 Now we are going to look at the mobility in terms of service provisioning. It is also interesting to look at provisioning mobility management in terms of the service continuity. Service continuity actually means either to have allowance for interruption or have no interruption at all whenever handover or handoff takes place. It is usually defined in terms of connectivity or session or both. It means that the service has to continue whenever handover takes place or it would not continue. An example of providing service continuity is the handover known as the soft handover or the seamless handover. It is a complex process but it allows the service level agreement QoS parameters to remain consistent when a user moves from one network to the other. In this case, the session is kept intact. It means the endpoints of the socket, the IP addresses are not interrupted. Think about using mobile IP. The complexity of providing seamless handover and its cost in terms of the traffic overhead is not very small but the overall advantage is that the user would have a very comfortable experience. A relatively lower kind of handover known as sometimes hard handover or kind of a jittery handover is that service can continue but there would be some impact on the service quality The service quality can deteriorate depending upon the quality of the network in terms of bandwidth and other QoS parameters and the current load on the network. So it means the existing network and the network to which handover shall take place may have some discrepancy or inconsistency. Similar to service continuity, we can also think about service discontinuity. It means the service may not continue. It is disrupted at the handover. Obviously we are talking about higher layer connectivity that is a session being maintained. So when service discontinuity is allowed or the users opt for service discontinuity it actually means that the handover would entail the disconnection of the session. It may involve disconnection of the point of contact between the existing network, the mobile phone and the future network and the mobile phone. So when connectivity breaks or the session breaks or both breaks then the session has to be re-established end-to-end with the application server. An example of service discontinuity is being nomadic. The travelling people or the nomads actually change their location or the users change their point of attachment while moving such that whenever the terminal or the mobile phone moves from one network to the other the service comes to a complete stop. How the user is experiencing that is dependent upon if there is some management mechanism available at the application layer like buffering, jitter mitigation etc. But nonetheless, since service discontinuity is now being allowed by the user itself so when a user moves to a newer network it has to be established again with a new network point of contact and then nomadicity actually means that the user is frequently on the move but there is something known as portability. Portability actually means that the user moves from one place to the other and stays there for some significant amount of time. In that case, the network which the user or the mobile terminal leaves the address space there now becomes vacant so any new user that enters into the old network can take those addresses which means the addressing like IP addresses now can be allocated to different devices and the portable user when it moves into another network would now be assigned an address which is specific to the new network.