Internet Architecture

Interconnection, peering, Data centers. How the Internet works. IXPs, transit, and other topics. Routing and Control Planes such as BGP and OSPF protocols. RPKI and IP resources are also covered.

Cisco BGP Troubleshooting: Essential Commands Every Network Engineer Should Know

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abstract futuristic digital tunnel illusion

When BGP (Border Gateway Protocol) misbehaves, the ripple effect can be massive—routes disappear, prefixes flap, and connectivity grinds to a halt. Whether you’re managing a large enterprise edge or an ISP core, knowing how to quickly diagnose BGP issues on Cisco routers is critical. Here’s a hands-on guide to the most useful Cisco IOS BGP … Read more

Border Gateway Protocol (BGP): How the Internet’s Routing Protocol Works

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Border Gateway Protocol (BGP) is a protocol that makes the Capital I Internet run. It is the fundamental system that Internet Service Providers (ISPs) and large networks use to exchange reachability information and ensure data finds its way across the complex web of networks making up the global Internet. This post will demystify how BGP … Read more

Private vs. Public Autonomous System Numbers (ASN): What’s the Difference?

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Interconnection

In the world of internet networking, Autonomous System Numbers (ASNs) play a crucial role in routing data efficiently between different networks. ASNs are unique identifiers assigned to Autonomous Systems (AS)—large networks or groups of IP addresses that operate under a single organization, such as ISPs, cloud providers, or large enterprises. However, not all ASNs are … Read more

Patreon Post: Mikrotik tagging incoming routes with a community

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This content is for Patreon subscribers of the j2 blog. Please consider becoming a Patreon subscriber for as little as $1 a month. This helps to provide higher quality content, more podcasts, and other goodies on this blog.To view this content, you must be a member of Justin’s Patreon Unlock with PatreonAlready a qualifying Patreon … Read more

IPv4 Subnet Mask Cheat Sheet: A Handy Guide

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LAN cables plug in

IPv4 Subnet Mask Cheat Sheet CIDR Notation Subnet Mask Total Subnets Hosts per Subnet (usable) /8 255.0.0.0 1 16,777,214 /9 255.128.0.0 2 8,388,606 /10 255.192.0.0 4 4,194,302 /11 255.224.0.0 8 2,097,150 /12 255.240.0.0 16 1,048,574 /13 255.248.0.0 32 524,286 /14 255.252.0.0 64 262,142 /15 255.254.0.0 128 131,070 /16 255.255.0.0 256 65,534 /17 255.255.128.0 512 32,766 … Read more

Understanding the Types of Power in a Data Center

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A data center is the beating heart of modern businesses, housing critical IT infrastructure that powers applications, processes, and data. Behind this infrastructure lies a robust power system designed to ensure uninterrupted operation. Power systems in a data center are complex and include various types of power sources and components, each serving a unique purpose. … Read more

How Does TCAM Work in Routers?

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In a previous post, I asked if TCAM is still needed in modern routers. In this post, I will examine how TCAM works in routers and provide some more insight into TCAM. In a router, TCAM stores and processes rules for various functions. These rules are typically derived from: Steps for TCAM Lookup: Why Do … Read more

Data Center physical security

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Physical security in a data center is critical as it serves as the first line of defense against unauthorized access, vandalism, theft, and environmental threats. Here’s a deeper dive into the various layers and strategies involved in ensuring comprehensive physical security for a data center. 1. Strategic Location Selection A. Risk Assessment for LocationChoosing the … Read more

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