Information technology - Generic cabling systems for customer premises - Part 9905: Guidelines for the use of installed cabling to support 25GBASE-T application<br />

This Technical Report provides guidance to determine whether and which installed channels will support 25GBASE-T. It also provides mitigation procedures to improve the performance of installed channels to the point where the 25GBASE-T application is supported. Additionally, it recommends the use of Class I and Class II channels to support 25GBASE-T in new installations.

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Publication Date
07-Feb-2018
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PPUB - Publication issued
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08-Feb-2018
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08-Feb-2018
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ISO/IEC TR 11801-9905:2018 - Information technology - Generic cabling systems for customer premises - Part 9905: Guidelines for the use of installed cabling to support 25GBASE-T application<br />
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ISO/IEC TR 11801-9905
Edition 1.0 2018-02
TECHNICAL
REPORT
Information technology – Generic cabling for customer premises –
Part 9905: Guidelines for the use of installed cabling to support 25GBASE-T
application
ISO/IEC TR 11801-9905:2018-02(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
ISO/IEC TR 11801-9905
Edition 1.0 2018-02
TECHNICAL
REPORT
Information technology – Generic cabling for customer premises –
Part 9905: Guidelines for the use of installed cabling to support 25GBASE-T
application
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN978-2-8322-5373-1

Warning! Make sure that you obtained this publication from an authorized distributor.

---------------------- Page: 3 ----------------------
– 2 – ISO/IEC TR 11801-9905:2018
© ISO/IEC 2018
CONTENTS

FOREWORD ........................................................................................................................... 5

INTRODUCTION ..................................................................................................................... 7

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms, definitions and abbreviations ............................................................................... 8

4 Cabling channel specifications for 25 GBASE-T ............................................................... 9

4.1 General ................................................................................................................... 9

4.2 25GBASE-T application specifications .................................................................... 9

4.2.1 Return loss ...................................................................................................... 9

4.2.2 Insertion loss/attenuation ............................................................................... 10

4.2.3 NEXT ............................................................................................................. 11

4.2.4 Attenuation to crosstalk ratio at the near-end (ACR-N) .................................. 13

4.2.5 Attenuation to crosstalk ratio at the far-end (ACR-F). ..................................... 13

4.2.6 Propagation delay .......................................................................................... 15

4.2.7 Delay skew .................................................................................................... 15

4.2.8 Unbalance attenuation and coupling attenuation ............................................ 15

4.2.9 Alien crosstalk ............................................................................................... 16

4.3 Associated risk of 25GBASE-T operation over installed cabling ............................ 17

4.4 Characterization of balanced channels using Category 7 components ................ 17

4.4.1 General ......................................................................................................... 17

4.4.2 Selection of channels for qualification ............................................................ 18

4.4.3 Return loss .................................................................................................... 18

4.4.4 Insertion loss ................................................................................................. 19

4.4.5 Near-end crosstalk loss (NEXT) ..................................................................... 19

4.4.6 Attenuation to crosstalk loss ratio near-end (ACR-N) ..................................... 21

4.4.7 Attenuation to crosstalk ratio far-end (ACR-F) ............................................... 22

4.4.8 Alien (exogenous) crosstalk ........................................................................... 24

4.4.9 Propagation delay .......................................................................................... 25

4.4.10 Delay skew .................................................................................................... 25

4.4.11 Coupling attenuation ...................................................................................... 25

4.4.12 Alien crosstalk and coupling attenuation ........................................................ 26

4.5 Characterization of balanced channels using Category 7 components ................... 26

4.5.1 General ......................................................................................................... 26

4.5.2 Selection of channels for qualification ............................................................ 27

4.5.3 Return loss .................................................................................................... 27

4.5.4 Insertion loss ................................................................................................. 28

4.5.5 Near-end crosstalk loss (NEXT) ..................................................................... 28

4.5.6 Attenuation to crosstalk loss ratio near-end (ACR-N) ..................................... 30

4.5.7 Attenuation to crosstalk ratio far-end (ACR-F) ............................................... 31

4.5.8 Alien (exogenous) crosstalk ........................................................................... 33

4.5.9 Propagation delay .......................................................................................... 34

4.5.10 Delay skew .................................................................................................... 34

4.5.11 Coupling attenuation ...................................................................................... 34

4.5.12 Alien crosstalk and coupling attenuation ........................................................ 35

4.6 Characterization of balanced channels using Category 6 components ................ 35

4.6.1 General ......................................................................................................... 35

4.6.2 Selection of channels for qualification ............................................................ 36

---------------------- Page: 4 ----------------------
ISO/IEC TR 11801-9905:2018 – 3 –
© ISO/IEC 2018

4.6.3 Test specifications for channels made out of Category 6 components ......... 36

5 Guidance for mitigation procedures to improve the cabling of existing installations ........ 36

5.1 General ................................................................................................................. 36

5.2 Mitigation procedures related to internal noise ...................................................... 36

5.3 Mitigation procedures related to exogenous noise (alien crosstalk) ....................... 36

6 Guidance for cabling for new installations ...................................................................... 37

Bibliography .......................................................................................................................... 38

Table 1 – Return loss for a channel ........................................................................................ 9

Table 2 –Return loss values for a channel at key frequencies .............................................. 10

Table 3 – Insertion loss for a channel ................................................................................... 10

Table 4 – Insertion loss values for a channel at key frequencies .......................................... 11

Table 5 – NEXT for a channel ............................................................................................... 11

Table 6 – NEXT values for a channel at key frequencies ...................................................... 12

Table 7 – PS NEXT for a channel ......................................................................................... 12

Table 8 – PS NEXT values for a channel at key frequencies ................................................ 13

Table 9 – ACR-F for a channel .............................................................................................. 13

Table 10 – ACR-F values for a channel at key frequencies .................................................. 14

Table 11 – PS ACR -F for a channel ..................................................................................... 14

Table 12 – PS ACR-F values for a channel at key frequencies ............................................. 14

Table 13 – Propagation delay for a channel .......................................................................... 15

Table 14 – Propagation delay values for a channel at key frequencies ................................. 15

Table 15 – Delay skew for a channel .................................................................................... 15

Table 16 – PS ANEXT for a channel ..................................................................................... 16

Table 17 – PS ANEXT values for a channel at key frequencies ............................................ 16

Table 18 – PS AACR-F for a channel .................................................................................... 17

Table 19 – PS AACR-F values for a channel at key frequencies .......................................... 17

Table 20 – Risk of 25GBASE-T operation over installed cabling channels ............................. 17

Table 21 – Formulae for return loss limits for a channel ........................................................ 18

Table 22 – Return loss limits for a channel at key frequencies ............................................. 18

Table 23 – Formula for insertion loss limits for a channel ...................................................... 19

Table 24 – Insertion loss limits for a channel at key frequencies ........................................... 19

Table 25 – Formulae for pair-to-pair NEXT limits for a channel ............................................. 19

Table 26 – Pair-to-pair NEXT limits for a channel at key frequencies ................................... 20

Table 27 – Formulae for PS NEXT limits for a channel .......................................................... 20

Table 28 –PS NEXT limits for a channel at key frequencies .................................................. 20

Table 29 – ACR-N limits for a channel at key frequencies ..................................................... 21

Table 30 – PS ACR-N limits for a channel at key frequencies ............................................... 22

Table 31 – Formulae for ACR-F limits for a channel .............................................................. 22

Table 32 – ACR-F limits for a channel at key frequencies ..................................................... 23

Table 33 – Formulae for PS ACR-F limits for a channel ........................................................ 23

Table 34 – PS ACR-F limits for a channel at key frequencies ............................................... 23

Table 35 – Formulae for PS ANEXT limits for a channel ....................................................... 24

Table 36 – PS ANEXT limits for a channel at key frequencies ............................................... 24

---------------------- Page: 5 ----------------------
– 4 – ISO/IEC TR 11801-9905:2018
© ISO/IEC 2018

Table 37 – Formula for PS AACR-F limits for a channel ........................................................ 24

Table 38 – PS AACR-F limits for a channel at key frequencies ............................................ 25

Table 39 – Formula for propagation delay limits for a channel ............................................... 25

Table 40 – Propagation delay limits for a channel at key frequencies ................................... 25

Table 41 – Formula for coupling attenuation limits for a channel ........................................... 26

Table 42 – Coupling attenuation limits for a channel at key frequencies ............................... 26

Table 43 – Alien crosstalk and coupling attenuation .............................................................. 26

Table 44 – Formulae for return loss limits for a channel ........................................................ 27

Table 45 – Return loss limits for a channel at key frequencies ............................................. 27

Table 46 – Formula for insertion loss limits for a channel ...................................................... 28

Table 47 – Insertion loss limits for a channel at key frequencies .......................................... 28

Table 48 – Formulae for pair-to-pair NEXT limits for a channel ............................................. 28

Table 49 – Pair-to-pair NEXT limits for a channel at key frequencies ................................... 29

Table 50 – Formulae for PS NEXT limits for a channel .......................................................... 29

Table 51 – PS NEXT limits for a channel at key frequencies ................................................. 29

Table 52 – ACR-N limits for a channel at key frequencies .................................................... 30

Table 53- PS ACR-N limits for a channel at key frequencies ................................................. 31

Table 54 – Formulae for ACR-F limits for a channel .............................................................. 31

Table 55 – ACR-F limits for a channel at key frequencies ..................................................... 32

Table 56 – Formulae for PS ACR-F limits for a channel ........................................................ 32

Table 57 – PS ACR-F limits for a channel at key frequencies ................................................ 32

Table 58 – Formulae for PS ANEXT limits for a channel ....................................................... 33

Table 59 – PS ANEXT limits for a channel at key frequencies .............................................. 33

Table 60 – Formula for PS AACR-F limits for a channel ........................................................ 33

Table 61 – PS AACR-F limits for a channel at key frequencies ............................................ 34

Table 62 – Formula for propagation delay limits for a channel ............................................... 34

Table 63 – Propagation delay limits for a channel at key frequencies ................................... 34

Table 64 – Formula for coupling attenuation limits for a channel ........................................... 35

Table 65 – Coupling attenuation limits for a channel at key frequencies ............................... 35

Table 66 – Alien crosstalk and coupling attenuation for shielded channels ............................ 35

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ISO/IEC TR 11801-9905:2018 – 5 –
© ISO/IEC 2018
INFORMATION TECHNOLOGY –
GENERIC CABLING FOR CUSTOMER PREMISES –
Part 9905: Guidelines for the use of installed cabling
to support 25GBASE-T application
FOREWORD

1) ISO (International Organization for Standardization) and IEC (International Electrotechnical Commission) form the

specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in

the development of International Standards. Their preparation is entrusted to technical committees; any ISO and

IEC member body interested in the subject dealt with may participate in this preparatory work. International

governmental and non-governmental organizations liaising with ISO and IEC also participate in this preparation.

2) In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.

Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting.

Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote.

3) The formal decisions or agreements of IEC and ISO on technical matters express, as nearly as possible, an

international consensus of opinion on the relevant subjects since each technical committee has representation

from all interested IEC and ISO member bodies.

4) IEC, ISO and ISO/IEC publications have the form of recommendations for international use and are accepted

by IEC and ISO member bodies in that sense. While all reasonable efforts are made to ensure that the

technical content of IEC, ISO and ISO/IEC publications is accurate, IEC or ISO cannot be held responsible for

the way in which they are used or for any misinterpretation by any end user.

5) In order to promote international uniformity, IEC and ISO member bodies undertake to apply IEC, ISO and

ISO/IEC publications transparently to the maximum extent possible in their national and regional publications.

Any divergence between any ISO/IEC publication and the corresponding national or regional publication

should be clearly indicated in the latter.

6) ISO and IEC provide no marking procedure to indicate their approval and cannot be rendered responsible for

any equipment declared to be in conformity with an ISO/IEC publication.

7) All users should ensure that they have the latest edition of this publication.

8) No liability shall attach to IEC or ISO or its directors, employees, servants or agents including individual experts

and members of their technical committees and IEC or ISO member bodies for any personal injury, property

damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees)

and expenses arising out of the publication of, use of, or reliance upon, this ISO/IEC publication or any other IEC,

ISO or ISO/IEC publications.

9) Attention is drawn to the normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

10) Attention is drawn to the possibility that some of the elements of this ISO/IEC publication may be the subject of

patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights.

The main task of the joint technical committee is to prepare International Standards. However,

the joint technical committee may propose the publication of a Technical Report when it has

collected data of a different kind from that which is normally published as an International

Standard, for example "state of the art".

ISO/IEC TR 11801-9905, which is a Technical Report, was prepared by subcommittee 25:

Interconnection of information technology equipment, of ISO/IEC joint technical committee 1:

Information technology.

The list of all currently available parts of the ISO/IEC 11801 series, under the general title

Information technology — Generic cabling for customer premises, can be found on the IEC

website.
---------------------- Page: 7 ----------------------
– 6 – ISO/IEC TR 11801-9905:2018
© ISO/IEC 2018

This Technical Report has been approved by vote of the member bodies, and the voting

results may be obtained from the address given on the second title page.

This Technical Report is to be read in conjunction with ISO/IEC/IEEE 8802.3:2017/AMD3.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 8 ----------------------
ISO/IEC TR 11801-9905:2018 – 7 –
© ISO/IEC 2018
INTRODUCTION

This document provides guidance to determine whether and which installed channels will

support 25GBASE-T. It takes into account the design goals for 25GBASE-T equipment such

as:
a) the frequency signal range up to 1 250 MHz;
b) the support of two-connector channels up to 30 m in length.

The requirements of 25GBASE-T are fully defined in ISO/IEC/IEEE 8802-3:2017/AMD3.

Installed two-connector channels which are characterized up to 1 250 MHz and support all the

requirements of the ISO/IEC/IEEE 8802-3:2017/AMD3 link segment are expected to support

the 25GBASE-T application.
Characterization of channels using Category 7 components is described in 4.4.
Characterization of channels using Category 7 components is described in 4.5.
Characterization of channels using Category 6 components is described in 4.6.

This document also provides mitigation procedures to improve the performance of installed

channels to the point where the 25GBASE-T application is supported. Additionally, this

document recommends the use of Class I and Class II channels to support 25GBASE-T in

new installations.

Class I and Class II channels according to ISO/IEC 11801-1 will support 25GBASE-T without

mitigation.

Component requirements are not provided in this document and should not be inferred from

the channel limits provided.
---------------------- Page: 9 ----------------------
– 8 – ISO/IEC TR 11801-9905:2018
© ISO/IEC 2018
INFORMATION TECHNOLOGY –
GENERIC CABLING FOR CUSTOMER PREMISES –
Part 9905: Guidelines for the use of installed cabling
to support 25GBASE-T application
1 Scope
This part of ISO/IEC 11801, which is a Technical Report,

a) provides guidance on how to select and assess installed channels which conform to

ISO/IEC 11801-1, and clarify if they also support ISO/IEC/IEEE 8802-3:2017/AMD3 for

25GBASE-T;

b) specifies the methods to assess whether installed channels constructed with Category 7 ,

7, or 6 components meet the 25GBASE-T requirements;
c) provides guidance to identify which channels are likely to meet the 25GBASE-T
requirements to avoid unnecessary testing;

d) provides mitigation techniques to improve the performance of installed channels to meet

the 25GBASE-T requirements;
e) provides cabling recommendations for new installations.

NOTE 1 The channel transmission performance specified in this document is derived from the 25GBASE-T

requirements in ISO/IEC/IEEE 8802-3:2017/AMD3.

NOTE 2 This document does not re-specify component or channel definitions of ISO/IEC 11801-1.

2 Normative references

The following referenced documents are indispensable for the application of this document.

For dated references, only the edition cited applies. For undated references, the latest edition

of the referenced document (including any amendments) applies.

ISO/IEC 11801-1, Information technology – Generic cabling systems – Part 1: General

requirements
ISO/IEC/IEEE 8802-3:2017/AMD3, Information technology – Telecommunications and

information exchange between systems – Local and metropolitan area networks – Specific

requirements – Part 3: Standard for Ethernet – Amendment 3: Physical layers and
management parameters for 25 Gb/s and 40 Gb/s operation, types 25GBASE-T and
40GBASE-T
3 Terms, definitions and abbreviations

For the purposes of this document, the terms, definitions and abbreviations given in

ISO/IEC 11801-1 apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
---------------------- Page: 10 ----------------------
ISO/IEC TR 11801-9905:2018 – 9 –
© ISO/IEC 2018
4 Cabling channel specifications for 25 GBASE-T
4.1 General

This document provides guidelines for the assessment of installed cabling channels for the

additional requirements of ISO/IEC/IEEE 8802-3:2017/AMD3 for 25GBASE-T. It is assumed

that each installed channel does fulfil the requirements of its appropriate cabling class defined

in ISO/IEC 11801-1.

The requirements defined in Clause 4 are a combination of the original class requirements of

the installed cabling and the requirements in support of 25GBASE-T.
For a balanced cabling installation covered by this document:

a) the channel performance is specified according to ISO/IEC 11801-1 and additionally

according to Clause 4 (or appropriate subclause);

b) the interfaces to the cabling are specified according to ISO/IEC 11801-1:2017, Clause 10,

with respect to mating interfaces;
c) local regulations concerning safety and EMC apply.

The test procedures for balanced cabling installations are specified in IEC 61935-1 in

accordance with ISO/IEC 11801-1 and ISO/IEC 14763-2.
4.2 25GBASE-T application specifications

NOTE 1 These specifications are consistent with the link segment specifications of

ISO/IEC/IEEE 8802-3:2017/AMD3.

NOTE 2 All specifications are based on a channel length of 30 m with 2 connections.

4.2.1 Return loss

The return loss (RL) of each pair of a channel is specified in Table 1. The limits shown in

Table 2 are derived from the formulae at key frequencies.

The return loss requirement is specified for both ends of the cabling. Return loss (RL) values

at frequencies where the insertion loss (IL) is below 3,0 dB are for information only.

Table 1 – Return loss for a channel
Class Frequency Minimum return loss
MHz dB
1 ≤ f < 10
19,0
10 ≤ f < 40
24− 5 lg( f )
40 ≤ f < 130 16,0
130 ≤ f < 1  000 35− 9 lg( f )
1  000 ≤ f ≤ 1 250
8,0
---------------------- Page: 11 ----------------------
– 10 – ISO/IEC TR 11801-9905:2018
© ISO/IEC 2018
Table 2 –Return loss values for
a channel at key frequencies
Frequency Minimum return loss
MHz dB
Class
1 19,0
16 18,0
100 16,0
250 13,4
500 10,7
600 10,0
1  000 8,0
1  250 8,0
4.2.2 Insertion loss/attenuation

The insertion loss (IL) of each pair of a channel is specified in Table 3. The limits shown in

Table 4 are derived from the formulae at key frequencies.
Table 3 – Insertion loss for a channel
Frequency Maximum insertion loss
Class
MHz dB
0,078
1 < f ≤ 500
0,634 ff+0,00156×+
0,078
500 < f ≤ 1 250 0,60698 ff+0,00277×+

Insertion loss (IL) at frequencies that correspond to calculated values of less than 4,0 dB revert to a

maximum requirement of 4,0 dB.
 
0,25
 
This formula is derived using:
0,312× 1,8 f + 0,005× f+ + 2×(0,02× f )+ 0,032 4× f
 
This formula is derived using:
 
0,25
 
0,312× 1,8 f + 0,005× f+ + 2×(0,006 49× f + 0,000 605× f)+ 0,032 4× f
 
 
---------------------- Page: 12 ----------------------
ISO/IEC TR 11801-9905:2018 – 11 –
© ISO/IEC 2018
Table 4 – Insertion loss values for
a channel at key frequencies
Maximum insertion loss
Frequency
MHz
Class
1 4,0
16 4,0
100 6,5
250 10,4
500 15,0
600 16,5
1  000 22,0
1  250 24,9
4.2.3 NEXT
4.2.3.1 Pair-to-pair NEXT

The NEXT between each pair combination of a channel is specified in Table 5. The limits

shown in Table 6 are derived from the formulae at key frequencies.

The NEXT requirement is specified for both ends of the cabling. NEXT values at frequencies

where the insertion loss (IL) is below 4,0 dB are for information only.
Table 5 – NEXT for a channel
Frequency Minimum NEXT
Class
MHz dB
75,3− 15 lg ( f ) 94− 20 lg ( f )
 
 
− 20 − 20
1 ≤ f ≤ 500 - 20 lg 10 + 2× 10
 
...

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