1. 1 LoST: Location-to-URL Mapping cluster serves VSP 2 NY US NJ US Bergen County NJ US 123 Broad Ave Leonia Bergen County NJ US cluster serving VSP 1 replicate root information search referral root nodes Leonia NJ US sip:psap@leonianj.gov VSP 1 LoST

2. 2 LoST Architecture T1 (.us) T2 (.de) T3 (.dk) G G G G G broadcast (gossip) T1:.us T2:.de resolver seeker 313 Westview Leonia, NJ US Leonia, NJ  sip:psap@leonianj.gov forest guide

3. Desirable properties Get correct answer regardless of where query enters system –intentionally or accidentally –queries are directed “upwards”, “downwards” as needed each node knows coverage of nodes above and below Allow different architecture choices

4. 4 LoST: Query example Uses HTTP or HTTPS <findService xmlns="urn:…:lost1” recursive="true" serviceBoundary="value" > Germany Bavaria Munich Neu Perlach 96 urn:service:sos.police

5. 5 LoST “Find Service” response/warning example München Polizei-Abteilung urn:service:sos.police Germany Bavaria Munich 81675 sip:munich-police@example.com 110