I’ve just brought new 951 device and upgraded it to last 6.29 (looks like it is not RC anymore). I’ve plugged it to test network, added DHCP client on it and IP was assigned (as it intended to be). My PC was connected to different port of 951 so I can read logs etc without disconnection.
After that I disconnected the line that supplied IP and internet, and noticed that default route was marked as inactive, but the IP assigned by DHCP won’t be removed from interface that went down. I suspect this is not that is intended to be, am I right?
Once again: as I connected LAN to port 1 of the router and set up DHCP client on port 1, I can see the router received an IP, and a route to 0.0.0.0/0 was added to routing table. But as I disconnected the line from port 1 I expect that IP should disappear from the IP Address list, but it stays there even after the port went down! It is marked as Dynamic, but it won’t disappear. At the same time, default route that was received from DCHP was disappear as well, it just painted in blue color and stays at the routing table.
I downgraded to 6.28, but the test given the same result.
AFAIK, this is intended. DHCP gives you an IP with an expire time. The IP would only be removed after that time passes, or if you explicitly release it (or try to renew it). I think it should automatically be renewed if you plug the cable back in, and the gateway is not reachable.
As I think about I come to conclusion this can be the truth, but… I just tested again: plug in LAN, got the IP, disconnected LAN, and tried to ping IP that was assigned to the device. And know what - the ping within device was ok!
I don’t think this way it is intended. If connected network is no more “connected”, we should not keep in mind route to it, isn’t it?
Since the IP belongs to the router itself, when you’re pinging that IP, the router is able to route you to that IP (with or without a route; disable the “add default route” option, and you’ll see it’s the same), and that’s why the ping works.
To check whether the router is connected to a particular network, you’d ping that network’s gateway instead. Pings will fail if the device is not connected, since the gateway would be unreachable if the cable is unplugged.