The summary.
ROUTING IS POLICY BEFORE IT IS GEOGRAPHY
The shortest path is not chosen; the commercially preferred one is. That is why traffic between nearby networks can travel a long way.
PEERING SUPPLEMENTS TRANSIT; IT DOES NOT REPLACE IT
Transit buys reachability to everywhere. Peering buys a shorter, cheaper path to specific networks.
Ask any hosting provider how many transit providers they have, who they peer with, and which exchanges they attend.
LOCAL EXCHANGE POINTS ARE WHY LOCAL TRAFFIC NO LONGER TRAVELS TO EUROPE AND BACK
BGP DOES NOT KNOW WHICH PATH IS FASTER
Outbound traffic is yours to control through local preference; inbound is a matter of influence only.
Most routing incidents are configuration error, not attack. Filter what you accept, publish origin authorisations, and validate.
FOR WEB BROWSING, LATENCY MATTERS MORE THAN BANDWIDTH
Adding bandwidth beyond a point does not make pages load faster. Measure latency under load, not idle speed.
A TRACE DOES NOT SHOW THE RETURN PATH
And intermediate hop latency frequently means nothing. Only latency that persists at every subsequent hop indicates a problem.
