New post from Sarah Chen on ignaonline.com:

BGP carries the internet's routing table, but raw prefixes alone aren't enough for complex policy decisions. BGP communities are the mechanism that lets you attach metadata to routes — tagging them by origin, relationship, or intended treatment — so every router in the path can apply consistent policy without hardcoding lengthy prefix-lists everywhere.

In this guide, Sarah covers:

• Standard, extended, and large community types
• Enabling community propagation on Cisco IOS-XE
• Setting and matching communities with route-maps
• Remotely Triggered Black Hole (RTBH) for DDoS mitigation
• Verification commands and common gotchas
• A complete dual-homed enterprise BGP policy example

Read the full post →