Announcing a /19 from a /16

Mon Jul 5 20:02:14 UTC 2004

Hi-

I'm working on a project within a large corporation and asked their network
folks about getting a /19 from one of their /16s.  I wanted it to avoid NAT
and any possible overlapping from using RFC1918 addresses.  This project
gets connected to the internet at different times throughout the year at
different locations through different ISPs.  I would announce the /19 for a
short period of time, maybe a month or so.

The response I got back was that this was impossible since ISPs require an
announcement of the /16 the /19 would come from.  I have done work with ISPs
before (and have read the NANOG list for many years) but haven't heard of
such a requirement nor can I find any standards that indicate the same
thing.

Does anyone have requirements of a /19 announcement requires the /16 to be
there as well?  The company has plenty of /16s that it uses internally that
are not being announced on the Internet at all.

Thanks-

-Eric