Subnetting Practices

[Seth Mattinen]

Gert Doering wrote:
> Hi,
> 
> On Sat, Jul 14, 2007 at 11:16:56AM -0700, Seth Mattinen wrote:
>> I'm inclined to use something *way* smaller (like a /126 since /127's 
>> are bad) for router links. I thought the push behind IPv6 was because 
>> we're running out of v4 space, and I see standard practice blowing a /64 
>> on a link that'll never have more than 2 devices on it. Lots of stuff I 
>> read encourages seemingly wasteful practices in v6 space as a good thing 
>> and it confuses me.
> 
> Please try to get rid of your IPv4 mindset, and do a bit of math:
> 
> If each "end site" gets a /48, this leaves about 1000 /48s for each
> possible inhabitant of the planet, out of FP001 (the first 8th of the
> address space).  So this is something not overly wasteful.
> 
> Inside that /48, each end site has over 65.000 subnets.
> 

I can do math, thanks, which is why I realize how large a /64 really is 
and was asking why that is the accepted practice. Back in the day 
someone's dog could get a /8 or /16 because there was so much space to 
spare. Same thing, different century.

~Seth