BGP

Border Gateway Protocol, the path-vector protocol that holds the internet together and increasingly runs inside enterprise data centers. Articles tagged BGP cover fundamentals, neighbor states, path attributes, best-path selection, traffic engineering, and Cisco IOS XE configuration.

36 posts

BGP

BGP MED (Multi-Exit Discriminator): Influencing Inbound Traffic

MED tries to influence how traffic enters your AS by suggesting which of your entry points the neighbor should prefer. It is optional non-transitive and easy to misuse. How MED actually works, and how to set it safely.

Mar 28, 2026 4 min read

BGP

Manipulating BGP Local Preference for Inbound Path Selection

Local preference tells every router in your AS which exit to prefer for specific destinations. It rides iBGP throughout the AS and resolves in step 2 of best path. The cleanest tool for inbound exit engineering.

Mar 28, 2026 4 min read

BGP

BGP Communities: Standard, Extended, and Large

BGP communities tag routes with meaning: customer route, prefer this path, do not advertise outside our region. A complete guide to standard, extended, and large BGP communities with practical policy examples.

Mar 28, 2026 4 min read

BGP

BGP Route Maps: Matching, Setting, and Manipulating Paths

Route maps are the primary BGP traffic engineering tool on Cisco IOS XE. Match on AS-path, community, or MED, then set attributes to steer paths. A practical guide to matching, setting, and manipulating BGP routes.

Mar 28, 2026 4 min read

BGP

BGP RPKI and Route Origin Validation on IOS XE

RPKI lets prefix owners sign ROAs that say which AS is authorized to originate their prefixes. Route Origin Validation rejects invalid routes. A practical guide to RPKI and ROV on Cisco IOS XE for internet-facing networks.

Mar 28, 2026 4 min read

BGP

BGP Route Leaks and Hijacks: Detection and Prevention

BGP was designed when every AS was trusted. Accidental route leaks and deliberate prefix hijacks have caused repeated major outages. How to detect them, prevent them, and protect your AS from the blast radius when others make mistakes.

Mar 28, 2026 4 min read