Archive for June, 2011

One of those nights…

June 27th, 2011 No comments

Studying for the CCNA ICND2 exam has moved into the final countdown, with only 3 weeks to go until the test. Up until this point I have focused on each concept as it has come up and not really thought about all the concepts covered on the ICND2 exam. Well, the sheer amount of content hit me like a ton of bricks tonight. I can’t believe how much information is covered in this exam. You could seriously split the exam in two with routing as one test and switching as another and they would still be two beefy exams. Though, to be honest, I felt this exact same way about ICND1 at about this time and did not have any issues passing the exam, so here’s to hoping the same applies to ICND2.

Anyway, tonights topic was the Open Shortest Path First (OSPF) routing protocol. Commonly used as a replacement to EIGRP for those networks not running cisco equipment. OSPF is a link state protocol with each router forming a map of the network. OSPF uses the Hello protocol to inform its neighbors about the routes it knows and periodically letting it’s neighbors know that it is still up and running. This is much more efficient than a distance vector protocol, such as RIP, which advertises it’s entire routing table with each broadcast.

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Round 2: Fight!

June 23rd, 2011 No comments

I had a chat with one of our network engineers a couple of days ago regarding the path of understanding your brain seems to take while studying for a Cisco exam. The first time you go through the information your brain says, “that’s cool I get the general concept, but I don’t think I could flawlessly implement it without having to look some things up”. The second time through goes something like this, “ok, I understand this stuff and I think I can implement it without breaking things horribly”.  The last time through, two weeks before the exam, “I understand this information, quick take the test while the nitty-gritty details stick!”. And finally, when you move on to another more difficult test you look back on the old stuff and think, “I remember when ICND2 stuff used to be hard, what have I gotten myself into now!”. 🙂

Speaking of studying, here is a quick run down of where I am with the ICND2 exam prep:

In the past couple of weeks I finished up the cbtnuggets ICND2 course for the first time. Similar to studying for the ICND1 exam I am making a second run through the content on, at this point I just finished covering the switching part of the cbt course material. Once I am done with CBT for the second time I will hit the cisco press book for the ICND2 exam until I take the test.

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Frame Relay

June 2nd, 2011 No comments

First, a little disclaimer, Frame Relay is falling out of favor as a WAN connectivity solution for organizations, MPLS and VPN (and MPLS VPN) connections have risen in its place. Alas, Frame Relay is still covered in the ICND2 exam, so we are going to cover it anyway!

Frame Relay is designed to cheaply connect to points together through a network providers cloud. Versus a dedicated leased line Frame Relay is much cheaper because it uses the concept of shared bandwidth. You are guaranteed a Committed Information Rate (CIR) for your data however, your connection is allowed to burst above the CIR if there is additional bandwidth available and based on what you pay for.

Multiple Frame Relay connections can share one serial connection on a router, which helps save on the cost of additional WICs that are needed for multiple dedicated leased lines.

There are two standard Frame Relay designs. The first is using a multipoint configuration where the ip of each router in the network is in the same subnet as every other router. This however, causes some issues with split horizon. Thus, the preferred design method would be a point-to-point design. The point-to-point design takes advantage of sub-interfaces and multiple subnets to avoid the problems with split horizon and a multipoint configuration.

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