We have a Config Man 2012 CU4 environment with 1 CAS, 1 Pri and some secondaries and quite a few DP's.
The issue is that when we sync Software updates it seems to trigger the clients to check in with the PRIMARY all at once with 40-60MB sync files for each machine all at once. This times 1000's of machines kills the bandwidth of the network as everything is hitting the Primary.
We have looked around to try and determine why and what causes this with little luck. This just started happening in the last couple months.