👋 Advanced Path Manipulation in BGP
📈 This video is essential for network engineers and those preparing for networking interviews.
🛣️ To understand path manipulation, one must first grasp best path selection in BGP, which relies on various attributes.
🔍 The first attribute is Next Hop. It checks if the next hop IP address is reachable. If both next hops are reachable, the router checks the next attribute.
⚖️ The second attribute is Weight. BGP does not carry weight information in updates, but self-advertised prefixes have a weight of 32768, while received prefixes have a weight of 0.
🏷️ The third attribute is Local Preference (LP). This is only carried for iBGP neighbors. If LP values are the same, the router checks the next attribute.
🔗 The fourth attribute is AS Path. A shorter AS path is preferred. If AS paths are equal, the router checks the next attribute.
📜 The fifth attribute is Origin Code. It can be I (IGP), E (EGP), or ? (incomplete). I is preferred over E.
📊 The sixth attribute is Metric. BGP does not carry metric information in updates.
🌐 The seventh attribute is External vs. Internal. External paths are preferred over internal paths.
💰 The eighth attribute is IGP Cost to reach the next hop. Lower costs are preferred.
⏳ The ninth attribute is Oldest Path. The oldest path is preferred if all other attributes are equal.
🔢 The tenth attribute is Router ID. The router with the lower ID is preferred.
🔄 Path Manipulation Techniques:
📊 Load Balancing: BGP can perform load balancing if the IGP cost to reach the next hop is the same.
🔄 Aggregation in BGP: This is used to summarize multiple prefixes into a single route to reduce the size of the routing table.
📜 Community Attribute: This is used for tagging and path manipulation. It includes predefined communities like No Export, No Advertise, and Internet.
🔑 Key Takeaways:
📅 Stay tuned for more detailed discussions in future videos!