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Next: 4.2.3 Avoiding Congestion Up: 4.2 Analysis of the Previous: 4.2.1 Avoiding Call Blocking

4.2.2 Ensuring Accurate Bandwidth Reservation

Figure 3: Ensure Accurate Bandwidth Reservation

In section 4.1, only the case of too little allocated bandwidth was considered, as only this case would lead to cell losses for a connection. However, to ensure the correct amount of allocated bandwidth for a connection, we need to consider both cases, i.e. too little and too much allocated bandwidth. So for completeness, the 'too-much' case was added in Figure 3. For the discussion of this branch please refer to section 4.2.1.

The allocation of too little bandwidth is indicated by a raise of the 'policing counters'. The policing counters available for a connection vary according to the equipment used. For simplicity, they are considered here to be counter for 'discarded cells'.

One has to find a value for the amount of discarded cells, that indicates problems on this connection. It would be reasonable to set the action value in relation to the amount of cells transported with this connection. As this is not possible, we again have to try to find a good approach in using a relationship to usually transported cells on a connection of a particular link. The action to perform when this value is exceeded is to inform the user and to allocate more bandwidth to this connection, i.e. again perform a renegotiation.

The control part of the searched, self-regulating system, as depicted in Figure 1, is used to adjust the selected relationship. This means that it has to validate that the discarding of cells is transparent to the user until the system 'acts', in particular, the control has to be performed manually after a user told that she has some problems.

Anja Schuhknecht
Wed May 31 09:56:07 MET DST 1995