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Comment by agwa | Hacker News Reader

> It'd be nice if they gave out a proper prefix delegation. Instead the best I can get allocated is a /60. Pretty sure the RFC recommends /48's to be allocated to customers.

Out of curiosity, what's your use case for more than 16 subnets? I agree on principle they should give you a /48 if you ask for it, but the truth is that I'm extremely grateful they rethought their original stance, which was that a measly /64 was enough for anyone! That would have been extremely harmful and short-sighted; I feel pretty comfortable with a /60.

On that note, does anyone know what Time Warner's maximum prefix delegation size is?

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I have several subnets (WiFi, LAN, virtual machines, guest WiFi, etc). I don't just bridge WiFi and LAN together like most, I prefer more control.

I'll fine with 16 subnets today, but I don't know what'll change in the future. I'm sure I'll have use cases for more.

I can see use for maybe about 4, not sure about more, but if I recall correctly the privacy extensions require a /48 don't they?

No, the privacy extensions simply use a random interface ID instead of deriving it from the MAC address. You still use a single /64 subnet as usual.

(Unless there is an aspect of the privacy extensions I'm not familiar with, but this is what people usually mean when they say "privacy extensions.")

As far as I know the privacy extensions only cycle through the host portion of the address (lower 64 bits) so they should work fine with just a /64. Access to a bigger prefix may help you get around systems that do IP banning in /64 chunks though.

I have been perfectly happy with my /64 for many years. I can't imagine needing multiple subnets for home or small office use.

I think the most compelling use case is a separate guest network (which is firewalled from your normal network; some wireless access points tout this as a feature). Power users might also run a VPN and allocate a subnet to VPN clients. There are also home automation standards that put all your devices on a separate subnet.

I think the single most compelling use case is to segment WiFi and Ethernet traffic. No point in broadcasting useless Ethernet ARPs to the WiFi network when bridged for example.

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