Roles of MTP Trunk, MTP Harness, MTP Conversion Harness in 40G/100G Migration

With bandwidth demands continuing to grow, higher and higher capacity and throughput are required in the data center. And to address these needs efficiently and effectively, a strategic approach focusing on existing user expectations and future capacity requirements is wanted. MTP/MPO cable is the good choice that can meet various network requirements. This post will list the roles of different MTP/MPO cables (MTP trunk, MTP harness, MTP conversion harness) in 10G/40G/100G migration.

10G/40G/100G Migration Solutions

For upgrading connection data rates, several common scenarios are available with using MTP/MPO fiber cables. Following part will list these applications out for your reference.

10G to 40G: 8-Fiber MTP Harness Cable

One commonly used upgrade possibility beyond 10G incorporates four 10G SFP+ transceiver connections to a 40G QSFP+, which requires a 8-fiber MPO-LC harness cable. Figure 1 illustrates one side of the transmission path utilizing this MPO harness cable in conjunction with a 40G QSFP+ to aggregate four 10G SFP+ transceivers. QSFP+ transceivers on the switches yield higher port densities and throughput.

8-fiber MTP LC harness cable in 10G to 40G migration

Figure 1: 10G to 40G upgrade by using MTP/MPO LC harness cable

40G to 40G: 12-Fiber MTP Trunk Cable

MTP trunk cable incorporates interconnected banks of QSFP+ transceivers (MPO to MPO connectivity). Figure 2 illustrates the connectivity. In this connection, 12-fiber MPO trunk cables are needed to connect the transceivers. Four fibers transmit light, four receive and four unused.

12f MTP trunk cable used in 40G connection

Figure 2: 40G to 40G connection by using MTP/MPO trunk cable with four fibers unused

40G to 40G: 2×3 MTP Conversion Harness/Module

MTP conversion harness and MTP conversion module both take advantage of 100% fiber utilization. For those needing 100% fiber utilization, 2×3 MTP conversion harness or conversion module can achieve the purpose. Connectivity of the 2×3 MTP conversion harness and conversion module is the same. They are interchangeable, but must be used in pairs: one (MTP conversion harness or module) at each end of the link. Figure 3 shows an example of how MTP conversion module uses all fibers to achieve 100% fiber utilization. The eight live fibers from each of the three QSFP+ transceivers are transmitted through the trunks using the full 24 fibers. The second 2×3 conversion module unpacks these fibers to connect to the 3 QSFP+ transceivers on the other end.

MTP conversion cable/module used in 40G with 100% fiber utilization

Figure 3: 40G to 40G connection with MTP conversion module ensuring 100% fiber utilization

100G to 100G: MTP Trunk Cable

For 100G to 100G connection, 24-fiber MTP trunk cable allows direct attach capability of 100GBASE-SR10 CXP or CFP equipped devices, while 12-fiber MTP trunk cable can be used to allow the direct connection for 100G QSFP28 (MPO to MPO) connection.

24f MTP trunk cable in 100G connection

Figure 4: MTP trunk cable for 100G to 100G connection

10G to 100G/120G: 24-Fiber MTP Harness Cable

To achieve 10G to 100G/120G connection, one popular implementation is to use the high density 100G/120G CXP for space-saving. This deployment can leverage the 10G-per-lane channels to distribute the 10G data anywhere in the data center. Figure 5 uses a 24-fiber MTP harness cable that separates each TX and RX pair, allowing connectivity to any duplex path reachable by a patch panel. Simply connect this cable to a 120G CXP transceiver and the customer can access the 12 individual transceiver pairs. When used with a patch panel, this method offers the ultimate in flexibility, allowing connectivity to any row, rack, or shelf.

24 fiber MTP LC harness cable in 10G to 100G connection

Figure 5: 10G to 100G connection by using 24-fiber MTP LC harness cable

40G to 120G: 1×3 MTP Conversion Harness

One way to break out a 120G CXP is to use 1×3 MTP conversion harness cable. Figure 6 shows a 24-fiber fanout that utilizes 24 fibers to split the 12 transceivers into three groups of eight. These eight-fiber groups match the TX/RX fibers used on a QSFP+ transceiver for direct connection to three separate QSFP+ transceivers. Like the 12x10G segregation mentioned above, once split, the 3×8-fiber QSFP+ channels can be distributed through patch panels and 12-fiber based trunking to any area of the data center.

1x3 MTP conversion harness used in 40G to 120G connection

Figure 6: 40G to 120G connection by using 1×3 MTP conversion harness


Several solution scenarios have been illustrated in this post. From 10G to 40G/100G/120G, we can see that different MTP/MPO fiber cables are used for data transmission. Generally, MTP/MPO trunk cables are used for direct connection between two switches. MTP harness cables are used for data migration to higher data rates. And MTP/MPO conversion cables are used to achieve 100% fiber utilization between two switches. All of those different MTP/MPO fiber cables (MTP trunk, MTP harness, MTP conversion harness) can be found in FS.COM. For more details, please visit

Other post you may be interested: No Conversion vs. Conversion Module vs. Conversion Harness: Which to Use for 40G Parallel Solution?