Exchange 2003 to 2010 migration without Front End

Hi.

I have a on Exchange Organization with the folow topolofy:

1 Exchange server 2003 BackEnd Server (EX1)

1 Exchange server 2003 BackEnd Server  (EX2)

Cluster name (EX2)

My organmization is without Exchange Front End servers.... because I have only one (cluster) of Exchange Back End server.

In this cenary I have necessary install a Front End server to upgrade to Exchange 2010?

Tks!