Multiplex communications – Fault recovery – Bypass an inoperative channel
Reexamination Certificate
2000-02-23
2004-10-05
Jung, Min (Department: 2739)
Multiplex communications
Fault recovery
Bypass an inoperative channel
C370S397000, C709S239000
Reexamination Certificate
active
06801498
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to asynchronous transfer mode communication equipment and a method for switching a virtual path of the same and more particularly to the asynchronous transfer mode communication equipment having a function to switch the virtual path based on a redundant structure for a remedy of the virtual path in the case of its failure and the method for switching virtual paths of the above asynchronous transfer mode communication equipment.
2. Description of the Related Art
FIG. 4
is a schematic block diagram of general asynchronous transfer mode (hereinafter referred to as ATM) communication equipment used when its virtual path (hereinafter referred to as a VP) is switched. A conventional method for switching the VP will be hereinafter described by referring to FIG.
4
. As shown in
FIG. 4
, the ATM communication equipment is provided with the VPs mounted dually and bidirectionally between a node A
1
-
1
constituting one terminating point of the VP and a node B
1
-
2
constituting the other terminating point of the VP, and one set of the VPs is used as active VPs and the other set of the VPs as standby VPs. If a failure occurs in the active VP, switching from the active VP to the standby VP is performed to prepare for malfunctions of a link and the node. In
FIG. 4
, the active VPs
201
-
1
and
201
-
2
are shown by solid lines being connected bidirectionally among the node A
1
-
1
, a node C
1
-
3
and the node B
1
-
2
. The node A
1
-
1
and the node B
1
-
2
constitutes each of terminating points for bidirectional sending and receiving of signals, while the standby VPs
202
-
1
and
202
-
2
used for bidirectional communication are shown by dotted lines among the node A
1
-
1
, a node D
1
-
4
and the node B
1
-
2
.
Next, operations of the ATM communication equipment will be described below. First, when the node B
1
-
2
receives a notice of a failure in the active VP
201
-
1
, the node B
1
-
2
starts to retrieve the corresponding VP
202
-
1
from a VP paired information table containing information created by pairing information about the source VP with one about the switched VP and outputs a request for switching of the VP by using the standby VP
202
-
2
.
When the node A
1
-
1
receives the request for switching the VP, in order to switch the VP from the active VP
201
-
1
to the standby VP
202
-
1
and from the active VP
201
-
2
to the standby VP
202
-
2
, it retrieves the information from the VP paired information table to renew line setting information and to perform the switching of the VP. After the switching is complete, the node A
1
-
1
informs the node B
1
-
2
of the completion of the VP switching. When the node B
1
-
2
receives the notice of the completion of the VP switching, by renewing the line setting information, it performs the VP switching. By the above operations, the VP switching is now complete. That is, in the described conventional method for switching the VP, the terminating node B
1
-
2
having received the notice of the failure in the VP is adapted to inform the oppositely-disposed terminating node A
1
-
1
of the request for the VP switching and, after having confirmed the switching request, the node B
1
-
2
is adapted to perform the switching of the self-node.
Moreover, another conventional method for switching a VP is known in which a terminating node B
1
-
2
having received a notice of a VP failure firstly performs a switching of its own VP and, after having completed the switching, it informs an oppositely-disposed terminating node A
1
-
1
of a request for the VP switching and then performs the switching of the VP of the oppositely-disposed terminating node A
1
-
1
.
As shown in the above two conventional methods for switching the VPs, when nodes A
1
-
1
and B
1
-
2
disposed at VP terminating points identify a switched VP, retrieving of the VP paired information table is necessary.
In the ATM communication equipment provided with conventional VP switching functions, both all line setting information tables within the equipment and the paired information tables created by pairing the active VP being in operation with the standby VP used for switching of the active VP are managed by a control section adapted to control whole equipment.
Therefore, the control section controlling the whole equipment, if there is any active VP requiring switching due to failures or the like, by retrieving necessary information from the table in which the VP paired information for the whole equipment is registered, detects a standby VP to be used as one constituting a pair of the VPs and performs the VP switching.
FIG. 5
is a schematic block diagram of configurations of ATM communication equipment having a conventional VP switching function.
As shown in
FIG. 5
, the ATM communication equipment is comprised of a control panel (SYS-CONT)
110
to control whole equipment, control panels (BAY-CONT)
115
-
1
and
115
-
2
to control frames
102
-
1
and
102
-
2
, units
120
-
1
to
120
-
4
in the frames, line interfacing sections
124
-
1
and
124
-
2
mounted on the units
120
-
1
to
120
-
4
, an ATM switch
113
and control panels (UNIT-CONT)
121
-
1
and
121
-
2
to control the units
120
-
1
to
120
-
2
and line interfacing sections
124
-
1
and
124
-
2
.
The control panel (SYS-CONT
110
) contains a line setting information controlling section
111
, a line setting information section
112
, a VP switching controlling section
122
and a VP paired information table
123
. Information from the line setting information section
112
is fed from the line setting information controlling section
111
through the control panels BAY-CONT
115
-
1
and
2
on each frame to the UNIT-CONT
121
-
1
and
121
-
2
on each of units
120
-
1
and
120
-
2
and then is set to each of the line interfacing sections
124
-
1
and
124
-
2
. Also, information from the line setting information section
112
is set to the ATM switch
113
from the line setting information controlling section
111
.
Next, operations of the line setting information section
112
and the VP paired information table
123
will be described.
FIG. 6
is one example of a VP paired information table
123
employed in the conventional ATM equipment and
FIG. 7
is one example of a line setting information provided by the line setting information section
112
employed in the conventional ATM equipment.
The identification of each of the VPs is performed based on a number (Bay) of a frame in which the VP is housed, a unit number (Unit), a line interfacing section number (IF), asending and receiving circuit number (HW) stored in the line interfacing sections
124
-
1
and
124
-
2
and VPI.
Line setting information provided by the line setting information section
112
will be described by referring to FIG.
7
. In
FIG. 7
, a source connection represents connection information to be inputted to the equipment and a destination connection represents connection information to be outputted from the equipment following a routing process. One registration allows setting of one directional VP connection to be made. For example, in the table in
FIG. 7
, in the case of a connection having the registration number being
1
, a VP having the VPI being
100
to be inputted to a receiving section with a sending and receiving number (HW) to be stored in the interfacing sections
124
-
1
and
124
-
2
, the frame number (Bay) being
1
, the unit number (Unit) being
1
, the line interfacing section number (IF) being
1
is outputted as the VP having the VPI being
101
, from a sending section with the Bay being
2
, the Unit being
1
, the IF being
1
and the HW being
1
.
Moreover, the connection for the registration number being
2
is in the direction opposite to that for the registration number being
1
. (i.e., Input: Bay=
2
, Unit=
1
, IF=
1
, HW=
1
and VPI=
101
; Output: Bay=
1
, Unit=
1
, IF=
1
, HW=
1
and VPI=
100
). The
Jung Min
NEC Corporation
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