Computer Science and Engineering

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Intelligent Environments

• Computer Science and Engineering
• University of Texas at Arlington

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Networking for Intelligent Environments

• Requirements
• Technologies
• Networking
• Service Discovery
• Network Architecture

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Intelligent Environments

• Network Requirements

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Sensor 1
Sensor 5
Sensor 2
Sensor 6
Sensor 3
Sensor 7
Sensor 4
Sensor 8
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Network Requirements Sensors

• Camera (15) 320x240, 8-bit color
• Motion (15) distance, direction, velocity
• Temperature (12)
• Humidity (12)
• Light (12) frequency, intensity
• Microphone (12) 8000 Hz
• Gas (4)
• Pressure (100)

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Network Requirements Sensors
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Other Network Requirements

• Audio
• Phones (16 kHz, 8 bit)
• Radios (44 kHz, 16 bit)
• TVs (44 kHz, 16 bit)
• Media players (44 kHz, 16 bit)
• Monitoring (16 kHz, 8 bit)
• 2.4 Mbits/sec (one each)
• Internet, control,

• Video
• Phones (30fps, 320x240, 8-bit color)
• TVs (60 fps, 1024x768, 24-bit color)
• Video players (60 fps, 1024x768, 24-bit color)
• Monitoring (30 fps, 320x240, 8-bit color)
• 6.9 Gbits/sec (one each)

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Other Network Requirements
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Network Requirements

• Worst-case throughput 10 Gbits/sec
• Maximum throughput 5 Gbits/sec
• Quality of Service (QoS)
• Audio, video
• Plug and play (service discovery)

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Intelligent Environments

• Network Technologies

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Wired Network Technologies

• Phone line
• Home Phoneline Networking Alliance (HomePNA)
• Power line
• X10
• Consumer Electronics Bus (CEBus)
• HomePlug
• LonWorks
• New wire
• Ethernet (coax, twisted pair, optical fiber)
• Universal Serial Bus (USB)
• IEEE 1394 Firewire
• Home Audio Video Interoperability (HAVi)
• Specialty audio, video

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Wireless Network Technologies

• Digital Enhanced Cordless Telecommunications
  (DECT)
• HomeRF
• Bluetooth
• IEEE 802.11
• HiperLAN2
• Infrared

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Phoneline Networking

• Home Phoneline Networking Alliance (HomePNA)
• www.homepna.org
• IEEE 802.3 (Ethernet)
• Carrier Sense Multiple Access with Collision
  Detect (CSMA/CD)
• 10 Mbps (HPNA 2.0)
• Length 500 feet

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HomePNA Packet
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HomePNA Frequencies

• Standard voice (POTS) 20Hz - 3.4kHz
• UADSL 25kHz - 1.1MHz
• Home network 5.5MHz - 9.5MHz

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Phoneline Network Issues

• Random wiring topologies signal attenuation
• Home phoneline wiring system is a random tree
  topology
• Simply plugging in the phone or disconnecting the
  fax changes the tree
• This topology can cause signal attenuation
• Signal noise
• Appliances, heaters, air conditioners, consumer
  appliances telephones can introduce signal
  noise onto the phone wires

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Powerline Networking

• Ubiquity of power lines
• 10 Mbps
• Technologies
• X10
• Consumer Electronics Bus (CEBus)
• HomePlug
• LonWorks

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X10

• X10 controllers send signals over existing AC
  wiring to receiver modules
• X10 technology transmits binary data using the
  Amplitude Modulation (AM) technique
• www.x10.com

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X10

• To differentiate the data symbols, the carrier
  uses the zero-voltage crossing point of the 60Hz
  AC sine wave on the cycles positive or negative
  transition
• Synchronized receivers accept the carrier at each
  zero-crossing point
• X10 uses two zero crossings to transmit a binary
  digit so as to reduce errors

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X10

• Every bit requires a full 60 Hertz cycle and thus
  the X10 transmission rate is limited to only 60
  bps
• Usually a complete X10 command consists of two
  packets with a 3 cycle gap between each packet
• Each packet contains two identical messages of 11
  bits (or 11 cycles) each
• A complete X-10 command consumes 47 cycles that
  yields a transmission time of about 0.8s

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Consumer Electronics Bus (CEBus)

• Open standard providing separate physical layer
  specification for communication on power lines
  and other media
• Electronic Industries Association (EIA-600)
• www.cebus.org
• Data packets are transmitted by the transceiver
  at about 10 Kbps
• Carrier Sense Multiple Access/Collision Detect
  (CSMA/CD)
• Employing spread spectrum technology (100Hz-400
  Hz)

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OSI and CEBus (EIA-600)
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Spread Spectrum Modulation

• Frequency spectrum of a data-signal is spread
  using a code uncorrelated with that signal
• Sacrifices bandwidth to gain signal-to-noise
  performance

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HomePlug

• HomePlug Powerline Alliance
• www.homeplug.org
• Spread-spectrum technology

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HomePlug

• Speed
• Support file transfers at 10BaseT-like rates
• Either node-to-node file transfer or scenarios
  with multiple nodes performing simultaneous file
  transfers
• HomePlug 1.0 (14 Mbps)
• Voice over IP (VoIP)
• Maintain adequate QoS while supporting multiple,
  simultaneous VoIP calls while other nodes are
  transferring files and during multiple media
  streams

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HomePlug

• Interoperability
• Interoperate with other networking technologies
• Co-exist with existing powerline networking
  technologies such as X-10, CEBus and LonWorks
• Security
• Contain strong privacy features
• Support multiple logical networks on a single
  physical medium
• Be applicable to markets in North America, Europe
  and Asia

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LonWorks

• Local Operation Networks (LonWorks)
• Developed by Echelon Corporation
• www.echelon.com
• Provides a peer-to-peer communication protocol,
  implementing Carrier Sense Multiple Access (CSMA)
  techniques
• 1.25 Mbps
• Works for other wired and wireless media

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LonWorks

• A common message-based communications protocol
• LonTalk protocol implements all seven layers of
  the OSI model using a mixture of hardware and
  firmware on a silicon chip
• Protocol can be run as fast as 20 MHz

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Powerline Network Issues

• Noise
• Switching power supplies
• Wound motors
• Vacuum cleaners, kitchen appliances, drills
• Dimmers
• Security
• Signal attenuation

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New Wire Networking

• Ethernet (coax, twisted pair, optical fiber)
• Universal Serial Bus (USB)
• IEEE 1394 Firewire
• Home Audio Video Interoperability (HAVi)
• Specialty audio, video

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Ethernet

• IEEE 802.3
• CSMA/CD
• Up to 1 Gbps
• IEEE 802.3ae
• 10GBase-X, 10 Gps
• Lengths up to 40 km
• www.ethermanage.com/ethernet

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IEEE 802.3
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Universal Serial Bus (USB)

• www.usb.org
• 480 Mbps
• Plug and Play
• Hot pluggable
• Up to 127 devices simultaneously
• Powered bus
• 5m maximum cable length

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IEEE 1394 Firewire (i.LINK)

• Digital interface
• No need to convert digital data into analog and
  tolerate a loss of data integrity
• Transferring data _at_ 100, 200, 400 Mbps
• Physically small
• The thin serial cable can replace larger and more
  expensive interfaces

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IEEE 1394 Firewire

• No need for terminators or device IDs
• Hot pluggable
• Users can add or remove 1394 devices with the bus
  active
• Scaleable architecture
• May mix 100, 200, and 400 Mbps devices on a bus

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IEEE 1394 Firewire

• It can connect up to 63 devices _at_ transfer rate
  of 400Mbps
• Up to 16 nodes can be daisy- chained through the
  connectors
• Standard cables up to 4.5 m in length for a total
  standard cable length of 72 m

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IEEE 1394 Firewire

• Flexible topology
• Support of daisy chaining and branching for true
  peer-to-peer communication
• Non-proprietary

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IEEE 1394b

• 1394b is a significant enhancement to the basic
  1394 specification that enables
• Speed increases to 3.2 Gbps
• Distances of 100 meters on UTP-5, plastic optical
  fiber and glass optical fiber
• Significantly reduces latency times by using
  arbitration
• Fully backwards compatible with the current 1394
  and 1394a specifications

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Home Audio Video Interoperability (HAVi)

• HAVi is a digital Audio Video networking
  initiative that provides a home networking
  software specification
• Seamless interoperability among home
  entertainment products
• Designed to meet the particular demands of
  digital audio and video
• www.havi.org

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HAVi

• Defines operating-system-neutral middleware that
  manages
• Multi-directional AV streams
• Event schedule
• Registries
• Takes advantage of chips built into modern audio
  and video appliances
• Provides the management function of a dedicated
  audio-video networking system
• IEEE 1394 (i. LINK or FireWire) has been chosen
  as the interconnection medium

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Specialty Wiring

• Audio
• Coax
• RCA
• Speaker wire
• Video
• Coax
• RCA
• VGA
• 100m maximum cable lengths

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Intelligent Environments

• Wireless Networking Technologies

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Wireless Network Technologies

• Digital Enhanced Cordless Telecommunications
  (DECT)
• HomeRF
• Bluetooth
• IEEE 802.11
• HiperLAN2
• Infrared

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General Wireless

• Narrow band
• Spread spectrum
• Direct Sequence (DSSS)
• Frequency Hopping (FHSS)
• Orthogonal Frequency Division Multiplexing (OFDM)

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DECT

• Digital Enhanced Cordless Telecommunications
  (DECT)
• www.dectweb.com
• Digital radio technology
• Dynamic channel selection
• Encryption, authentication, identification
• 500 Kbps 2 Mbps
• Cordless phones

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HomeRF

• www.homerf.org
• Shared Wireless Access Protocol (SWAP)
• IEEE 802.11 for data
• DECT for voice

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HomeRF

• Specifications
• 2.4 GHz band
• FHSS
• 1.6 Mbps (10 Mbps with SWAP 2.0)
• 50m range
• 127 nodes

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Bluetooth

• www.bluetooth.com
• Ericsson, the principal inventor, borrowed the
  name from Harald Bluetooth (son of Gorm)
• The King of Denmark circa 900AD
• United Denmark and Norway

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Bluetooth

• Specifications
• 2.4 GHz
• FHSS (79 channels)
• 1600 hops per second
• Error correction
• 1 Mbps capacity, 780 Kbps throughput
• 10m distance
• Low power (1 mW)

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Bluetooth

• Personal Area Networks (PANs)
• Piconet
• Collection of up to 8 devices using same hopping
  sequence
• Scatternet
• Collection of piconets, each with different
  hopping sequence

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IEEE 802.11
Data rate degrades with distance.
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HiperLAN2

• www.hiperlan2.com
• 5 GHz
• 54 Mbps
• OFDM
• Automatic frequency allocation
• TDMA/TDD (Time Division)
• QoS support

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Infrared

• www.irda.org
• Directed line of sight
• 1m range
• Diffuse reflective
• Limited to room size
• Speed
• 4 Mbps available
• 16 Mbps coming
• 50 Mbps possible

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Wireless Networking
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Wireless Issues

• Distance
• 2.4 GHz interference
• Microwave ovens
• Cordless phones
• Security
• Not a backbone solution

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Intelligent Environments

• Service Discovery

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Service Discovery

• Self-configuring devices
• Device becomes aware of network, network services
  and other devices
• Automatic, as opposed to manual (e.g., DHCP, DNS,
  LDAP)
• Several incompatible protocols

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Service Discovery Protocols

• Salutation
• Service Location Protocol (SLP)
• Jini
• Universal Plug and Play
• Zero-Configuration Networking

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Salutation

• www.salutation.org
• Architecture for looking up, discovering and
  accessing services and information

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Salutation

• Abstractions for devices, applications, and
  services
• Current definitions
• Printers
• Fax machines
• Document storage devices
• Address book
• Schedule
• Voice message answer, send, storage
• More coming (e.g., display, OS)

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Salutation

• Capabilities exchange protocol
• Service request protocol
• Personalities (standardized protocols for
  common services)
• APIs for information access and session management

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Service Location Protocol (SLP)

• Developed by Internet Engineering Task Force
  (IETF)
• Applies existing Internet standards to service
  discovery problem
• www.srvloc.org
• www.openslp.org

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SLP Agents

• User Agent (UA)
• The SLP User Agent is a software entity that is
  looking for the location of one or more services.
  
• Service Agent (SA)
• The SLP Service Agent is a software entity that
  provides the location of one or more services.
• Directory Agent(DA)
• The SLP Directory Agent is a software entity that
  acts as a centralized repository for service
  location information.

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SLP Messages

• Service Request (SrvRqst)
• Message sent by UAs to SAs and DAs to request the
  location of a service.
• Service Reply (SrvRply)
• Message sent by SAs and DAs in reply to a
  SrvRqst.  The SrvRply contains the URL of the
  requested service.

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SLP Messages (cont.)

• Service Registration (SrvReg)
• Message sent by SAs to DAs containing information
  about a service that is available.
• Service Deregister (SrvDeReg)
• Message sent by SAs to inform DAs that a service
  is no longer available.
• Service Acknowledge (SrvAck)
• A generic acknowledgment that is sent by DAs to
  SAs as a reply to SrvReg and SrcDeReg messages.

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SLP Messages (cont.)

• Attribute Request (AttrRqst)
• Message sent by UAs to request the attributes of
  a service.
• Attribute Reply (AttrRply)
• Message sent by SAs and DAs in reply to a
  AttrRqst.  The AttrRply contains the list of
  attributes that were requested.

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SLP Messages (cont.)

• Service Type Request (SrvTypeRqst)
• Message sent by UAs to SAs and DAs requesting the
  types of services that are available.
• Service Type Reply (SrvTypeRply)
• Message by SAs and DAs in reply to a
  SrvTypeRqst.  The SrvTypeRply contains a list of
  requested service types.

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SLP Messages (cont.)

• DA Advertisement (DAAdvert)
• Message sent by DAs to let SAs and UAs know where
  they are.
• SA Advertisement (SAAdvert)
• Message sent by SAs to let UAs know where they
  are.
• Unicast or multicast messaging

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SLP Template Example
template-typeNet-Transducer
template-version0.0 template-description
This is an abstract service type. The purpose of
the Net- Transducer service type is to
organize into a single category all network
enabled Transducers which have certain
properties. template-url-syntax url-path
Depends on the concrete service type.
See these templates. sample-units
string L The units of sample that the
Transducer provides, for instance C (degrees
Celsius), V (Volts), kg (Kilograms), etc.
sample-resolution string L The resolution of
the Transducer. For instance, 10-3 means
that the Transducer has resolution to 0.001
unit. sample-rate integer L The speed at
which samples are obtained per second. For
instance 1000 means that one sample is obtained
every millisecond.
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SLP Template Example
template-typeserviceNet-TransducerThermometer
template-version0.0 template-description
The Thermometer is a Net-Transducer capable
of reading temperature. The data is read by
opening a TCP connection to one of the ports
in the service URL and reading an ASCII string
until an NULL character is encountered. The
client may continue reading data at no faster
than the sample-rate, or close the connection.
template-url-syntax url-path "ports"
ports-list port-list port / port ","
ports port 1DIGIT
See the Service URL ltportgt production rule.
These are the ports
connections can be made on. location-descriptio
nstring The location where the Thermometer
is located. operatorstring O The operator
to contact to have the Thermometer serviced.
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Jini

• Service discovery for networks of Java-enabled
  devices
• www.sun.com/jini
• www.jini.org

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Jini
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Jini

• Services
• Lookup
• Communications
• Java-RMI, CORBA,
• Security
• Leasing
• Events

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Universal Plug and Play

• Microsofts service discovery approach
• IP-based discovery protocols
• XML
• www.upnp.org
• Examples

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Universal Plug and Play

• Devices
• Containers for services
• XML description
• Services
• Actions (i.e., methods)
• Control server
• Event server
• State (i.e., variables)
• XML description

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Universal Plug and Play

• Control points
• Retrieve the device description and get a list of
  associated services.
• Retrieve service descriptions for interesting
  services.
• Invoke actions to control the service.
• Subscribe to the services event source. Anytime
  the state of the service changes, the event
  server will send an event to the control point.

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UPnP Interoperability
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UPnP Protocols

• Protocols
• UDP, TCP/IP, HTTP, XML
• Simple Service Discovery Protocol (SSDP)
• Generic Event Notification Architecture (GENA)
• Send/receive event notifications using HTTP over
  TCP/IP and multicast UDP
• Simple Object Access Protocol (SOAP)
• XML and HTTP for remote procedure calls

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UPnP Protocol Stack
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Zero-Configuration Networking

• Zeroconf (www.zeroconf.org)
• IETF standard
• Objectives
• Allocate addresses without a DHCP server
• Translate between names and IP addresses without
  a DNS server
• Find services, like printers, without a directory
  server
• Allocate IP Multicast addresses without a MADCAP
  server
• Multicast Address Dynamic Client Allocation
  Protocol

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Zeroconf Protocols

• Address autoconfiguration
• Configure interfaces with unique addresses
• Determine which subnet mask to use
• Detect duplicate address assignment
• Cope with collisions
• Name-to-address translation
• Multicast DNS
• Decentralized

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Zeroconf Protocols

• Service discovery
• Service Location Protocol (SLP)
• DNS Service Resource Record
• Use expanded DNS for service requests
• Multicast address allocation
• Zeroconf Multicast Address Allocation Protocol
  (ZMAAP)
• Allocate unique addresses and maintain them over
  time
• Prevent reallocation of assigned addresses
• Be notified of multicast allocation collision

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Intelligent Environments

• Network Architecture

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Network Architecture

• Networking
• Phoneline, powerline
• New wire
• Wireless
• Service discovery
• SLP, Jini, UPnP, Salutation, zeroconf
• Communication
• CORBA, Java-RMI, DCOM

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Network Architecture