Network Infrastructure Blog

Q:         When will category 8 standards be ratified? ANSI/TIA‑568‑C.2‑1, which contains requirements for category 8 cabling constructed from category 8 components to support the 25GBASE‑T and 40GBASE-T applications, was approved for publication in June, 2016. ISO/IEC 11801‑1, which contains requirements for class I cabling constructed from category 8.1 components and class II cabling constructed from category 8.2 components, was ratified in November, 2017.

Q:         What are the main characteristics of category 8 cabling and how will they affect data center infrastructure? Class I, class II, and category 8 cabling is characterized to 2 GHz and intended to support 30 meter cabling channels that contain no more than 2 connectors.  These channels and the emerging 25G/40GBASE-T applications that they support are specifically targeted for deployment at the data center “edge” where server to switch connections are made.  Data center designers that can arrange their rack and cabinet layouts to support maximum 30‑meter channel connections at these locations today will be well-positioned to migrate to  25G/40GBASE-T when the technology becomes available.

Q:         How is the performance of category 8 cabling improved over its predecessor versions? Interestingly, for every transmission parameter except return loss, ISO/IEC class F_A channel and permanent link limits are more severe than those proposed specified for class I and category 8 up to 1 GHz. In the case of internal crosstalk parameters, the differences are significant; with class F_A beating class I and category 8 performance by more than 20 dB! Class I and category 8 do have an advantage in that they are characterized out to double the bandwidth of class F_A. Class II requirements represent the most stringent performance specifications for balanced twisted-pair cabling that the industry has ever seen. The end result is that class I, class II, and category 8 cabling will offer unprecedented signal-to-noise margin for support of 25 Gb/s and higher transmission rates.

Q:         Is category 8 cabling mainly for support of 40GBASE-T? Class I, class II, and category 8 cabling has a unique channel topology that is optimized for support of both 25GBASE‑T and 40GBASE‑T server to switch connections in the data center.

Q:         Will category 8 cabling be backward compatible with lower category cabling? Class I, class II, and category 8 cabling will be backward compatible with lower classes and categories of cabling. For example, a category 8 connector can be used in a class E_A channel and class E_A channel performance will be assured.

Q:         Will a new type of connector be required for category 8 or can a modular eight-position modular RJ-45 interface be used? Class I and category 8 cabling specifications support modular RJ-45 style connectors. The performance associated with class II cabling can only be realized when category 8.2 cables are used in conjunction with non RJ-45 interfaces such as the Siemon TERA® connector.

Q:         Will category 8 cables be physically similar to category 6A and 7_A cables and can category 8 cabling be installed leveraging existing infrastructure and termination methods? Class I, class II, and category 8 cabling will have a similar “look” and “feel” to lower grades of cabling and installation methods will not be significantly different. This cabling may be installed in existing pathways and conduit; however, the existing infrastructure will need to be upgraded to support 25GBASE-T and 40GBASE-T.

Q:         Will category 8 cabling require more power? Class I, class II, and category 8 cabling does not require more power to operate. In fact, due to lower dc resistance and insertion loss, these cables may more efficiently support remote powering applications (e.g. Power over Ethernet or “PoE”) and offer improved heat dissipation. Higher speed Ethernet equipment, however, does tend to consume more power and it is realistic to expect that first generation 25G/40GBASE-T equipment will consume more power per port than 10GBASE-T equipment. As technology evolves, it is likely that 25G/40GBASE-T equipment port power consumption will be comparable to 10GBASE-T equipment port power consumption.

Q:         Will the arrival of category 8 cabling impact the adoption of category 7A cabling? Since class II channel performance can be achieved with many of the category 7A connectors (e.g. Siemon TERA®) that are commercially available today, end-users should not see the arrival of class I and category 8 products significantly change the landscape of available high speed cabling options. In fact, the superior performance offered by class II cabling may encourage more users to adopt fully-shielded cabling solutions constructed from non RJ-style connectors. Furthermore, while it’s too early to guarantee 25GBASE-T application support, there are efforts in place to characterize the capability of existing installed class F_A/category 7_A cabling plants to support 25 Gb/s data transmission.

These summary table provide information regarding support distances for Ethernet applications that operate over balanced twisted-pair and singlemode and multimode optical fiber cabling and direct attach twinaxial cable assemblies.  This information can assist the cabling designer in determining appropriate media for the building infrastructure based on required throughput and reach.  Consult IEEE 802.3 application standards and network equipment manufacturers’ specifications to establish complete system and cabling requirements and capabilities.

Passive optical networking (PON) is an in-building optical fiber application that is capable of distributing voice, video, and data to the desktop over one single-mode fiber.   The three main components to a Passive optical networking (PON) implementation are the:

1. passive optical networking line terminal (OLT) located in the building or campus entrance facility,
2. passive optical networking splitters located in the telecommunications closet on each floor, and
3. passive optical networking terminals (ONT) located in end-user work areas

While PON equipment may be connected using point-to-point cabling, the flexibility of the system is greatly enhanced if the network is deployed over a TIA and ISO/IEC compliant structured cabling system.  These advantages include:

• ease of upgrades to new technologies,
• the ability to replace equipment with minimal service disruption,
• support of moves, adds, and changes (MACs),
• the ability to change equipment vendors,
• enhanced administration and labeling capability, and
• support of back-up and redundant connections

To ensure compliance with ANSI/TIA-568-C.1 and ISO/IEC 11801 Edition 2.2, a minimum of two permanent links shall be provided for each work area.  For an infrastructure anticipated to support PON technology, Siemon recommends that a minimum of one 2-fiber single-mode permanent link supported by duplex SC or LC connectivity and one category 6A or higher balanced twisted-pair permanent link be provided at each work area.  The availability of a category 6A copper cabling link supports future adoption of remote powering (e.g. Power over Ethernet or PoE) technology and 10GBASE-T transmission speeds with minimal need to upgrade or replace existing PON equipment.

The figure below depicts Siemon’s recommended minimum PON-ready backbone and horizontal cabling topology for buildings having a main cross connect  and a horizontal cross connect only.  This recommended minimum topology may also be applied to larger build outs that support Cabling Subsystem 2 and 3 runs and an intermediate cross connect or configurations where the PON splitter is housed in a zone box.

Recommended Standards Compliant PON Deployment Topology

Equipment Outlet (EO) is the designation for the outermost connector in a generic structured cabling deployment.  The EO provides a point of connection, administration, and testing to a telephone, computer, building automation system (BAS) device, wireless access point (WAP), camera, or any other networkable device.  The EO is different from the Telecommunications Outlet (TO), which is the assembly consisting of one or more connectors mounted on a faceplate, housing, or supporting bracket used exclusively in the work area in a commercial building application.

While it is well-known that Standards require a minimum of two permanent links be brought to each TO in the work area, practices related to EO usage when supporting BAS device and WAP connections can be confusing.  Here is some useful guidance excerpted from Standards that address structured cabling for BAS devices and informative bulletins that provide supplemental guidance on how to use a grid-based structured cabling approach for wireless access point connections.

BAS device (including camera, security, fire alarm, access control, energy management, HVAC, lighting/power control, audio/video paging, digital signage, service/equipment alarm, and other non-voice/data communications) connections:

•  A Horizontal Connection Point (HCP) supports flexibility in a zone cabling topology for fast and easy reconfiguration of BAS device coverage areas and may be configured as an interconnect (i.e. one patch panel or connecting block) or a cross-connect (i.e. two patch panels or connecting blocks)
• When the HCP is configured as a cross-connect, an EO shall not be installed to ensure that the cabling system serving the BAS device contains no more than four connection points
• When the HCP is configured as an interconnect, the use of an EO is optional (i.e. direct connections from the BAS device to the HCP are allowed)
• If an HCP is not present, then an EO must be used
• Only one permanent link connection is required to each BAS device
• Refer to ANSI/TIA-862-A and ISO 16484 for additional information

WAP connections:

• EOs are shown in all example deployment figures provided in applicable TIA and ISO/IEC guidelines addressing cabling to WAPs – there are no provisions for making the EO an optional connection point in these technical bulletins
• A minimum of two permanent link connections to each IEEE 802.11ac wireless access point is recommended to support link aggregation
• Refer to TIA TSB-162-A and ISO/IEC TR 24704 for additional information

Siemon recommends a grid-based zone cabling topology using an interconnect at the HCP and an EO at each BAS device or WAP connection as shown in the figure below. This design supports ease of coverage area reconfiguration, administration, and cable management, as well as the ability to overlap coverage areas and allocate spare HCP ports to support new equipment or telecommunications outlet connections.

Recommended Grid-Based Zone Cabling Topology

Siemon recommends that two or more category 6A or higher rated shielded channels, deployed as part of an overall zone cabling configuration, are provided to every 802.11ac access point connection for three very important reasons:

1.  TSB-162-A, “Telecommunications Cabling Guidelines for Wireless Access Points”, expressly provides the following recommendation and note:

Cabling for wireless access points should be balanced twisted-pair, category 6A or higher, as specified in ANSI/TIA-568-C.2, or two-fiber multimode optical fiber cable, OM3 or higher, as specified in ANSI/TIA-568-C.3.

NOTE – The use of category 6A (or higher) twisted-pair and OM3 (or higher) optical fiber cabling is recommended to support higher data rates and, in the case of twisted-pair cabling, lower temperature rise when remote power is applied.

2.  As highlighted in the TIA note, temperature rise resulting from Type 2 PoE used to power 802.11ac access points should be considered.  Shielded cabling, which has superior heat dissipation properties compared to UTP cabling, significantly reduces or eliminates concerns of excessive temperature build-up in cable bundles, especially for cable bundles installed in hot environments.  The use of solid equipment cords, which exhibit better thermal stability and lower insertion loss than stranded conductor cords, is recommended for access point connections for this same reason.

3.  Deploying a minimum of two category 6A shielded channels will support link aggregation of not only today’s 1.3 Gb/s and 2.6 Gb/s 802.11ac implementations, but also future 3.5 Gb/s and higher data rate (Huawei recently achieved a record transmission data rate of 10.53 Gb/s in the 5 GHz frequency band!) implementations.  A zone cabling approach utilizing floor or ceiling enclosures containing consolidation points with spare port capacity, which are positioned in a grid pattern throughout the building space, allows for rapid reconfiguration of wireless coverage areas and provides redundant and future-proof access point connections.

 Refer to the following white papers for more information:

• Killer App Alert!  IEEE 802.11ac 5 GHz Wireless Update and Structured Cabling Implications

• Advantages of Using Siemon Shielded Cabling Systems To Power Remote Network Devices