katz, stoica f04 eecs 122: introduction to computer networks evolution of the internet computer...

Katz, Stoica F04

EECS 122: Introduction to Computer Networks

Evolution of the Internet

Computer Science Division

Department of Electrical Engineering and Computer Sciences

University of California, Berkeley

Berkeley, CA 94720-1776

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R U RDY 4 WOTS NXT?

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Automobiles663 Million

Telephones1.5 Billion

Electronic Chips30 Billion

X-Internet

“X-Internet” Beyond the PC

Forrester Research, May 2001

93Million

407 Million

Internet Computers

Internet UsersToday’s Internet

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“X-Internet” Beyond the PC

Forrester Research, May 2001

0

5000

10000

15000Millions

Year

XInternet

PCInternet

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The Old Days

All will demand broadbandInternet connectivity

Shape of Things Today: Diverse Appliances and

Devices

Game ConsolesPersonal Digital Assistants

Digital VCRsCommunicators

Smart TelephonesE-Toys

… and 10BaseT won’t be sufficient

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Future of the Internet

Mobile IP Networked Everything: Sensor Nets Internet Economics

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Why Mobile IP?

Need a protocol that maintains network connectivity while hosts move between nets

Must avoid massive changes to router software, etc.

Must be compatible with large installed base of IPv4 networks/hosts

Confine changes to mobile hosts and a few support hosts that enable mobility

G. G. Richard III, UNO

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Mobile IP: Basics

Proposed by IETF (Internet Engineering Task Force)

- Standards development body for the Internet

Allows a mobile host (MH) to move about without changing its permanent IP address

Each mobile host has a home agent (HA) on its home network

MH establishes a care-of address when it's away from home


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Mobile IP: Basics

Correspondent host (CH) is a host that wants to send packets to the MH

CH sends packets to the MH’s IP permanent home address

Packets routed to the MH’s home network HA forwards IP packets for MH to current care-of

address MH sends packets directly to correspondent,

using permanent home IP as source IP


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Mobile IP: Basics

home agentcorrespondent host


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Mobile IP: Care-of Addresses

When MH connects to a remote network:- Care-of can be the address of a foreign agent (FA) on

the remote network

• FA delivers packets forwarded from HA to MA

- Care-of can be a temporary, foreign IP address obtained through, e.g., DHCP

• HA tunnels packets directly to the temporary IP address

Care-of address must be registered with HA


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IP header

IP-in-IP Tunneling

Packet to be forwarded is encapsulated in a new IP packet

In the new header:- Destination = care-of-address

- Source = address of home agent

- Protocol number = IP-in-IP

IP headerdata IP header

data


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At the Other End...

Depending on type of care-of address:- FA or

- MH

… strips outer IP header of tunneled packet, which is then fed to the MH


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Routing Inefficiency

home agentcorrespondent host

MH and CH may even be on the same network!!


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Route Optimizations

Possible Solution:- HA sends current care-of address to CH

- CH caches care-of address

- Future packets tunneled directly to care-of address

But …- Cache consistency problem arises ...

- Cached care-of address becomes stale when the MH moves

- Potential security issues with providing care-of address to correspondent


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Embedded Sensor Nets: Enabling Technologies

Embedded Networked

Sensing

Control system w/Small form factorUntethered nodes

ExploitcollaborativeSensing, action

Tightly coupled to physical world

Embed numerous distributed devices to monitor and interact with physical world

Network devices to coordinate and perform higher-level tasks

Exploit spatially/temporally dense, in situ/remote, sensing/actuationJim Kurose, UMass

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Sensor Nets: New Design Themes

Self configuring systems that adapt to unpredictable environment

- Dynamic, messy (hard to model) environments preclude pre-configured behavior

Leverage data processing inside the network- Exploit computation near data to reduce communication- Collaborative signal processing- Achieve desired global behavior with localized algorithms

(distributed control) Long-lived, unattended, untethered, low duty cycle

systems - Energy a central concern- Communication primary consumer of scarce energy

resource

Jim Kurose, UMass

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From Embedded Sensing to Embedded Control

Embedded in unattended “control systems”- Control network, and act in environment

Critical apps extend beyond sensing to control & actuation

- Transportation, precision agriculture, medical monitoring and drug delivery, battlefield apps

- Concerns extend beyond traditional networked systems and apps: usability, reliability, safety

Need systems architecture to manage interactions- Current system development: one-off, incrementally tuned,

stove-piped- Repercussions for piecemeal uncoordinated design:

insufficient longevity, interoperability, safety, robustness, scaling

Jim Kurose, UMass

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Why Not Simply Adapt Internet Protocols, “End-to-End” Architecture?

Internet routes data using IP Addresses in Packets and Lookup tables in routers

- Humans get data by “naming data” to a search engine

- Many levels of indirection between name and IP address

- Embedded, energy-constrained (un-tethered, small-form-factor), unattended systems cant tolerate communication overhead of indirection

Special purpose system function(s): don’t need want Internet general purpose functionality designed for elastic applications

Jim Kurose, UMass

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Sample Layered Architecture

Resource constraints call for more tightly integrated layers

Open Question:

What are definingArchitecturalPrinciples?

In-network: Application processing, Data aggregation, Query processing

Adaptive topology, Geo-Routing

MAC, Time, Location

Phy: comm, sensing, actuation, SP

User Queries, External Database

Data dissemination, storage, caching

Jim Kurose, UMass

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Sensors

Passive elements: seismic, acoustic, infrared, strain, salinity, humidity, temperature, etc.

Passive Arrays: imagers (visible, IR), biochemical Active sensors: radar, sonar

- High energy, in contrast to passive elements

Technology trend: use of IC technology for increased robustness, lower cost, smaller size

- COTS adequate in many of these domains; work remains to be done in biochemical

Jim Kurose, UMass

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Fine Grained Time and Location

Unlike Internet, node time/space location essential for local/collaborative detection- Fine-grained localization and time sync to detect events in

3D and compare detections across nodes

GPS provides solution where available (with diff-GPS providing finer granularity)- GPS not always available, too “costly,” too bulky- Other approaches under study

Localization of sensor nodes has many uses

- Beamforming for localization of targets and events

- Geographical forwarding

- Geographical addressing

Jim Kurose, UMass

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Coverage Measures

Area coverage: fraction of area covered by sensors

Detectability: probability sensors detect moving objects

Node coverage: fraction of sensors covered by other sensors

Control:- Where to add new nodes for

max coverage

- How to move existing nodes for max coverage

S

D

x

Given: sensor field (either known sensor locations, or spatial density)

Jim Kurose, UMass

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In-Network Processing

Communication expensive when limited- Power- Bandwidth

Perform (data) processing in network - Close to (at) data- Forward fused/synthesized

results- e.g., find max. of data

Distributed data, distributed computation

Jim Kurose, UMass

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Distributed Representation and Storage

Data Centric Protocols, In-network Processing goal:- Interpretation of spatially distributed data

(Per-node processing alone is not enough)

- Network does in-network processing based on distribution of data

- Queries automatically directed towards nodes that maintain relevant/matching data

Pattern-triggered data collection- Multi-resolution data storage and retrieval

- Distributed edge/feature detection

- Index data for easy temporal and spatial searching

- Finding global statistics (e.g., distribution)

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Jim Kurose, UMass

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Directed Diffusion: Data Centric Routing

Basic idea- Name data (not nodes) with externally relevant attributes: data

type, time, location of node, SNR,

- Diffuse requests and responses across network using application driven routing (e.g., geo sensitive or not)

- Support in-network aggregation and processing Data sources publish data, data clients subscribe to data

- However, all nodes may play both roles

• Node that aggregates/combines/processes incoming sensor node data becomes a source of new data

• Node that only publishes when combination of conditions arise, is client for triggering event data

- True peer to peer system?

Jim Kurose, UMass

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The Big Picture

Supply

Price(s)

Market Structure & Mechanisms

Welfare (surplus)

Demand

Producer SurplusConsumer SurplusSocial Surplus{

John Chueng

katz, stoica f04 eecs 122: introduction to computer networks evolution of the internet computer...

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