an and d Im Impl plementa ementation tion (01 0120 20442 - - PowerPoint PPT Presentation

an and d im impl plementa ementation tion
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an and d Im Impl plementa ementation tion (01 0120 20442 - - PowerPoint PPT Presentation

Net etwork work Ke Kerne nel l Ar Archi chitect tectures ures an and d Im Impl plementa ementation tion (01 0120 20442 4423) ) Naming aming an and Ad Addressing ressing Chaiporn Jaikaeo Chaiporn.j@ku.ac.th Department of


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Net etwork work Ke Kerne nel l Ar Archi chitect tectures ures an and d Im Impl plementa ementation tion (01 0120 20442 4423) ) Naming aming an and Ad Addressing ressing

Chaiporn Jaikaeo Chaiporn.j@ku.ac.th Department of Computer Engineering Kasetsart University

Materials taken from lecture slides by Karl and Willig

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Na Name mes vs. . Add Addre resses

Names: s: Refer to “things”

  • Nodes, networks, data, transactions, …
  • May or may not be globally unique

Ad Addres esse ses: : Information needed to fi find these things

  • Street address, IP address, MAC address
  • May or may not be globally unique

Services to map between names and addresses

  • E.g., DNS

Some names are also addresses

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Na Nami ming ng in in WS WSN

Nodes are not independent

  • But collaborate to solve a given task

Better to shift view from naming nodes to na naming ing data

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Add Addre ress s Man Manage ageme ment nt Is Issue ues

Address dress al allo loca catio ion: n: Assign an entity an address from a given pool of possible addresses

  • Distributed address assignment (centralized

like DHCP does not scale)

Address dress deal allo locat cation: ion: Once address no longer used, put it back into the address pool

  • Because of limited pool size
  • Graceful or abrupt, depending on node actions
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Add Addre ress s Man Manage ageme ment nt Is Issue ues

Address representation

Conflict detection & resolution (Duplicate Address Detection - DAD)

  • What to do when the same address is assigned

multiple times?

  • Can happen e.g. when two networks merge

Binding

  • Map between addresses used by different

protocol layers

  • E.g., IP addresses are bound to MAC address

by ARP

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Un Unique iqueness ness of f Add Addre resses

Globally unique

  • Appears at most once all over the wo

worl rld

Network-wide unique

  • Appears at most once in a given netwo

work rk

Locally unique

  • Appears at most once in a defined

neighbo borho rhood

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Add Addre ressing sing Ov Overh rhead ead

The fewer bits per address, the better

Global > Network-wide > Local

Tradeoffs

  • Address length  management overhead

Typically, address negotiation runs only at the beginning

  • Except when there is mobility
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Di Distributed tributed Ad Addr dress ess As Assignment ignment

Option ion 1: Random assignment

  • Unacceptable high risk of duplicate addresses
  • No-conflict probability for n addresses and k

nodes is

  • By Stirlings approximation
  • Similar to the birthday paradox
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Di Distributed tributed Ad Addr dress ess As Assignment ignment

Option ion 2: Still random, but avoid addresses used in local neighborhood

  • By overhearing exchanged packets
  • Good enough in many WSN apps where data

sent to a certain sink

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Di Distributed tributed Ad Addr dress ess As Assignment ignment

Option ion 3: Repair any observed conflicts

  • Randomly pick a temporary address and a

proposed fixed address

  • Send an addres

ess requ quest t to the proposed address, using temporary address

  • If addres

ess s reply y arrives, address already exists

  • Collisions in temporary address unlikely, as
  • nly used briefly

Option ion 4: Similar to 3, but use a neighbor that already has a fixed address to perform requests

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Lo Locally cally Un Unique ique Add Addre resses

Fewer bits are needed, due to

  • Each address can be reused several times

across the same network

  • Lower-number addresses tend to be used more

frequently

  • Addresses can be compressed
  • E.g., using Huffman coding
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Is Issues ues wi with th As Asym ymme metr tric ic Li Link nks

Assume nodes communicate with bidirectional neighbors only

  • All bidirectional neighbors of each node must have

distinct addresses

  • The address of any inbound neighbor must be different

from all bidirectional neighbors

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Cont ntent ent-Base Based d Add Addre ressing ing

Recall: Paradigm change from id-centric to data-centric networking in WSN

Supported by content-based names/addresses

  • Do not described involved nodes (not known

anyway), but the co content nt itself the interaction is about

Classical option: Put a naming scheme on top of IP addresses

  • Done by some middleware systems
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De Descr cribing ibing In Inte terests rests

Inter eres ests ts describe relevant data/event

  • Nodes match these interests with their locally
  • bserved data

Format: Attribute-Value-Operation (AVO)

  • E.g.: <TEMP, 20°C, GE>
  • Operations:
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Des Describing cribing In Inte tere rest/Sensor/Data st/Sensor/Data

List of AVOs

E.g.,

<type,temperature,EQ> <threshold-from-below,20,IS> <x-coordinate,20,LE> <x-coordinate,0,GE> <y-coordinate,20,LE> <y-coordinate,0,GE> <interval,0.05,IS> <duration,10,IS> <class,interest,IS>

Interest

<type,temperature,IS> <x-coordinate,10,IS> <y-coordinate,10,IS>

Sensor

<type,temperature,IS> <x-coordinate,10,IS> <y-coordinate,10,IS> <temperature,20.01,IS> <class,data,IS>

Data

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Mat Match ching ing Al Algo gorithm rithm

Check whether an interest matches the locally available data

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Di Dire rected cted Di Diffu ffusion ion

An example of data-centric networking

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Ge Geographic graphic addr addressing ing

Express addresses by denoting physical position of nodes

  • Considered a special case of content-based

addresses

  • Attributes for x and y (and z) coordinates

Options

  • Single point
  • Circle or sphere centered around given point
  • Rectangle by two corner points
  • Polygon
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Conclusion nclusion

Addresses can be assigned distributedly

Non-id-centric addresses give additional expressiveness, enables new interaction patterns than only using standard addresses

These addresses have to be supported by specific protocols, in particular, routing protocols