How to use proxy server as part of Exchange 2013 and Avamar 7.1.101-145

I've been tasked with setting up Avamar backups for an Exchange 2013 DAG.  I'm currently in the planning stage.

I read "EMC Avamar 7.1 for Exchange VSS User Guide".  On page 21 of the guide it says, "The recommended configuration for GLR in most environments is to use a proxy server".

1. Is the proxy server supposed to be part of the DAG?
2. If the proxy server is not supposed to be part of the DAG, is it supposed to have Exchange databases?

Thanks!