Problem statement for distributed and dynamic mobility management
Mobility solutions deployed with centralized mobility anchoring in existing hierarchical mobile networks are more prone to the following problems or limitations compared with distributed and dynamic mobility management: (1) Routing via a centralized anchor is often longer, so that those mobility protocol deployments that lack optimization extensions results in non-optimal routes, affecting performance; whereas routing optimization may be an integral part of a distributed design. (2) As mobile network becomes more flattened centralized mobility management can become more non-optimal, especially as the content servers in a content delivery network (CDN) are moving closer to the access network; in contrast, distributed mobility management can support both hierarchical network and more flattened network as it also supports CDN networks. (3) Centralized route maintenance and context maintenance for a large number of mobile hosts is more difficult to scale. (4) Scalability may worsen when lacking mechanism to distinguish whether there are real need for mobility support; dynamic mobility management, i.e., to selectively provide mobility support, is needed and may be better implemented with distributed mobility management. (5) Deployment is complicated with numerous variants and extensions of mobile IP; these variants and extensions may be better integrated in a distributed and dynamic design which can selectively adapt to the needs. (6) Excessive signaling overhead should be avoided when end nodes are able to communicate end-to-end; capability to selectively turn off signaling that are not needed by the end hosts will reduce the handover delay. (7) Centralized approach is generally more vulnerable to a single point of failure and attack often requiring duplication and backups, whereas a distributed approach intrinsically mitigates the problem to a local network so that the needed protection can be simpler.