Switching router and a datagram transfer system

Details Switching router and a datagram transfer system Switching router and a datagram transfer system

1998-07-24

2001-06-26

Cangialosi, Salvatore (Department: 2732)

Multiplex communications

Diagnostic testing

Fault detection

C370S227000

Reexamination Certificate

active

06252853

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention generally relates to a network apparatus for use in building an IP (Internet Protocol) network and, more particularly, to a switching router for performing high-speed transfer (cut-through) of an IP datagram by use of an ATM (Asynchronous Transfer Mode).
With wide popularization of applications such as the WWW (World Wide Web), the quantity of information transferred over the Internet has been steadily increasing, thereby involving a problem as a bottleneck to the communication performance of the Internet, especially of the router, a network apparatus for transferring IP datagrams between adjacent networks. Datagrams as used herein represent data and/or programs. This problem is caused by that the transfer processing requires confirmation of destination for each of the IP datagrams.
To solve this problem, switching routers such as a label switching routine have been proposed in which the ATM switch is combined with a controller for performing transfer and control of IP datagrams. Specific schemes include a CSR (Cell Switch Router) disclosed on February 1997 in IETF (Internet Engineering Force) RFC (Request For Comments)
2098
.
However, it is not taken into consideration for the switching routines such as the above-mentioned label switching router obtained by combining the ATM switch with the controller to cope with a fault occurring on the controller connected to the ATM switch. This may cause a problem in the transfer of IP datagrams between adjacent nodes. Therefore, the inventor hereof examined the case in which the controller fails. The following describes a result of this examination with reference to FIG.
6
.
FIG. 6
shows a data relay controller
100
for performing transfer and control of an IP datagram, detecting data satisfying a particular condition in the transfer IP datagram, and controlling an ATM switch based on the result of the detection, an ATM switch
110
for switching between ATM cells, and an adjacent node
120
connected through an ATM line.
The adjacent node
120
and the data relay controller
100
presets a standard VC (Virtual Channel) route for transferring the IP datagram, or a so-called default VC route
140
, on a given VP (Virtual Path) route
130
through the ATM switch
110
. Normally, the IP datagram is transferred along the default VC route relayed by the data relay controller
100
.
Then, when the IP datagram satisfying a certain condition is detected, the data relay controller
100
sets a VC route for directly connecting the destination of the detected IP datagram to the adjacent node
120
of the destination through the ATM switch
110
, this VC route being referred to as a cut-through VC route
150
. Between the adjacent nodes, IP datagrams are transferred over the cut-through VC route not relay by the data relay controller
100
. This allows communication between the adjacent nodes
120
without confirming the destination of each IP datagram and performing transfer processing, thereby significantly enhancing the transfer performance of IP datagrams.
It should be noted that the communication route in the ATM is set by use of the VC route and the VP route
130
that bundles a plurality of VC routes. It should also be noted that a different network communicable only through the data relay controller
100
is originally provided between the adjacent nodes
120
; in order to transfer IP datagrams directly between the adjacent nodes
120
through the cut-through VC route
150
, each adjacent node
120
is mounted with a mechanism for encapsulating the IP datagrams addressed to the adjacent nodes
120
of the original IP datagrams.
Therefore, if IP datagrams are transferred between the adjacent nodes
120
through the data relay controller
100
in the above-mentioned constitution composed of the data relay controller
100
, the ATM switch
110
, and the adjacent nodes
120
, occurrence of a fault on the data relay controller
100
connected to the ATM switch may disable the data transfer between the adjacent nodes
120
even if the ATM switch has no trouble.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a switching router such as a label switching router capable of providing continuous data communication between adjacent nodes if a trouble occurs on a data relay controller without changing the same in any manner and automatically restoring the failed data relay controller.
In carrying out the invention and according to one aspect thereof, there is provided a switching router comprising a switching mechanism for transferring fixed-length data by hardware and a relay mechanism for computing an optimum route to a destination of variable-length data and transferring the same by software. Normally, data is transferred beforehand through the relay mechanism and data that satisfies a certain condition is transferred only through the switching mechanism without using the relay mechanism.
In the above-mentioned constitution, an ATM switch of the above-mentioned switching mechanism is provided with a monitoring means for monitoring an operation state of a data relay controller (the relay mechanism), a storage means for storing VP route information to be set if fault occurs on this data relay controller, and a VP route information storage managing means for setting a PV to the ATM switch and clearing the setting according to the above-mentioned VP route information storage means based on the operation state of the data relay controller monitored by the above-mentioned monitoring means.
As mentioned above and according to the invention, if a fault occurs on the data relay controller, use of the ATM switch based on the present invention can continue communication by automatically setting a fault circumventing route between user-specified adjacent nodes according to user definition, thereby protecting the users connected to the adjacent nodes concerned from being affected by the fault on the data relay controller.
Moreover, the ATM switch according to the present invention can automatically restore the data relay controller, thereby allowing the system manager to restore the system only by restoring the data relay controller.


REFERENCES:
patent: 5949974 (1999-09-01), Ewing et al.
patent: 2000-31989 (2000-01-01), None

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