Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1997-12-01
2001-06-05
Nguyen, Chau (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
Reexamination Certificate
active
06243383
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to address resolution in an asynchronous transfer mode (ATM) communications network. When deploying ATM networks, network providers must deal with the recent proliferation of ATM address types and formats. A network provider has to decide on the type of ATM address to be deployed in its own network, under the influence of administrative, technical, and other factors. For example, ATM End System Addresses (AESAs) may be deployed in some private and public networks because of the difficulty in obtaining native E.164 addresses. For some of the public carriers, native E.164 addresses may be chosen since they already own them. The notion of “public” and “private” is blurred in ATM networks—even so-called “public” ATM networks have segregated address domains that are very different from the traditional telephony public network.
In addition to the different administrative aspects, various addresses are also involved directly with a variety of signaling protocols and routing algorithms. For example, the ATM Forum Private Network-Network Interface (P-NNI) routing protocol runs on the structure of 20 bytes AESA, whereas Broadband ISDN User's Part (B-ISUP) signaling was originally based on native E.164.
One approach to the problem of address resolution has been to use only native E.164 address in public ATM networks, assuming that every public network can route on native E.164. As for connections between public networks and private networks, private networks translate the Network Service Access Point (NSAP) formatted address into a native E.164 address for the public network to route on. Some public networks, however, use NSAP addresses instead of native E.164 addresses. Further, this approach cannot handle number portability issues, and does not provide the internal/external address separation for public carriers. Another approach—resolution based on interface type—is also limited since different network providers may opt for different interfaces and signaling messages to connect networks. These limitations render the prior approaches to address resolution unacceptable.
It is desirable, therefore, to provide an end-to-end address resolution scheme sensitive to the related signaling and routing protocols involved in order to set up connections across different ATM network addressing domains. As yet, no ATM standards provide a complete mechanism adequate for address planning and interworking, which is imperative for ATM networks to scale and interconnect.
It is also desirable to provide a generic end-to-end address resolution scheme applicable to all signaling protocols (e.g., ATM Forum v. ITU-T standards, DSS2 (Digital Signal System #2)-based v. B-ISUP-based protocols) at all different types of ATM standard interfaces to achieve complete ATM network interconnection. It would also be desirable for such a generic scheme to allow ATM switches to handle address interworking without changing the control software for every specific application or interface, for example where one network uses ATM Forum P-NNI and another uses ITU-T B-ISUP.
SUMMARY OF THE INVENTION
This invention satisfies those desires by providing a generic methodology for end-to-end ATM address resolution applicable to all signaling protocols.
A method consistent with the present invention for use with a network comprises the steps of translating the destination address into a local address on which the first network can route the call, repacking the signaling message with the local address as the routing address, routing the call through the first network using the local address, repacking the signaling message with the destination address as the routing address, and forwarding the call to the second network for routing toward the destination address. The method further comprises the step of carrying the destination address across the first network transparently. The method further provides the step of carrying a second destination address across the first network transparently, supporting a bi-level address scheme which includes a network-level and a user-level destination address.
Apparatus and networks are also provided for carrying out the methods consistent with the present invention.
The advantages accruing to the present invention are numerous. The inventive address resolution scheme can be adopted by the signaling protocols for all ATM interface types, such as User-Network Interface (UNI), Interim Interswitch Signaling Protocol (IISP), P-NNI and Q.2931/2971 based on DSS2 protocols and B-ISUP/B-ISDN Inter-Carrier Interface (B-ICI) based on SS7 protocols. Because the scheme is generic, network providers can choose to either maintain their existing configurations without having to reconfigure the network with different ATM interfaces or to change addressing formats in order to resolve the address interworking issues. Network providers can always maintain their internal address format and address scheme independent of the external environment. Further, the address resolution scheme is backward compatible with existing ATM address interworking standards, and can interwork with all switching equipment that supports the existing addressing guidelines. Consequently, the procedures for software upgrade are simplified for the existing ATM networks. Additionally, routing efficiency is improved by minimizing the size of the topology database or routing table when the address space is segmented (i.e., scattered across different network boundaries). Also, the scheme requires no end-to-end agreement on the use of bi-level addressing. Lastly, the scheme allows ATM Name Service (ANS) to be adopted by ATM switches to support name resolution and number portability requirements.
The above desires, other desires, features, and advantages of the present invention will be readily appreciated by one of ordinary skill in the art from the following detailed description of the preferred implementations when taken in connection with the accompanying drawings.
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Li Li
Mistry Nalin
Morris Todd Douglas
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Hyun Soon-Dong
Nguyen Chau
Nortel Networks Limited
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