Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
2000-04-12
2002-08-27
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C709S223000, C709S224000, C709S225000, C709S226000, C709S235000, C709S241000, C709S242000
Reexamination Certificate
active
06442615
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a traffic data evaluating apparatus, and in particular to a traffic data evaluating apparatus for a network using dynamic routing according to the preamble of claim
1
.
Further, the present invention relates to a traffic data evaluation method.
BACKGROUND OF INVENTION
In U.S. Pat. No. 5,598,532 there is described a traffic data evaluation apparatus comprising a traffic data collection unit adapted to collect data with respect to a real traffic flow in a network which may then be used to achieve an improved network performance through a modified network resource arrangement.
Further, digital communication networks of the future will largely be based on networks using dynamic routing, e.g. networks using the asynchronous transfer mode ATM technology. Telecom operators today invest heavily on such new technology. Here, it is important that network operators have tools to insure that the own network works efficiently and further tools to predict where new investments in the form of extensions of the network should be realized.
FIG. 9
illustrates the principle of timesharing multiplexing where the complete message is split into packets. Thus, when two or more senders deliver packets to a router, the router can transmit both senders' information on the same physical circuit by re-sending one packet from the first, then one packet from the other, and so on. In normal circuit switched networks, only one of the senders could transfer information at one time. Now the circuits are instead only perceived at a higher level of abstraction, i.e. virtual circuits. The path of every connection's circuit may be determined using dynamic routing.
As shown in
FIG. 10
, the packets usually consist of a header, which contains all information necessary in order for the network to transmit the packet through the net, a body which consists of user data and a cyclic redundancy check code, CRC, which is used for bit transmit error detection.
In packet switched networks these packages may arrive at destination in disorder. The connection is here maintained at a higher level of abstraction with advanced buffering methods, so that the end user perceives a connection, where there is in fact none.
However, in circuit switched networks, as ATM, the route through the network is determined in advance, possibly using dynamic routing. Hence, all packets are guaranteed to arrive in correct order. Also, since the route in ATM networks is determined and relayed to the nodes in advance, the packets need not contain all the information usually found in packet headers, because the node already knows how to switch cells on a certain connection. The header size of the packets can therefore be reduced and hence, they are called cells. By the same reason, the routing algorithms can be much simplified, which reduces the amount of computational power needed to perform the switching. Because of the high transmission reliability in ATM-networks, cells do not have a CRC.
FIG. 11
shows an ATM network as typical -example for a network using dynamic routing. Here, the principle components are the ATM adaptation layer AAL, statistical concentrators, ATM switches, transmission links, and control computers. The statistical concentrators and ATM switches contain smoothing buffers to temporarily store arriving data packets that cannot be immediately delivered because in the case of a concentrator, data packets generated by active users arrive in parallel, but are delivered to the output sequentially, or in case of a switch, several data packets may arrive in parallel for the same output, but are delivered to that output sequentially. Thus, as a function of time the number of data cells stored in and transmitted by any smoothing buffer will rise and fall in accordance with end user data packet generation patterns.
Further, the control devices limit the traffic intensity on the various links such that quality of service QoS guaranties are maintained. For this reason, prior to receiving service, a given user must request a connection to the intended receiver and then the admission controller checks on the route found through the network. If such a route can be found, virtual connection numbers are assigned and the routing tables in the intervening switches are provided with instructions for routing of each ATM data cell bearing the right virtual connection number within its cell header. The user is then free to communicate over this new established virtual connection.
In addition, as shown in
FIG. 11
, the AAL is responsible for converting a user's data packet message into a sequence of ATM data cells and for re-assembling ATM data cells into complete messages. Here, a message may be an individual data cell, e.g., data or image, or a continuous bit stream, e.g., voice or video.
In particular, it should be noted that some networks using dynamic routing like the ATM communication system are virtual connection oriented networks where resources are not assigned on an exclusive basis, but rather are statistically shared among multiple connections.
Overall, these networks rely on virtual paths to segregate the collection of virtual connections into independently manageable groups. This concept is vital for creation of a viable admission policy since it decomposes a large job into independent sets of much smaller tasks.
Also, networks using dynamic routing provide for a route choice in advance. Here, the resources for every connection are negotiated before the establishment of the connection itself. The result of this negotiation then determines the transfer capacity of the connection, i.e. bit rate or bandwidth demand and the quality of service.
Apparently, there is reserved an amount of transfer capacity, bandwidth, during the establishing of a connection. However, when using services with varying bit rate the efficiency may be raised by the statistical multiplexing approach where not the full amount of capacity needed to cope with every eventuality is allocated, but it is instead assumed that bandwidth may be “borrowed” from other connections.
Thus, in considering the aspect of resource allocation in a network using dynamic routing, different factors such as quality of service, usage parameter control, connection admission control, and statistical multiplexing, should be taken into account. The parameter quality of service considers the demands on the quality of a connection. Here, a connection in the network may be established such that cells are transferred within a certain time, i.e. restriction on cell delay, that the transfer does not vary too much, i.e. restriction on cell delay variation, and that cells are not lost within the network, i.e. restriction of cell loss. Further, usually within networks using dynamic routing there exist no limits on the amount of cells that a user may produce. Nevertheless, this amount of produced cells may be controlled through the specification of the usage parameter.
Still further, connection admission control relates to a function which in the first phase of connection establishment decides whether or not there exists sufficient resources to establish a new connection in the network. Connection admission control considers whether the connection may be established with the requested bandwidth and quality of service while simultaneously upholding the quality of service for already established connections.
As already outlined above, statistical multiplexing relates to a sharing of bandwidth between different connections in a network using dynamic routing so as to avoid to allocate bandwidth according to peak levels for the different connections.
Taking into account the above principles, in a network using dynamic routing, finally a route in the network is determined through which the cells may be transported before the establishment of the actual connection. Thus, as routes are only established on demand, no advanced time consuming routing is required in the network nodes and cells may be switched in a simple way.
As shown in
FIG.
Nordenstam Yngve
Tjäder Johan
El-Hady Nabil
Maung Zarni
Telefonaktiebolaget LM Ericsson (publ)
LandOfFree
System for traffic data evaluation of real network with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for traffic data evaluation of real network with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for traffic data evaluation of real network with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2926881