cabling requirements for 10 gb/s ethernet · 2008-08-27 · csc presentation – june 2006 ......

CSC Presentation – June 2006 © 2006 Fluke Networks 1

Cabling Requirements for Cabling Requirements for 1010 GbGb/s Ethernet/s Ethernet

Overview & Status of Standards WorkFluke Network Test Solutions

© 2006 Fluke Networks 2CSC Presentation – June 2006

IntroductionOverview and status of 10GBASE-T development10 Gb/s Ethernet over twisted pair cablingFocus

The development of the performance specification of the cabling requirementsThe impact on field testing

An overview of measurement techniquesFluke Networks is an active contributor in the research, testing and modeling of cabling requirements for 10GBASE-T

RecommendationsWhat can or should you do today?


10GBASE-T Applications

Application10GBASE Fiber

(802.3ae)10GBASE-T 10GBASE-CX4

(802.3ak)

Data CenterServer Clustering Yes Yes Yes (< 15m)

HorizontalIn Building No Yes No

VerticalRiser Backbone Yes No No

Campus Yes No No


Twisted-Pair Cabling Expected to Support 10GBASE-T

Currently Installed Cabling

Channel Length (m)

Comments

ISO Class F 100 Supported (IEEE objective)

ISO Class E/TIA Cat 6 UTP

55 Supported (IEEE objective)

ISO Class E ScTP 100 Expected to meet requirements

ISO Class E / TIA Cat 6 with PS AXTalk testing

55 to 100 Requires additional (field) test of PS AXTalk parameters

Future CablingTIA Cat 6 AugmentedISO Class E Augmented

100 To be defined; supports 10GBASE-T alien crosstalk requirements over the full 100 m. Contains also improvements of internal parameters (not needed for 10GBASE-T).


Relevant Cabling documents

To support 10GBASE-T over Cat 6/Class E cablingTIA: TSB-155 (Technical Service Bulletin)ISO/IEC: TR24750 (Technical report

To support 10GBASE-T alien crosstalk requirements over the full 100 m

TIA: Addendum #10 to TIA/EIA-568-B.2ISO/IEC: 2nd Amendment of ISO/IEC 11801.

Note: the 55 m for TIA Cat 6 or ISO Class E is being questioned.Some believe that it anything longer than 37 m may be subject to

alien crosstalk failures! See draft 5.0 of TIA TSB-155.


TIA/EIA-TSB155 – Draft 5.0Additional Cabling Guidelines for 4-pair 100 Ω Category 6 Cabling for 10GBASE-T applicationsExtended frequency transmission performance of Cat 6 cabling from 250 MHz to 500 MHz

Channel and Permanent Link guidelines and test limitsAlien Crosstalk coupling between 4-pair Cat 6 cabling channels in close proximity of each other.

Measured by PS ANEXT and PS AACR-FAdditional guidelines for field test equipment and field test methods

Accuracy Level IIIe for field certificationAlien Crosstalk testing

This document is in the final revision stage with final committee ballot – Will be published October 2006


TIA/EIA-568-B.2-10 – Draft 4.0

Transmission Performance Specifications for 4-pair 100 ΩAugmented Category 6 CablingPerformance Specifications for all test parameters

Worst pair-to-pair and multi-disturber (power sum) requirements for cable NEXT Loss and ELFEXT

Alien NEXT (PS ANEXT) and Alien FEXT (PS AACR-F)Performance requirements for Cat 6A components

Design specification for Balance of cable and connecting hardwareConnecting hardware specifications

Critical topic to provide interoperability of Cat 6A Will require significant amount of work past the publication of IEEE 802.3an and TIA TSB155

Patch cord requirements: NEXT and Return Loss


Transmission Performance AnalysisMeasure Signal strength (or signal loss) over the specified frequency range

Insertion Loss measurement (used to be called Attenuation)

Must meet specified performance level (less than maximum loss allowed)

Identify and measure noise parameters of interest over the specified frequency range

Standards define the number of test frequencies (step size)

For example: Cat 6 measurement contains 68,712 points/link

Each noise (test) parameter must meet the specified performance level over the total frequency range


Combined affects of all 3 disturbing pairs = Power Sum

Combined 7 Noise Sources - Disturbances

Combined NEXT disturbance from 3 wire-pairs: PSNEXTReturn Loss on same wire-pairCombined FEXT disturbance from 3 wire-pairs: PSELFEXT


Overview of Test Parameters

Measured Test Parameter

Calculated Test Parameter

Propagation Delay Delay Skew, Length Insertion Loss NEXT (pair-to-pair) PSNEXT, ACR, PSACR FEXT (pair-to-pair) ELFEXT, PSELFEXT Return Loss

All of these “familiar” test parameters will be specified for 10GBASE-T cable certification over the frequency range 1 through 500 MHz


10 10 Gb/sGb/s Ethernet Introduces Ethernet Introduces AnotherAnother

““ComplicationComplication””Discussion of Alien Crosstalk


Cabling Requirements for 10GBASE-T

The signal-to-noise budget analysis is complex and consists of two types of disturbances:‘In-channel’ disturbances – Initially set to ISO/IEC 11801 Class E limits extended to 500 MHz(Class E/Cat 6 defined from 1 to 250 MHz)‘Between-Channel’ disturbances for Crosstalk referred to as “Alien Crosstalk”

Alien Crosstalk has been identified as a “challenge” for UTP cabling systems

Proposed TIA cabling guideline and standard:TIA-TSB-155Standard for “Augmented Cat 6” (Cat 6A) TIA-568-B.2-10


Alien CrosstalkCrosstalk between wire-pairs in adjacent cables General rules:

The effect is due in first instanceby proximityThis crosstalk is worst betweenwire-pairs with the sametwist rateThe effect is greater for pairswith a lower twist rateImpact increases with the distanceover which the cables run in parallelImpact increases with the frequency of the transmitted signals


Transmit

Receive

WorkstationWorkstation

Transmit

Receive

LANLANEquipmentEquipmentSignal

External Noise from adjacent cables

Attenuated Signal

NEXT

Signal strength: measured by “Insertion Loss”Alien Crosstalk: An external source to NEXT, FEXT and RL

Alien Crosstalk Is An External Noise Source


ANEXT and AFEXT Along the Length of the Links

ANEXT is generated in the first 20 m (65 ft)

AFEXT is cumulative through the link and travels its length

Telecom Room Work Area

Channel configuration as defined

PCCP TOC2C1

Switch

ANEXT AFEXT

PCSwitch


Six-around-One Worst Case Alien Crosstalk (varies with link topologies though: distances between connectors and number of connectors).

TIA-TSB-155 defines the six-around-one test configuration as a laboratory test configuration. It is not intended to prove that installed cabling meets alien crosstalk requirements.The center cable is the disturbed or “victim”cabling linkThis creates a worst case Alien XTALK result, which still depends on detailed topology:

The cables stay in same relation the length of the test bundleThis is not likely to occur in real cabling pathways

PS ANEXT for all pairs in the victim link requires 96 pair-to-pair measurements


ANEXT and AFEXT For Varying Link Lengths

Telecom Room Work Area

Permanent link (90m)

CP TOC2

ANEXTAFEXT

AFEXT influence can be over-powering and cripple transmission on the longer link (victim link)10GBASE-T must back-off signal strength on the shorter link or a “normalization” as specified in all documents must be applied.

Victim Link


Fluke Networks Measurement Methods for 10GBASE-T Alien Crosstalk

The “tools” I will describe are not yet available for sale today (schedule early September 2006)These tools have been available as research tools:

Provide the means to perform experiments and gather data in the lab and in field installationsObtain data about real-world cabling systems

Support for standards developmentAssist in developing test procedures and test limits for field certification to 10GBASE-T


ANEXT Measurement

Channel under testMain

Remote

Synchronization connection

Termination Plugs100 Ω Diff and 50 Ω Common mode

Requires a synchronization communication module in the Main and Remote test units.


Termination Plugs

Provide proper termination for high-frequency applications100 Ω differential mode termination, combined with50 Ω common mode termination

50 Ω ± 0.1% Resistor25 Ω ± 1% Resistor

Test

Too

l


ANEXT Measurements Between Two LinksThe brown pair is “disturbed”by the four wire-pairs in the disturber cableThe measurement of the Power Sum ANEXT for this disturbed pair requires four pair-to-pair NEXT measurementsThe PS ANEXT for all wire-pairs requires 16 pair-to-pair measurements

DisturbersVictim Link

Measure all wire-pair combinations between two adjacent cables in approximately 25 seconds


AFEXT Measurement

Link under testMain

Remote

Synchronization connection Synchronization channel


Evaluation of ExperimentsThe experimental methods we described have been successfully used to perform Alien Crosstalk measurements and evaluationsThe tester interfaces with a PC for data acquisition and computational tasksThe test tools need a very high measurement floor

ANEXT noise floor greater than 95 dB over the frequency range (1 through 500 MHz)Very good correlation to lab equipment (Network Analyzer) – but much fasterAll wire-pair combinations between 2 links are tested in 25 seconds


Alien Crosstalk Measurement StrategyAlien Crosstalk Measurement Strategy

The approach (procedure) to certify a cabling installation for 10 GbE


Measurement Strategy

Measure the in-channel parameters for every linkFrequency range 1 through 500 MHzUpload the results to LinkWare

Setup the laptop with the LinkWare test results data and the Alien Crosstalk Measurement Application (software)

Insertion Loss test results must be available for PS ANEXT and PS AACR-F evaluations

PS ANEXT and PS AACR-F must be based on a “sampling method”

Experiments have shown that PSAXTALK between bundles is negligible


Practical PSAXTalk Strategy (1)

Depends on whether one tests for 10GBASE-T (TIA TSB-155 or ISO TR24750) or an Augmented Cabling standard.10GBASE-T based standards have limits that depend on the insertion loss of the victim link. For shorter links, the requirements are far easier to pass. The guidelines are pretty much agreed upon.Augmented Cat 6/Class E requirements are intended to be application independent, and have limits that are likely not length dependent, but may have escape clauses, which have not yet been agreed upon. (In any case, the processing of measured data includes the insertion losses of victim and disturber links “normalization”.) Issues may arise that do not affect the signal-to-noise ratios, but could affect pass or fail.


Practical PSAXTalk Strategy (2)When you are testing for 10GBASE-T specifications, you select the longest links as victim links, since the limits are far more demanding than for shorter links.When you test per 10GBASE-T, you have to test the channel configuration.When you test per TIA TSB-155, you can test the permanent link or the channel configuration. The limits are identical.

Note: if you test the channel configuration, all user patch cords must be in place, and not be

changed!


Practical PSAXTalk Strategy (3)When you are testing for Augmented Cat 6 or Class E specifications, you select the longest links and some links with the shortest distances between connectors. These configurations tend to provide the worst results.You will have options to select the channel or permanent link configuration.The pass/fail limits are NOT stable yet!

Note: if you test the channel configurations, all user patch cords must be in place, and not be

changed!


Other PSAXTalk Strategy considerationsOnly consider ANEXT and AFEXT between links that run in the same bundleVictim Links: select per the previous slides.PS ANEXT

Test the alien crosstalk “contribution” of all links in a bundle by using all links in the bundle as disturber links

Standards recommend that a minimum of 10 links in an installation are tested as disturbed (victim) linksLimited number of bundles (data center)

Select 10% of the links in a bundle as disturbed (victim) links


The Number of Tests for PS ANEXTA “complete” test is not practical

ANEXT between two cabling links consists of 16 pair-to-pair combinations plus Power Sum calculation

In a bundle of 24 Links:the PS ANEXT calculation for the pairs in one “victim”link

Requires ANEXT measurements of 368 combinationsTime estimate: ~17¼ minutes

The PS ANEXT measurement combinations when every link must be considered a victim link

Requires ANEXT link-to-link measurements of 276 link combinations 4,416 pair-to-pair combinationsTime estimate: 207 minutes or 3 hours and 45 minutes


Recommendations for Design of New(Data Center) Cabling Systems

CautionThe 10GBASE-T definition is complete and finalThe specifications for Augmented Cat 6 (Cat 6A) are not yet complete and may change

Cabling DecisionsMany Cat 6A cables have a larger OD to put distance between wire pairs in adjacent cables

Impact on pathways: fill rate and sizeImpact on wire management: larger bend radius

For ‘Channels’ up to 55? m, Cat 6 UTP offers high probability to meet the Alien XTALK specifications

Alternatives: select ScTP cable types


Recommendations (Cont’d)Connecting hardware decisions

Select Cat 6a componentsConnecting hardware has a significant impact on the frequency specifications of the installed linkPatch panels are likely a source of AXTALK

Keep bundles small (around 12 links)Alien XTALK of wire-pairs in different bundles is most often negligibleANEXT occurs in the first 20 meters of the bundle: affected by patch cords and cable management in the TR Smaller bundles mean fewer links need to be tested for Alien XTALK interactionSpace the bundle ties to 2 or 3 feet; do not over tighten

less rigid bundles create less AXTALK


Recommendations (Cont’d)

Select a quality installation contractorHigh quality workmanship will preserve Cat 6 or Cat 6A component specifications

Incorporate the bundle or pathway name in the Cable IDIf you need to test cabling links for AXTALK performance, you only need to test among links in the same bundle

Last, but not least …Certify the cabling to one of the new standards (or latest draft)

TIA TSB-155 or TIA-568-B.2-10This is the only way to know that the completed installation meets the requirements and offers some safety margin


Fluke Networks Online Reference Material

www.flukenetworks.com

Fluke Networks’ web site. The resource center contains white papers and the knowledge base contains articles of interest.

www.flukenetworks.com/consultants

Statement of Work – proposed text for Field test requirements


Time for questionsContact Information:

[email protected]


10Gb/s Fiber optic testing 10Gb/s Fiber optic testing challengeschallenges


Data Rates of Fiber Technologies

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10GBASE-S (850 nm laser) MBW Loss Distance62.5 micron multimode fiber: 160 2.60 dB 26 m62.5 micron multimode fiber: 200 2.50 dB 33 m50 micron multimode fiber: 400 2.20 dB 66 m50 micron multimode fiber: 500 2.30 dB 82 m50 micron multimode fiber: 2000 2.60 dB 300 m

10GBASE-LX4 (1310 nm laser)62.5 micron multimode fiber: 500 2.50 dB 300 m50 micron multimode fiber: 400 2.00 dB 240 m50 micron multimode fiber: 500 2.00 dB 300 m50 micron multimode fiber: 2000 2.00 dB 300 msinglemode fiber: 6.30 dB 10 km

Current 10 Gigabit Ethernet Limits


TSB-140

TIA/TSB-140:

Additional Guidelines For Field-Testing Length, Loss And Polarity Of Optical Fiber Cabling Systems

Approved by TR-42 in February 2004


Two-Tier Testing

Tier 1: OLTS (Optical Loss Test Set)− Conforms to TIA-526-14A and TIA-526-7

(Most closely simulates system)

− Measures the total loss of a fiber channel− Verify polarity using OLTS or VFL

Tier 2: OTDR Trace− Can show segment lengths, connector locations &

losses, and losses not at a connector− Provides evidence that cable is installed without

degrading events (e.g., bends, connection, splice)− Can do single-ended testing


Test Example: Tier 1 (OLTS)

Horizontal Cables

Backbone Cables

TR

MC

62.5/125 μm cabling100 m from the wall outlet7 m patch cord110 m in the backbone

2.15 dB

X

XX X

Source Meter

850 nm1300 nm


Test Example: Tier 2

MCX

XX X

100 m 7 m 110 m


Event Table from OTDR

Location(m)

850nm(dB)

Event Pass/Fail

0 .18 Reflect Pass

100 .14 Reflect Pass

107 .88 Reflect Fail

217 .19 Reflect Pass

1.39 + 0.76 (for cable) = 2.15 dB

100 m 7 m 110 m


Recommendations for Design of Fiber Systems to support 10 Gig

For new fiber optic installations select laser enhanced 50 micron fiber (MBW=2000) and/or singlemodeFor existing installations verify modal bandwidth and length to determine suitability for 10 GigRefer to TSB-140 for field testing of fiber optic systems

Tier 1: mandatory power meter / light source test w/ length and polarity verificationTier 2: OTDR trace to verify quality of installation

Use inspection device to verify no contamination of connectors (dirt is public enemy #1!)

cabling requirements for 10 gb/s ethernet · 2008-08-27 · csc presentation – june 2006 ......

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