You can configure this for the SEPM (server) under
Admin > Servers > Local Site > Edit Site Properties > LiveUpdate
There are two important settings for you:
- Download schedule (default: 4 hours). As Symantec is sending about 3 definition packages per day, this is a reasonable setting in most cases.
- Disk Space Management for Downloads (default setting depends on size of your environment). That's the number of the saved definition packages ("content") on the SEPM. SEPM needs these packages to create incremental small delta packages that saves much bandwidth. For instance, to cover a week you should save 21 (3 * 7) packages. If the number of the packages is small (e.g., 3), many clients will download the full definition package (~ 200 MB) instead of delta files (which can be smaller than 1 MB). That's a common reason for overstrained networks. However, 21 packages will take about 25 GB of disk space. But 3 packages aren't even covering a weekend.
The schedule for clients in the LiveUpdate policy (Clients > [Group] > Policies > LU > Schedule) only affects clients updating from external (internet) or internal (LiveUpdate Administrator) sources but it's not relevant if the clients get their content from their SEPMs.
After a SEPM has updated itself, the clients will automatically get the new definitions the next time they check in. This is controlled by communication settings (push/pull mode, heartbeat interval). See this article:
Configuring push mode or pull mode to update client policies and content
http://www.symantec.com/docs/HOWTO55197