Methods of Recording actual clock events into SAP R/3

Dear Experts,

My client wish to implement any one of the following mechanisms to capture actual clock events of employees  and want to transfer actual clock events into SAP R/3.

1. 1. Access Card
2. 2. Domain Login
3. 3. MAC id

I would like to know the following details in this regard.

1. How Domain Login and MAC id would work and it’s functionality?
2. How can we transfer clock events data from Domain Login and MAC id to into time events (IT 2011)

Incase if top management do not approve to use none of Access Card, Domain Login and MAC id,they want to use ESS/MSS to enter working times. If client use ESS/MSS alone to enter daily attendances, then I can implement negative time management.

It is also mentioned by the client that they want to use any one of 3 mechanisms mentioned above along with ESS to enter daily attendance of employees. In this regard, I want to clarify the following queries.

What are the challenges that I would come across as a time consultant if we use any one of 3 mechanisms mentioned above along with ESS to enter daily attendance of employees.

How SAP system knows which data should be processed in time evaluation and what are the configuration settings need to be done.

I have already mentioned client that they should

1. Use ESS/MSS for any attendance types and leave management
2. Use any one of 3(1.access card 2.domain login and 3.MAC id to capture actual attendances.

but they want to use even daily attendances in ESS/MSS.If this is the case,how daily attendances will be transferred to IT 2011.

I would really need help from sap time experts.I hope you would throw some light on this.

With regards

SAP HR Professional