AM little confused on the terms T1/E1 and T3/E3
As far as I am concerned there are T1/E1 and T3/E3 in ISDN. And there are T1/E1 and T3/E3 in our normal leased line connection (inter office WAN link connection) where we are not using any ISDN service. What is the difference between these two??
=================================================================== Secondly I have seen the configuration commands
Interface controller t1 0/0 Pri-group / channel-group Clock Framing Line code
Interface serial 0/0 :23 Ip addrss
My question is that is that is enough for a T1/E1 configuration. And why in some configurations Pri-group and in some other configurations channel-group is configured. What is the difference between these two?