“AS-Path Prepend Deep Dive for both Inbound & outbound traffic When and Why It Works” скачать в хорошем качестве

“AS-Path Prepend Deep Dive for both Inbound & outbound traffic When and Why It Works”

AS-Path Prepend Deep Dive | Inbound vs Outbound Traffic Explained with Real Examples ⏱ Suggested Video Length 12–15 minutes 🧠 INTRO (0:00 – 1:00) In this video, we’ll do a deep dive into AS-Path Prepending and answer the most confusing question in BGP: 👉 Does AS-Path prepend control inbound traffic, outbound traffic, or both? We’ll cover: What AS-Path prepend really does Why it is mainly used for inbound traffic engineering Why it does NOT truly control outbound traffic Real-world CLI examples When prepend fails and what to use instead 🔍 WHAT IS AS-PATH PREPEND? (1:00 – 2:30) In BGP, AS-Path is the list of Autonomous Systems a route has traversed. BGP prefers: Shortest AS-Path Before considering MED, origin, or IGP metric AS-Path prepend means: Artificially adding your own AS number multiple times to make a path look longer and therefore less attractive. Example: Original AS-Path: 65001 After prepend: 65001 65001 65001 🚦 BGP PATH SELECTION (Quick Reminder) (2:30 – 3:30) Key BGP decision steps (simplified): Highest Weight (Cisco only) Highest Local Preference Shortest AS-Path ← prepend affects this Origin MED eBGP over iBGP IGP metric to next-hop ⚠️ Important: AS-Path is evaluated only after Local Preference If Local Preference is different, prepend will be ignored 📥 AS-PATH PREPEND FOR INBOUND TRAFFIC (3:30 – 7:00) 🔑 THIS IS THE PRIMARY USE CASE Inbound traffic = Traffic coming FROM the internet or external AS INTO your network Scenario: You have two ISPs ISP-A (Primary) ISP-B (Backup) You want incoming traffic to prefer ISP-A Solution: