A distributed software defined network, SDN, packet core system comprising: a plurality of interconnected local SDN infrastructure instances, each local SDN infrastructure instance corresponding to a respective local mobility domain, LMD, and including a plurality of processors arranged geographically in proximity, and communicatively coupled, to a respective plurality of radio access technology, RAT, specific access points, the processors for each local SDN infrastructure instance being configured to execute: a plurality of RAT-specific front-end modules associated with two or more RATs, each RAT-specific front-end module being configured to handle intra-RAT and intra-LMD mobility events that involve switching connectivity of client devices between two radio access points coupled to the local SDN infrastructure instance and associated with a first common RAT that is also associated with that RAT-specific front-end module; and a mobility manager coupled to the front-end modules and configured to: handle intra-RAT and inter-LMD mobility events that involve switching connectivity of client devices between two radio access points coupled to separate local SDN infrastructure instances and associated with a second common RAT; maintain a data structure that includes for each client device attached to the distributed SDN packet core system a binding between an Internet protocol, IP, address of the client device and an IP address of a front-end module serving the client device, and handle inter-RAT and intra-LMD mobility events that includes: receiving, by the mobility manager from a SDN mobility controller of the local SDN infrastructure instance, a request to update its data structure responsive to a handover request associated with the client device; and updating the data structure by changing a first IP address of a first RAT-specific front-end module previously serving the client device with a second IP address of a second RAT-specific front-end module, the first and second RAT-specific front-end modules located in a single LMD and are associated with different RATs. a plurality of RAT-specific front-end modules associated with two or more RATs, each RAT-specific front-end module being configured to handle intra-RAT and intra-LMD mobility events that involve switching connectivity of client devices between two radio access points coupled to the local SDN infrastructure instance and associated with a first common RAT that is also associated with that RAT-specific front-end module; and a mobility manager coupled to the front-end modules and configured to: handle intra-RAT and inter-LMD mobility events that involve switching connectivity of client devices between two radio access points coupled to separate local SDN infrastructure instances and associated with a second common RAT; maintain a data structure that includes for each client device attached to the distributed SDN packet core system a binding between an Internet protocol, IP, address of the client device and an IP address of a front-end module serving the client device, and handle inter-RAT and intra-LMD mobility events that includes: receiving, by the mobility manager from a SDN mobility controller of the local SDN infrastructure instance, a request to update its data structure responsive to a handover request associated with the client device; and updating the data structure by changing a first IP address of a first RAT-specific front-end module previously serving the client device with a second IP address of a second RAT-specific front-end module, the first and second RAT-specific front-end modules located in a single LMD and are associated with different RATs. handle intra-RAT and inter-LMD mobility events that involve switching connectivity of client devices between two radio access points coupled to separate local SDN infrastructure instances and associated with a second common RAT; maintain a data structure that includes for each client device attached to the distributed SDN packet core system a binding between an Internet protocol, IP, address of the client device and an IP address of a front-end module serving the client device, and handle inter-RAT and intra-LMD mobility events that includes: receiving, by the mobility manager from a SDN mobility controller of the local SDN infrastructure instance, a request to update its data structure responsive to a handover request associated with the client device; and updating the data structure by changing a first IP address of a first RAT-specific front-end module previously serving the client device with a second IP address of a second RAT-specific front-end module, the first and second RAT-specific front-end modules located in a single LMD and are associated with different RATs. receiving, by the mobility manager from a SDN mobility controller of the local SDN infrastructure instance, a request to update its data structure responsive to a handover request associated with the client device; and updating the data structure by changing a first IP address of a first RAT-specific front-end module previously serving the client device with a second IP address of a second RAT-specific front-end module, the first and second RAT-specific front-end modules located in a single LMD and are associated with different RATs.