how can you upgrade the symentec 11x client to 12.1 client in silent mode.give me the graphical image doc .
HI,
Check this artical
https://www-secure.symantec.com/connect/articles/upgrade-clients-sep-121-auto-upgrade-feature
And videos
https://www-secure.symantec.com/connect/videos/upgrade-clients-sep-121-using-auto-upgrade-feature
Some more documentation about migration to 12.1 that may be helpful to you:
http://www.symantec.com/docs/TECH197426