1.
WHITE PAPER
FS.COM White Paper | Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration
In 2002, the IEEE ratified the 802.3ae standard for 10GbE over duplex fibers (one fiber transmits and
the other receives) terminated with duplex LC-style connectors and vertical cavity surface-emitting
laser (VCSEL) transceivers. With the increasing need for high speed data transmission, in 2010, the
IEEE ratified the 802.3ba standard for 40/100G to satisfy this demand. Similar to how transportation
highways are scaled to support increased traffic with multiple lanes at the same speed, the 40/100G
standards use parallel optics, or multiple lanes of fiber transmitting at the same speed. Running 40G
requires 8 fibers, with 4 fibers each transmitting at 10Gbit/s and 4 fibers each receiving at 10Gbit/s.
Running 100G requires a total of 20 fibers, with 10 transmitting at 10Gbit/s and 10 receiving at
10Gbit/s. Both scenarios call for high-density MPO-style connectors, which can be either 12-fiber or
24-fiber. However, 24-fiber MPO/MTP cabling is often considered to be the better solution for
40/100G migration. Why? Reading this post and you will get the reasons.
12-Fiber and 24-Fiber MPO/MTP Cabling
A 12-fiber MPO/MTP connector is used for 40G Ethernet. Among the 12 fibers, only 8 optical fibers
are required—4 for Tx and 4 for Rx, and each channel has a transmission rate of 10Gbps (typically
40G applications use only the 4 left and 4 right optical fibers of the 12-fiber MPO/MTP connector,
while the inner 4 optical fibers are left unused). To run 100GbE, there are two solutions. One is to
use two 12-fiber MPO/MTP connectors—one transmitting 10Gbit/s on 10 fibers and the other
receiving 10Gbit/s on 10 fibers. The other solution is to use a 24-fiber MPO/MTP connector—20
fibers in the middle of the connector transmitting and receiving at 10Gbit/s and the 2 top and
bottom on the left and right unused. 12-fiber can be both used for 40/100G solutions, but why said
the 24-fiber is better than 12-fiber? The following part will explain in details. The figure 1 below
shows different construction of 12-fiber and 24-fiber MPO/MTP.
Choosing 24-Fiber
MPO/MTP Cabling for
40/100G Migration

2.
WHITE PAPER
FS.COM White Paper | Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration
Figure 1. Different Construction of 12-Fiber and 24-Fiber MPO/MTP
Why Is the 24-Fiber the Right Migration Path to 40/100G?
 Fiber Utilization to the Extreme
Using 24-fiber trunk cables with 24-fiber MPO/MTP connectors on both ends to connect from the
back of the switch panel to the equipment distribution area can utilize the fibers to the extreme. As
we have mentioned above, 40G will uses 8 fibers (4 Tx and 4 Rx) of the total 12-fiber trunk cable
with 12-fiber MPO/MTP connectors, leaving 4 fibers unused. Nevertheless, when three 40G links
are using three separate 12-fiber trunk cables, it will result in a total of 12 unused fibers, or 4 fibers
unused for each trunk, which can be a waste. With the use of 24-fiber, running three 40G links will
use all 24 fibers of the trunk cable, which recoups 33 percent of the fibers that could be lost with
12-fiber trunk cables, providing a much better return on investment. For 100G applications, which
require 20 fibers (10 Tx and 10 Rx), a 24-fiber trunk cable can provide a single 100G link instead of
using two 12-fiber trunk cables.
 Spacing Saving
With more and more equipment and patch cables used in data centers, space is a premium. Using
24-fiber trunk cable will cause less cable congestion in already-crowded pathways, which can save
more space and make cable management easier. For example, for a 40G application, it takes three
12-fiber trunk cables to provide the same number of links as a single 24-fiber trunk cable which can
take about 1.5 times more pathway space.
 Increasing Fiber Density
With today’s large core switches occupying upwards of one-third of an entire rack, density in fiber
switch panels is critical. 24-fiber MPO connectors offer a small footprint which can ultimately

3.
WHITE PAPER
FS.COM White Paper | Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration
provide increased density in fiber panels at the switch location.
 Cost Effective
The 24-fiber data center fiber trunking and interconnect solution offers a simple and cost effective
migration path from 10G-40G-100G, providing future-readiness for three generations of active
equipment. With 24-fiber trunk cables effectively supporting all three applications (shown in the
figure 2), there is no need to recable the pathway from the back of the switch panel to the
equipment distribution area.
Figure 2. 24-Fiber MPO/MTP trunk for 10G/40G/100G Applications
Conclusion
With increasing concerns about the cost to upgrade and the complexity involved, data center
managers need a solution that simplifies the process and provides better return on investment,
while meeting both current and future needs. Taking the advantages of maximum fiber utilization,
space and cost saving and high density, it is no doubt that 24-fiber MPO/MTP cabling is better
solution for 40/100G migration.

4.
WHITE PAPER
FS.COM White Paper | Choosing 24-Fiber MPO/MTP Cabling for 40/100G Migration
Contact Us
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Tel: +44 (020) 3287 6810
Notice: This document is for informational purposes only and does not set forth any warranty, expressed or
implied, concerning any equipment, equipment features, or service offered or to be offered by FS.COM.
FS.COM reserves the right to make changes to this document at any time, without notice, and assumes no
responsibility for its use. This information document describes features that may not be currently available.
Contact a FS.COM sales team for information on feature and product availability.
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