Cisco Cisco DWDM Transceiver Modules 白皮書

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Structured cabling requires additional initial investment to create the cabling infrastructure, but the recurring

benefits more than outweigh the slight additional incremental cost. Imagine the cost of deploying a two-fiber

optical jumper each time a new server is placed in the data center. Further, regardless of whether the data center

has a raised floor or uses overhead cabling, both result in time-consuming and inefficient deployment in an

unstructured environment. Likewise, management of such an environment is cumbersome, increasing the risk of

outages caused by human errors.

Structured cabling uses fiber termination connector panels that are connected through permanent links of optical

cabling, typically configured in a star topology. All cabling in the data center coming from the server area is

consolidated in a central location near the core, aggregation-layer, or spine switch in the network (analogous to

the breaker or power panel in the home electrical system analogy). The permanent pre-terminated trunk cables

branch to the zones in the data center, which contain servers, storage, or network devices. Note that with

structured cabling, you still need some device-to-device connections at the access layer. As you can see in Figure

1, when you make these short connections within the same cabinet or even a few cabinets away, patch panels

may not be required. Likewise, patch panels would not be required for inter-switch link connections.

Figure 1. Structured Cabling with Patch Panels

Unstructured cabling occurs when optical links are deployed point to point or device to device with no patch panels

installed in the link. In this situation, cabling pathways become congested with an entangled mess of two-fiber

optical patch cords (Figure 2). Likewise, routing new patch cords in ceiling or floor trays all the way across a data

center each time a new device is deployed is extremely inefficient.