[ih] Some Questions over IPv4 Ownership

[Tony Finch]

On Thu, 14 Oct 2010, Ben Clifford wrote:
> Noel Chiappa <jnc at mercury.lcs.mit.edu> wrote:
> >
> > Pure serendipity. The basic mechanism used (the bit-mask) allowed
> > non-continguous masks as a natural consequence of the mechanism; we would
> > have had to specifically disallow them, and we didn't bother to. I seem to
> > recall we thought we'd leave them in, and see if people found some good use
> > for them.
>
> did anyone find a good use for them?

I played around with them a bit in about 1998 at Demon. The "homepages"
service had a /16 and two /18s for HTTP virtual hosts (the service
predated widespread support for the Host: header). These address ranges
were routed to a number of reverse proxy caches running Squid on FreeBSD,
which was patched so each one could accept connections to any of the 96K
IP addresses. (http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/12071)

Addresses were allocated from these networks sequentially, and the oldest
web sites tended to get the most traffic, so a straightforward setup that
spread the six /18s across the reverse proxies didn't balance the load
particularly well. I toyed with using 0xffff0003 netmasks to split the /16
so that successive addresses could be routed to each of the four London
reverse proxies in turn.

This worked in testing but I didn't deploy it because it broke my
colleagues' brains and non-contiguous netmasks were an unsupported
feature.

Tony.
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