A critical issue in peer-to-peer (P2P) streaming systems is to find a peer that can provide required streaming data (eligibility determination) with good quality (quality optimization) to a given peer. For P2P on-demand streaming systems that fetch data directly from the streaming buffer of the supplying peer, e.g. buffer chaining, the content of the streaming buffer change constantly, but the requesting peer may jump to any point in the stream. It is very expensive to track buffer contents for eligibility determination. This paper presents a novel eligibility determination strategy, which, instead of using directories, embeds relationship of buffer contents through the interconnection of peers. The resultant peering structure is called the Overlapping Buffer Network (OBN). We will discuss why this interconnection-based approach is more desirable than directory-based approaches, such as distributed hash table. Performance of OBN will be evaluated with simulation.