[R2]ip pool 1
Info: It's successful to create an IP address pool.
[R2-ip-pool-1]network 12.1.1.0 ma 
[R2-ip-pool-1]network 12.1.1.0 mask 255.255.255.0
[R2-ip-pool-1]gateway-list 12.1.1.1
[R2-ip-pool-1]dns-list 114.114.114.114 8.8.8.8

[R2-Serial1/0/0]ip add 12.1.1.2 255.255.255.0
[R2-Serial1/0/0]remote address pool 1
[R2-Serial1/0/0]ppp authentication-mode chap

[R1-Serial1/0/0] ip address ppp-negotiate
[R1-Serial1/0/0] ppp chap user hcip
[R1-Serial1/0/0]ppp chap password cipher 123