The structure of the control architecture

Figure: Structure of the control architecture

The structure finally decided is as follows (shown in figure ):

• The core of the agent is basically a parser. It is given an RSVP message. It processes it (which means that it checks the current state and decides what has to be done), updates the state and then forwards the packet to the next/previous hop.

• In order to make decisions, the parser needs to get routing information. It therefore needs a routing interface querying the routing tables.

• The states are more or less independent from the core of the program: the parser just reads information in the different states, and can modify them by adding, modifying or deleting entries. Therefore, a separate structure for the RSVP state (path, reservation and blockade states) was to my mind the cleanest solution. It would also be handling the traffic control state.

• As RSVP has a ``soft'' state, there are timers indicating the expiration of each entry. A separate module has been introduced to handle the time-outs: the time-out handler.

So far, we have everything to make the RSVP process work. We just need to add communication modules in order to receive and send RSVP messages and to manage the switch.

• The RSVP process needs to receive RSVP packets from the switch, and to send back the forwarded messages to it. This is achieved using the switch interface.

• Finally, traffic control is responsible for recording reservations. Therefore, it will be the interface with the switch's Ariel interface.