Thursday, July 31, 2008

QoS exam 642-642

I'm feeling pretty good about this exam and will take it either next week or the following week. It's amazing how much LESS material there is in a professional level exam vs an expert level one.

As there's a lot of overlap with my R&S CCIE and my previous voice experience, I'm not stressing out much over this. Of course, there's always the fear of taking it for granted and failing and wondering how the heck I can pass the CCIE written and Lab and bomb the QoS exam.

Anyway--here are the topics I need to commit to memory:
  • Higher drop precedence means more likely to be dropped. But higher IP precedence means less likely do be dropped. Huh? Who designs this stuff anyway? Just remember, AF11 will be dropped before AF21; however AF12 will be dropped before AF11. That last number means drop precedence, as in higher priority to be dropped. Whereas the first number means the traffic itself is higher priority, and less likely to be dropped. It makes me think they designed it this way simply because they knew they'd get a few good test questions out of it.
  • RTP Header Compression also compresses the UDP and IP headers, and therefore must be enabled on both sides of a link. Could the name be any more misleading?
  • COPS, aside from one of my wife's favorite TV shows, is a protocol that allows centralized monitoring and control of RSVP. Bad packets, bad packets, what'cha gonna do? What'cha gonna do when QoS comes for you?
  • ECN is like frame-relay adaptive shaping, except it's not shaping and there's no frame-relay. If a router is nearing congestion, it can use the last two bits of the ToS field to notify the upstream host. Then the upstream host relays this information to the sender. Finally, the sender slows down sending. It's like FECN and BECN, and like being issued a warning before WRED steps in and destroys your packet.
  • BGP can use communities to propagate QoS policy information (bgp-policy command)

Monday, July 28, 2008

CCIE Service Provider Next

It's official, I'm definitely going for Service Provider next.

I'm considered studying for the lab first and then knocking out the written once I'm comfortable with the hands on, but I'm changing my approach.

I'm going to go ahead and knock out the CCIP first. This should put me well on the way toward passing the written. It's also a little more manageable to cover the material this way.

The first exam I'm going for is QoS, since there's a lot of overlap with R&S and I've had a decent amount of experience with it. I picked up the Boson ExSim test for the exam. I've always been pretty fond of Boson and have been using them for over 6 years. They have a heck of a lot of material, are inexpensive, have great explanations, and the questions cover the topics well without being too close to the real exam.

My strategy is as follows:
  1. Take a 20 question Boson practice test every day
  2. Review the DocCD on anything I miss
  3. Review Safari Books Online if I need further explanation of the topic
Since there are roughly 250 questions, I should be ready to knock out each professional level exam in about 2 weeks with this approach.

Friday, July 25, 2008

Goodbye, Randy Pausch

I first learned about Randy's story last fall from one of my professors. The night after I heard, I watched The Last Lecture on Youtube. I've seen quite a few inspirational speakers over the years, and most have a knack for making me feel all pumped up for a few days. But after a week or two I can barely remember any of their lessons.

This is not true with Randy Pausch. I can honestly say his lecture changed my life. I'm going to paraphrase a bit, but two points in particular had a big impact on me:
  • Brick walls aren't there to stop you, they're there to prove how bad you want something
  • You have four categories of tasks: urgent and important, non-urgent and important, urgent and unimportant, and non-urgent and unimportant. Do the non-urgent important tasks before the urgent unimportant ones.
These are two VERY important pieces toward the CCIE. The lab exam is a BIG brick wall. It will make you prove how bad you want it. It is also generally going to be non-urgent and important. If you really want it, study for it before the things that "need" to be done right away but don't really matter.

Thank you Randy, you will be missed.

Thursday, July 10, 2008

What to do next redux

If you've noticed, I have bounced around the last few months regarding what I want to expend my efforts on next. I know I need to do something, I'm just not sure what. Since whatever it is will turn out to be a major undertaking, I don't mind if it takes a long time to make up my mind. In no particular order, some of the items on the list are:
  • Get all of the CCIEs (probably Service Provider next)
  • Get a PhD in Computer Science (finishing MS this summer)
  • Author/co-Author a book
Those are the main three, of which I'd like to complete one in the next five years. I'm leaning toward the CCIE route since I think it's most in line with my career aspirations. I'm not planning on being a researcher or professor, so all the PhD would really get me is another suffix to my name.

I was previously thinking of going for a CCIE in Security next, but that was mostly because I didn't see myself doing much with SP networks. As it turned out, that has changed so it makes more sense now.

Wednesday, July 9, 2008


I dropped in a new Firefox plugin called Stumble! the other day that really caught my attention.

If you've ever had a Tivo, it's a similar concept to that, but for websites. When you're on a webpage, you give it a thumbs up or thumbs down.

From there, it ranks pages (which you can view on Google in an Amazon style star raking system), or you can have it give you random pages based on your preferences.

You can even view the pages I gave thumbs up to here.

Thursday, July 3, 2008

Goodbye Microsoft

A few months ago the upgrade path for my MCSE in NT and 2000 expired and I'll have to take a bunch of tests if I ever want to upgrade it. However, since it's been about 4 years since a company has given me domain admin rights, I'm not very concerned.

Last year I installed Vista on my home PC because I got the business version for free--or I should say included with the $20,000+ I paid Towson University over the past 3 years in the quest for a Master's degree.

I'm not a Vista hater. It was ok, but more than anything it's just plain slow. With 1GB of ram and a 3GB single core processor it was having a rough time. Like my MCSE, my computer's upgrade path had expired (DDR1 RAM, Socket 478, no PCI Express).

So I could have went back to XP, which has reached end-of-sale status, or give something else a try. I chose the later and went with Ubuntu.

I've always had a linux box on the side, but never ran one full time. Now I'm running two. There are some things I like, and some things I'm not so fond of. But without a doubt the single biggest thing I love is the sheer speed. The install took 20 minutes. My computer takes about 20 seconds to boot up or shut down. Gone are the days of starting it up and getting a cup of coffee. No more hard drive thrashing or blue screens of death.

So far there are only four needed programs I haven't been able to get to work natively. Wine solved two of these by simulating a Windows environment for the program. Unfortunately two other programs (I'm not naming them because they may work and I just haven't quite figured them out yet) don't work and I am stuck with vmware for these two programs for the time being.

I'm liking Ubuntu more and more every day. If you've thought about giving it a try, here are some reasons.

Wednesday, July 2, 2008

The Importance of HSRP groups

When using the standby command to setup HSRP, one optional parameter is to use a group number. When I configure it, I typically always use one, even though I never really had a good reason to do it.

One thing to keep in mind is dealing with the virtual MAC address HSRP uses. By default, this MAC address is 0000.0c07.ac00, if no group number is specified. If a group number is used, it is added to the last word. For example, group three becomes 0000.0c07.ac03. Further details here.

In general, you will usually only use one HSRP group per vlan, so this isn't a problem. But if you have another device spanning multiple vlans that needs to talk to multiple HSRP speakers simultaneously, this can create MAC address conflicts if the same HSRP groups are used.