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1073.Inter-LAN.2008.01.18.v01.ppt SLIDE 1 IEEE 11073 Inter-LAN Work Group Status in association with HL7 DEV SIG & ISO TC 215 @ HL7 Working Group Meeting, San Antonio, TX, USA, 2008Jan18 Mark Schnell, [email protected]

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IEEE 11073 Inter-LAN Work Group Status in association with HL7 DEV SIG & ISO TC 215 @ HL7 Working Group Meeting, San Antonio, TX, USA, 2008Jan18. Mark Schnell, [email protected]. 11073 Inter-LAN Agenda. History / Goals from Re-factor work items between… - PowerPoint PPT Presentation

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Page 1: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 1

IEEE 11073 Inter-LAN Work Group Statusin association with HL7 DEV SIG & ISO TC 215 @ HL7 Working Group Meeting, San Antonio, TX, USA, 2008Jan18

Mark Schnell, [email protected]

Page 2: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 2

11073 Inter-LAN Agenda

• History / Goals from <Atlanta, GA, USA, 2007.09.20>• Re-factor work items between…

•-30200 Cable connected•-30400 Cabled Ethernet

• -20401 Common Network Infrastructure

• Status

• Next Steps

• Back up

Page 3: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 3

Re-factored work items:

• 30400: Cabled Ethernet - POC

• 10/100 Ethernet signaling compatible with 30200• MIB power vs. Ethernet PoE “cross connect”

annex

Use “Slide Show” mode: build a slide

Old breakdown

• 30200: Cable Connected

• IrDA over RS232 signaling• MIB powering (2 options)• 10 Mbps Ethernet signaling (optional)

• 30400: Cabled Ethernet – Infrastructure

• 10/100/1G Mbps Ethernet over Cat5• Real Ethernet signaling• Real Power over Ethernet

• NOT POC scope (i.e. BCC upstream only)

New breakdown

• 30200: Cabled Connected

• IrDA over RS232 signaling• MIB powering (2 options)• 10 Mbps Ethernet signaling (optional)• 10/100 Mbps Ethernet signaling (optional)• MIB vs. Ethernet PoE “cross connect” annex• POC scope only

goals

(update and re-ballot)

Page 4: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 4

Clinical Point of Care deployment diagram

: BCC

NetworkConnectedMedical

Device

: BCC

<any>

“A” reference point

Point of Care area Non-PoC area

Infrastructure Ethernet

DCC MIB: Aggregation

Device

“C” “D”

: BCCDCC MIB

: AggregationDevice

“B” “E”

“F”

“Curtain”

“H”

DCC

“I”

“J”

= not allowed by definition

= -30200 connector

= -30400 connector

= Traditional Ethernet connector

“G”

Page 5: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 5

-20401 Work Item List:

B. Logging/audit mechanism1. alarms2. alerts3. interesting events4. misc. notes/messages

Ö

Ö

ÖÖÖ

Device list, data rates, event intervals, ….

Latency/reliability “12-box”• Application typical use: continuous, episodic, control,

alarm, document• Transport: streaming, transaction, batch

• 11073 “Upper Layers” support this directly.

• Revisit Discovery Analysis due to Microsoft not putting WS-Discovery into an SDO.

goals

1. Device communications characteristics

2. Application & Transport data types & characteristics

3. IP Interoperability Framework AnalysisA. IP address assignment mechanismB. Service discovery (w/ service attribute matching)C. Service definition mechanismD. Control (aka command/response) mechanismE. Notification (aka async event reporting) mechanismF. Data transport

1. Continuous (via streaming) data type2. Episodic, Control, Alarm (via transaction) data types3. Document (via batch) data type

4. Inter-LAN test cases A. Functionality definedB. Control Specifics definedC. Data transport Specifics defined

5. Test case system “Extended Services” DefinedA. In service fault detection mechanism

1. dropped packets2. latency measure3. …

Use “Slide Show” mode: build a slide

Page 6: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 6

11073 Inter-LAN Agenda

• History / Goals from <Atlanta, GA, USA, 2007.09.20>

• Status• -30400 Cabled Ethernet• -30200 Cable connected• -20401 Common Network Infrastructure

• Next Steps

• Back up

Page 7: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 7

-30400 Work Item List: goals

1. 11073-30400 Cabled Ethernet Infrastructure “Intent”• High level goals. (i.e. Cat 5 cabling; 10/100/1000 baseT; special features)• NOT POC scope (aka BCC upstream only)

2. Documentation strategy• Start with 802.3-2005 (the latest monolithic 802.3 spec)• Clause by clause (1 thru 67) and annex by annex: record thumbs up or thumbs

down with an explanation/rationale as to the choice.

3. Turn the crank• Technical content is complete

4. Balloting logistics• Ballot group invitation started• IEEE editorial review complete & comments folded in• Ballot group invitation closes• Ballot started• Disposition comments• Ballot complete

(Presentation mode: build-a-slide)

Ö

Ö

Ö

ÖÖ

& status

– 2008Jan25, Fri

Use “Slide Show” mode: build a slide

Page 8: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 8

-30200 Work Item List: goals

1. Document strategy• No Word version of existing doc• Only generate/review deltas to existing -30200 spec• Have IEEE editors merge changes into a new, full -30200 spec• Ballot resulting spec

2. Start with existing -30200 Cable Connected spec• Add current errata

3. Change existing -30200 Annex F• From: 10 Mbps Ethernet signaling (optional)• To: 10/100 Mbps Ethernet signaling (optional)

4. Add new (informative) -30200 Annex O• From: MIB power vs. Ethernet PoE “cross connect” -30400 annex A

To: MIB power vs. Ethernet PoE “cross connect” -30200 annex O• Update “cross connect” details with latest “termination” information

5. Ballot logistics

Thanks Todd, for this suggestion!

Use “Slide Show” mode: build a slide

& status

Ö

Ö

Ö

Yet to do.

75% complete

Page 9: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 9

-20401 Work Item List: goals

B. Logging/audit mechanism1. alarms2. alerts3. interesting events4. misc. notes/messages

Ö

Ö

ÖÖÖ

Device list, data rates, event intervals, ….

Latency/reliability “12-box”• Application typical use: continuous, episodic, control,

alarm, document• Transport: streaming, transaction, batch

• Revisit Discovery Analysis due to Microsoft not putting WS-Discovery into an SDO.

• 11073 “Upper Layers” support this directly.

Use “Slide Show” mode: build a slide

1. Device communications characteristics

2. Application & Transport data types & characteristics

3. IP Interoperability Framework AnalysisA. IP address assignment mechanismB. Service discovery (w/ service attribute matching)C. Service definition mechanismD. Control (aka command/response) mechanismE. Notification (aka async event reporting) mechanismF. Data transport

1. Continuous (via streaming) data type2. Episodic, Control, Alarm (via transaction) data types3. Document (via batch) data type

4. Inter-LAN test cases A. Functionality definedB. Control Specifics definedC. Data transport Specifics defined

5. Test case system “Extended Services” DefinedA. In service fault detection mechanism

1. dropped packets2. latency measure3. …

4. Macro use scenariosA. 11073-20601 (PHD) over IP. (i.e. 1-agent to 1-manager)B. Classic 11073 upper layers over IP. (i.e. 1-agent to 1-

manager and 1-agent to n-managers)

5. Profile outline1. Data plane:2. Control plane:3. Security plane:

6. Test case system “Extended Services” DefinedA. In service fault detection mechanism

1. dropped packets2. latency measure3. …

Common Network Infrastructure

channel use models<investigating><investigating>

& status: (

No progress

Moreonnext slides

Page 10: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 10

Data plane: Possible channel use models

• Role A: start up path• Initial contact• Negotiate for ‘transport

control channel”• Note: temporary role

• Role B: Transport control path

• Negotiate for ‘data channel(s)”

• Note: permanent role

• Role C: 11073 data path(s)• 11073 APDUs• Real measurement data• Note: permanent role

1 chan mode

Well known port: <WKP>

TCPsocket

n chan mode

Well known port: <WKP>

Ephemeral port:<EP0>

Ephemeral port(s): <EP1-x>

TCPsocket

TCPsocket

TCPor

UDPor

SCTPor

<whatever>socket(s)

2 chan mode

Well known port: <WKP>

Ephemeral port:<EP>

TCPsocket

TCPsocket

m chan mode

Well known port: <WKP>

TCPsocket

Ephemeral port(s): <EP1-x>

TCPor

UDPor

SCTPor

<whatever>socket(s)

Page 11: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 11

Macro use scenarios

“upper layer” option

s

“lower layers” option

s

-30200Cable

connected

-30300Infraredwireless

-90101 POCT1-A

IPcentric

POCTA-1overIP-30200/30300

Classic’ 11073or PHDoverIP

Agt

Mgr :

1 to n

Mgr

-20601 PHD

BlueToothMDP

USBPHDC

Mgr

Agt

1 to 1

PHD overUSBBTIP

Agt

1 to 1

-20101 Classic 11073

Mgr

Agt

1 to 1

Classic 11073overIP-30200/30300

Dev/Networkmgt tools??

Page 12: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 12

-30000 Items

1. Re-kick off -30000: Transport Framework & Overview• Officially open PAR now

2. -30000 Topics• Transport Service Model (TSM)• Seed with Transport Independent SubLayer (TISL)• Seed with Generic Transport Model (GTM)• Seed with “12 box” reliability.latency model• “PHD/11073” “dev spec” discovery….• Real transports stacks characteristics• Map real transports to “transport characteristics”• Transport characteristics : FlowCtl, Reliable, Latency, Wired/wireless, …• New idea of a “fast-reconnect” (i.e. preserve state agent/manager over a

TCP timeout)• Use 2-3 representative examples from 11073 lower layers

3. Use case collection?• Possible sources:

• RF guidelines doc (-00101)• -20401 Inter-LAN analysis• PHD

Page 13: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 13

11073 Inter-LAN Agenda

• History / Goals from <Atlanta, GA, USA, 2007.09.20>

• Status• -30400 Cabled Ethernet• -30200 Cable connected• -20401 Common Network Infrastructure

• Next Steps

• Back up

Page 14: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 14

Next steps

1. -30400 Cabled Ethernet• Finish ballot process

2. -30200 Cable connected• Finish ‘delta’ document• Start and finish ballot process

3. -20401 Common Network Infrastructure• Develop transport architecture• Overlay supporting network services

4. -30000 Transport Framework & Overview• ??work as back ground to -20401 activities??

Page 15: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 15

Logistics/contacts

Emails:list: [email protected]: [email protected]

Weekly calls:•Date: Weekly on Tuesday•Time: 12:00 PM (noon) USA/Eastern Time

Page 16: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 16

Back up / details

Page 17: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 17

(Item 1 from -20401 Work List) Device communications characteristics

Data type bins

epis

odic

contin

uous

bulk

ala

rm

dev ctl

Device name Measur. Data type Raw data size notestyp. min max

Blood pressure cuff BP parameter 160 bits / meas. x73-00101 typical xHeart rate monitor HR parameter 160 bits / meas. x73-00101 typical xWeight scale weight parameter 160 bits / meas. x73-00101 typical xGlucose meter Glucose parameter 160 bits / meas. x73-00101 typical x

Pulse oximeter (SpO2) HR parameter 160 bits / meas. x73-00101 typical x

SpO2 parameter 160 bits / meas. x73-00101 typical xpleth waveform 600 bits / sec Nonin iPod @ 75Hz xpleth waveform 50 120 bits / sec x73-00101 typical x

Thermometer (body temperature) temp parameter 160 bits / meas. x73-00101 typical xSpirometer <derived> waveform 4020 bits / sec http://www.iqteq.com/downloads/brochurespiro.pdf xCalorie Calculator/Monitor parameter 160 bits / meas. x73-00101 typical xPeak flow meter parameter 160 bits / meas. x73-00101 typical xCholesterol monitor parameter 160 bits / meas. x73-00101 typical xEKG/ECG (1-lead) <derived> waveform 8000 bits / sec SWAG from: "Paul's "ECG data rate" email xPedometer/cadence/wheel rpm parameter 160 bits / meas. x73-00101 typical xBreathing rate parameter 160 bits / meas. x73-00101 typical x

CO2 meter parameter 160 bits / meas. (CO2 =? ETCO2) x73-00101 typical x

EKG/ECG (3-lead) <derived> waveform 3600 bits / sec Paul's "ECG data rate" email xEKG/ECG (12-lead) <derived> waveform 64000 bits / sec Paul's "ECG data rate" email xEKG/ECG (6-lead) <derived> waveform 48000 bits / sec SWAG based on "Paul's "ECG data rate" email xEEG (1-lead) <derived> waveform 8000 bits / sec SWAG: 500sps@16b/s xMedication compliance device parameter 160 bits / meas. x73-00101 typical xBed occupant sensor parameter 160 bits / meas. x73-00101 typical xEEG (21-lead, 10-20 system) <derived> waveform 168000 bits / sec SWAG: 500sps@16b/s xEEG (2-lead) <derived> waveform 16000 bits / sec SWAG: 500sps@16b/s xEEG (4-lead) <derived> waveform 32000 bits / sec SWAG: 500sps@16b/s xEEG (74-lead, 10-10 system) <derived> waveform 592000 bits / sec SWAG: 500sps@16b/s xEEG (8-lead) <derived> waveform 64000 bits / sec SWAG: 500sps@16b/s xFall detector parameter 130 bits / sec x73-00101 typical xSleep quality sensor parameter 20 bits / sec x73-00101 typical x

Support data

printing 10 10M bytes / print job xtransfer medical summery 10 10M bytes / summary xphysiological alarm 512 bits / alarm x73-00101 typical xequipment alarm 512 bits / alarm x73-00101 typical xdevice control 512 bits / stat/ctlx73-00101 typical x

IP Transport optionsUDP xTCP w/ std time out x x x xTCP w/ "short" time out x x x xRTP xSCTP x x x

Page 18: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 18

(Item 2 from -20401 Work List) Healthcare data types

App Data Type(& typical use)

Relative reliability

Good Better Best

Very high (<20s)

QueuedEpisodic

Document

High(<2s)

Alarm

Medium(<200ms)

Episodic Control

Low(<20ms)

Continuous

App data type & “typical use”

General Description

1Continuous

raw information rates are in the 50 bit/sec to 1.2M bit/sec range

The analog sampling rates in the 1 ms to 50 ms range

The sampled analog data can easily be grouped together. Packets of grouped analog samples could easily have a packet period in the 10s of millisecond range.

‘good’ relative reliability needs

5Episodic

a measured parameter (BP, SpO2, HR, ...)typical raw information payload in the 10s of bytes range

The fastest communications rate is in 1 sec per measurement range

‘better’ relative reliability needs

6Control

aka get/set device parameters; aka events and/or notifications; aka request/response

control/status of both physiological and equipment functionality

typical raw information payload in the 10s of bytes range

'human response time' sort of delay metrics (<1 sec)

‘best’ relative reliability needs

9Alarm

both physiological driven alarms and equipment issued alarms

supports multiple alarm level (e.g. HIGH, MEDIUM, LOW, NOTE) with multiple latency needs. Latency requirements differ by situation. (i.e. clinical to city to rural)

typical raw information payload in the 10s of bytes range

[Worst case is clinical maximum @ 10sec per AAMI ECG-13 onset-to-alarm time]

‘best’ relative reliability needs

11

Queue Episodic

off line collection and delayed transfer of episodic type measurements

typical raw information payload if a single measurement in the 10s of bytes range

variable depth (1s, 10s even 100s of measurements) for the queue

very delay tolerant data category (can live with 10s of seconds or even longer)

‘better’ relative reliability needs

12Document

print or transfer summaries, reports or historiesvast range of overall payload size (10s of bytes to mega or even gigabytes of data)

very delay tolerant data category (can live with 10s of seconds)

‘best’ relative reliability needs

Data type& typical use

Maximum latency tolerance(transport latency budget)

Relative reliability

Transport data type

1 Continuous

Low (<20ms) Good Streaming

5 Episodic Medium (<200ms) Better Transaction

6 Control Medium (<200ms) Best Transaction

9 Alarms High (<2s) Best Transaction

11 Queued Episodic

Very high (<20s) Better Transaction

12 Document

Very high (<20s) Best Batch

Presentation mode: build a slide

Max. laten

cy toleran

ce(transport latency budget)

2

5

8

11

1 3

4 6

7 9

10 12

Page 19: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 19

A Day In The Life Of A Networked Medical Device

Set up in hospital IT??

Find a network

Get on the IP network

Get the “clinical framework”

AssociateMed. end pts

Disassociate Med. End pts

• Encryption keys??• Home “domain”??

(enables HLR/ VLR from cellular)

• L2 activity• AAA (Authentication,

Authorization, & Accounting)?

• 802.1x, Bluetooth “pairing”, other out-of-band pairing, … ?

• IP addr• Sub-net• Local domain• Gateway• Pri/sec “Clinical

Framework” server (aka config server)

• NAC (Network Access Control)?

• Med SLA check?

Network services• Pri/sec association

server• NTP• “Home” POC (for

HLR/VLR for POC roaming?)

• …Clinical “services”• Which VS Mon• Which Nurse station• Which printer• Which plotter• …Dimensions• Static part• Dynamic part (esp.

w/ wireless access) (use a “touch” association?)

• Association negotiation (esp. Med SLA check) (SIP w/ SDP ?)

• RTP/RCTP (w/ new profiles?) (use a ‘test stream’ to measure the net at set up?) (like a telephony ‘continuity tone’?)

• RSVP??• Transfer data

• Release association (aka release end point & network resources)

Stage 0Stage 0 Stage 1Stage 1 Stage 2Stage 2 Stage 3Stage 3 Stage 4Stage 4 Stage 5Stage 5

Note: The 11073 Inter-LAN working group is using the above working diagram to assist in keeping focus on the appropriate scope for each step of our work

Data PathEstablishment

ServiceDiscoveryÖ

(Presentation mode: build-a-slide)

Page 20: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 20

(Item 3 from -20401 Work List)

IP Interoperability Framework: definitions

A. IP address assignment mechanism• How are IP addresses assigned to all the devices in an 11073 MDC system?

B. Service discovery (w/ service attribute matching)• How are the various “services” of a given device advertised and discovered by other devices in the 11073 MDC system?

C. Service definition mechanism• How are the various “services” of a given device actually described and defined such that the “service” is usable &

understandable by other devices in the 11073 MDC system?

D. Control mechanism• aka command/response mechanism• How is a generic “command” sent to a device and how is a response (if any) returned to the caller?

E. Notification mechanism• aka subscribe/notify mechanism• aka receive specific/interesting async events• How does an “interested party” register with a device such that it will be notified when a particular event occurs?

F. Data transport• How are the specific medical data transported over the IP network…

• Document/batch data types• Episodic/transaction data types• Continuous/streaming data types

…such that their specific latency & reliability requirements are met?

3. IP Interoperability Framework feature areas:

(Presentation mode: build-a-slide)

Page 21: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 21

(Item 3A & 3B from -20401 Work List) Service Discovery Analysis: Short list

1.WS-Discovery

2.SLP

3.ZeroConf

Web Services Discovery

Service Location Protocol

Zero Configuration

Preferred

Risks/Issues

•No Discovery Proxy•No standards body home

•No Interoperable Directory Agent• “Service description framework” is out of scope

• “Service description framework” and…

•Discovery “query matching” are out of scope

• Revisit Discovery Analysis due to Microsoft not putting WS-Discovery into an SDO.

Page 22: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 22

(Item 3A & 3B from -20401 Work List) Service Discovery Analysis: Summary

Selection Criteria

WS-Discovery

SLP+DHCP+ LinkLocal

ZeroConf (e.g. Bonjour)

DICOM discovery

JXTA+DHCP+ LinkLocal

UPnP Jini + DHCP +Link Local Addr

Ala carte 1

Network topology:- ad hoc:- managed:

X

X

X

Discovery mechanism- ad hoc:- managed:

distribcentral

distribcentral

distrib.central

XCentral

distribcentral

distribX

distribX

distribCentral

Incremental code size (assume TCP stack & tasking OS)

45KB -- 40-60KB -- 2.9MB -- JVM: 4.5MBJini: --

--

Open source client available?

1 2 3 many 3 1 JVM: several; Jini: 1

--

Licensing costs no no no no no no JVM: sometimesJini: no

no

Implied SW language no no no no no no Java no

Target/classic uses ad hoc & mng net

Networked devices

Locally networked devices

Med image eqpt

Peer to peer

Home networks

Locally networked devices

Medical devices

Usable for ‘general’ service discovery

yes yes yes yes yes yes yes NO

Required network services (ad hoc & managed)

none &(DHCP+ DP)

none &(DHCP + DA)

none &(DHCP + DNS)

DHCPLDAP

none &(DHCP + RP)

none none none &(DHCP+ DNS)

Usable network services DHCPDNS

DHCPDNS

DHCPDNS

DHCPLDAP

DHCPDNS

DHCPDNS

DHCPDNS

Naming and registration of new services

W3C stds process

-- Email:[email protected]

ISO GlobalUID process

-- UPnP stds process

-- NA

Standards organization almost yes yes yes yes yes yes NO

‘Chattiness’ measure-Ad hoc: advertisement/discovery-Manage: advertisement/discovery

1 / 2to61 / 2to6

--0 / 21 / 2

-- -- -- -- --

Network access control 802.1x 802.1x 802.1x 802.1x 802.1x 802.1x 802.1x 802.1x

Service Capability Query/Matching

yes yes out of scope out of scope yes yes yes out of scope

Service definition/ descrip. framework

yes out of scope

out of scope out of scope -- -- yes out of scope

Page 23: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 23

Transport Stack Overview

L3 - net

L4 - xport

L2 - link

L1 - phy

eth

ern

et

11073“upper layers”

Wi-F

i

Ce

llula

r D

ata

Wi-M

ax

802.3

10/100/1000BT

802.11

RF

GPRSEDGE1xRTT

RF

802.16

RF

IP

RTPTCP UDP SCTP

IrLAP

IR

IrLMP

TinyTP

RS-232

IP Support Services

11073 config service

11073 assoc service

DHCP

DNS

Net. capacity service

LDAP

NTP

Radius

Location services

Presence servicesSNMP

802.1xNAT

US

B

Blu

eT

oo

th

PHDC MDP

current In process

point to point links

short term possible future

IP centric links

US

B

etherclass drv

Blu

eT

oo

th

IPprofile

MICSWMTS

Zig

Be

e

possible future

Interface to ‘upper layers”

Page 24: Mark Schnell, mschnell@cisco

11073.Inter-LAN.2008.01.18.v01.ppt SLIDE 24

The Eight Fallacies of Distributed Computing

1. The network is reliable2. Latency is zero3. Bandwidth is infinite4. The network is secure5. Topology doesn't change6. There is one administrator7. Transport cost is zero8. The network is homogeneous

Attribution: The true origins of this list are somewhat mythic, being largely based on the collective experience of many hackers in the early days of building distributed systems. Peter Deutsch is the one who first enumerated them as a clear way to frame thinking about why distributed systems are fundamentally different. He says the following on his home page:

“I first published the "8 Fallacies of Networking" internally while working at Sun Microsystems Labs in 1991-92. (The first 4 were originally described by either Bill or Dick Lyon; I added the other 4.)

“Essentially everyone, when they first build a distributed application, makes the following eight assumptions. All prove to be false in the long run and all cause big trouble and painful learning experiences.“