Comment on Is the bitwise AND of subnet masks and IP addresses redundant?

• DmMacniel@feddit.org ⁨1⁩ ⁨week⁩ ago

  but rather a raw binary sequence, e.g., the first 24 bits of an IP address, therefore allocating 3 bytes of memory for storing the NID.

  That would require dynamic memory allocation, since you can never know what CIDR your stack encounters. It could be a nibble, a byte, a byte and a nibble, …, 4 bytes. So you would allocate a int32/int64 anyway to be on the safe side.

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  • ricdeh@lemmy.world ⁨1⁩ ⁨week⁩ ago

    Yep, I agree. Though one could make a hypothetical argument for expanding the array dynamically when needed. Of course, due to the varying sizes of NIDs resulting from CIDR (which you correctly mentioned), you would need to have a second array that can store the length of each NID, with 5 bits per element, leaving you with 3 bits “saved” per IP address.

    That can end up wasting more memory than the 32-bit per NID approach, e.g., when the host identifier is smaller than 5 bits. And there’s the slowness of memory allocation and copying from one array to another that comes on-top of that.

    I think that it is theoretically possible to deploy a NID-extracting and tracking program that is a tiny bit more memory efficient than the 32-bit implementation, but would probably come at a performance overhead and depend on you knowing the range of your expected IP addresses really well. So, not useful at all, lol

    Anyway, thanks for your contributions.

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    • DmMacniel@feddit.org ⁨1⁩ ⁨week⁩ ago

      sure thing buddy, and never feel discouraged to ask “stupid questions”, it’s how we learn after all :)

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