Methods and systems are provided for facilitating intra-domain mobility. A first network or domain includes a home agent or SIP proxy of a mobile node. A second network includes two or more subnetworks and at least one mobility agent (MA). Each subnetwork includes an associated subnet agent. To communicate, the mobile node first registers with a subnet agent, receives a local care-of-address and a global care-of-address, and then registers with an MA. The mobile node may then provide the global care-of-address to the home agent. The local care-of-address may enable communication with the mobile node without determining a specific route to the mobile node. The global care-of-address received from the subnet agent may include the address of the MA. Accordingly, the mobile node may transition from any of the subnetworks to another subnetwork without communicating to the home agent information about the transition and without communicating to the MA information about a security association between the mobile node and the home agent.