Cisco Cisco DWDM Transceiver Modules 白皮書
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To economize trunk fiber in a structured cabling environment, a 2 x 3 MPO fiber conversion module could combine
three SR4 links onto two 12-fiber ribbon cables. But even then the 40-Gbps SR4 trunk still uses 8 fiber strands per
link compared to 2 fiber strands in the case of 10-Gbps SR.
At best, the connector change and increased fiber density needed for SR4 require a significant cable plant
upgrade, making it expensive and disruptive for customers to migrate from 10-Gbps connectivity to 40-Gbps
connectivity in their existing data centers.
Figure 1. Concept of Existing 40-Gbps Transceivers: Of the 12 Fiber Strands Terminated by MPO-12 Connectors, 8 Fiber
Strands (4 Fiber Pairs) Carry Traffic and 4 Are Unused
Solution with Cisco 40-Gbps QSFP BiDi Transceiver
The Cisco QSFP BiDi transceiver, shown in Figure 2, transmits full-duplex 40-Gbps traffic over one dual-fiber LC-
connector OM3 or OM4 MMF cable. It provides the capability to reuse 10-Gbps fiber infrastructure. In other words,
it enables data center operators to upgrade to 40-Gbps connectivity without making any changes to the previous
10-Gbps fiber cable plant.
Figure 2. Cisco QSFP BiDi Transceiver (QSFP-40G-SR-BD)