Cisco Back-to-Back T1 Interface Configuration

Background Information

Step	Instruction	Command	Example
1	Set the card to T1 mode	card type t1 slot subslot	card type t1 0 0
2a	Set the clock source to internal (on each DCE port)	controller t1 slot/subslot/port clock source internal	controller t1 0/0/0 clock source internal
2b	Set the clock source to line (on each DTE port)	controller t1 slot/subslot/port clock source line	controller t1 0/0/1 clock source line
3	Set the channel group 0 to include all 24 T1 timeslots	controller t1 slot/subslot/port channel-group 0 timeslots 1-24	controller t1 0/0/0 channel-group 0 timeslots 1-24
4	Set the port framing to esf	controller t1 slot/subslot/port framing esf	controller t1 0/0/0 framing esf
5	Set the linecode to b8zs	controller t1 slot/subslot/port linecode b8zs	controller t1 0/0/0 linecode b8zs

You should now have a Serial0/0/0:0 interface and/or Serial0/0/1:0 interface which you can assign an IP address to and use as with any normal serial interface, make sure to include the :0 on the end of the interface though.

Sample Two Card Configuration

DCE IS S/0/0/0 AND DTE IS S0/0/1

card type t1 0 0
controller t1 0/0/0
clock source internal
chan 0 time 1-24
framing esf
linecode b8zs
controller t1 0/0/1
clock source line
chan 0 time 1-24
framing esf
linecode b8zs

DTE IS S0/0/0 AND DCE IS S0/0/1

card type t1 0 0
controller t1 0/0/0
clock source line
chan 0 time 1-24
framing esf
linecode b8zs
controller t1 0/0/1
clock source internal
chan 0 time 1-24
framing esf
linecode b8zs

4000 Series routers use slightly different hardware nomenclature

DCE IS S/0/1/0 AND DTE IS S0/1/1

card type t1 0 1
controller t1 0/1/0
clock source internal
chan 0 time 1-24
framing esf
linecode b8zs
controller t1 0/1/1
clock source line
chan 0 time 1-24
framing esf
linecode b8zs

DTE IS S0/1/0 AND DCE IS S0/1/1

card type t1 0 1
controller t1 0/1/0
clock source line
chan 0 time 1-24
framing esf
linecode b8zs
controller t1 0/1/1
clock source internal
chan 0 time 1-24
framing esf
linecode b8zs