Archive for the ‘642-813’ tag
Stubby Post – VTP Clients Send Updates
VTP clients send VLAN updates. Did you know that?
I had a VTP server and client in the same VTP domain, and, when I cabled up the trunk, the client overwrote the VLAN database on the server.
The moral of the story is that the best revision number will win no matter what the operating mode of the switch.
SWITCH – Epic Regression
Just because I like giving more money to Pearson Vue, I took the BCMSN test today to see how I would do. I passed with no problem.
In my mind, the CCNP is a technical certification, so I expect to be tested on technical topics. Are there topics beyond technology that P-levels should know? Of course there are, but I really don’t think whole chunks of the test should be about a preparation plan and rollback procedures. The BCMSN had a lot more technical questions at a much higher level of expertise; it seems much better suited to the CCNP track than the SWITCH test did.
I was really surprised at how many questions today were repeats from the SWITCH test last week. Of the three lab exercises I worked, two of them were exactly the same as last week. I would venture to guess that there were also 8 to 10 repeated multiple choice questions. It seems that this is going against my argument of being more technical, though, doesn’t it? If you mix in the remaining questions that were at a much higher technical level, you wind up with a pretty darn good test.
I’ve really got nothing more to say about the BCMSN. It’s a good test with an appropriate level of technical (and paper-pushing) detail. I’m very glad I was able to take it before the 31 July 2010 deadline, and I advise anyone who needs the SWITCH test to try and do the same.
The next stop is ROUTE (642-902) for me. I’m taking a class on that one soon, so I’m confident I can pass it in the next 11 weeks we have left until the deadline.
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SWITCH – Epic Fail
I did my standard 2ish-hour drive to the closest testing center today to take the SWTCH test (642-813). Utter failure. That’s 3 for those scoring at home.
The test was the absolute worst I’ve ever taken. I know that I complain a lot, but this is totally justified in my eyes. My 4th grade spelling tests were better than this. I’ve seen kindergarten plays with better production value.
First of all, it was poorly written. Whoever wrote those questions has a few pieces of information about English sentence structure missing from their skill set. A sentence needs a verb, right? Well, a lot of the sentences were missing those. It’s kind of important to know what the whole point of the sentence is, or is that too much to ask? The “drag this over here” exercise questions all started with the same 13-word phrase that left the question so long that it was unreadable. A couple of commas would have been nice in some. Others I just had to infer from the answers what they were trying to ask.
There were lots of spelling errors as well. Most of them were just stupid stuff like switched letters or missing characters, but, at one point, I had to figure out that I needed to look at the “router” instead of the “route”. That’s not really cool. The misspellings were so bad that they were actually misspelling the hostnames on the diagrams provided. Does anyone even try any more?
Let’s talk about the technical level of the test. If I didn’t know any better, I would swear I was taking a CCNA test. The technical material was so elementary that it bordered on comical. If I recall correctly (which I never do), there were about 3 questions on trunking which were so easy that my wife could answer them. There were about 4 FHRP questions that were out of the “Cisco for Dummies” book. I could go on, but I have better things about which to complain.
“So,” you might ask, “why did you fail it if it was so easy?” That’s a great question. I failed it because the name of the test is misleading. When Cisco says “Implementing Cisco IP Switched Networks”, they really mean “Collecting Documentation About VLANs.” There were at least four questions on this test that asked what information you need to collect before implementing some unknown step of a project involving VLANs. Sometimes, the reference was to rollback plans. Sometimes it discussed IP assignments. Sometimes it even talked about collecting user requirements. It seemed that nearly half of the questions on the test discussed planning for making changes or preparing change documentation. There was very little “implementing.”
To top it all off, too, one of my labs froze. I entered a command into a router, and it didn’t come back. I couldn’t change to the other lab windows, either (the “Scenario” or “Topology” windows included), but my timer kept ticking. I could click around in the testing software, but the lab itself was toast. I got the administrator who helped me out a bit after the machine was rebooted. I didn’t run out of time or anything, but getting up to find help to troubleshoot a problem really throws you off.
How about some closing words? First of all, I have given up on the Cisco Press books and other materials. Each time I use them they have little to no coverage about topics on the test itself. The ISCW was that way, and we all know about my problems with the ONT. I figured that those were just aged text, but SWITCH is only a month or two old, isn’t it? That means the test hasn’t had that much time to change, but the materials are totally different already.
I actually have an example of the books leading the reader directly away from the test materials. I’m reading from the “CCNP SWITCH 642-813 Quick Reference” book by Donohue. On page 8, it discusses the PPDIOO lifecycle approach.
Network engineers at the CCNP level will likely be involved at the implementation and following phases. They can also participate in the design phase.
That doesn’t make any sense, does it? Didn’t I just say that there were a good number of questions on preparation (the first P) and planning (the second P). Both of those come before the design phase.
Somebody help me out here. What am I missing? Is there some magical book series that has the answers?
I should have bought testing vouchers in bulk when they were $150.
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UPDATE: It seems that the idea of seeing topics on the exam that aren’t are the test go beyond just me. I’m getting in touch with as many people related to the SWITCH book as I can to let them know that this is a serious problem. I’m sure I’ll have a post or two on the outcome of that effort.
SWITCH – STP Exercise #1 Solution
Did you guys have any trouble with the solution to the STP exercise? Let’s work through it and see what happens. I got a few responses to the solution, and everyone seems to get the same answer, so I assume we’re all right.
Before we get started, I wanted to mention the tie breakers since there can be ties in STP. If there is a tie in any calculation, the same tie breakers are used, so I’ll list them here to use as we move through the calculations.
- Lowest root bridge ID (which I hope we’ll never have to use)
- Lowest root path cost
- Lowest bridge ID
- Lowest port ID
In our exercise, we only have to go to the tie breakers once, but, in the wild, you may run into more. I would guess that this is a requirement to know for the SWITCH test.
Before we get started, you can assume that a bridge is a switch since, technically, a switch is a many-ported bridge. Let’s get started. There are only 5 steps to take, so it shouldn’t take long.
1. Find the path costs of each segment
This is done with a table lookup. Each segment (link between switches) gets a cost based on the technology that it is using. For example, GigabitEthernet has a cost of 4 while FastEthernet has a cost of 19. There are other values, but these are the only ones that are used in the network here. I did find a good table on STP path costs at HowStuffWorks.com if you want to take a look at more of them. Let’s put the path costs on the diagram.
2. Find the root bridge
After we find the path costs, we find the root bridge. The root bridge is the switch that has the lowest bridge ID, which is the switch priority and the MAC address concatenated together. Since all the bridges have the same priority, we can just look at the MACs to figure out which one has the lowest bridge ID. Switch E has the lowest MAC (0000.0000.0003), so that’s the root bridge.
3. Find the root ports of each bridge
The root port is a port on a switch that has the lowest total path cost back to the root bridge; every switch has a one and only one root port except for the root bridge itself which has none (it’s the root; it already knows where it is). The root bridge sends out BPDUs that are passed to each switch. When a switch receives it (not sends it), it increments the root path cost field and passes that along, The port on which the lowest root path costs is received is the root port, and the value in the root path cost field is the root path cost for that switch. The finger trace method works for us humans for now; there’s not that many switches involved. Let’s add the root ports along with the root path costs to the diagram.
4. Find the designated ports
Each segment of the network has a designated port. This is a port on the bridge with the lowest root path cost. Since the root bridge always has the shortest path to itself, all of its ports are designated ports. Root ports can’t be designated ports, too, so it’s pretty easy to find the designated ports on segments with root ports. There are two segments (A-B and B-C) that we need to calculate, though. Let’s go to the tie breakers!
All the bridges have the same root bridge ID, so that’s a wash. C has a lower root path cost than B, so it wins that segment. A and B both have the same root path cost, though, so we move down the list to bridge ID. Since A has a lower bridge ID, it wins that segment.
Let’s put all the designated ports on the diagram so you can see them.
5. Find the blocked ports
There aren’t many ports left, are there? There are three actually, and all those go into a blocked state. To get rid of the loops, any port that’s not a root port or a designated port is blocked. Here’s the network with the blocked ports marked.
And we’re done. That wasn’t so hard.
Send me any summer home rentals questions.
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SWITCH – STP Exercise #1
Here’s an STP exercise for you. Given the bridge priorities, MAC addresses, and interface types in the diagram, calculate the root bridge, root ports, designated ports, and blocked ports. You can click on the image to enlarge it. I’ll post a solution in the next few days. As always, feel free to comment and ridicule my utter idiocy. Be gentle, though; I don’t usually post exercises like this.
Send any configuration BPDUs questions my way.
STP Exercsie #1