In a CDMA2000 network, a mobile node (MN) gets packet data service by establishing a PPP session with a packet data serving node (PDSN). The PDSN acts as the muter for the IP packets transported over the PPP session. A packet control function (PCF) sits between the radio access network and the packet network, selects the PDSN for the MN during session setup, and relays the PPP frames between the MN and the PDSN during the session. The PCF selects a PDSN based on the MN's device identity. Due to this, the data services that a mobile user subscribes become tightly coupled with the device that the user registers with the service provider. Because the PCF selects a PDSN based only on mobile device identity, it is unable to select the "best" PDSN to support the services subscribed by a specific user. This work presents the design and implementation of an entity called radio-packet session redirector (RPSR) that works within the current standard and alleviates this shortcoming. The RPSR intercepts a PPP session, parses the user identity, selects a PDSN based on the user identity, creates a PPP session with the selected PDSN and splices the sessions together so that PPP frames can be seamlessly forwarded between the MN and the PDSN with very little overhead. We identify a number of services that RPSR enables in the network. We describe a prototype stand-alone device implementation of the RPSR in the Linux kernel and present performance results.
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