Archive for July, 2009

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DTP Negotiation for Dummies

Posted in Layer 2 Technologies with tags , on July 31, 2009 by Gerren

Warning: there is nothing formal about this post, just a way to help me (and maybe you, who knows) remember DTP port states:

Dynamic Desirable: “Hey, I want to trunk and I’m letting everyone know” (3550′s are DD by default)

Dynamic Auto: “I want to trunk, but I’m not announcing it. BUT! I’ll answer DTP trunking requests” (3560′s are DA by default)

DD + DA = Trunk (And use ISL unless configured otherwise — assuming Cisco switches)

DD + DD = Trunk

DA + DA = No Trunk for You!

You can disabled DTP by either:

  1. Setting the interface to static access using the switchport mode access command
  2. Turn off DTP all together with switchport nonegotiate


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Week 1 Down…??? to Go

Posted in CCIE Written with tags on July 26, 2009 by Gerren

For various reason, which for now will remain a mystery, a I lost a lot of motivation this week, but still managed to get in a decent chunk of studying. Instead of updating several sources, I’ve made my time tracking sheet available as a Google doc. This link will take you to the public spreadsheet I am using to keep track of my hours.

Friday and Saturday were my weak days, which both tie in to the lack of motivation. I managed to get back into the game on Sunday with a solid 4+ hours, but I would’ve liked to do more.  The past week has been dedicated to spanning tree, and all of its various incarnations. I forgot how much I liked studying spanning tree…or maybe I should say that I’ve come to like spanning tree more as time goes on. This coming week will be focused on VLANs and VTP, along with Etherchannel.

I’m going to try this week to see if I can get my company to cover the cost of ordering the INE CCIE 2.0 study package. The only thing I need to figure out is if they are going to have a CCIE R&S v4 package out soon. I want to dive in and get started, but don’t want to buy the v3 package if its going to be updated soon.

Anyhow, hopefully this week I can stay focused a bit more.  I think I’ve managed to get myself out of the funk that I was in, but we’ll see how the week plays out.

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Dork Alert

Posted in General Announcements on July 21, 2009 by Gerren

So, I’m a bit of a dork. I scored a Google voice number that ends with CCIE. I figured that while it doesn’t hold true right now, it will be a good “personal branding” tool in the (hopefully near) future.

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Starting Book Collection

Posted in General Announcements on July 19, 2009 by Gerren

This post has no significance to it other than to be able to look back in a few months/years and see where I began.

Starting Book Collection

Starting Book Collection

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CCIE R&S Written Exam Prep

Posted in CCIE Written with tags on July 19, 2009 by Gerren

I’ve begun the task of preparing for the written exam, and I have to say that the concept of actually passing this thing is a bit overwhelming. I’m sure that most people feel that way at first, but holy hell! there’s so much damn information to keep track of.

I’ve started using Google tasks to try and keep me on track. So far, I’ve broken down section 1.10 of the R&S v4.0 Written Exam Blueprint and I’ve got a full week scheduled (damn you spanning tree and all of your diabolical offspring). It’s painful to think that there’s 11 main topics to cover!

For those of you that are interested, I’ve started bookmarking sites that I will be using/reading in accordance with the lab topics and have tried to categorize them using the exam topic number (for example – 1.10 is spanning tree). You can view my list here: http://delicious.com/gerren.murphy

Does anyone have any good tips on keeping things straight during their exam prep?

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Heading Down the CCIE R&S Path

Posted in General Announcements on July 16, 2009 by Gerren

After some good advice from a bunch of people over at ieoc.com, I’ve decided that the R&S path is the way to, rather than doing another P level certification. Maybe at some point while studying, I can tackle the BGP and QoS exams for the CCIP, but we’ll cross that bridge when we come to it.

For now though, I think the IE will have the best ROI in the long run as there is no immediate career need for another P cert. I’ll be documenting the journey here of course, but there’s a lot of planning to do up front.

So…on that note, I’m off to begin gathering resources for my journey! Looking forward to every minute of it. (Easy to say that now of course…)

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Full ONT Notes

Posted in General Announcements on July 14, 2009 by Gerren

As promised, here are my complete notes on the OECG for ONT. Good luck in your studies.

See here

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Finally a CCNP – Now what?

Posted in General Announcements with tags on July 13, 2009 by Gerren

Last Friday, on a bit of a whim, I went ahead and scheduled for ONT for the following day. I’m not sure why I did that really, but it payed off. For all of the spam bots reading this so far, you’ll be happy to know what I have finally completed all 4 CCNP exams and am officially a CCNP!

Now, don’t get me wrong…it was a great feeling. After it was over though (and I’m sure many of you experience this), there’s this feeling of not necessarily emptiness, but of something…it’s hard to describe. You spend all that time studying, labbing, etc., and once you pass, there’s no fanfare (except from my wife which I appreciate), no fireworks go off, no…nothing. My mind automatically thinks “Ok, what’s next?” Is that sick? Some would say so, but I don’t think it’s such a bad thing.

I really can’t decide where I want to go with it next. I like the thought of the CCSP, but do I spend another 6-9 months for an CCNxP cert, or spend some extra time and go straight for the big letters? Anyone?

Either way, it’s a relief that it’s over with, but a bit of a stressor as well. As a side note, I’ll be putting the rest of my notes online sometime soon…from chapters 4-10 of the ONT OECG.

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ONT Chapter 4 – Conegstion Management and Queuing

Posted in Notes with tags , on July 4, 2009 by Gerren

Also available as a PDF here

Introduction to Congestion Management and Queuing

  • Congestion occurs when the rate of input to an interface exceeds the rate of output
  • Speed mismatch problem – when traffic on a high speed interface enters the router but exits on a low speed interface
  • Aggregation problem – when traffic from multiple interfaces aggregates into a single interface
  • Tail drop – occurs when buffers fill up and new incoming traffic is dropped
  • Default queuing method is FIFO (first in first out)
  • Queuing mechanisms consist of hardware and software components
    • Hardware queue is called the transmit queue (TxQ)
    • If TxQ becomes full, packets are held in the software queue and release to the TxQ based on the queuing mechanism
    • TxQ is always FIFO
  • Software queuing has a number of queues – one for each class of traffic
    • If the software queue is full, the packet is dropped
    • If TxQ is full, packet is held in software queue based on it’s class
    • Even if a packet is in one of the software queues, it can still be dropped if WRED is applied to that queue
  • The IOS determines the hardware queue based on the configured bandwidth on the interface
    • You can manually set the queue size with the tx-ring-limit command

    Read more »

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ONT Chapter 3 – Classification, Marking, and NBAR

Posted in General Announcements with tags , , on July 3, 2009 by Gerren

Also available as a PDF here

Classification and Marking

  • Packets should be marked (colored) after the first classification
    • Usually performed at the edge of the network
  • The match statement in a class map can refer to either a:
    • Traffic descriptor
    • Access list
    • NBAR protocol
  • Packets should be marked as close to the source as possible
  • What gets marked depends on whether you want to mark the L2 frame or the L3 packet
  • Layer 2 markings include
    • CoS (on ISL or 802.1q header)
    • EXP (MPLS)
    • DE on FR header (Discard eligibility)
    • CLP on ATM cell header
  • Layer 3 markings include
    • IP precedence
    • or DSCP  on the IP header

    Read more »

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