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This is my home network setup:
Internet ---> External IP (cable modem) Internal IP ---> External IP (wireless router) 192.168.20.1 ---> (laptop) 192.168.20.102
Am I correct to assume that the WAN IP / Public IP assigned to me by my ISP is at the external side of the modem or is it on the external side of the wireless router? I am guessing that the External IP of my wireless router has to be on the same subnet of the internal IP of my modem
Where do these 3 IP addresses go into my home network as shown above
- WAN IP / Public IP (static)
- WAN gateway (the static Gateway associated with WAN IP)
- Modem internal IP ( I found it to be
192.168.100.1
a Cisco DPC3008 )
I was thinking more like it goes like this:
Internet ---> WAN IP / Public IP (cable modem) WAN GATEWAY ---> External IP (wireless router) 192. 168. 20. 1 ---> (laptop) 192.168.20.102
Then on this assumptions I'm leaving behind modem internal IP, and External IP of the wireless router would have to be on the same subnet of the WAN gateway which is getting a bit confusing.
What I know for sure is that the External IP of my wireless router should be on a different subnet than 192.168.20.1
so that it can route the packets into another network which is in my case, the internet.
Here is the diagram:
Added by barlop
The item the OP describes as a (cable) modem, is a cable modem router.
Cisco DPC/EPC 3008 has one cable modem connector, and one ethernet port, and also, it is a gateway/router (the document I liked to describes it as such) So it's a cable modem router with one ethernet port. It's sold as a cable modem. (Note that Cisco also do the cisco DPC/EPC2325 which is sold as a gateway but is a cable modem router with multiple ethernet ports)
Additional Info: must read
just wanted throw out a bit of info to make sure everything is crystal, it might or may not sway your answers
Both WAN IP / Public IP (static) and WAN gateway (the static Gateway associated with WAN IP) are present on the WAN tab of the wireless router's admin page which is accessible at 192.168.20.1
On the Routing table of the wireless router's admin page, it shows that destination 0.0.0.0 of Netmask 255.255.255.0 is having the WAN gateway (above) as the determined Gateway using interface eth2.2
Doing a tracert WAN IP, yielded 1 hop/node
Doing a tracert WAN gateway, yielded 5 hops/node (nodes 2 to 4 are all request time out)
side note:
it felt odd that number 3 and 4 suggests that my home network setup is
Internet ---> External IP (cable modem) WAN GATEWAY ---> WAN IP / Public IP(wireless router) 192. 168. 20. 1 ---> (laptop) 192.168.20.102
the reason I thought of this is because tracert means that the packets are being pushed from the wireless NIC of my laptop going outwards into the next node/device
still quite lost.. I have known that the cisco DPC3008 could be originally installed without a router in between and directly connects to your computer or laptop by ethernet which means the cable modem itself assigns an IP address to your computer's MAC to communicate with it , whereas in my setup has been with a router in between ever since. Can somebody confirm that my router does acquire its external IP from the modem ? if it is so, would it be in the 192.168.100.0/24 subnet? – amdc – 2015-08-27T05:13:06.190
on a (cable modem)---(computer/Laptop) setup, regarding with the cable modem assigning an IP to the computer/laptop , im not sure if it's the WAN / Public IP or in the range of 192.168.100.0/24, but to think of that as far I know the cable modem does not have a dhcp server but it might be able to give 1 private IP..not sure though – amdc – 2015-08-27T05:19:39.833
Modems don't assign IPs. And modems don't have IPs. These devices are boxes with particular functions. You have to figure out what functions these boxes have. From my experience of cable modems , cable modems tend to just be cable modems, not having additional functionality. – barlop – 2015-08-27T22:06:54.757
Modems don't assign IPs. And modems don't have IPs. These devices are boxes with particular functions. You have to figure out what functions these boxes have. Usually cable modems tend to just be cable modems, though cisco does cable modem routers. Though it could be a current/new thing that devices that function as cable modems nowadays tend to or often function as routers too. Regardless. DHCP servers hand out IPs. Routers have IPs, modems don't. One must isolate the function one is speaking about, within the internet device. – barlop – 2015-08-28T10:10:40.840