Location-to-URL Mapping Protocol (LUMP) draft-schulzrinne-ecrit-lump-00

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Location-to-URL Mapping Protocol
(LUMP)draft-schulzrinne-ecrit-lump-00

• Henning Schulzrinne
• Dept. of Computer Science
• Columbia University
• hgs_at_cs.columbia.edu

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Overview

• Support global-scale resolution of service
  identifiers (e.g., service URNs) locations to
  other URLs
• Attempts to be reliable and scalable
• borrow concepts, but not protocol limitations,
  from DNS
• Architecture Forest of trees with a cloud
  above
• avoid root as only deployment alternative
• Uses standard web services building blocks

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Overall architecture
carrier X customers
knows all trees caches results
R
R
R
R
flooding
R
R
nj.us
ny.us
bergen.nj.us
leonia.bergen.nj.us
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Resolution

• Client queries local resolver
• doesnt know which tree to query!
• If not in cache, find tree root
• Resolver queries tree root
• recursively or iteratively

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Cluster architecture

• Each resolver or auth. server is actually a
  cluster of 1 nodes
• Automatically replicates changes (per record) to
  all other nodes
• tested with mSLP

nj.us
node
node

R
node
node
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Split jurisdictions
Im responsible for (parts of) Anytown
Anytown
asks both child nodes
query
Elm Street Oak Street Oak Street Anytown
Main Street Broad Street Main Square Anytown
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Building trees

• Trees are built from the top down
• Parents add children
• query for coverage region
• Next level down may differ for
• each service type (sos.fire vs. sos.police vs.
  roadside-assistance)
• geo vs. civic

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Top-level distribution

• Top-levels of trees distribute their coverage
  region to peers
• either civic pattern (CUS, A1NJ) or polygon
• Peers distribute data to other peers
• ? top-level scope data gets flooded to all
  resolvers
• new resolvers query peer for current data set
• periodic do you have any new data to avoid sync
  loss
• volume of data modest since top-level coverage
  changes slowly
• estimate one map/month (few thousand
  bytes/month)

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Caching

• Caching at all levels
• best effort update if expired and auth. server
  cant be contacted within T, use local value ? no
  good alternative
• Cache populated by verification queries
• MSAG validation and/or access testing
• Query returns hints
• e.g., ask for specific geo location
• get back enclosing polygon with service area

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Operations

• Query record (recursive, redirection)
• either from LObj or LRef
• Query range (poly, civic)
• return map or list of civic ranges
• Provide update vector (from peer)
• identified by time hash
• also used to seed data
• Obtain updates via vector
• get list of objects
• Push new data object
• for cluster synchronization

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Discovery

• LUMP resolver discovery via
• DHCP (if offered by ISP)
• likely close-by and with full cache
• SIP configuration (MSP)
• most likely to be operated by MSP?
• Bonjour
• subnet

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Design assumptions

• Cant predict deployment model
• May change over lifetime of protocol
• from peer to root model
• Want to have diverse implementations in each
  cluster and tree ? need standardized
  synchronization mechanisms

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Open issues

• Clean up architecture description and terminology
• Need to define WSDL
• Define coverage maps for geo and civic
• Estimate bandwidth usage for flooding
• Security how to trust tree scope announcements
• sign (XMLDSIG) announcements
• who can sign for what some authority (e.g.,
  regulator, NENA in US?)
• mediator (trust aggregator) may do job