Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-09-01
2004-12-14
Nguyen, Chau (Department: 2667)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S395540
Reexamination Certificate
active
06831918
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ATM transmission system which utilizes an inter-cluster multicast protocol (ILMP), a method for the simultaneous transmission (i.e. multicasting) of IP data packets using ATM as a carrier network, and a telecommunication system including the ATM transmission system of the present invention.
2. Discussion of the Background
In multicasting, one message is simultaneously transmitted to a number of receivers, i.e. transmitted at the same time to a number of users of a multicasting service. With a multicasting service, use of the network's resources may be optimized by copying the multicast messages in the net rather than at the user terminals. Many of the existing services, offered by network operators, could have been implemented, in a more effective manner, if support for multicasting had been available for use with such services. In future, many multimedia applications will be dependent on a multicasting service. Some examples of multimedia applications, which could be more effectively implemented with the aide of a multicasting service, are as follows:
exchange of information in real time;
video conferences;
distance working, for example, working at a location remote from a central office, company premises, administration center, etc.; and
video games.
IP (Internet Protocol) networks, in which ATM (Asynchronous Transfer Mode) is used as a carrier network, do not have support for multicasting. Known existing solutions, for example, MARS (Multicast Address Resolution Service), work for a limited number of users, i.e. about 255 users.
The Internet Engineering Task Force (IETF) have published a Request for Comment (RFC), namely, RFC 2022, which specifies a method that provides multicast support for IP end-systems, or routers, over an ATM network. However, the RFC 2022 (MARS) solution is restricted to intra-LIS communication.
In Telia's IP/ATM network, known as Broadway, multicasting can be provided using the MARS protocol. However, such a solution does not scale since any multicasting protocol has to deal with both intra-LIS and inter-LIS multicasting.
There is, therefore, at the present time, a distinct lack of established methods for inter-LIS multicasting for use in IP/ATM telecommunication systems.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an ATM transmission system in which multicasting between clusters utilizes inter-cluster multicasting protocols, and in which multicasting within a cluster utilizes MARS. A cluster is a collection of hosts and routers belonging to the same domain. The use of an inter-cluster multicasting protocol (ILMP) makes it possible to provide a multicast service to a much larger number of users, i.e. up to 65,000 users, than is possible using present day solutions, for example, MARS which is, in essence, limited to one LIS and about 255 users.
It is another object of the present invention to provide a method for the simultaneous transmission (i.e. multicasting) of IP data packets, using ATM as a carrier network.
It is a further object of the present invention to provide a telecommunication system including the ATM transmission system of the present invention, or operating in accordance with the method of the present invention.
According to one aspect of the present invention, there is provided, an ATM transmission system, adapted for the simultaneous transmission (i.e. multicasting) of IP data packets to a plurality of system users, using ATM as a carrier network, characterised in that said transmission system includes an IP/ATM network including clusters of Logical IP Systems (LISs); a multicast address resolution server (MARS) for each cluster; and a multicast router (MCR) for each cluster, in that said clusters are interconnected through said MCRs which form an inter-cluster backbone for said IP/ATM network, in that multicasting of IP data packets within a cluster utilizes a MARS protocol, and in that multicasting between clusters utilizes an inter-cluster multicasting protocol (ILMP). The ATM transmission system may include means for gaining access to the Internet. Said means for gaining access to the Internet may include a non-ATM IP Subnet connected to said inter-cluster backbone. One of said MCRs may be adapted for use as an entry point for the IP/ATM network to the Internet.
Each cluster may consist of an integral number of ATM hosts and LISs, the size of a cluster being dependent on physical and administrative constraints, each LIS, within a cluster, may be adapted to support a number of ATM hosts, and all ATM hosts within a cluster, even if supported by different LISs, may be adapted to be configured with an address of the same MARS. For each cluster, the functionality of MARS and MCR may be adapted to be co-located.
In the presence of multiple MCRs belonging to the same cluster, said IP/ATM network may be adapted to select a MCR with the highest IP address as a default MCR.
MARS may be adapted to operate in server mode.
Said MCRs may be adapted to promiscuously receive all multicast traffic on a cluster.
Said MCRs may be adapted to support point-to-multipoint connections provided by UNI 3.0 signalling.
In accordance with the ATM transmission system of the present invention, all ATM hosts and MCRs, associated with the same cluster, may be adapted to be configured with the address of the same MARS, MARS may be adapted to operate in server mode, said IP/ATM network may be adapted to enable IP/ATM endpoints, within a cluster, to register as a member of an inter-cluster multicast group utilizing MARS procedures, said MCRs may be adapted to support point-to-multipoint connections provided by UNI 3.0 signalling, and a multicast server may be provided and adapted to manage said point-to-multipoint connections, and to distribute multicast traffic therefrom (i.e. as root) to all other leaves of said multipoint connections.
A MCR may be adapted, in advance of multicasting, to select a well known end-node and establish a connection thereto, said well known end-node being adapted to provide a database for the ATM addresses of inter-cluster multicast group members, and said well known end-node may be adapted to establish a point-to-multipoint tree and to distributing multicast traffic sent by a member of said inter-cluster multicast group to other members of said group using said tree. Each group address may have a corresponding well known end-node address.
Said IP/ATM network may be adapted to enable multicast packets to be sent to members of an inter-cluster multicast group, even if the sender is not a member of said group.
Said MCRs may be adapted to operate in either a server mode, or a Virtual Circuit (VC) mesh mode, the mode used being dependent on several criteria, such as, the number of inter-cluster multicast groups, the grouping mode (i.e. sparse, dense, etc.), traffic density, charging policies of a network operator, performance, reliability and system complexity.
When MCRs is adapted to operate in a server mode, said well-known end-node may be adapted to provide a database for IP multicast addresses, and corresponding ATM addresses for members of an inter-cluster multicast group, said MCRs may be adapted to issue multicast packets to said well known end-node for distribution to members of an inter-cluster multicast group, and said well known end-node may be adapted to establish a point-to-multipoint tree to said group members and to distributing multicast packets, received from said MCRs, to said group members using said tree.
When MCRs is adapted to operate in VC mesh mode, said well known end-nodes may be adapted to keep track of IP multicast addresses, and corresponding ATM members of said MCRs, and said IP/ATM network may be adapted to report changes in membership of an MCR to a respective well known end-node, and to establish point-to-multipoint trees between MCRs belonging to the same inter-cluster multicast group(s), when an association between said IP multicast addresses and said ATM members has been d
Lam Daniel K.
Nguyen Chau
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Telia AB
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