The 15.7(3)M release is part of the "Extended Maintenance" train for Cisco IOS, offering stability and a wide range of enterprise capabilities.
The i86bi linuxl3 adventerprisek9-m2 157 3 may 2018.bin is built between 2018 and 2024. i86bi linuxl3-adventerprisek9-m2 157 3 may 2018.bin