A new deep-dive is up on ignaonline.com — BGP communities and route filtering on Cisco IOS-XE.

This one covers:

• Standard, extended, and large BGP communities
• Enabling community propagation on eBGP sessions (the step everyone forgets)
• Setting communities with route-maps: tagging customer routes, NO_EXPORT, additive keyword
• Bogon filtering with prefix-lists — full RFC 5735 list included
• AS-path access-lists and regex patterns for route origin filtering
• Community-based local-preference for traffic engineering
• Selective AS-path prepending with community tags
• Troubleshooting: received-routes, prefix-list hit counts, soft resets

Real IOS-XE CLI with show command output throughout. Plus a production checklist at the end.

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