i86bi-linux-l3-adventerprisek9-ms.155-2.T.bin is a Cisco IOS on UNIX (IOU)
# Make executable chmod +x I86bi-linux-l3-adventerprisek9-ms.155-2.t.bin I86bi-linux-l3-adventerprisek9-ms.155-2.t.bin
for this image publicly – it is copyrighted Cisco software. Only use it if you have a valid Cisco support contract and are running it in a licensed emulator for learning/lab purposes. i86bi-linux-l3-adventerprisek9-ms