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They might have to interact with a lot of devices that only support IPv4, and will never upgrade. These include a lot of industrial PLCs and various embedded d

They might have to interact with a lot of devices that only support IPv4, and will never upgrade. These include a lot of industrial PLCs and various embedded devices. 10.0.0.0/8 might seem like a lot of addresses, but certain large companies have enough fans and chillers and miscellaneous things that can fill that space, and it takes a lot of effort to reorganize their network to better allocate those addresses.

helf 2y ago
Sadly I'm in that position. I have hundreds of PLCs and legacy controllers on my network that are IPv4 only and will never be replaced. At least not in a reasonable time frame. I'm talking 20+ year life expectancies.
michaelt 2y ago
> 10.0.0.0/8 might seem like a lot of addresses, but certain large companies have enough fans and chillers and miscellaneous things that can fill that space Do these large companies really have 16,777,216 fans and chillers? That would be enough for each of Wal-Mart's 10,586 stores to have 1500 IPs each. Or do they just have legacy allocation mistakes?
- omoikane 2y ago
  > Do these large companies really have 16,777,216 fans and chillers? Some of those might be regular servers or networking gear that are required to have IPv4 addresses for one reason or another. For example, they might need to interact with fans and chillers. > legacy allocation mistakes Requiring the same globally unique prefix for devices that share locations or functions would eat up allocations faster than the number devices would grow. But there are definitely good reasons for allocating addresses that way, just as there are probably good reasons why the number of ports on a switch isn't always a power of 2.
- Control8894 2y ago
  Sometimes they might have been able to allocate it more compactly - but how do you predict exactly what your needs will be in 20 years? Other times they might not have been able to allocate it more compactly - are you really going to go make routes for a /25 and a /26 and a /27 when you need 200 IPs, just to save a single /27 over giving it the whole /24? There can also be reasons to structure it more sparsely than required for UX, namely to give a more hierarchical structure - maybe by region and store, or similar. tl;dr it's not necessarily a mistake that your allocations mean you use more space than strictly necessary
Symbiote 2y ago
If they will never upgrade then they can't use 240/4 either.

helf 2y ago

Sadly I'm in that position. I have hundreds of PLCs and legacy controllers on my network that are IPv4 only and will never be replaced. At least not in a reasonable time frame. I'm talking 20+ year life expectancies.

michaelt 2y ago

> 10.0.0.0/8 might seem like a lot of addresses, but certain large companies have enough fans and chillers and miscellaneous things that can fill that space Do these large companies really have 16,777,216 fans and chillers? That would be enough for each of Wal-Mart's 10,586 stores to have 1500 IPs each. Or do they just have legacy allocation mistakes?

omoikane 2y ago
> Do these large companies really have 16,777,216 fans and chillers? Some of those might be regular servers or networking gear that are required to have IPv4 addresses for one reason or another. For example, they might need to interact with fans and chillers. > legacy allocation mistakes Requiring the same globally unique prefix for devices that share locations or functions would eat up allocations faster than the number devices would grow. But there are definitely good reasons for allocating addresses that way, just as there are probably good reasons why the number of ports on a switch isn't always a power of 2.
Control8894 2y ago
Sometimes they might have been able to allocate it more compactly - but how do you predict exactly what your needs will be in 20 years? Other times they might not have been able to allocate it more compactly - are you really going to go make routes for a /25 and a /26 and a /27 when you need 200 IPs, just to save a single /27 over giving it the whole /24? There can also be reasons to structure it more sparsely than required for UX, namely to give a more hierarchical structure - maybe by region and store, or similar. tl;dr it's not necessarily a mistake that your allocations mean you use more space than strictly necessary

Symbiote 2y ago

If they will never upgrade then they can't use 240/4 either.