“Deep dive into rich coexistence between Exchange Forests”: that’s a new
multi-part article written by Henrik Walter in msexchange.org.
He covers “how rich coexistence is configured between 3 separate
Exchange forests with different versions of Exchange deployed”.
As reason for a coexistence he describes: “… One reason could be
that company policies states that specific entities within a company
must run isolated from the other entities. This is typically because of
legal requirements. It could also be because of a merger or acquisition,
where one company purchased another company or several other companies.
The companies could continue to run isolated or be consolidated into
one large Active Directory forest….”
As basic conditions Walter assumes “. . . an infrastructure using DNS
name resolution between each forest as well as an established trust
relationships between them…”
We experience that a lot of companies do not want or are not allowed
to establish a trust relationsship. To publish the own internal DNS
structure is mostly also forbidden.
So we developed a smart software to overcome these limitations: with
NETsec GALsync you can share directory information and free/busy between
different forests using different Exchange versions. You do not need a
trust or a “shared” DNS.