Autonomous system number (ASn) is a unique identifier of a dedicated network in BGP protocol. The number is configured on the router or routers in the relevant end network. Assigning your own ASn is essential when the network is connected to multiple service providers (e.g. due to backup) or when the network is connected directly to one of connection nodes (IXP, e.g. NIX.CZ, SIX.SK, NIX.SK, Peering.CZ , BR-IX.CZ).