Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1998-05-12
2001-11-06
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S474000
Reexamination Certificate
active
06314098
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an asynchronous transfer mode (ATM) communication system, and more particularly, to an ATM connectionless communication system having a session supervising function and a connection supervising function.
2. Description of the Related Art
Recently, Internet protocol traffic is accommodated in an ATM network, and the traffic is processed at a high speed by layer
2
switching. In a standard ATM communication system, which is connection-oriented, however, an inter-user connection needs to be explicitly set before data is transmitted from a source user terminal to a destination user terminal. Therefore, a connection establishing process is independent of a data transmitting process. In the connection establishing process, a switched virtual connection (SVC) is carried out. That is, a connection supervising process is carried out by using a global connection identifier (GCID) and an ATM layer cell label including a virtual path identifier (VPI) and a virtual channel identifier (VCI), so that one VCI is allocated to each link between the user terminals.
A prior art ATM connectionless communication system is based on ITU-T Recommendation I. 364 (see JP-A-74767). That is, a server unit and user units are connected by a transmission line. Data cells on links are multiplexed to two-layer logical connections. This will be explained later in more detail.
In the prior art ATM connectionless communication network system, a packet managements depends upon a connection management, and both the managements are carried out by the AAL. Therefore, it is impossible to identify cells and reconstruct packets therefrom, and thus, it is difficult to realize a multicast service.
Also, in the prior art ATM connectionless communication network system, a multipoint-to-multipoint connection realizing procedure is not defined as an ATM standard. As a result, the complexity of the multipoint-to-multipoint connection realizing procedure as well as the allocation of ATM connection (VCI) and the load of informing VCI to the user equipments may delay data transfer.
Further, in the prior art ATM connectionless communication network system, however, since a processing load is concentrated on the server unit, the processing ability of the server unit is a bottleneck in the processing of the entire system. Additionally, if the server unit becomes in a fault state, the entire system may be in a fault state.
SUMMARY OF THE INVENTION
It is an object of the present invention to be able to carry out a multipoint-to-multipoint multicast communication in an ATM connectionless communication system.
According to the present invention, in an ATM connectionless communication system for delivering connectionless datagram in the form of sessions through an ATM network, each one of multiple edge units is connected to a user network where QoS sessions an No-QoS sessions are mixed. Each of the edge units accommodates an IPv
4
packet from the user network into an Intermediate frame and accommodates the intermediate frame into ATM cells. The edge units are connected to core units by permanent virtual paths to form a connectionless network. Each of the edge units has a session supervising section for determining whether the IPv
4
packet is a QoS session or a No-QoS session, to allocate a control flow number to the IPv
4
packet when the IPv
4
packet is a QoS session.
Also, a connection supervising section specifies the No-QoS sessions by source IP addresses and destination IP addresses and by aggregating the No-QoS sessions for every destination number of the edge units when the IPv
4
packet is a No-QoS session.
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“A New Scheme of Connectionless Transmission over ATM”, pp. 97-102; vol. 97, Nol. 131.
Cisco Systems, “Scaling The Internet With Tag Switching”,White Paper,1996, pp 1-7.
Cisco Systems and StrataCom, “Seamless Switching From The Campus To The WAN”,White Paper,1996, pp 1-6.
Masuda Michio
Nishihara Motoo
Ogawa Makoto
Chin Wellington
Foley & Lardner
NEC Corporation
Tran Maikhanh
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