Starting NOS v6.0.2b, firmware upgrades can done using TFTP protocol. TFTPD32 is a small lite weight application typically used to perform the firmware upgrades.
A common problem seen during the firmware upgrade using TFTP is:
sw3# firmware download tftp host 10.110.33.18 directory /nos6.0.2a file release.plist
Performing system sanity check...
Cannot access the server. Please check whether the server name or IP address is valid.
In the TFTP32 application's log viewer, it shows there's a problem with the path.
Connection received from 10.18.8.34 on port 43474 [15/03 17:54:00.183]
Read request for file <//SWBD137/release.plist>. Mode octet [15/03 17:54:00.183]
Error EACCESS on file \\SWBD137\release.plist. Ext error The directory name is invalid. [15/03 17:54:00.183]
Connection received from 10.18.8.34 on port 50308 [15/03 17:54:00.213]
Read request for file <//install>. Mode octet [15/03 17:54:00.213]
Error EACCESS on file \\install. Ext error The directory name is invalid. [15/03 17:54:00.213]