How to use QSFP28 port to transmit 10G / 25G / 40G?

11 Oct.,2022

 

100G qsfp28

How to use QSFP28 port to transmit 10G / 25G / 40G?

Jan 05, 2021

QSFP28 optical module, also known as 100G optical module, is an important part of 100G network. It is mainly used in 100G Ethernet and EDR InfiniBand applications. It uses four 25Gbit / s transmission channels to transmit data.

 

QSFP28 optical module classification

1. QSFP28 SR4 optical module

QSFP28 SR4 optical module is also known as 100Gbase-SR4 QSFP28 optical module. Because most of the multi-mode optical fibers are used in the data center, IEEE has formulated a special standard for 100G QSFP28 optical module to support the application of multi-mode optical fiber short distance transmission: 100Gbase-SR4. QSFP28SR4 optical module adopts MTP interface (8-core), and the transmission distance is 70m when it is used with OM3 multimode fiber, and 100m when it is used with OM4 multimode fiber, which is suitable for short distance transmission. QSFP28SR4 optical module is a parallel 100G optical module, which has the advantages of high port density and low cost.

2. QSFP28LR4 optical module

QSFP28 LR4 optical module is also known as 100Gbase-LR4 QSFP28 optical module. QSFP28 LR4 optical module also uses four fiber channels. The difference is that it introduces WDM technology, which can multiplex different wavelengths of four fiber channels to one fiber for transmission, so QSFP28 LR4 optical module adopts duplex LC interface, and the transmission distance can reach 10km when used with single-mode optical fiber, which provides a solution for the increasing transmission distance of super large data center.

3. QSFP28 PSM4 optical module

QSFP28 PSM4 optical module, also known as 100Gbase-PSM4 QSFP28 optical module, has the advantages of high speed, low power consumption, etc., with the appearance of hot pluggable QSFP and built-in digital diagnosis function. 100Gbase-PSM4 is a multi-source protocol (MSA), mainly for 100G QSFP28 optical module. QSFP28 PSM4 optical module is mainly used for medium and long distance transmission applications. It uses MTP interface, and when used with single-mode multi-core fiber, the transmission distance can reach 500m, and it has eight fibers, and the data rate of each fiber is 25Gbps.

The following figure shows the working principle of PSM4 QSFP28 optical module in 100G Ethernet

4. QSFP28 CWDM4 optical module

QSFP28 CWDM4 optical module, also known as 100Gbase-CWDM4 QSFP28 optical module, is mainly used in computing, high frequency trading and other fields. 100Gbase-CWDM4 is also a multi-source protocol (MSA). QSFP28 CWDM4 optical module also introduces WDM technology and adopts LC duplex interface. When used with single-mode fiber, the transmission distance can reach 2km.

The following figure shows the working principle of PSM4 QSFP28 optical module in 100G Ethernet

Features of QSFP28 optical module

1. Small size. Compared with CFP and CFP4 optical modules, QSFP28 optical module is smaller;

2. High port density. Compared with other 100G optical modules, QSFP28 optical module has higher port density on the switch. Generally, 36 QSFP28 optical modules can be installed on a 1RU switch;

3. Low power consumption. Compared with other 100G optical modules, the power consumption of QSFP28 optical module is lower, generally no more than 3.5W.

4. Cost. The current data center is mainly 10G network architecture, and its interconnection solution is mainly 10Gbase-SR optical module and duplex LC multimode optical fiber jumper. If the existing 10G network architecture is directly upgraded to 40 / 100G network, it will save a lot of time and cost.

5. Bandwidth. It adopts the most advanced 100G transmission technology to provide the connection between the rack switch and the core network for the data center, which improves the panel bandwidth density by 150% compared with the 40G QSFP scheme


The differences of four kinds of 100G QSFP28 optical modules are as follows:

Optical module   type

Interface

Fiber type

Transmission   distance

100GBASE-SR4 QSFP28

MTP/MPO-12

Multimode OM4 fiber

100m

100GBASE-LR4 QSFP28

LC Duplex

Single mode fiber

10km

100GBASE-CWDM4 QSFP28

LC Duplex

Single mode fiber

2km

100GBASE-PSM4 QSFP28

MTP/MPO-12

Banded single mode fiber (8-core)

500m

 

Application selection of QSFP28 optical module

In 100G network, how to choose the appropriate QSFP28 optical module can be considered from the following three aspects:

1. Multimode optical fiber wiring between switches: 5-100m

QSFP28 SR4 optical module can be selected. It adopts MTP interface (8-core). When it is used with OM3 multimode fiber, the transmission distance is 70m. When it is used with OM4 multimode fiber, the transmission distance is 100m. It is suitable for 100G network with short distance transmission (less than 100m).

2. Single mode optical fiber wiring between switches: > 100m-2km

QSFP28 PSM4 optical module or QSFP28 cwdm4 optical module can be selected, which are suitable for medium and short distance 100G network. QSFP28 PSM4 optical module uses 8 parallel single-mode optical fibers together, and the transmission distance is about 500 meters; QSFP28 cwdm4 optical module uses single-mode optical fiber together, and the transmission distance can reach 2km.

3. Long mode single mode fiber: ≤ 10km

QSFP28 LR4 optical module can be selected. It adopts duplex LC interface, and the transmission distance can reach 10km when used with single-mode optical fiber. It is suitable for 100G network with long distance (more than 2km and less than 10km).


How to run 40Gbps on QSFP28 port?

If the client device uses 40G, the speed of QSFP28 port should be reduced to 40G, allowing 40G QSFP + optical module to connect.

Hardware equipment

40G QSFP + optical module with MTP / MPO interface, MTP / MPO 12 core optical fiber jumper

40G QSFP + to QSFP + DAC high speed cable

40G QSFP + to QSFP + AOC active optical cable

The external dimensions of 100G QSFP28 optical module are the same as that of QSFP optical module. The 100G QSFP28 optical module can support 4 * 25G and 4 * 10G, and the 40G QSFP + optical module can support 4 * 10G.

How to run 10Gbps on QSFP28 port?

If the client device uses 10G, the port speed of QSFP28 will be reduced to 40G, and the 40G QSFP + optical module will be split into 4 * 10G mode.

Hardware equipment

40G QSFP + optical module with MTP / MPO interface, 10G SFP + optical module with LC interface, MTP / MPO-LC optical fiber jumper

40G QSFP + to 4 * 10G SFP + DAC high speed cable

40G QSFP + to 4 * 10G SFP + AOC active optical cable

The QSFP28 port of the switch is reduced to 40G, and then divided into 4 * 10G mode.

How to run 25Gbps on QSFP28 port?

Four SFP28 channels can realize 100G transmission

Hardware equipment

100G QSFP28 optical module of MTP / MPO interface, SFP28 25G optical module of LC interface, MTP / MPO-LC branch jumper

100G QSFP28 to 4 * 25G SFP28 DAC high speed cable

100G QSFP28 to 4 * 25G SFP28 AOC active optical cable


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