New post from Sarah Chen on ignaonline.com:

BGP Communities and Route Filtering on Cisco IOS-XE: A Practical Deep Dive

If you've been working with BGP for a while, you already know the protocol can do a lot more than just advertise routes. One of the most powerful — and often underutilized — tools is BGP Communities.

In this deep dive, Sarah covers:

• Standard communities (RFC 1997) and well-known communities
• Setting communities with route-maps and the additive keyword
• Community-lists for flexible matching (standard and regex)
• Real-world RTBH blackhole filtering for DDoS mitigation
• Large communities (RFC 8092) on IOS-XE 16.6+
• Traffic engineering with upstream provider community schemas
• Stripping internal communities at AS boundaries
• Designing a scalable community schema
• Troubleshooting and soft reset after policy changes

All examples use real IOS-XE CLI syntax with show command output.

Read the full post