Physical Layer management in 10G to 40G/100G Ethernet migration


This vendor-written tech primer has been edited by Network World to eliminate product promotion, but readers should note it will likely favor the submitter’s approach.

The ability to migrate from 10G to 40G or 100G Ethernet (GbE) hinges on knowing the particulars about your data center backbone. If you don’t know the length of the circuit, connector style (LC, 12 or 24 fiber MPO) or the fiber type (OM2, OM3, OM4, SM, etc.), you don’t know if it will support the higher speeds. While this type of information is rarely collected, Physical Layer Management (PLM) systems can fill in the blanks.

Ideally migration to 40G or 100GbE should occur selectively on the paths that have priority in the data center. By having all physical layer cabling, components and their details documented, circuits requiring upgrade can be identified, selectively prioritized and deployed as needed, allowing for a controlled migration as well as maximum recovery or repurposing of existing circuits and infrastructure and efficient management of pathways and spaces. Panel upgrades, for example, would be by module or blade rather than entire chassis or enclosure.

This discrete migration will be more cost-effective than a forklift upgrade, will migrate the most needed paths more quickly, and will avoid the overspending and complexity of a wholesale migration.

The problem is most data centers lack documentation about the physical state of the network. So if they want to selectively upgrade they have to manually measure cable pathways to determine if they’re the appropriate length, and then plug the new cable in and hope everything works. Since a typical fiber circuit has 3-5 segments of trunk cables and path cords, manual network audits are labor-intensive and time-consuming. Enterprise industry average statistics are approximately 50-55 minutes just to trace the circuit manually (this is based on a circuit from switch port to panel to station/cabinet).

PLM systems, on the other hand, enable IT managers to understand the physical characteristics of their networks down to the connector and port level. In a PLM system, each physical cable connector has an identity chip that stores information about the connector type, color, cable length, location, and other manufacturer metrics.

A managed patch panel reads the information and forwards it to a database and software management system. By viewing the PLM database, IT managers can determine precisely how long a cable pathway is, how many hops it takes, what type of cable it is, and how it will perform. The PLM system measures a variety of metrics, including:

* Media type – The type of cable and connector, such as LC or MPO, 12- or 24-strand fiber cable.

* Wiring pattern – 12- and 24-strand cables won’t have the same wiring patterns, and it’s essential to track the wiring pattern coming out of trunk cable A and know whether it’s compatible going into trunk cable B.

* Performance level – Whether it is a 40G or 100GbE cable, OM3 or OM4. This also provides details about the expected performance of a cable assembly.

* Insertion and cleaning – The number of insertions is used as an indicator of how often a particular fiber should be cleaned. If the fiber has been re-connected four or five times, it’s a good idea to clean it to remove dust or oil.

* Length of cable – The intelligent connectors enable the database to add up all the components on a circuit and see if the circuit exceeds the length budgets for 10-, 40-, or 100-GbE. Even if the circuit segments are different lengths, it will base the length determination on the media type and expected performance level.

With a PLM system in place, IT managers can determine the most critical network segments to upgrade first, where they are, and how long they are. This allows managers to upgrade only the areas of the network that have the greatest need, enabling a gradual migration that brings higher-level service to key segments quickly.

PLM systems provide all of the critical information an IT manager needs to determine whether a given circuit can support migration. As soon as a circuit layout is planned, the IT manager knows whether or not the assets are in place to support it.

When faced with the choice of whether to fund a wholesale network migration or to implement a PLM system and migrate selectively, most IT managers will determine that a PLM system is less expensive and offers greater overall responsiveness to network needs. Investing in a PLM system allows network managers to give differential service to their clients, yield revenues for high-speed service more quickly, and efficiently and confidently manage their network each day.

Thompson is director of global product management for TE Connectivity, responsible for physical layer management solutions. In this role, Mr. Thompson is responsible for identifying, developing and introducing new solutions that address the customers need to grow and operate their networks in a faster and more cost effective manner.

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