If you are using either PAP or CHAP authentication, you can assign IP addresses to callers by the sppp unit number. The following shows an example of this usage.
myclient ISP-server mypassword 10.10.111.240/28+
The plus sign (+) indicates that the unit number is added to the IP address. Note the following:
Addresses 10.10.111.240 through 10.10.111.255 are assigned to remote users.
sppp0 gets IP address 10.10.111.240.
sppp1 gets IP address 10.10.111.241 and so on.