Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-10-26
2004-07-27
Patel, Ajit (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S475000
Reexamination Certificate
active
06768743
ABSTRACT:
FIELD OF INVENTION
This invention relates to computer networks. More specifically, it relates to a method and system for address server redirection for multiple network address networks.
BACKGROUND OF THE INVENTION
The Internet Protocol (“IP”) is an addressing protocol designed to facilitate the routing of traffic within a network or between networks. The Internet Protocol is used on many computer networks including the Internet, intranets and other networks. Current versions of Internet Protocol such as Internet Protocol version-4 (“IPv4”) are becoming obsolete because of limited address space. With a 32-bit address-field, it is possible to assign 2
32
different addresses, which is 4,294,967,296, or greater than 4 billion globally unique addresses.
However, with the explosive growth of the Internet and intranets, Internet Protocol addresses using a 32-bit address-field may soon be exhausted. Internet Protocol version-6 (“IPv6”) proposes the use of a 128-bit address-field for Internet Protocol addresses. However, a large number of legacy networks including a large number of Internet subnets will still be using older versions for Internet Protocol with a 32-bit address space for many years to come. As is known in the art, a subnet is smaller of part of a larger network using a similar network addressing scheme.
Network Address Translation (“NAT”) has been proposed to extend the lifetime of Internet Protocol version 4 by allowing subnets with private Internet Protocol addresses to exist behind a single or small number of globally unique Internet Protocol addresses (see e.g., Internet Engineering Task Force (“IETF”) RFC 2663, “IP Network Address Translator (“NAT”) Terminology and Considerations,” by P. Srisuresh and M. Holdrege, August 1999). Each private host uses a single global Internet Protocol address is used for communication with external networks such as the Internet.
As is known in the art, the Internet Engineering Task Force (“IETF”) has assigned three sets of private Internet Protocol addresses: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. The number after the “/” indicates a number of bits used as a private network identifier. For example, the “/8” indicates that the first eight bits are used as a private network identifier. A network address represented as “network address
-network bits” indicates that the first n-network bits represent a network identifier. The number of bits remaining represent the number of available host network addresses. For example, if a total of 32 bits are used for a network address (e.g., 32-bits for IPv4 addresses) and a “network address/8” notation is used, then 32−8=24 bits remain for host network addresses. In this example at most 224 host network addresses are available. Thus, the three sets of private Internet Protocol addresses: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 include at most 2
24
,
2
20
, and 2
16
addresses respectively. A private network may use any of these addresses without consulting any official Internet administrative entity.
Internally, a subnet may use local private addressing. Local private addressing may be any addressing scheme that is different from the public Internet Protocol addressing. The local addresses on a subnet are not available to the external, global Internet. When a device or node using local addressing desires to communicate with the external world, its local address is translated to a common external Internet Protocol address used for communication with an external network by a network address translation device. That is, network address translation allows one or more global Internet Protocol addresses to be shared among a larger number of network devices using local private addresses.
There are several problems associated with using network address translation to extend the life of the Internet Protocol. Network address translation interferes with the end-to-end routing principal of the Internet that recommends that packets flow end-to-end between network devices without changing the contents of any packet along a transmission route (see e.g., “Routing in the Internet,” by C. Huitema, Prentice Hall, 1995, ISBN 0-131-321-927).
Current versions of network address translation replace a local network address in a data packet header with an external global network address on outbound traffic, and replace an external global network address in a data packet header with a local private network address on inbound traffic. This type of address translation is computationally expensive, causes security problems by preventing certain types of encryption from being used, or breaks a number of existing applications in a network that cannot coexist with network address translation (e.g., File Transfer Protocol (“FTP”)).
Current versions of network address translation may not gracefully scale beyond a small subnet containing a few dozen nodes or devices because of the computational and other resources required. Network address translation potentially requires support for many different application layer internal network protocols be specifically programmed into a translation mechanism such as a network address translation router.
Computational burdens placed on a network address translation router may be significant and degrade network performance, especially if several network address translation-enabled sub-networks share the same network address translation router. In a worst case scenario, a network address translation router translates every inbound and outbound data packet.
Some of the problems associated with network address translation of private network addresses into public network addresses have been overcome with Distributed Network Address Translation (“DNAT”) described in co-pending applications Ser. No. 09/035,600, 09/270,967 and 09/271,025 assigned to the same Assignee as the present application. See also “Distributed Network Address Translation”, by Michael Borella, David Grabelsky, Ikhlaq Sidhu, and Brian Petry, IETF Internet Draft, <draft-borella-aatn-dnat-01.txt>, October 1998. Distributed Network Address Translation is also called “Realm Specific Internet Protocol” (“RSIP”) by the IETF. For more information on Realm Specific Internet Protocol see “Realm Specific IP Framework,” by M. Borella and J. Lo, IETF draft, <draft-ieft-nat-rsip-framework-02.txt>, October 1999, and “Realm Specific IP: Protocol Specification,” by M. Borella and J. Lo, IETF draft, <draft-ietf-nat-rsip-protocol-02.txt>, August 1999.
For the Distributed Network Address Translation methods described in the co-pending applications, network devices request a set of locally unique ports with a Distributed Network Address Translation Protocol called a “Port Allocation Protocol” (“PAP”) from a Distributed Network Address Translation server for external communications with a public network like the Internet. A network device on a private network replaces default or ephemeral ports (e.g., such as Transmission Control Protocol or User Datagram Protocol) with the locally unique ports. The network device uses a combination network address including a locally unique port and a common external network address (e.g., an IP address) for the Distributed Network Address Translation server for communications with the external networks. The network devices use private network addresses for local communications on the private network.
A Distributed Network Address Translation server maintains a port-to-private network address table as locally unique ports are allocated to network devices. Network devices send data packets to external networks using a combination network address including a locally unique port and the common external network address via the Distributed Network Address Translation server. For inbound data packets from an external network, the Distributed Network Address Translation server uses the port-to-private network address table to route data packets back to the appropriate network device on the private network.
It is becoming commonplace for private stub network or subnets to be “mu
Borella Michael S.
Grabelsky David
3Com Corporation
McDonnell & Boehnen Hulbert & Berghoff
Patel Ajit
Shah Chirag
LandOfFree
Method and system for address server redirection for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for address server redirection for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for address server redirection for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3230763