Cisco Cisco DWDM Transceiver Modules 白皮書
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Figure 5. Simple Example of 10-Gbps Structured Cabling
For migration of a data center with a structured 10-Gbps cabling system, Cisco QSFP BiDi technology allows you
to repurpose the existing cabling system - including the patch cables, patch panels with MTP/MPO LC modules,
and fiber trunks - for 40-Gbps connectivity. In contrast, QSFP SR4 transceivers require new patch cables and
patch panels because the connector types differ and the size of the fiber trunk needs to be quadrupled.
This case study examines a simple nonblocking two-tier fabric design (Figure 6) that provides 1536 10-Gbps edge
ports on its leaf layer. Its spine layer is composed of two Cisco Nexus 9508 Switches, and its leaf layer consists of
32 Cisco Nexus 9396PX Switches, each with six 40-Gbps links to every spine Cisco Nexus 9508. There are 384
40-Gbps links total between the leaf and spine layers.
Figure 6. Two-Tier Network Example
If 384 x 10-Gbps connections are to be reused to construct this network, no additional spending on cabling will be
needed if Cisco QSFP BiDi transceivers are used for all the 40-Gbps links. This scenario thus offers a 100 percent
cost savings compared to the cost of reconstructing the cabling system using QSFP SR4 transceivers, including
the cost of new patch cables, new patch panels, and expansion of the current fiber trunk.
If the cabling for this network is a new (greenfield) deployment or an expansion of an existing cabling system, the
384 x 40-Gbps connections can be built by using MMF cables and either QSFP SR4 transceivers or Cisco QSFP
BiDi transceivers. Figures 7 and 8 show design examples for each option. Table 2 compares real-world cost
estimates for these two designs. The design with Cisco QSFP BiDi offers 77 percent savings over that with QSFP
SR4 transceivers, which is equivalent to a savings of US$2077 per 40-Gbps connection.