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.
The prefix is in the BGP table and show ip route says % Network not in table. The leading status characters are the whole diagnosis. Captured live on IOS XE 17.18.2 in CML, where a missing next-hop-self leaves an iBGP path valid, inaccessible and never installed.
Active is a failure state and Idle is where the FSM gives up. Organised by the state you are looking at right now, with a lab finding that matters: on IOS XE 17.18.2 both "no route to peer" and "TCP 179 blocked" showed up as Idle.
OMP is to Catalyst SD-WAN what BGP is to the internet: the one protocol that carries everything. Routes, next-
BGP is the most powerful choice for the PE-CE protocol in an MPLS L3VPN - it scales, it carries policy,
You have an IPv4 MPLS L3VPN running. Your customers each have their own VRF, their own routing table, their own
Redistribution between two routing protocols at a single point is easy. Redistribution between two routing protocols at two points is
The CCIE troubleshooting section does not ask you to explain BGP. It hands you a broken network and a clock.
Here is a problem that a great many service providers had, and some still have: a fully working, fully tuned,
BGP installs one best path. That is the default and it is deliberate: BGP is a policy protocol, and the
Most networks use BGP communities the way most people use a junk drawer: things get put in, nobody agrees what
Dampening penalises a prefix for flapping and refuses to use it even after it recovers. Captured live on CML with IOS XE 17.18.2: penalty 2818 from three flaps, the prefix held at *d while an identical prefix from the same neighbor stays best, plus the advertisement-interval gotcha that makes...
Inbound prefix filtering is normal hygiene: you accept the routes you want and drop the rest. But think about what