Specifying and Configuring Routing Policies of Relative AS in RPSL

Routing policies specification language (RPSL) allows a network operator to specify routing policies at various levels in the Internet hierarchy, for example at the autonomous system (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that the low level router configurations can be generated from them. This paper is a discussion on using the RPSL to describe routing policies of relative AS in the Internet routing registry (IRR). We first analyze the relationships between a pair of ASes, and then explain how to specify various relative AS routing policies in RPSL. At last, we show an example of configuring routing policies using RtConfig that is a tool developed by the Routing Arbiter Project (RAP).