Hi, Sheldon.
The 172.xxx.xxx.xxx IP Addresses are private addresses - meaning they are not internet routable. Any organization can freely use these IP addresses for their own purposes (along with 169.xxx.xxx.xxx, 10.xxx.xxx.xxx and 192.168.xxx.xxx addresses) without worrying about colliding with anyone elses ip address space.
In your case, these 172. addresses are assigned by your cable company.
WIthout knowing the network topology, it's impossible to say for certain what these devices are, but can take a guess.
172.28.86.1 *could* be your cable modem. In reality, you should probably get a latency of 1 ms for your cable modem's IP address (unless you're having network issues between you and the cable modem - like a relatively slow wireless connection, or something similar). It could also be inside your cable provider's complex itself - on the other side of the cable line.
The other 172. address could be inside your cable providers complex somewhere.
The latency spikes you see in the graphs at hop 2 and hop 12 are *not* translated into latency spikes at your final destination, so these are not problems you should be chasing. For more discussion on this, see
http://www.nessoft.com/kb/24.
- Pete
