Patent ID: 8072973

Claim:
A method of operating a service gateway, comprising: maintaining a plurality of forwarding components, each forwarding component being operative to provide forwarding of data packets within a corresponding one of a plurality of virtual private networks (VPNs) accessible via the service gateway; maintaining respective subscriber sessions for a plurality of subscribers coupled to the service gateway via respective subscriber interfaces, each subscriber session involving the forwarding of data packets between a corresponding subscriber and a corresponding VPN by action of a corresponding forwarding component, the association between the subscribers and the forwarding components being independent of the subscriber interfaces such that the respective subscriber sessions of those subscribers reachable via a given interface are associable with respective different ones of the forwarding components; and upon detecting an event indicating that a subscriber session is to be transferred from a first VPN to a second VPN, (1) modifying the respective forwarding components of the first and second VPNs to reflect that the subscriber session is active in the second VPN and is not active in the first VPN, and (2) effecting a change of a network address identifying the corresponding subscriber from a first network address defined in the first VPN to a second network address defined in the second VPN, wherein effecting the change of the network address comprises exercising a mechanism for dynamically causing the subscriber whose session is to be transferred to change the network address the subscriber utilizes in data communications packets to the second network address, and wherein the subscriber session is an IP session initially associated with the first network address, the first network address having been provided by a preceding dynamic host control protocol (DHCP) process, and wherein effecting the change of the network address comprises (1) rejecting a DHCP renewal request from the subscriber attempting to renew a lease on the first network address, and (2) responding to a subsequent DHCP discovery request from the subscriber by providing the second network address to the subscriber for subsequent use in the data packets exchanged between the subscriber and the second VPN.