1. Thoughts on dividing the P2P functionality Henning Schulzrinne Columbia University hgs@cs.columbia.edu

2. Diversity in DHT Generally, only super nodes really need to know DHT –thus, can imagine “provider-P2P” that runs proprietary DHT Three basic interfaces: –UAs treat SN as DNS server (get SRV) doesn’t work: SN depends on user, not just domain –UAs have common lookup protocol: user  SN but this is essentially SIP functionality –UAs treat SN as outbound proxy can redirect or proxy

3. Two-layer architecture DHT SN Supernodes act as proxies

4. How to run multiple DHTs Idea: no perfect DHT  provide multiple DHTs –need at least one mandatory-to-implement one Unlikely to have common information across all plausible DHTs –intersection of information = TCP –no major advantage of common protocol: all the hard work is in the DHT, not the protocol We have no plausible global resource discovery mechanism to find such nodes –but might be able to have DNS-based “seed” lists: PTR _supernodes._tcp.p2psip.org