Author: ccie14023

Two Years of Ten Years a CCIE

Two years ago I published my Ten Years a CCIE series.  Actually, I had written the series a couple years before I published it, but as I say in my introduction to the series, I felt it was a bit self-indulgent an uninteresting, so I scrapped it for a while.  The original pieces were dictated, and I’ve been meaning to go back and clean up some of the grammatical errors or grating phrases, but haven’t had the time.  Not a lot of people have read it, nor did I expect many to read it, since I generally don’t advertise the blog in social media, or anywhere really.  But the feedback from the few who have read it has been positive, and I’m gratified for that. Things have changed a lot since I got into networking in 1995, and since I passed my CCIE in 2004.  But it’s also amazing how much has stayed the same.  TCP/IP, and in fact IPv4, is still the heart of the network.  Knowledge of OSPF and BGP is still key.  For the most part, new controllers and programmable interfaces represent a different way of managing fundamentally the same thing. The obvious reasons for this are that networks work and are hard to change.  The old protocols have been sufficient for passing data from point A to point B for a long time.  They’re not perfect but they...

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TAC Tales #14: Stuck in Active

Everyone who’s worked in TAC can tell you their nightmare case–the type of case that, when they see it in the queue, makes them want to run away, take an unexpected lunch break, and hope some other engineer grabs it.  The nightmare case is the case you know you’ll get stuck on for hours, on a conference bridge, escalating to other engineers, trying to find a solution to an impossible problem.  For some it’s unexplained packet loss.  For others, it’s multicast.  For me, it was EIGRP Stuck-in-Active (SIA). Some customer support engineers (CSEs) thought SIA cases were easy.  Not me.  A number of times I had a network in total meltdown due to SIA with no clue as to where the problem was.  Often the solution required a significant redesign of the network. As a review, EIGRP is more-or-less a distance-vector routing protocol, which uses an algorithm called DUAL to achieve better performance than a traditional DV protocol like RIP.  I don’t want to get into all the fun CCIE questions on the protocol details, but what matters for this article is how querying works.  When an EIGRP neighbor loses a route, it sets the route as “Active” and then queries its neighbors as to where the route went.  Then, if the neighbors don’t have it, they set it active and query their neighbors.  If those neighbors don’t have...

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Book Sprint

I’m somewhat recovered from an exhausting week.  I spent last week with a team of 10 others locked up in building 4 at Cisco writing a book using the book sprint methodology. Several of the TMEs who report to me got together and wrote a book on Software-Defined Access earlier this year.  The PDF version of that book is available here.  Then, just over a month ago, some TMEs (including one member of my team) got together and wrote a book on the Catalyst 9000-series, available here.  Both of these were also produced with the book sprint methodology, and...

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TAC Tales #13: All Zeros

A common approach for TAC engineers and customers working on a tough case is to just “throw hardware at it.”  Sometimes this can be laziness:  why troubleshoot a complex problem when you can send an RMA, swap out a line card, and hope it works?  Other times it’s a legitimate step in a complex process of elimination.  RMA the card and if the problem still happens, well, you’ve eliminated the card as one source of the problem. Hence, it was not an uncommon event the day that I got a P1 case from a major service provider, requeued (reassigned) after multiple RMAs.   The customer had a 12000-series GSR, top of the line back then, and was frustrated because ISIS wasn’t working. “We just upgraded the GRP to a PRP to speed the router up,” he said, “but now it’s taking 4 hours for ISIS to converge.  Why did we pay all this money on a new route processor when it just slowed our box way down?!” The GSR router is a chassis-type router, with multiple line cards with ports of different types, a fabric interconnecting them, and a management module (route processor, or RP) acting as the brains of the device.  The original RP was called a GRP, but Cisco had released an improved version called the PRP. The customer seemed to think the new PRP had performance issues,...

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Where I’ve been, and what a TME is

Jesse, a recent commentor, asked why I haven’t been posting much lately.  In fact, my last post was August of 2017.  Well, there are several reasons I don’t post much these days.  In part, I’m not convinced anyone is reading.  It’s nice to see a comment now and again to realize it’s not just spambots looking at SZ. The other major reason was a job change.  I moved to Cisco over two years ago, and I came in as an individual contributor (IC).  I liked to joke that I had never been so busy since…the last time I worked at Cisco.  However, as an IC, I had no idea how easy I had it. Someone got the crazy idea to make me a manager.  So now, not only do I have the Principal Technical Marketing Engineer title, I also manage a team of 10 TMEs.  The team happens to be driving Software-Defined Access, currently Cisco’s flagship product.  So, the time for blogging is a bit limited.  I’m still working on programmability in my spare time, and I’m continuing to do Cisco Live sessions at least twice a year.  My hair is turning white and I don’t think it’s just my age. That said, I cannot image a better job or place to be than this job at this time.  It’s an exciting company to work for, and an exciting...

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