RE: Announcing a /19 from a /16

> 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.

Maybe one of the (fairly rare, from what I see) actors that
ingress filter
(or takes into account those small few that does) by




? (What
prefixes are yopu talking about?)