Hi,
Thank you for posting in Symantec community.
I would be glad to answer your query.
To give proper solution we need more info from your side.
1) Total number of SEPM's & version details
2) Total number of remote sites if any, clients per site.
3) Bandwidth available between central server and remote sites.
4) Is there any GUP configured?.
5) Will be there any future expansion?
6) What's the existing network design issue?
Till the time refer this article:
Top 10 Symantec Best Practices - Deploying Symantec Endpoint Protection Architecture
http://www.symantec.com/business/support/index?page=content&id=TECH92051&locale=en_US