have internet access, but cant ping router.

[kubicle]

Re: have internet access, but cant ping router.

IF my computer is on and echoing pings to my IP address someone can rightly deduce that they have contacted my machine and that it does exist. Ditto for specific port probes. The ping was directed to my IP address via the routing table entry created by my ISP, on their servers, when they leased that IP address to me. BUT, if my machine (or more specifically my wireless routher) does not echo pings then no packet is returned to the machine sending out the ping, so no conclusion can be made as to whether a machine exists at that IP address or not.

If the IP is the outward facing IP of your NAT router, it's the router that answers (or not) to the pings, not your computer on the LAN side. The router does not forward pings (icmp) to your LAN network. This is different from tcp/udp packets which can be forwarded to a specific host IP on your LAN via the router's configuration.

Ole Juul's reply of

100% packet loss

without any other msgs is what his ping should give. Juul was given no information to indicate that there is a real, live working computer at 24.223.246.8 or that it is an unused IP address with no machine or router present. In this situation my ISP's server did NOT reply with "host unreachable", or any other msg, even though my network has been up continuously for almost a month. The only way for Juul to see if there was a machine at my IP address is for him to hack into my ISP's server(s) and view the routing table OR account for all the packets traveling in the trunk to which I am attached.

As the ping timed out, one can easily deduce that there is something in that IP that is dropping the pings (your router)...your ISPs router knows the IP exists and forwards the ping to your IP (router) and as there is no response, the ping times out (which ping eventually reports as 100% packet loss).

If the IP is not in use, your ISP's router should send an error back to the ping source because the IP is on it's address range, but is not active...in this case it does not forward the ping to the IP but sends an error back instead. And ping will translate the error as the "destination host unreachable" message.

Once again, the key is whether your router is online (has an active IP lease)...whether any host computers are on or not in the LAN side of your router does not affect the result.

If the ping times out, as it did Ole Juul's ping, ping received no error messages from any of the hops (routers) between the source and the destination, which means the ping was forwarded to the destination IP succesfully (otherwise you would get an error message back from the router that wasn't able to forward the ping because the IP does not exist)...and since there was no response (even though it was successfully forwarded) one can deduce there is something in that IP that is dropping the pings.

My computer had no need, nor did it, respond with some "destination unreachable" message.

It's not your computer nor your router that sends the "host unreachable" message, you only get that with a really dead IP, from the error that is sent by the ISP's router that handles the IP in question.

General rules (but not 100% accurate in all cases):
1. ping reply == there is something in the IP that responds to pings (in this case it would be the router)
2. ping timeout == there is something in the IP that is dropping pings (in this case it would be the router)
3. host unreachable == there is nothing in that IP