hich are used to take traces in their respective interfaces. The Gb and Iu-PS protocol analysers are essentially more complex, since they are decoding protocols such as BSSGP and RANAP, which are far more complex, cryptical and also efficient than the IP based protocols, which can be easily visualised in powerful tools, even available as freeware. The processes of troubleshooting that are used in optimisation normally focus on the following: Verify normal execution of the standard procedures, which is especially important in multivendor environments with poor interoperability verifications. Analyse the consistency and integrity of the packets, according to the expected behaviour based on the protocol characteristics. Issues such as fragmentation, packet losses, packets out of order and jitter at the IP level can be observed using tracing tools. After this type of analysis, it is sometimes possible to find some abnormal or suboptimal issues, which can be corrected through a normal process of implementing change requests for the originating parameters, if those are clearly identified. The worst-case scenario is when no abnormal behaviour is detected, and specific test cases should be defined in order to repeat an observed problem that appears randomly. This might be a cumbersome exercise in some cases, well beyond the scope of a normal optimisation exercise. 4.15 Security In recent times security has become one of the biggest concerns for most mobile operators. Most of the threats are essentially similar to those known to have existed for a long time in a normal service provider environment. However, it might be useful to review some basics of security, from the optimisation point of view. 4.15.1 Planning for Security During the planning phase, all traditional network security procedures should be a design constant and a major concern at this stage, where all the possibilities are still open. Most of the application servers can be protected by implementing appropriate firewall solutions, generally part of the desig