Independent operator networks are called either Autonomous Systems (AS) or domains. Numerous studies based on complex measurement platforms have been carried out for over ten years now in order to discover the Internet topology on domain level. The routing realized by Border Gateway Protocol (BGP) is strongly influenced by commercial relationships which exist between domains, because domain operators do not want to make public the routes they know, as announcing certain routes would deprive them of a possible financial benefit. Consequently, routes available in BGP tables are valley-free and they are "Spanned" on the inter-domain hierarchy. This property of BGP routes has an impact on the performance of protocols which are proposed to assure the QoS.