Method for network address translation

• US 6,006,272 A
• Filed: 02/23/1998
• Issued: 12/21/1999
• Est. Priority Date: 02/23/1998
• Status: Expired due to Term

• Current Assignee: WSOU Investments, LLC (WSOU Holdings, LLC)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Tzeng, Hong-Yi, Aravamudan, Murali
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): Najjar, Saleh
• Application Number:
  US09/027,708
• Time in Patent Office: 666 Days
• Field of Search: 709/220, 709/227, 709/228, 709/238, 709/245
• US Class Current: 709/245
• CPC Class Codes: H04L 2101/622 Layer-2 addresses, e.g. medium access control [MAC] addresses
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/2514 between local and global IP addresses
• CPC Class Codes: H04L 61/2517 using port numbers
• CPC Class Codes: H04L 61/2546 Arrangements for avoiding unnecessary translation
• CPC Class Codes: H04L 61/2596 Translation of addresses of the same type other than IP, e.g. translation from MAC to MAC addresses

Abstract

A method for translating non internet unique addresses of a home network device to an internet unique address for internet communication through a router. Every device within a given home network is assigned three addresses:(i) a configured address identical to the network address of the router enabling access to an Internet; (ii) a logical address visible only to the other devices in the same home network; and (iii) a medium access control ("MAC") address. Every packet originating from a home network source device includes its MAC address, the router MAC address, its configured address and the network destination address, and is forwarded to its destination through the router. The router examines the network destination address to determine whether the communication is intranet or internet. For intranet communications the router replaces the configured address of the home network source device with the logical address of the home network source device, the logical address of the home network destination device with the configured address, its MAC address with the MAC address of the home network destination device, and forwards the packet to the home network destination device. For Internet communications the router forwards the packet along the Internet without replacing any of the source or destination information in the headers of the packet. Based on the source MAC address, however, the router records the logical address of the home network source device as well as the DA, SP, DP and PT in order to identify a response to the packet from the Internet destination device.

Claims

1. In a data communications system comprising an internet and at least one home network, each of said home networks comprising a plurality of home network devices and having access to said internet through a router with an internet-unique network address, said system employing a method for network address translation of a packet having at least a network layer and a datalink layer, originating from one of said home network devices, said method comprising the following steps:

including in the network layer of said packet a configured logical address to represent the network layer source address of the source home network device, and a logical destination address, said configured logical address being common to each home network device with a common home network, and its router,

including in the datalink layer of said packet the MAC address of said router as the datalink layer destination address of the packet;

forwarding said packet from said source home network device to said router,

determining whether said packet is intended for a home network device;

if said packet is intended for a home network device, replacing said configured logical address at the network layer of said packet with the logical address of said source home network device, replacing said logical address of the destination home network device with said configured logical address, and replacing said router MAC address with the MAC address of the destination home network device;

if said packet is intended for an internet destination device, recording packet identifying information; and

forwarding said packet to its intended destination device.

2. In a system according to claim 1 wherein said packet identifying information includes the logical address of said source home network device, the network layer destination address, the datalink source and destination addresses and the protocol type specified in the packet.

3. In a system according to claim 1 further employing a method for MAC address resolution comprising the following steps:

forwarding all requests for address resolution of a second home network device from a requesting first home network device to said router; and

said router responding to said request for address resolution by forwarding to said first home network device the MAC address of said second home network device.

4. In a system according to claim 3 wherein said router is designed to intercept all gratuitous requests for address resolution originating from said home network.

5. In a system according to claim 1 further employing a method for MAC address resolution comprising the following steps:

forwarding all requests for address resolution of a second home network device from a requesting first home network device to said router; and

said router responding to said request for address resolution by forwarding to said first home network device the MAC address of said router.

6. In a system according to claim 5 wherein said router is designed to intercept all gratuitous requests for address resolution originating from said home network.

7. In a data communications system comprising an internet and at least one home network, each of said home networks comprising a plurality of home network devices and having access to said internet through a router with an internet-unique network address, said system employing a method for network address translation of a packet having at least a network layer and a datalink layer, originating from a source device on said internet, received at said router and intended for one of said home network devices, said method comprising the following steps:

determining whether the network layer of a first packet from said source device includes information that matches that of any packet previously transmitted from a home network device to said source device on said internet;

if said network layer of said first packet includes information that matches that of any packet having previously been transmitted from a home network device to said source device on said internet, then replacing the network layer destination address of said first packet with a configured logical address, said configured logical address being common to each home network device with a common home network, and its router and adding at said datalink layer the MAC address of said home network device as the datalink destination address;

if network layer information of said first packet matches an entry in a default service profile, then forwarding said first packet in accordance with said default service profile;

if said first packet includes a TCP or UDP protocol type, then broadcasting said first packet to all of said plurality of home network devices;

if any of said home network devices respond to said broadcast first packet, then forward subsequent packets with the same network layer information as said first packet, only to said responding home network devices; and

discarding all packets not forwardable by the foregoing steps.