From the network side its always the client (agent) that establishes connection to the server (service). Sometimes it is missleading where the service is, f.e. when talking about push/tickle an agent (there the agent has a tickle service listening).
Detailed information:
http://www.symantec.com/business/support/index?page=content&id=DOC1892
For Package Services its quiet easy.
Clients -> Package Server
Package Server -> Notification Server
For the Task Service, see the ports and protocols in the KB article.