mSLP - Mesh-Enhanced Service Location Protocol

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mSLP - Mesh-Enhanced Service Location Protocol

• Weibin Zhao
• zwb_at_cs.columbia.edu

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Background

• Service discovery protocol
• objects
• devices, applications, and services
• environments
• IP, wireless, mobile, Java
• models
• directory-centric register/query
• peer-to-peer ad hoc network

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Background (2)

• Typical systems
• SLP IETF
• Jini Sun
• UPnP Microsoft
• Salutation consortium
• Bluetooth SIG
• irDA (Infrared Data Association)

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Jini

• Federation
• coordination between autonomous devices
  
• Lookup service
• maintain dynamic information on available devices
• discover lookup services before entering a
  federation
• know before hand or by multicast
• Basic operations
• announce presence (register) discovery other
  devices (query)
• describe capabilities attribute/value pairs

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UPnP

• SSDP
• Simple Service Discovery Protocol
• with or without lookup service
• HTTP over UDP HTTPU, HTTPMU (multicast)
• Announce (register) / Options (query)
• XML describe capability
• Self configuration
• IP address AutoIP if no DHCP server
• DNS name multicast DNS

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SLP

• Service Location Protocol
• SA Service Agent (announce / register)
• UA User Agent (query)
• DA Directory Agent (optional)

App
Service
UA
SA
DA
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SLP (2)

• Small service radius No DA

SA
SA
Multicast SrvRqst
UA
Unicast SrvRply
SA
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SLP (3)

• Medium service radius DAs (one scope)

UnicastSrvReg
SA
UnicastSrvRqst
DA
UnicastSrvAck
UA
UnicastSrvRply
SA
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SLP (4)

• DA discovery
• Active
• Passive

Multicast SrvRqst
DA
UA/SA
Unicast DAAdvert
Multicast DAAdvert
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SLP (5)

• Large service radius DAs (multiple scopes)

SA
DA (CU)
UA
SA
SA
DA (NYU)
UA
SA
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SLP (6)

• Scalability
• DA
• Enhance scalability performance
• Scope
• Group services, further scalability
• Location, administrative group, etc
• Reliability
• Multiple DAs for each scope

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mSLP Mesh-enhanced SLP

• Problem target
• Interaction scheme when multiple DAs present
• Original SLP
• SA register with all DAs
• mSLP
• SA register with one DA
• Automatic propagation of registrations among DAs

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mSLP (2)

• Peer DA
• Share one or more scopes
• Fully meshed persistent TCP
• Peer stages
• Setup, maintain, tear down
• Message flows
• Initial data exchange
• New SA registrations forwarding

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mSLP (3)

• Setting up peer relationship

Multicast DAAdvert
DA1
DA2
attr mesh-enhanced
DA2 creates peering TCP connection to DA1
DAAdvert (TCP)
DA2
DA1
attr peering-connection-indication
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mSLP (4)

• Initial data exchange

DAAdvert (TCP) attr data-copy-request
DA1
DA2
SrvReg (TCP), ltdata of shared scopesgt
Avoid redundant transmission
DA1
new DA
DA2
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mSLP (5)

• New registration forwarding (one-hop)

MF-extension
Next Ext. Off. (NEO)
NEO contd.
Action
Action To-Be-Forwarded, Has-Been-Forwarded
DA2
SrvReg (HBF)
SrvReg (TBF)
SA
DA1
SrvAck
SrvAck
DA3
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mSLP (6)

• Data structure
• Peer DA table
• URL, scopes, boot timestamp, TCP ID
• Peering TCP connection table
• Keeping peer relationship
• Keepalive
• Tearing down peer relationship

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Status

• Internet-draft
• draft-zhao-slp-da-interaction-02.txt
• Implementation
• Java2 UA/SA, DA
• Future work
• Experimental RFC
• Inter-domain DA interaction?