Yes, Cisco SFP28 (Small Form-factor Pluggable 28) modules are designed to be backward compatible with SFP+ (Small Form-factor Pluggable Enhanced) ports. This means that you can use a Cisco SFP28 module in an SFP+ port on Cisco networking equipment.

The backward compatibility ensures flexibility in network upgrades, allowing users to transition from lower data rates (such as 10 Gigabit Ethernet with SFP+) to higher data rates (such as 25 Gigabit Ethernet with SFP28) without the need to replace the entire networking infrastructure.

It's important to note that while SFP28 modules can be used in SFP+ ports, the overall data rate will be limited to the capabilities of the SFP+ port. In other words, if you insert a Cisco SFP28 module into an SFP+ port, it will operate at the data rate supported by the SFP+ standard (e.g., up to 10 Gbps) rather than the higher data rate supported by the SFP28 module.

Always check the compatibility and specifications provided by Cisco for your specific networking equipment to ensure proper operation when using SFP28 modules in SFP+ ports.