Confused with ppp0e ubuntu server 16?

Question

linux

I got a gateway in the office on ubuntu16. I'm trying to figure out the topology, the Internet works through pppoe, the interface settings are strange and mtr to Google DNS too. Here is ifconfig ppp0

Link encap:Point-to-Point Protocol
inet addr:46.149.*** PtP:172.20.1.254 Mask:255.255.255.255
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1492 Metric:1
RX packets:35428427 errors:0 dropped:0 overruns: 0 frame:0
TX packets:22536371 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:3
RX bytes:42287559346 (42.2 GB) TX bytes:4442357417 (4.4 GB)

It is not clear how and why my ip is external, and the gateway is gray ip how is it generally routed? is this set up correctly? (although there is Internet)
Now a strange mtr to the Internet from the gateway:

mtr 8.8.8.8
1) 172.20.1.254
2) 172.16.1.252
3) 172.16.1.251
4) 172.16.1.253
5) 172.16.1.254
6) 194.44.4.254
7) 209.85.248.10gl5
and beyond

My question is: what is this series of gray gateways through which my packets pass? is it an ISP network? rather its routers? why are there so many of them? Thank you!