AbstractWe study the interdomain traffic as seen by a non‐transit ISP, based on a six days trace covering all the interdomain links of this ISP. Our analysis considers the relationships between the interdomain traffic and the interdomain topology. We first discuss the day‐to‐day stability of the interdomain traffic matrix to evaluate the feasibility of interdomain traffic engineering. Then, we study the variability of the interdomain flows for several aggregation levels (prefix, AS and sink tree) and with respect to the interdomain topology seen by BGP. We show that despite the important variability of interdomain flows, it would be useful for a non‐transit ISP to traffic engineer its access traffic by relying on a sink tree aggregation level.