Telephonic communications – With usage measurement – Call traffic recording by computer or control processor
Reexamination Certificate
1999-02-02
2002-03-12
Matar, Ahmad (Department: 2642)
Telephonic communications
With usage measurement
Call traffic recording by computer or control processor
C379S111000, C379S112010, C379S112040, C379S112060, C379S133000
Reexamination Certificate
active
06356629
ABSTRACT:
1. Field of the Invention
The invention relates generally to communications and networking. More specifically, the invention relates to the usage of resources in networking devices.
2. Background of the Invention
In connection-oriented networking schema such as ATM (Asynchronous Transfer Mode), connections or “calls” must be established between one information device such as a computer system or router and another. This call or connection is sometimes referred to as a “virtual circuit” (VC) particularly where a specified data pipe is artificially, through software, segmented into separate data-pathways, each pathway servicing a particular VC. Often a switch acts as an intermediary to direct one or more of these VCs through a particular network node, and thus these calls are collectively referred to as SVCs (Switched Virtual Circuits).
FIG. 1
shows an exemplary wide-area networking system serviced by ATM. A wide-area network (WAN) link
120
interconnects a first network
100
with a second network
110
. Each network has a plurality of nodes which may each contain switching devices that regulate data traffic to one or more user terminals. Network
100
is shown having nodes
102
,
103
,
104
,
106
and
108
, while network
110
is shown having nodes
112
,
114
,
116
and
118
. A first user terminal
105
is connected to node
102
of network
100
while a second user terminal
115
is connected to node
118
of network
110
. In order for user terminal
105
and user terminal
115
to communicate with one another, a call must first be established between them. This call may be switched through a plurality of nodes. one possible route for sending data from user terminal
105
to user terminal
115
is for data to go from node
102
to
106
to
108
and then across the WAN link to node
112
and node
118
finally reaching user terminal
115
.
Similar to PSTN (Public Switched Telephone Network) communications such as telephone calls, the period of SVC call operation for a given call can be split into three distinct phases-establishment (setup), active (data transfer) and disconnect (hang-up). Once a call is established, say between user terminal
105
and user terminal
115
across a specified path, a virtual circuit will have been created and the call can proceed into the active phase where data is transferred. Once the data transfer is complete, the call can be disconnected which will release the virtual circuit.
Each node has a controller device (SVC controller) and switch which facilitates the calls through its node. The SVC controller has processing, memory and other resources to interpret, forward and process messages and initiate other messages as appropriate, while the switch ordinarily handles the physical routing of messages among nodes and user terminals.
In a wide-area network, as that shown in
FIG. 1
, call setup may have to proceed through an arbitrarily large and unknown number of nodes before it can be completed.
FIG. 2
shows a call setup session between a first user terminal and a second user terminal that proceeds through a series of N nodes. Each of the nodes
1
,
2
, . . . , N have a controller device that performs, among other functions, the data link layer (Layer
2
) and transport layer (Layer
3
) processing and forwarding of messages. Among such messages are call setup messages. For instance, in
FIG. 2
, when establishing a call between user terminal
1
and user terminal
2
, user terminal
1
will first initiate a setup message informing the node
1
controller that a connection wishes to established with user terminal
2
. The node
1
controller sends back an acknowledgement message informing user terminal
1
that the call establishment is still in progress (call proceeding). The node
1
controller will then forward the call setup initiator message to next down-the-line node, node
2
. Upon receiving the setup message, the node
2
controller responds with a call proceeding message to the node
1
controller. The node
2
controller forwards the call setup message to another node's controller, which responds with a call proceeding message to node
2
, and on and on, until reaching the second user terminal
2
which is directly accessible from node N. User terminal
2
sends a call proceeding message back to the node N controller, and after a time, when the call is connected through, the user terminal
2
sends to the node N controller a call connected message which is forwarded back through the nodes numbered one to N until reaching user terminal
1
. At this point, the call is considered “established” and the data transfer phase commences.
The above exemplifies the number of messages needed to setup a single call over N nodes. Each node's controller would have to process and forward at least three messages to facilitate call establishment. Assuming each node is capable of supporting/switching multiple user terminals or other devices, many unique point-point calls are possible. A particular node controller may thus have to process many call setup messages. Each SVC controller has finite resources to provide these and other services, namely, message buffers, call records, CPU processing capacity, I/O bandwidth and so on which are often taxed. Thus, a high setup message arrival rate can potentially consume all of a controller's processing and memory resources. This can result in the controller delivering degraded service to all user terminals. A high setup message arrival rate due to one terminal can thus act to degrade the service provided to all other user terminals.
SUMMARY OF THE INVENTION
What is disclosed is a method of managing congestion in a network controller having a plurality of interfaces comprising monitoring the utilization and potential utilization of resources in a due to message traffic received by the network controller, and instituting controls to limit further message traffic where the measurements exceed upper thresholds.
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patent: 5479604 (1995-12-01), Lorenz et al.
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Mito, M. et al; “B-ISDN Signalling Protocol Processing for Large Multiplexed Subscriber System,” 1995 IEEE International Conference on Communications. Converging Technologies for Tomorrow's Applications. ICC '96. Proceedings of ICC/SUPERCOMM '96—International Conference on Communications, Dallas, TX, USA, pp. 663-668 vol. 2, XP002140624 1996.
International Search Report mailed Jul. 4, 2000 in counterpart PCT application No. PCT/US00/02604.
Fourie Henry
Karia Snehal G.
Bui Bing
Cisco Technology Inc.
Matar Ahmad
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