Can QSFP+ optical module be used on QSFP28 ports?

Date: 2020-04-16 04:02:18 From: C-light Onclick:

The development speed of 100g Ethernet is speeding up gradually. With the popularization of 100g network, there are more and more problems in the process of building network. For example, the QSFP28 optical module commonly used by people can support 10km transmission distance in 100g application through WDM technology, but WDM equipment is more expensive, and when the transmission distance exceeds 10km, the use of QSFP28 optical module can not meet the requirements, because this requires QSFP+ optical module on 100g switch. Can we plug QSFP+ optical module on QSFP28 port of 100g switch? Or can QSFP28 optical module be used on QSFP+ port? In this paper, c-light.COM will discuss the feasibility of these solutions.

QSFP28 optical module is a 100g optical module, with four transmission channels, each channel can reach a rate of 25g. The following table is the common information of QSFP28 optical module.

QSFP28	Jumper	Transmission Distance
100GBASE-SR4QSFP28	MTP / MPO multimode fiber	≤100m
100GBASE-LR4QSFP28	Duplex LC single mode fiber	≤10km

QSFP+ optical module is a 40g optical module, which also has four transmission channels, each channel has a 10g rate. The following table shows three common 40g QSFP+ optical module information.

QSFP+ optical module can be used on QSFP28 port
QSFP28 optical module and QSFP+ optical module are similar in shape and size, And each channel of QSFP28 module can support 25g rate. However, each channel of QSFP+ optical module has a speed of 10G, so QSFP28 port can support QSFP+ optical module downward; on the contrary, QSFP+ port can not use QSFP28 optical module, because it can not meet its requirements in speed.

Summary
The principle of mixed use of optical modules with different rates for switches is basically attributed to the optical fiber and switch port used. The port of optical module must match the port shape of the switch. At the same time, the switch port rate must be equal to or greater than the optical module rate used. The C-light Network communication provides different models of QSFP28 optical module and QSFP+ optical module. Welcome to page of optical transceiver modules.

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Can QSFP+ optical module be used on QSFP28 ports?