Multiplex communications – Communication techniques for information carried in plural... – Combining or distributing information via time channels
Reexamination Certificate
2000-02-04
2002-07-23
Ton, Dang (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Combining or distributing information via time channels
C370S466000
Reexamination Certificate
active
06424662
ABSTRACT:
BACKGROUND OF THE INVENTION
The present application is a continuation-in-part application of US patent application filed on Sep. 2, 1997, based on Japanese Patent Application No. 8-233045, which is currently pending.
1. Field of the Invention
The present invention relates to a router apparatus which switches packets entailing the processing of a packet switching type layer
3
like IP (Internet Protocol), etc. by using an ATM (Asynchronous Transfer Mode, and particularly to a router apparatus for multiplexing plural transmission paths for one physical port of the ATM switch.
2. Description of the Related Art
An IP (Internet Protocol) switching network which has been proposed by Epsilon Company has been known as a network which enables high-speed IP-packet transmission by using an ATM technique. As shown in
FIG. 48
, this network includes an IP switch
1
and an IP switch gateway
2
, and enables high-speed transmission and switching of IP packets which have been communicated between conventional LAN/IP networks such as Ethernet, FDDI or the like which is connected to the IP switch gateway
2
.
In
FIG. 48
, a network is illustrated as being divided into a layer
2
(base or subordinate) and a layer
3
(enhancement or superordinate), and a heavy line connecting both the layers
2
and
3
represents the shift of processing between the layers. An IP node
4
serving as a router of a LAN?IP network or the like first performs LAN protocol processing of the layer
2
of Ethernet or the like on an arriving packet (datagram), and then performs IP protocol processing of the layer
3
of the superordinate (i.e., enhancement layer
3
) on the packet. Subsequently, after a route through which the packet will be transmitted is determined, the processing of the layer
2
is performed again and the packet is transmitted to an adjacent node. In the IP switch gateway
2
of the IP switching network, the processing of the layer
2
and the processing of the layer
3
are also performed on all the packets to be transmitted. The IP switch
1
also performs the processing of the layers
2
and
3
, however, packets which are cut through in communications between an IP switch gateway
2
and an IP switch
1
or between IP switches
1
are subjected to only the processing of the layer
2
, and then transmitted. In
FIG. 48
, heavy lines which should be originally illustrated between the layers
2
and
3
are replaced by heavy dotted lines in order to show that the processing of the layer
3
is cut through.
FIG. 49
shows a constitution example of the IP switch
1
and the IP switch gateway
2
. The IP switch
1
comprises an ATM switch
11
and an IP controller
12
, and it switches ATM cells with the IP switch gateway
2
connected to the physical port of the ATM switch
11
and with an IP node
3
for performing ATM communications. The IP switch gateway
2
comprises plural LAN interfaces
21
A,
21
B each of which is individually connected to each transmission path of the LAN?IP network connected to the IP node
4
, an IP datagram multiplexing/ demultiplexing unit
22
for multiplexing/demultiplexing IP packets which are communicated in the LAN interface, an IP processor
23
, and an ATM interface
24
which is connected to the physical port of the ATM switch
11
. In this constitution, the IP controller
12
of the IP switch
1
and the IP processor
23
of the IP switch gateway
2
perform communication control on IP in cooperation with each other on the basis of a protocol which is called IFMP (Ipsilon Flow Management Protocol). Here, “flow” represents a train of packets which are transmitted from a transmitting side (transmission source) terminal to a transmitted side (transmission destination) terminal, for example. The IP controller
12
controls VC (Virtual Channel) connection in cooperation with the ATM switch
11
on the basis of a protocol which is called GSMP (General Switch Management Protocol).
The communication between the IP switch gateways
2
which are connected to each other through the IP switch
1
will be described with reference to FIG.
50
. IP packets A and B which are transmitted from plural IP nodes
4
of the LAN?IP network to the IP switch gateway
2
are serially multiplexed in this order in the IP datagram multiplexing/demultiplexing unit
22
. After the multiplexed IP packets are successively subjected to IP processing in the IP processor
23
, they are converted to ATM cells in the ATM interface
24
and then transmitted to the IP switch
1
. The ATM cells which are transmitted to the IP switch
1
are transmitted to the IP switch gateway
2
serving as a transmitting side, and processed in the ATM interface
24
and the IP processor
23
. Thereafter, the ATM cells thus processed are successively synthesized into IP packets in the IP datagram multiplexing/ demultiplexing unit
22
and then transmitted to the LAN interface
21
serving as a transmitted side. After receiving all data of the IP packet, each LAN interface
21
individually transmits the IP packet to the transmission path of the LAN?IP network.
SUMMARY OF THE INVENTION
In the conventional system, all the IP packets which are transmitted by the IP switch gateway
2
must be processed in the IP processor
23
, and thus the amount of communication to be performed in the IP switch gateway
2
is restricted, so that the multiplicity of the communication in the overall system cannot be enhanced.
Further, in the IP switch gateway
2
, the IP packet is serially multiplexed and then subjected to the IP processing. Therefore, as shown in
FIG. 50
, when an IP packet A having a large data amount is transmitted from a transmission path, the processing and the transmission of an IP packet B which is transmitted from another transmission path are greatly delayed. This is a critical drawback in a public network which needs fairness with respect to access.
Still further, when applied to a public network, not only a service of IP packets, but also various services of frame relays, low-speed ATMs, channel emulation, etc are required, however, the IP switch gateway
2
is structurally restricted so that it can support only the service of IP packets and thus the practical use of the network is restricted.
Therefore, the present invention has an object to provide a router apparatus which enhances the multiplicity of communications performed through an ATM switch.
Further, the present invention has another object to provide a router apparatus which reduces the delay variation between communications of different multiplexing transmission paths.
Still further, the present invention has a further object to provide a router apparatus which can support various types of communications.
In order to attain the above objects, a router apparatus according to the present invention in which packets entailing the processing of a packet switching type layer
3
in a communication are switched by using an ATM switch, is characterized by comprising an ATM switch for switching cells, plural interfaces which are connected to plural transmission paths for transmitting the packets, a cell multiplexing/demultiplexing unit which is connected to one physical port of the ATM switch and the plural interfaces, and a layer
3
controller for executing and managing the processing of the layer
3
in the apparatus itself, wherein each interface comprises means for converting packets transmitted from the connected transmission path to cells and then transmitting the cells to the cell multiplexing/ demultiplexing unit, means for converting the cells transmitted from the cell multiplexing/demultiplexing unit to packets and then transmitting the packets thus obtained to the transmission path being connected, and means for converting information on the header portions of the cells and the packets which are transmitted and received for processing of the layers, and the cell multiplexing/ demultiplexing unit includes means for serially multiplexing cells transmitted from the plural interfaces being connected and then transmitting
Kunimoto Masao
Miki Kazuho
Murakami Masaru
Takase Akihiko
Takatori Masahiro
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Ton Dang
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