1. 1 mSLP - Mesh-Enhanced Service Location Protocol Weibin Zhao zwb@cs.columbia.edu

2. 2 Background Service discovery protocolService discovery protocol –objects: devices, applications, and servicesdevices, applications, and services –environments: IP, wireless, mobile, JavaIP, wireless, mobile, Java –models: directory-centric: register/querydirectory-centric: register/query peer-to-peer: ad hoc networkpeer-to-peer: ad hoc network

3. 3 Background (2) Typical systemsTypical systems –SLP: IETF –Jini: Sun –UPnP: Microsoft –Salutation consortium –Bluetooth SIG –irDA (Infrared Data Association)

4. 4 Jini –Federation coordination between autonomous devicescoordination between autonomous devices –Lookup service maintain dynamic information on available devicesmaintain dynamic information on available devices discover lookup services before entering a federationdiscover lookup services before entering a federation know before hand or by multicastknow before hand or by multicast –Basic operations announce presence (register); discovery other devices (query)announce presence (register); discovery other devices (query) describe capabilities: attribute/value pairsdescribe capabilities: attribute/value pairs

5. 5 UPnP –SSDP Simple Service Discovery ProtocolSimple Service Discovery Protocol with or without lookup servicewith or without lookup service HTTP over UDP: HTTPU, HTTPMU (multicast)HTTP over UDP: HTTPU, HTTPMU (multicast) Announce (register) / Options (query)Announce (register) / Options (query) XML: describe capabilityXML: describe capability –Self configuration IP address: AutoIP if no DHCP serverIP address: AutoIP if no DHCP server DNS name: multicast DNSDNS name: multicast DNS

6. 6 SLP –Service Location Protocol –SA: Service Agent (announce / register) –UA: User Agent (query) –DA: Directory Agent (optional) App UASA Service DA

7. 7 SLP (2) Small service radius: No DASmall service radius: No DA UA SA Multicast SrvRqst Unicast SrvRply

8. 8 SLP (3) Medium service radius: DAs (one scope)Medium service radius: DAs (one scope) UA DA SA Unicast SrvRqst Unicast SrvRply Unicast SrvReg Unicast SrvAck

9. 9 SLP (4) DA discoveryDA discovery –Active –Passive UA/SA DA Multicast DAAdvert Multicast SrvRqst Unicast DAAdvert

10. 10 SLP (5) Large service radius: DAs (multiple scopes)Large service radius: DAs (multiple scopes) UA DA (CU) SA UA DA (NYU) SA

11. 11 SLP (6) ScalabilityScalability –DA Enhance scalability & performanceEnhance scalability & performance –Scope Group services, further scalabilityGroup services, further scalability Location, administrative group, etcLocation, administrative group, etc ReliabilityReliability –Multiple DAs for each scope

12. 12 mSLP – Mesh-enhanced SLP Problem targetProblem target –Interaction scheme when multiple DAs present –Original SLP SA register with all DAsSA register with all DAs –mSLP SA register with one DASA register with one DA Automatic propagation of registrations among DAsAutomatic propagation of registrations among DAs

13. 13 mSLP (2) Peer DAPeer DA –Share one or more scopes –Fully meshed persistent TCP –Peer stages Setup, maintain, tear downSetup, maintain, tear down Message flowsMessage flows –Initial data exchange –New SA registrations forwarding

14. 14 mSLP (3) Setting up peer relationshipSetting up peer relationship DA1 DA2 DA1 Multicast DAAdvert attr = mesh-enhanced DAAdvert (TCP) attr = peering-connection-indication DA2 creates peering TCP connection to DA1

15. 15 mSLP (4) Initial data exchangeInitial data exchange DA1DA2 DAAdvert (TCP) [attr = data-copy-request] SrvReg (TCP), new DA DA2 DA1 Avoid redundant transmission

16. 16 mSLP (5) New registration forwarding (one-hop)New registration forwarding (one-hop) MF-extensionNext Ext. Off. (NEO) NEO contd.Action Action = { To-Be-Forwarded, Has-Been-Forwarded } SADA1 DA2 SrvReg (TBF) SrvReg (HBF) SrvAck DA3

17. 17 mSLP (6) Data structureData structure –Peer DA table URL, scopes, boot timestamp, TCP IDURL, scopes, boot timestamp, TCP ID –Peering TCP connection table Keeping peer relationshipKeeping peer relationship –Keepalive Tearing down peer relationshipTearing down peer relationship

18. 18 Status Internet-draftInternet-draft –draft-zhao-slp-da-interaction-02.txt ImplementationImplementation –Java2: UA/SA, DA Future workFuture work –Experimental RFC –Inter-domain DA interaction?