The Cisco IOS XR Software Release 5.1 has been retired and is no longer supported.
End-of-Sale Date: 2015-10-01
End-of-Support Date: 2020-10-31
Cisco's End-of-Life Policy
You can view a listing of available null offerings that best meet your specific needs
If you want support information for the Cisco IOS XR Software Release 5.1 documentation, it may be available through Cisco.com Search or in the Cisco Community