8.1 Constraints

This section describes how the constraints presented in the SRS are addressed in the design.

8.1.1 Performance Constraints

The only performance constraints in the project concern the running of FCM. While it's impossible to design for a precise performance criteria, it is possible to have a design which is close to optimal. This is how the design caters for the performance constraints [SRS Reference 4.2.1]:

• Clearing of the global hash table in the Receiver module will be performed only once every $n$ packets, where $n$ will be determined empirically. This choice can be made, because the connections will not change for every packet, since at most one connection can be added or removed for every packet.
• The checksum will not be checked and recalculated for every packet which passes through the modules. Instead, any changes made will have the corresponding change made to the checksum.
• Testing will be performed to ensure the product meets the performance targets. If it does not, further optimisations will be made, or if it proves impossible, the targets may have to be renegotiated.

8.1.2 Design and Implementation Constraints

The design of FCM:

• Contains two modules which are to be implemented as standard Linux kernel modules [SRS Reference: 4.2.2.1]
• Will require no modification to existing Linux kernel code; that is, the two FCM kernel modules are designed to be stand-alone modules [SRS Reference 4.2.2.2]
• Uses the Client's window sizing algorithm on the Receiver [SRS Reference 4.2.2.3]
• Will be able to be implemented using the C programming language, but is not language specific [SRS Reference 4.2.2.4]

The design of SAM:

• Is written to be implemented using the language Python, which may easily be installed under Debian 3.0 (woody) [SRS Reference 4.2.2.5]
• When implemented in Python, will be able to be made into a Debian package, which will include all source code of SAM, and also any extra necessary packages to run SAM [SRS Reference 4.2.2.6, 4.2.2.7]

8.1.3 Hardware Constraints

The design of RAMI is created under the assumptions that the user has a processor capable of running the Linux kernel 2.4.18, and which also has access to a network. During implementation, a processor with the Linux kernel 2.4.18 which has access to a network will be used. [SRS Reference 4.2.3]