B−channel connection. In this case, the ADTRAN must be programmed to dial the second B−channel or have
the second number passed within the same dialer string. The router serial interface is a Point−to−Point
interface and has no idea of the number of B−channels configured on the ADTRAN.
Do not configure the command ppp multilink on the router, since the TA actually handles the multilink
connection, while the router need only process the synchronous stream from the TA.
Note: Using multiple dialer maps (as we would on BRI interfaces) does not help for this multilink issue.
DTR Dialing
Using this method, the router can only place calls to one particular phone number, it cannot receive incoming
calls. With this method, the phone number(s) of the remote site must be stored in the memory of the TA.
When the TA sees the DTR go high, it dials the number that is stored in the TA. This requires the dialer dtr
command under the serial interface. For example:
Example:
interface Serial0
ip address 172.25.254.97 255.255.255.252
encapsulation ppp
dialer dtr
dialer idle−timeout 300
ppp authentication chap
The ADTRAN must be configured for DTR dialing, multilink PPP, and so on, and have the destination phone
number programmed.
Both B−channels are dialed by the ADTRAN.
Keypad Dialing
Some TAs have keypads on them to allow for interactive dialing directly from the TA. With this method, the
user must input the number to dial in the TA keypad every time a connection is to be made. This method is
primarily used for testing purposes to verify connectivity. The required router configuration is shown below:
interface Serial0
ip address 172.25.254.97 255.255.255.252
encapsulation ppp
dialer in−band
dialer idle−timeout 300
dialer map ip 172.25.254.98 name Remote broadcast
ppp authentication chap
Cabling
To connect the serial port of the router to the TA use a V.35 DTE cable (with DB−60 serial port or smart
serial on one side). The following diagram shows a sample cable:
If the TA only has an RS−232 port, then you also need a V.35 to RS−232 (DB−25) Cable in addition to the
cable shown above. Alternately, you can use just one DB−60−to−DB−25 RS−232 Cable.
