Subnetting Practices

[Gert Doering]

Hi,

On Sun, Jul 15, 2007 at 08:01:12AM -0700, Roland Dobbins wrote:
> On Jul 14, 2007, at 2:45 PM, Gert Doering wrote:
> 
> >And indeed, router vendors need to do a bit of homework to avoid being
> >an "easy target" DoS due to sequential IPv6 address scanning - but  
> >then,
> >they would need this for a network size of a /112 as well (still room
> >for 65.000 hosts, and potential ARP/ND requests).
> 
> I don't know that it's a problem of 'homework' - it's more a matter  
> of, 'don't use an addressing scheme which turns your router into a  
> sinkhole'.  Nor is this particular concern tied to sequential  
> scanning, per se.

There is no addressing scheme (today) that will *not* have unused addresses
in on-link networks, while permitting network growth at the same time.

The specific amount of unused addresses doesn't really matter - if it's
"so many addresses that network administators do not need to worry about
network size" it's large enough that a simplistic implementation will run
into problems.  And then it doesn't matter whether you have 2^10 or
2^64 unused addresses on the link.

Gert Doering
        -- NetMaster
-- 
Total number of prefixes smaller than registry allocations:  113403

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