Please let me know the what are the problem / issue can cause by SEP client on machine. suppose i am deploying the SEP agents then what are problem faced duting implemenation aother than Firewall issue. What firewall things needs to be taken care to smooth service.

ideally it should not cause any issues.

you can consider create exclusions for your necessary programs. and known issues for client failure

Troubleshooting client installation failures

 http://www.symantec.com/business/support/index?page=content&id=TECH94258

creating exceptions

Troubleshooting client installation failures

The default policy *should* contain the necessary rules to allow your network traffic to flow smoothly. Some times you may run into problems where traffic from an app over a random port is being blocked. In which case you will need to monitor the logs to determine what rule(s) should be created to allow the traffic.

Have a look at some of the best practices:

Best Practices for using Windows Firewall with Symantec Endpoint Protection 12.1
http://www.symantec.com/docs/TECH196975

Best Practices for Deploying Symantec Endpoint Protection's Application and Device Control Policies
http://www.symantec.com/docs/TECH181679