That's a really tricky question. At some point, the packets are going to share a link with those from other customers, possibly oversubscribed...
Cable internet is clearly a shared medium at both the physical and link layers.
Fiber like GPON is shared physically-ish, but DWDM isolates individual waves so thoroughly that it's hard to think of that as a shared physical medium unless you're thinking about backhoe fade and the like.
That's a really tricky question. At some point, the packets are going to share a link with those from other customers, possibly oversubscribed...
Cable internet is clearly a shared medium at both the physical and link layers.
Fiber like GPON is shared physically-ish, but DWDM isolates individual waves so thoroughly that it's hard to think of that as a shared physical medium unless you're thinking about backhoe fade and the like.
With DSL, do you consider the DSLAM?
Etc