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Cisco Express Forwarding (2023 Edition)

Cisco Express Forwarding (2023 Edition)

CEF Deep Dive (commands) for IOS-XE C9300 used as example Model: C9300L-24UXG-4X Control Plane (CP) = R0 Data Plane (DP) = F0, UADP/ASIC CEF Background:  Why Cisco Express Forwarding (CEF)?  “Necessity is the mother of invention” -proverb Let’s take a trip in the networking time machine back to simpler times (late 80s, early 90s). I’m going to start with the fundamentals of software-based forwarding and all the pipeline steps involved. We didn’t have fancy ASICs like we do today, so everything was done…

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FN-70489: PKI Self-Signed Certificate Expiration

FN-70489: PKI Self-Signed Certificate Expiration

With the release of Star Wars TRoS this past Friday, the only “FN” on most people’s minds was FN-2187 (Finn). However, another FN was released on December 17th and that’s the topic of our post today. FN-70489 Now this FN on the surface sounds VERY concerning, but let’s dive a little deeper to see if in fact, you may be impacted. The most important statement is in the “Note” of the Problem Description “To be impacted by this issue, a…

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Cisco Switch Virtualization (Clustering)

Cisco Switch Virtualization (Clustering)

Network Virtualization vs Device Virtualization: Examples of Network Virtualization Virtual Port-channel (vPC) VLAN (L2) VRF (L3) VSAN Examples of Device Virtualization Security Context Virtual Device Context (VDC) Virtual Switch System (VSS) StackWise Virtual (SV) and Physical StackWise Virtual Machines (VMs) Why Use Switch/Device Virtualization? Eliminate STP blocked paths, FHRPs, and multiple device administration touch points Simplifies operations of campus access, distribution, and core topology Active/Active data plane path via Multi-chassis Etherchannel (MEC) = more bandwidth and lower latency Improve convergence…

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CCDE: “The Journey”

CCDE: “The Journey”

I promised an update on my CCDE journey last week on Twitter, so here we go… I’ve been preparing for the practical for about 4 months and finally took it for the first time on 5.30.18. So, here’s my story… In preparation for the practical, I attended a CCDE bootcamp by Jeremy Filliben and it was awesome. Several of my study buddies from Cisco also attended, so we were able to collaborate during and after the bootcamp which was cool….

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The Road to Network Engineering

The Road to Network Engineering

          I was inspired to document my career journey after reading a post by Packet Pushers @ecbanks. Circa 1997 I was working in a local computer shop called Circle Computer in Ephrata, PA. We were a Commodore Amiga shop, but Commodore went bankrupt and had to start pushing x86 PC’s. The Intel Pentium MMX processors were hot at this time and Duke Nukem 3D was the FPS of choice. I was mostly responsible for building PCs…

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KRACK

KRACK

  (K)ey (R)einstallation (A)tta(C)(K) Breaking WPA2 by forcing nonce reuse It’s been a long day and I wanted to have some fun with this post. I was onsite with several customers today when the news broke publicly. I only knew about it at a high-level in the morning and didn’t have time to digest the magnitude nor details of the vulnerability until this evening. You see, for me this feels somewhat like Deja Vu. I remember the day when it…

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Catalyst 9300: Hands-On Review

Catalyst 9300: Hands-On Review

Cisco Catalyst 9300 (First Impressions) I received an email from our awesome lobby ambassador about two packages that arrived in the Malvern office. I didn’t remember what I ordered and quickly forgot about the packages because, it was such a chaotic week. When I finally made my way to the office, I saw the boxes in the mail room and thought “NO! That can’t be them already…”. Upon closer inspection, they were in fact the Catalyst 9300’s I had ordered….

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The Network. Intuitive.

The Network. Intuitive.

A New Network for a New Era Well, the cat is finally out the bag… I’ve been biting my lips for the last several months working on campus designs with customers. That’s because internally at Cisco, all the buzz was around bringing SDN and most importantly intent driven networking to the campus in a BIG way. This is very much akin to how Cisco transformed the data center with ACI. In fact, I’ve heard verbatim from customers “why doesn’t Cisco…

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Cisco Nexus 9500 I/O Module Matrix

Cisco Nexus 9500 I/O Module Matrix

#ConfigBytes Updated 02.17.2017 Full PDF: Cisco Nexus 9500 IO Module Matrix This is a work in progress, so if there are fields you’d like to see added, please tweet me @Cisco_East or post in the comments section below.  

CCIE DNA: Reality or Myth?

CCIE DNA: Reality or Myth?

It all started at #CLUS Unfortunately, I was unable to attend Cisco Live US in Las Vegas this year. Don’t shed any tears for me as I was fortunate enough to have customers, friends, and co-workers attend. They got me some sweet swag and provided a play-by-play as things unfolded. One such morsel of information was regarding a “CCIE DNA” or “CCIE GUI”. At first I was just sitting in front of my monitor drifting into space thinking what the format of…

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