GGSN p-t-p address?

Hi all, idle curiosity here more than anything..... I noticed that if I bring up a pppd link with a GSM modem to an osmo stack GPRS network, I get assigned an IP address from the pool as configured on osmo-ggsn;   ip prefix dynamic 10.20.0.0/16   ip dns 0 192.168.11.2   ip dns 1 192.168.11.2   ip ifconfig 10.20.20.253/16 but the p-t-p address is 192.168.100.101; Sat Aug 18 15:45:38 2018 daemon.notice pppd[21227]: local  IP address 10.20.0.8 Sat Aug 18 15:45:38 2018 daemon.notice pppd[21227]: remote IP address 192.168.100.101 Here's the resulting ifconfig: 3g-gwan   Link encap:Point-to-Point Protocol            inet addr:10.20.0.8  P-t-P:192.168.100.101  Mask:255.255.255.255           UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1           RX packets:3 errors:0 dropped:0 overruns:0 frame:0           TX packets:4 errors:0 dropped:0 overruns:0 carrier:0           collisions:0 txqueuelen:3           RX bytes:54 (54.0 B)  TX bytes:76 (76.0 B) This is not really a problem but I thought it was weird so I looked for this IP (192.168.100.101) in the source code but it was nowhere to be found. I'm a bit rusty on ppp, but should it not be the address configured in the ggsn's ip config? I thought maybe it was coming from the local pppd stack, so I booted an old windows 7 machine and connnected the GSM modem, and it got the same p-t-p address of 192.168.100.101 thnx/ K.