What a BGP Neighbor Needs
What inputs are required to form a BGP neighbor, and where does the session stop when one of them is missing?
Open Session 01Sessions
BGP track sessions
How UPDATE Changes State
How does a BGP UPDATE change routing state, and why is route withdrawal different from session failure?
Open Session 02Best Path Selection As If Statements
Why does one BGP path become best, and which comparison produced the winner first?
Open Session 03Origin Validation Is A Separate Decision
How do we decide whether the origin AS is authorized, even after BGP has already selected a best path?
Open Session 04Validation State Does Not Act By Itself
What happens after origin validation returns valid, invalid, or not_found, and why does the result still need routing policy?
Where Routes Live
Where does a route live inside the router before selection, after selection, and right before advertisement?
Open Session 06Import Policy Rewrites Inputs
How does local import policy change or reject a path before best-path selection runs?
Open Session 07Export Policy Decides What Leaves
Why is the route we advertise to a peer not always identical to the route we installed locally?
Open Session 08Session Loss and Recompute
What happens to Loc-RIB when one peer disappears and the best path came from that peer?
Open Session 09One Route Through The Whole Pipeline
If you trace one received route end to end, which functions touch it before it becomes an advertisement or disappears?
Open Session 10Peer State Gates UPDATE
What has to be true before the control plane should accept an UPDATE from a neighbor?
Open Session 11Export Refresh After Recompute
When Loc-RIB changes, how do outbound advertisements get refreshed per peer?
Event Dispatches Announce, Withdraw, and Peer Down
What function decides which control-plane path to run for announce, withdraw, and peer-down events?
Open Session 13One Prefix Becomes A Decision Set
How do multiple received paths for one prefix become a policy-aware set of installable candidates?
Open Session 14Build The Toy Speaker Loop
What does the smallest readable BGP speaker look like when all previous sessions are connected?
Open Session 15