem: The Network Operations Team (desktop, server, communications, etc) is consistently not able to keep up on demands. Identify the demands, the why’s, and determine a fix.
So, the first thing I need to quantify, was how do we get so far behind in ticket closures in the first place. When does it happen, and find a pattern. By taking the net result of open to closed tickets per week, I created a “Gap” chart. The “Gap” is the difference of open to close. If the net result is positive, we opened more tickets than were closed adding to the backlog. If the net result is negative, we were decreasing the backlog. Source.
Analyzing a helpdesk can be quite difficult, especially because the problems can range from something simple to something complex that can take a long time to solve. It’s rough looking at it only on pure ticket volume because in order to get a good idea of what is going on its important to look at the types of tickets coming in as well.
Here is an exert from Aaron’s OSPF Story:
Right in the middle of the config, I see “area 50 nssa”. Yes, this single non-backbone area with no real costs being advertised was configured as a not-so-stubby area. Not only did they go out of their way to make it a non-backbone area but they also wanted it as a stub area. Since they had all the other networks redistributing into the area, they had to make it NSSA. It’s a week later, and I still roll my eyes.
I’ve never seen a configuration like this before. Crazy.
Routing protocols are able to dynamically update and talk to each other about changes that may occur in a network, such as a link going down. The beauty of this is that, if designed properly, redundant links can quickly be found with out the network going down or users even knowing there is an issue. There are several different kinds of routing protocols such as distance vector, link-state, and a combination of distance vector and link-state. Below is a list of 10 important things you should know specifically about link-state routing protocols like OSPF and IS-IS to help you get ready for your CCNA Exam.
(1) Each router running a link-state routing protocol creates it’s own map or table of all the other routers in the same area.
(2) Each link-state router runs the SPF (Shortest Path First) Algorithm to determine the best route to each of the routers in the network.
(3) Link-state routers will send a topology update as soon as a link goes down instead of waiting for a timer to expire for regular updates.
(4) Link-state routers send small hello packets every 10 seconds or so just to say hi to its fellow routers.
(5) Link-state routers will send their topology table update every 30 minutes. It’s a lot bigger than a hello packet so it get’s sent out less frequently.
(6) Each link-state router must be configured to the exact same update timers or they will not become neighbors.
(7) Link-state routers can be sub-divided into separate areas so that only routers in the same area have to re-calculate their SPF algorithm when there is a topology change.
(8) Link-state advertisements are sent out via a multicast address instead of broadcasting them out to every node in the network.
(9) Link-state protocols don’t just use distance to determine the best route, but take into account the link speed as well.
(10) Link-state protocols are processor and memory intensive.
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Image Credit: Thomas Hawk
EIGRP is an important topic on the CCNA exam. Just as important as RIP is for the CCENT exam. Currently I’m studying for my CCNP ROUTE exam and reading about the EIGRP routing protocol. While there are some new topics about it that I didn’t learn when preparing for my CCNA exam, everything that I’m learning about requires foundational knowledge that I gained for my CCNA Exam. I guess what I’m trying to get to is that you shouldn’t put to light the topics you are learning about for the CCNA Exam and think that you won’t need to know much about them afterwards. Your knowledge of the basics will be critical as you start to learn about more advanced features of EIGRP.
Here is a list of the core topics about EIGRP:
EIGRP is a proprietary routing protocol created by Cisco. It is an advanced distance vector routing protocol. It will support load balancing across links of different speeds. Instead of using broadcasts to communicate is uses multicast and unicast. EIGRP uses autonomous systems. One of the reasons why EIGRP is able to converge quickly is because it prepares a feasible successor route as a backup before the successor route goes down. Which means it can switch to the backup route without having to query all the neighboring routers.
I wake up at 4:30 am every morning to get a head start on the day and to my surprise on Thursday 10/20/2011 Junstyn Windsor left a very nice post on the Networking Exam Academy Facebook page just a couple of hours before I had woken up. It was very nice of him to do and it was a great way to start out my day.
Justyn purchased my CCENT Study Guide eBook only a week ago and wrote a book review and a status update about his progess toward getting his CCENT. Since his facebook comments took up three different entries I though it would make it easier for people to read if I posted it here all in one post. Enter Justyn:
Week One:-
Okay so its been a week since I purchased Blakes ebook. My first impressions? Very impressed! I’ve had a rather hectic week at work so the situation hasn’t been ideal for studying. (I’m a SC/UK Government cleared, Prince2, ITIL v3 project engineer and work on lots of big IT rollouts accross the country, this week I’ve been in London, Bristol and Manchester)
I’ve read the ebook start to finish. I choose to do this as I have dipped in and out of CCENT studies for quite a while, and one of the main reasons for buying the book, was that I wanted to understand the absolute scope of the ICND1 exam. Start – Finish. (When I have studied in the past, its been too easy for me to switch from one resource to another, ie. Checking out a video of YouTube) The problem being, all these diferent resources aren’t designed around me gaining my ICND1 exam, as they often go into topics to a level way too detailed for what I currently need to know.
So now I have read the ebook. I have myself a clear understanding of what to expect from the exam, and particularily what it appears I don’t seem to need to know. (Of what I have learned previously)
Having ended the ebook talking about the IOS, I have decided to buy some very old, and very cheap Cisco Routers and switches off ebay, and they have just arrived. So what I am going to do now is have a play with the simple commands I’ve just learned from the ebook. Then start the book again, but his time, following the guidance from Blake and ending each topic buy writing down everything I think I know about that topic, and then checking back over.
It seems clear the topic areas I’m going to need to focus of mostly, are the WAN areas, where there are lots of facts to get my head around, and lots of terminology for me to get a grasp of before the exam.
Why am I writing such a long comment on this page? Well…Blake seems like a nice guy, who I seem to associate with as he has recently gone through the CCENT process recently himself. And the fact he’s trying to turn that process into making a few £££’s or $$$’s then great idea! Good luck to him, he’s clearly put a lot of work into the process. I’ll update you again soon.
Links to the actual facebook posts:
http://www.facebook.com/NetworkingExamAcademy/posts/248595908522587
http://www.facebook.com/NetworkingExamAcademy/posts/248595991855912
http://www.facebook.com/NetworkingExamAcademy/posts/248596001855911
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Thank You
Blake here again… Once again Justyn thank you for the great review of my book and I can’t wait to hear more about your studies and when you get certified. For those of you in a similar situation as Justyn and have put off their CCENT studies for quite some time now, please purchase my CCENT Study Guide. With it you you can learn everything you need in order to pass the ICND1 exam so that you can continue to progress in your networking career.
Although it is rough out there in terms of jobs, if there is one industry that is constantly thriving, changing, and evolving; it’s technology. And not just technology is general, but specifically computers and networking. According to the Bureau of Labor Statistics, all computer-related sales are expected to grow faster than any other job through 2018. If there is one thing that is constantly in demand and almost a necessity to everyday life- it’s the internet.
With the majority of companies new and old expanding and converting their vision to the masses via Internet, the demand for networking professionals has never been higher. With that, overall employment of computer network, system, and database administrators is expected to increase by 30 percent according to BLS. With the industry being so competitively driven, companies and firms alike will constantly be looking to stay ahead of the game by expanding their websites, networks, etc. All positions are highly sought after- whether it be running websites, managing local area networks, or administrating larger networks. If you have been kicking around the idea of getting Certified; the time is now.
With becoming certified, comes all of the opportunities and potential career experiences that may have not been previously available. Even though these positions are in high demand- companies and firms are looking for professionals with the credentials to match. Not only will the certification give you the knowledge you seek to successfully evolve and fulfill your career choice, it will also help you stand out in the interview process. Bottom line- companies are more likely to seek and hire someone that is certified.
Now is the time to get certified. The demand for networking professionals is only going to grow. With the industry and Internet rapidly changing, the competition factor will play a major role in the acquisition of networking professionals. Now is the time to take advantage of the potential and future potential of this ever-expanding industry.
Employment growth will be driven by growing demand for the design and integration of sophisticated networks and Internet and intranet sites. Employment in management, scientific, and technical consulting services is anticipated to expand at a staggering 83 percent, making up about 31 percent of job growth in this sector. Demand for these services will be spurred by businesses’ continued need for advice on planning and logistics, the implementation of new technologies, and compliance with workplace safety, environmental, and employment regulations.(Bureau of Labor Statistics)
I released a new minor update to the Online Network Simulator (beta) this morning. Version 0.0.2 fixes a few bugs from version 0.0.1 and I added support for the ‘show version’ or ‘sh ver’ command.
Obviously there is still a lot of work to do, but there currently is a lot of functionality to help you get familiar with configuring interfaces, setting up RIP and verifying your settings using ‘sh run’. These commands are actually very important to become familiar with for the CCENT and CCNA Exam.
While it is no where close to being ready for 0.0.3 one of the reasons why it took me so long to release a minor update from version 0.0.1 is because I’ve been working on support for multiple routers. Once this is done you will be able to ping between routers and use commands like ‘debug ip rip’.
Go ahead and start using the Online Network Simulator now and let me know what you think!
Stuff like this fascinates me…
37Signals talks about how they came about getting a 1.5 gigabit internet connection.
Routers within a network use routing protocols to talk with one another so that updates and changes to the network can be adapted to dynamically without any major involvement from the network administrator. A router in a network has a routing table so that it can keep track of where his fellow routers are. It is like his contact list or address book. If routing protocols didn’t exist we would have to configure static routes manually to each router in the network on every single router. This can be a lot of work if you have a lot of routers. If you only have static routes and one of your links goes down in the middle of your network there is no real way for the routers to update each other on the status of the broken link. YOU, the network administrator, will have to go into every single router on the network and remove the bad link and define an alternate route. Again, this can be a lot of work if you have a lot of routers in your network creating a lot of down time.
Using a routing protocol will solve this issue of having to do all this manual work every time there is a change in your network. In the rest of this article we are going to focus on RIPv1 and its predicesor RIPv2, but there are several other routing protocols that we will learn about later for the ICND2 Exam and the CCNA Exam. RIP is a great tool to learn about routing protocols because it is simple to understand and easy to configure. Other routing protocols like EIGRP, OSPF and IS-IS are more advanced than RIP, but build upon RIP’s core functionality. We focus on learning RIP first because it builds a solid foundation of Routing Protocol knowledge that will make learning more advanced routing protocols much easier. For the ICND1 Exam you will need to know everything about RIPv2 (and RIPv1), and have only basic understanding for EIGRP, OSPF, and IS-IS.
So, what is a routing protocol? Basically it is a language or format that routers use to communicate with each other, so that they can automatically learn about new routes and make new routing dicisions incase a link goes down somewhere in the network. Having this ability to automatically make decisions can help keep your network running smoothly even when problems arise (Smoothly will depend largely on if you have redundant links in your network or not).
