HP Labs Technical Reports

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Address-Swapping Scheme for On-Demand Assignment of Global Addresses in a TCP/IP Network

Cohen, Reuven



Abstract: The paper proposes a new scheme for on-demand allocation of global IP addresses to hosts of an autonomous network. Such a scheme is needed in order to overcome the problem of IP address exhaustion. According to the new scheme, each host of the autonomous network is assigned a fixed local address which appears in the source field of all the IP datagrams the host sends and in the destination field of all the IP datagrams it receives. A host that needs an IP-level connectivity with external hosts is allocated a global address for a limited time. Such a host continues using its fixed local address as the source field of every sent datagram. However, if the datagram is destined for an external host, the autonomous network border gateway swaps the fixed local address of the source with the leased global one. When a external host sends a datagram to a local host, it uses the global address of the local host as destination address. When the datagram enters the autonomous network, the leased global address is swapped by the fixed local one. As the paper shows, the proposed scheme that employs IP address swapping has several important advantages. Most of these advantages are due to the fact that the leased global addresses are not visible to the internal routing gateways, and that local hosts always use a single local address.

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