An organization with dozens of LCS 2005 servers and hundreds of
users will likely perform a phased migration.
Upgrading Perimeter Servers
Migrating from LCS 2005 to OCS 2007 is an ???outside-in??? process, meaning that servers on
the perimeter are migrated fi rst, then intermediary servers are migrated, then front-end servers,
and fi nally user client software. Servers are fully backward-compatible, so perimeter and
intermediary servers can be migrated early and will allow existing LCS 2005 servers to interoperate
and communicate with the new servers. This drastically minimizes the downtime for clients,
as servers can be upgraded without impacting user communications.
Upgrading to Office Communications Server 2007 ??? Chapter 11 341
With this in mind, fi rst we are going to migrate the access proxy servers in LCS 2005
that will be replaced by OCS 2007 edge servers. Because migration from LCS 2005 to
OCS 2007 is a side-by-side process, a new OCS 2007 edge server is added to the network
fi rst, properly confi gured to routing information in and out of the network environment.
Once the system is working properly, the fi nal switchover of communications is done to
the edge server.
Preparing DNS
Because all OCS 2007 servers use the domain name system (DNS) to fi nd and communicate
with other servers, the fi rst step in upgrading perimeter servers is to make sure DNS is set up
and confi gured properly to support the new OCS 2007 edge server system. You need to
confi gure three groupings of DNS settings:
?– Set internal DNS so that LCS 2005 director and front-end servers can route outbound
messages through the new OCS 2007 edge server.
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