I think it's a distinction without a difference in this case. You can't know if the reason your water stopped is because the water is shut off, the pipe broke, or it's just slow.
When all you have to go on is "I stopped getting packets" the best you can do is give up after a bit. TCP keepsalives do kinda suck and are full of interesting choices that don't seem to have passed the test of time. But they are there and if you control both sides of the connection you can be sure they work.
There's a crucial difference in fact, which is that the peer you're defining connectedness to is a single well-defined peer that is directly connected to you, which "The Network" is not.
As for the analogy, uh, this ain't water. Monitor the line voltage or the fiber brightness or something, it'll tell you very quickly if the other endpoint is disconnected. It's up to the physical layer to provide a mechanism to detect disconnection, but it's not somehow impossible or rocket science...
> To re-word everyone else's comments - "Disconnected" is not well-defined in any network.
Parent said disconnected pipe, not network. It's sufficiently well-definable there.
I think it's a distinction without a difference in this case. You can't know if the reason your water stopped is because the water is shut off, the pipe broke, or it's just slow.
When all you have to go on is "I stopped getting packets" the best you can do is give up after a bit. TCP keepsalives do kinda suck and are full of interesting choices that don't seem to have passed the test of time. But they are there and if you control both sides of the connection you can be sure they work.
There's a crucial difference in fact, which is that the peer you're defining connectedness to is a single well-defined peer that is directly connected to you, which "The Network" is not.
As for the analogy, uh, this ain't water. Monitor the line voltage or the fiber brightness or something, it'll tell you very quickly if the other endpoint is disconnected. It's up to the physical layer to provide a mechanism to detect disconnection, but it's not somehow impossible or rocket science...
8 replies →
See https://news.ycombinator.com/item?id=40316922 : "pipe" is L3, the network links are L2.