Hi Navneet,
The 'controller' T1 and E1 are the internal 'CSU/DSU' of the T1 or E1 card. Controllers are what we refer to the CSU/DSU used in cisco 'Channelized' cards. If you are familiar this the 'Service-moduel' of our Fractional WIC-1DSU-T1 card this is the same functional component. The difference is the controller allows you to segment the T1 or E1 into seperate logical channel groups. In otherwords you can segment the T1 or E1 into seperate 'Fractions' of the T1 to represent independent point to point T1's.
As far as the show command. 'show controllers se0/0' this shows the controller of a serial interface. The word controller here represents a different meaning of the word and this command gives the 'Hardware' aspect of interface this is requested for.
To see the CSU/DSU controller outputs of a controller T1 or E1 card use the 'Show controller T1 (or E1) [controller #]
For example: show controller t1 0/0
(this assumes you have 'controller t1 0/0 in the running config).
Hope this helps.
Glen
