c2951-universalk9-mz.SPA.157-3.M8.bin is the specific firmware image for the Cisco 2951 Integrated Services Router (ISR) G2 , running IOS Release
The 15.7(3)M8 image fixes a boundary router crash condition when receiving Type 10 LSAs (OSPFv3 for IPv6). If you run dual-stack (IPv4+IPv6) with OSPF, this update is mandatory. c2951universalk9mzspa1573m8bin updated
If issues arise:
Router# show version | include IOS
c2951-universalK9-MZ.SPA.157-3.M8.bin