So far, this is all great, but it IS missing something Networks are useless unless you do something with it. In most cases, a device (in this case, we'll use a server) needs to connect via redundant links to a common Layer 2 segment. Why is this? Well, most servers are incapable of dynamic routing. Instead, the server …

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So far, all examples to date have been extremely simple, and stand rather well on their own (OSPF Clos would work just FINE in a campus network if you have cheap L3) but may not effectively address some more advanced use cases. In short, we're about to enter niche territory. Generally speaking, BGP is regarded as the …

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Overview First off, here's the reference diagram (YAML): Assumptions about difficulty Most people I've met outside of the carrier space are pretty intimidated by BGP, as it is truly impressive in scope. Here, we're going to break-out BGP usage into two categories: iBGP: This is where all nodes have the same Autonomous …

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Here's the example topology used in the Spine-and-Leaf labs: (YAML)

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As covered in the previous post, base configuration of a spine-and-leaf fabric is actually pretty simple. This will be pretty short, but we'll cover the conversion of the previously built fabric to OSPF. Here's the updated diagram: (YAML). As we move to a more full-fledged implementation, we'll do dual-stack. The …

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This is only slightly trolling, but is primarily to outline the topological simplicity of Spine-and-Leaf networking, in a way that is suspiciously similar to Cisco classes. First things first, here's the diagram. This is performed using a set of four Cat3560s, enterprise licensed and wired in a redundant square …

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Before we get too far - this is going to be a simple topology, relatively speaking. I'll be putting the switch configs on my GitHub account as well when I get to that point. The diagram is as follows: This was drawn programmatically with drawthe.net. File is here

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The two biggest problems a network engineer will face are changes and loops In our Cisco exams, an overwhelming majority of the educational content is on methods of preventing loops, and for good reason. Unfortunately, the methods we use to prevent loops are highly complex - and if we partially understand these …

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Datacenter Network Engineers have two problems: CHANGE LOOPS (let's cover this one later!) Change is everywhere. Emerging trends such as DevOps and/or CI/CD have created the need for dynamic, ephemeral allocation of data center resources; not only in large-scale deployments, but medium-sized companies are starting down …

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25 Gigabit implementations First of all - anyone who assumes they think Layer 1 is simple is wrong. That being said, 25G/50/100G/QSFP28 services are different beyond simply being 2.5x faster than 10G. 802.3by (or 25 Gig for those who use it): Full-Duplex is mandatory. Energy Efficient Operation Stackable Lanes …

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