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> Wireless connectivity is provided through a shared medium. For comparison you have wired networking where every customer has a dedicated medium, the wire, for

> Wireless connectivity is provided through a shared medium. For comparison you have wired networking where every customer has a dedicated medium, the wire, for themselves. Isn’t wire also a shared medium? It’s not that there is an end-to-end circuit when you connect to another machine on the Net; your packets will be send along with others’.

signa11 8y ago
> Isn’t wire also a shared medium? It’s not that there is an end-to-end circuit when you connect to another machine on the Net; your packets will be send along with others’. not since you have had ethernet switches.
- fulafel 8y ago
  But you can't access the Internet if you don't have an uplink on it - and it's shared.
adrianN 8y ago
Technically yes, but the traffic for a whole city fits through a single strand of fiber with room to spare.
- dx034 8y ago
  It does only because the end user has slow speeds. If anyone could stream 4k, the bandwidth for a whole city during peak hours would probably not fit through that fiber anymore.
  - adrianN 8y ago
    A strand of fiber can carry something like 20 Terabits/s. Streaming 4k takes less than 20 Megabits per second. That's still a million people streaming 4k simultaneously.
oasisbob 8y ago
> Isn’t wire also a shared medium? 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
- amazon_not 8y ago
  > 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. This is incorrect. GPON does not use DWDM, or any individual waves per subscriber. GPON is a shared medium with one wavelenght used in the upstream and one wavelenght used in the downstream direction. Each subscriber is allocated bandwidth on the shared medium. Not even next generation PON uses DWDM. Next generation PON still uses on upstream and one downstream wavelenght per PON tree, but there can be multiple PON trees on the same backhaul fiber. It's more like a CWDM overlay of PON trees. The only PON that uses DWDM is WDM-PON, but it isn't deployed commercially at scale yet.
  - oasisbob 8y ago
    Thanks for the correction - easy to forget that the P in PON is for passive.
sorenjan 8y ago
The difference is that if the cable gets full you can put a new cable next to the other one, and double your available bandwidth. If the ether is full, it's full. It's also mixed with all kinds of signals, obstacles, power losses, etc.

signa11 8y ago

> Isn’t wire also a shared medium? It’s not that there is an end-to-end circuit when you connect to another machine on the Net; your packets will be send along with others’. not since you have had ethernet switches.

fulafel 8y ago
But you can't access the Internet if you don't have an uplink on it - and it's shared.

adrianN 8y ago

Technically yes, but the traffic for a whole city fits through a single strand of fiber with room to spare.

dx034 8y ago
It does only because the end user has slow speeds. If anyone could stream 4k, the bandwidth for a whole city during peak hours would probably not fit through that fiber anymore.
- adrianN 8y ago
  A strand of fiber can carry something like 20 Terabits/s. Streaming 4k takes less than 20 Megabits per second. That's still a million people streaming 4k simultaneously.

oasisbob 8y ago

> Isn’t wire also a shared medium? 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

amazon_not 8y ago
> 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. This is incorrect. GPON does not use DWDM, or any individual waves per subscriber. GPON is a shared medium with one wavelenght used in the upstream and one wavelenght used in the downstream direction. Each subscriber is allocated bandwidth on the shared medium. Not even next generation PON uses DWDM. Next generation PON still uses on upstream and one downstream wavelenght per PON tree, but there can be multiple PON trees on the same backhaul fiber. It's more like a CWDM overlay of PON trees. The only PON that uses DWDM is WDM-PON, but it isn't deployed commercially at scale yet.
- oasisbob 8y ago
  Thanks for the correction - easy to forget that the P in PON is for passive.

sorenjan 8y ago

The difference is that if the cable gets full you can put a new cable next to the other one, and double your available bandwidth. If the ether is full, it's full. It's also mixed with all kinds of signals, obstacles, power losses, etc.