WO2001026308A2 - A dynamic programmable routing architecture with quality of service support - Google Patents
A dynamic programmable routing architecture with quality of service support Download PDFInfo
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- WO2001026308A2 WO2001026308A2 PCT/US2000/027663 US0027663W WO0126308A2 WO 2001026308 A2 WO2001026308 A2 WO 2001026308A2 US 0027663 W US0027663 W US 0027663W WO 0126308 A2 WO0126308 A2 WO 0126308A2
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0478—Provisions for broadband connections
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5619—Network Node Interface, e.g. tandem connections, transit switching
- H04L2012/562—Routing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5619—Network Node Interface, e.g. tandem connections, transit switching
- H04L2012/5623—Network design, dimensioning, topology or optimisation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5629—Admission control
- H04L2012/5631—Resource management and allocation
- H04L2012/5632—Bandwidth allocation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/54—Store-and-forward switching systems
- H04L12/56—Packet switching systems
- H04L12/5601—Transfer mode dependent, e.g. ATM
- H04L2012/5638—Services, e.g. multimedia, GOS, QOS
- H04L2012/5646—Cell characteristics, e.g. loss, delay, jitter, sequence integrity
- H04L2012/5651—Priority, marking, classes
Definitions
- the present invention relates to the automatic discovery of the topology, capacity and other state information of a network for computation of routes satisfying quality of service requirements.
- the present invention comprises a communications network consisting of a set of switches and computers with network interface cards interconnected via links.
- the goal of the invention is to collect and present views of the network.
- two views are presented in the preferred embodiment of the invented system, namely the networking capacity graph of an ATM network, and a set of routes between pairs of ATM switches or computers.
- One skilled in the art should understand the invention ' s general applicability to other types of connection-oriented networks (including soft-state networks).
- the invention applies to a virtual network as well in that the latter is logically a collection of virtual paths.
- the invention also provides a framework and application programming interface (API) for implementing a large class of route computation algorithms without the need for any distributed communication on the part of the latter, and for providing interested software entities the ability to register to receive alerts of any changes to a view of the network.
- API application programming interface
- An objective of the invention is to simplify and modularize the operations of systems such as route computing engines and connection controllers, though it is not limited to these.
- PNNI provides protocol-oriented interfaces between "peers”, but does not provide APIs between routing and signaling.
- the present invention addresses the need for networking capacity graph discovery and distribution, as well as independent and simultaneous route calculation and virtual circuit creation.
- a system discovers the networking capacity graph at every computer of the network. In other words, a copy of the networking capacity graph becomes available at every computer.
- route computation algorithms need only read the local copy of the networking capacity graph.
- Independent route computation algorithms may run simultaneously at various nodes on the network. Each of these algorithms however, need perform local computations only, without the need for any distributed computation or communication.
- the advantage of this approach is that every computer has a complete view of the networking capacity graph and hence may make control and management decisions locally, ranging from computing routes to dimensioning virtual networks.
- a system discovers the networking capacity graph by running software entities known as "controllers" at every computer in the network.
- these controllers communicate with each other via a packet-switched network, which may or may not be overlaid on top of the ATM network.
- the packet-switched network is taken to be IP. (However, no IP routing protocols are required if ATM is used as a link layer for IP.)
- they discover ATM links between ATM switches and/or computers.
- the controllers keep track of the connection state of all the links that each of them controls. These locally discovered or maintained pieces of state information are distributed by the controllers to every other computer. As a result, all the computers become aware of the entire networking capacity graph.
- controllers continue monitoring, thus discovering any failure or recovery of links, switches or computers. All such discoveries are forwarded to controllers at every computer so that the view of the networking capacity graph is up-to-date at every computer.
- All software entities that expressed an interest in such changes are alerted. Examples of such software entities are route computation engines and connection controllers.
- a route computation engine may re-compute routes and store them in the route repository, while a connection controller may reroute a call if, for example, a link or ATM switch utilized by the call fails.
- FIG. 1 shows the components of an ATM cell, namely a 5-byte header and a 48-byte payload
- FIG. 2 shows the header of an ATM cell when used in the UNI format
- FIG. 3 shows the format of the ATM cell header when used in the NNI format
- FIG. 4 shows the format of an AAL-5 packet
- FIG. 5 shows an external computer connected to the control port of an ATM switch. The former controls the latter through this connection;
- FIG. 6 illustrates the representation of an ATM network as a graph
- FIG. 7 illustrates a sample schedulable region with two traffic classes
- FIG. 8 illustrates a networking capacity graph corresponding to the physical connection graph of FIG. 6;
- FIG. 9 illustrates a computer with only an C-GOC for controlling its NIC(s);
- FIG. 10 illustrates a computer running an C-GOC and an S-GOC.
- the S-GOC controls a switch attached to the computer via an ATM link;
- FIG. 11 illustrates the set of meta virtual circuit segments that are setup on an ATM switch by its controller
- FIG. 12 illustrates the communication of two computers directly connected to each other by an ATM link
- FIG. 13 illustrates the communication of control computer (of a switch) with computer connected directly to the switch
- FIG. 14 illustrates the communication of the control of computers of switches that are directly connected to each other.
- FIG. 15 illustrates the communication of the control of computers of switches that are connected to each other via a virtual path.
- ATM networks are considered to meet the requirements of broadband networks that flexibly support the quality of service requirements of multimedia applications.
- ATM networks are well known in the art. In the present invention, only a very small subset of the ATM capabilities described by the ITU and ATM Forum is used. For example, the Traffic Management, PNNI, UNI and APS specifications of the ATM Forum are not used in the system we discuss herein. This is very important as it simplifies the system tremendously. However, the invention requires augmentation in the area of switch control.
- an ATM network is a packet-switched connection-oriented network in which every packet is of a fixed size, namely a 53 byte cell. It consists of ATM switches and computers with ATM interface cards interconnected via links - fiber, copper, wireless or otherwise.
- a cell contains two parts, the header and the payload. The header contains information that is used for switching a cell arriving at an input port of a switch to an output port of the switch.
- An ATM cell is shown in FIG 1 , and its content is as specified in the International Telecommunications Union ' s "'B-ISDN ATM Layer Specification" (ITU-T 1.361 , 1993.)
- the first five bytes are the header and the remaining 48 bytes are the payload.
- the header consists of, among other things, a virtual path identifier (VPI) and a virtual channel identifier (VCI) (FIG 2).
- the VCI occupies sixteen bits, starting from bit position 12.
- the VPI occupies either eight bits, as shown in FIG 2, or twelve bits, as shown in FIG 3.
- the eight-bit case is used if the ATM cell is either transmitted or received by a network interface card attached to a computer.
- the twelve-bit case is used otherwise.
- the starting positions for the two cases are bit positions 0 and 4, respectively.
- the VPI and VCI fields are used by switches for switching the cell to the appropriate output port. Moreover, they identify the connection that the cell belongs to and hence provide information about the quality of service requirements for it.
- the GFC and CLP fields in the header are not used in the present invention.
- the HEC field is used for error detection in the ATM header.
- the PTI field is used for adaptation, which is described next.
- There are five ATM adaptation layers known in the art International Telecommunications Union, "B-ISDN ATM Adaptation Layer (AAL) Specification, " ITU-T 1.363, 1993.
- the preferred embodiment of the present invention uses the fifth layer, namely AAL-5.
- the format of an AAL-5 frame is shown in FIG 4.
- One bit in the PTI field of the ATM header is used for indicating boundaries between AAL-5 frames.
- the other two bits of the PTI field are not used in the present invention.
- the candidate network must be connection- oriented, and provide individual control of each node via an interface.
- the network could be a virtual network, in which case the links are virtual paths in an underlying network.
- the switching could be packet based or circuit based.
- the form of this node control interfaces is not important. It could be functional, protocol oriented, or otherwise. The semantic requirements of this interface are delineated below, both for a switch as well as non-switch computers.
- some packet switches may support capabilities to configure the packet multiplexers in the switch. Such capabilities enable a switch controller to tune the system so as to achieve larger schedulable regions, thus improving the system performance. These capabilities are not required for the present invention, but rather they are enhancements. Switches with such capabilities will be called switches with resource model support.
- Some switches may support capabilities for reading the schedulable region or some other set of statistics that readily yield the schedulable region (defined below in the section on quality of service).
- An example of such a set of statistics is the set of moments of the instantaneous bit-rate corresponding to each traffic class (also defined below). This set is sufficient for traffic classes with tight delay requirements since it is well known in the art that the effect of temporal correlation has little effect on the small-buffer case.
- Switches with such capabilities will be called switches with Quality of Service (QoS) support.
- QoS Quality of Service
- the switch receives the above messages from a controller connected via a special port (which may be one of the ATM ports, a serial port, or otherwise), bus, intra-CPU communication, or some other means.
- a special port which may be one of the ATM ports, a serial port, or otherwise
- the communication is via one of the ATM ports.
- This port will be referred to as the control port.
- the messages must be received at the control port on a pre-assigned VPI VCI pair. Responses to these messages are sent out via the control port.
- NICs network interface cards
- Some operating systems might provide capabilities for configuring the cell multiplexers on the ATM NICs. Such operating systems are said to support a resource model. These capabilities are not required for the present invention, but they enable the system to be tuned for better performance.
- Some operating systems, with the aid of ATM NIC drivers might provide capabilities for reading the schedulable region or some other set of statistics that readily yield the schedulable region. An example of such a set of statistics was given above. Operating systems with the above capabilities are said to support QoS.
- IP networks are well known in the art.
- the present invention relies only on the TCP and IP protocols.
- Internet routing protocols such as OSPF, RIP and BGP are not required.
- OSPF OSPF
- RIP RIP
- BGP Internet routing protocols
- a traffic class is a statistical model for the bit-rate of a digital infonnation stream over time. It is represented using a set of quantitative parameters and a qualitative parameter. The former may consist of parameters such as the peak cell rate, average cell rate, etc. The latter is a qualitative characterization such as "video " , 'voice', 'audio ' or 'data'. With each traffic class a set of quality of service constraints is attached. Examples of quality of service constraints include maximum cell delay, average cell delay and cell loss ratio.
- a special traffic class, known as the premium class is defined with no specific characteristics. The bandwidth assigned to calls of the premium class are chosen on a per-call basis. This is in contrast to the other traffic classes, where all calls of any single traffic class share the same characteristics. The terms 'call', 'connection', and 'stream' are used interchangeably in this document.
- the vector consisting of the number of streams of each traffic class is termed the operating point of the system specified in the preceding paragraph.
- the only exception is the component of the vector that represents the premium class. This component gives the sum of the bandwidths assigned to each of the calls of the premium class.
- the operating point is said to be admissible if the multiplexer can provide the requested quality of service to each stream.
- the set of all admissible operating points is called the schedulable region of the system. It is a capacity characterization of the multiplexer and also a stability concept.
- a sample two-dimensional schedulable region (corresponding to two traffic classes) is given in FIG 7. The shaded area is the schedulable region.
- the multiplexer With the multiplexer at the output port of every switch and network interface card, there is an associated schedulable region and operating point.
- the schedulable region of the multiplexer will be called its networking capacity. It will also be referred to loosely as the networking capacity of the corresponding link.
- the traditional capacity (measured in bits/ seconds) will be referred to simply as the capacity of the port and link.
- FIG 8 illustrates the networking capacity graph corresponding to the ATM network shown in FIG 6.
- the concept is not limited to ATM networks, and can be used for all connection-oriented communication networks including telephone networks and soft-state networks.
- the networking capacity graph is very useful for evaluating end-to-end network quality of service. This paragraph provides a calculus for such evaluations.
- the end-to-end network delay bound (whether it be maximum delay or average delay) for this call is the sum of the delay bounds for classes Ci, c 2 , and c 3 on the respective multiplexers, and the propagation delay on the links.
- delay bounds along a path are additive.
- Loss bounds are approximately additive.
- the loss bounds on those output multiplexers are l ⁇ , / 2 , and / 3 , respectively.
- the loss along the route is bounded by 1 - (l-/ ⁇ )(l-/ 2 )(l-/ 3 ) which is approximately f + U + / 3 since l ⁇ , / 2 , and / 3 are typically much smaller than 1. If they are not small, then they should be added to the above computation.
- the architecture consists of two parts, the hardware component and the software component.
- the hardware component of the architecture consists of an ATM network and an IP network.
- the ATM network consists of a set of ATM switches and a set of computers interconnected via ATM links. Each computer is equipped with an ATM network interface card. Each ATM switch is connected on one of its ports to a particular computer designated its control computer, via a single ATM link.
- the IP network consists of a set of computers and a set of routers, Ethernet switches,
- Ethernet hubs, bridges, repeaters, etc. interconnected via a set of links.
- the entities of the IP network are not necessarily distinct from those of the ATM network.
- the computers in both networks could be the same.
- the IP network may be implemented entirely on top of the ATM network, in which case the ATM layer acts as a link layer for IP traffic.
- the software component of the architecture consists of a set of software modules that run on each computer.
- each such set of modules is termed a group of controllers ("GOC").
- each module is termed a controller.
- GOC group of controllers
- additional groups of controllers run, one for each ATM switch controlled by the computer.
- S-GOC S-GOC
- C-GOC C-GOC
- NDC Neighbor discovery controller
- the database controller contains repositories and APIs for storing and accessing a networking capacity graph and a set of routes.
- a C-GOC contains a network interface card controller and a S-GOC contains an ATM switch controller. Two controllers that are part of the same group of controllers are said to be local with respect to each other.
- a neighbor discovery controller discovers the neighbors of either the computer it resides on or the ATM switch it controls.
- a state distribution controller distributes the discoveries made by its local neighbor discovery controller to other state distribution controllers in the network. In addition it receives information from other state distribution controllers and updates its local networking capacity graph repository.
- the event channel controllers provide an event channel to aid the state distribution controllers.
- the routing controller computes routes by reading its local networking capacity graph repository and writing the results to its local route repository.
- the switch controller is an access point for other entities to setup and tear down connections on the switch, and reserve bandwidth and VPI/VCI space on the switch ports.
- the network interface card controller is an access point for reserving bandwidth and VPI/VCI space on the NIC.
- a network interface card controller is a piece of software that provides two functions: First, it controls and manages the set of resources of each of the network interface cards on a computer. This set of resources consists of the input and output VPI/VCI spaces and the output multiplexers. Second, it provides admission control services for these resources.
- the network interface card controller provides means to request the creation and tear down of virtual circuit originations and virtual circuit terminations. Each of the above is created by opening a socket. However, the following reservations are made first in order to avoid conflict and also to guarantee quality of service.
- a virtual circuit origination requires reservation of VPI, VCI and a slot of the specified traffic class in the schedulable region for the specified port (NIC). In the case of the premium class, multiple slots will be reserved. The number of slots is proportional to the requested bandwidth. This applies to all the operations below that involve the premium class, and will not be repeated.
- a virtual circuit termination requires reservation of VPI and VCI for the specified port. All of the tear down operations involve releasing the reserved resources.
- a switch controller is a piece of software that controls and manages an ATM switch.
- a virtual circuit segment requires reservation of VPI and VCI on both the input and output ports. In addition, it requires the reservation of a slot of the specified traffic class in the schedulable region of the output port.
- a virtual path segment requires the reservation of VPI on both the input and output ports.
- a virtual path origination requires reservation of VPI and multiple slots of the premium class in the schedulable region on the specified port.
- a virtual path termination requires reservation of VPI on the specified port.
- a multicast tree segment can be built by creating multiple virtual circuit segments.
- the switch controller polls the ATM switch periodically for a response.
- a message that does not affect the state of the switch (such as the request for the number of ports on the switch) may be used for polling.
- the switch controller At the time of boot up of the switch controller, the switch itself need not be powered up and connected. It could be powered up and connected at a later time.
- the switch controller continues to poll the switch. It considers the switch to be up and running as long as it receives responses to the polling messages. If it ceases to receive responses, it considers the switch to be down. At this point, it continues to poll, hoping to detect a switch at some future instant.
- a neighbor discovery controller is responsible for discovering all neighbors of the switch or computer it represents. Two switches, a switch and a computer, or two computers are said to be neighbors if they are connected via a single link or a virtual path.
- the NDC discovers its neighbors by sending a Hello message on all the ports of the switch or computer it represents, and listens for responses from those ports.
- Virtual path origination-termination pairs are also treated as ports. The only difference is that physical ports may use any VPI when transmitting data, whereas virtual path origination-termination pairs must use the VPI assigned to them. For simplicity, the following presentation refers only to physical ports, but with the understanding that virtual path origination-termination pairs could also be treated as additional ports.
- the Hello messages are sent over AAL-5 in the preferred embodiment. It contains the sender address, sender port number, receiver address and receiver port number.
- the 'sender address' refers to the address of the switch or computer that the respective NDC represents.
- an NDC does not know the identity of the switch or computer at the other end of a port (the receiver), it sends Hello messages with 'receiver address' and 'receiver port number' set to zero.
- the local NDC Upon receiving a Hello message from the remote NDC, the local NDC becomes aware of the remote NDC's address and port number. Addresses are flat in the system described herein.
- Two NDCs are said to be neighbors if they represent switches or computers that are neighbors.
- An NDC transmits a Hello message to all its neighbors periodically. Whenever an NDC receives a Hello message in which the 'receiver address' field is non-zero, it considers that it has discovered ATM connectivity with the neighbor on the port on which it received the Hello message. The address of the neighbor is given by the field 'sender address' in the received Hello message.
- the connectivity is assumed to be present until the NDC ceases to receive hello messages from the neighbor for a significant duration. At such time, the connectivity is assumed to be lost. Hardware-level detection of link failure would improve the detection time.
- an NDC that represents a switch In order for an NDC that represents a switch to communicate with neighboring NDCs, it must create a set of virtual circuit segments on the switch it represents. These virtual circuit segments will be referred to as meta virtual circuit segments. A pair of such meta virtual circuit segment must be created for each port.
- the meta virtual circuit segments between the control port (FIG 5) and every port of an ATM switch are shown in FIG 1 1. These are setup by the NDC at bootup time by invoking the 'create virtual circuit segment ' operation of the switch controller. Corresponding to each port ?, two virtual circuit segments are created as follows: The first virtual circuit segment has input port/?, input VPI 0, input VCI routing vci, and output port c, output VPI 0, output VCI vci(p), where c is the identifier of the control port and vci(p) is the meta VCI assigned to port ?. The value of vci(p) must be distinct for distinct values of p. The routing vci is some constant VCI.
- routing_vci 50.
- NDC controllers representing a computer communicate with their neighbors by sending and receiving Hello messages on VPI 0, VCI routing _vci.
- the neighbor could be another computer (FIG 12) or an ATM switch (FIG 13).
- vci(p) 103 for switch B. Since vci(p) takes distinct values for distinct values of/?, when the NCG controller receives a message on a particular VCI (e.g., 106) it knows the port of the switch on which the message was received (port 6 in the example). Communication between NDCs representing ATM switches which are interconnected via a virtual path is very similar. It is illustrated in FIG 15. In the preferred embodiment, all communication between neighboring controllers, except the Hello messages, is achieved by running IP over the meta virtual circuits. The Hello messages use AAL5 over the meta virtual circuits.
- the state distribution controllers coordinate in the following way with their neighbors to ensure that all Networking Capacity Graph Repositories contain the same information. .
- the Neighbor Discovery Controllers associated with the nodes in question discover the change and inform their local State Distribution Controller.
- the state distribution controller first synchronizes its local NCG repository with that of the discovered neighbor. Then, the state distribution controller distributes all changes made to its NCG database by pushing the changes to the local event channel controller. This second step is carried out even if the topology change was due to a loss of neighbor connectivity.
- the state distribution controllers In addition to maintaining a consistent topology database, the state distribution controllers also coordinate to maintain a consistent view of the link states in their NCG controllers.
- the state distribution controllers periodically poll their local switch controller or NIC controller to read the schedulable regions, operating points and other link-state parameters of all the links attached to their node (switch or computer). Any significant changes (the threshold of which is determined by configuration) will result in the change being propagated to all other state distribution controllers via an event that is pushed on the event channel.
- An event channel provides a model of communication whereby senders and receivers do not need to be aware of each other.
- the event channel is implemented by a set of event channel controllers, one such controller executing on each computer.
- the event channel is realized as follows: When a sender sends an event (using the term here interchangeably with message) to an event channel controller, the latter passes on the event to the following: (i) all listeners registered with that specific event channel controller; (ii) event channel controllers at all neighboring nodes. Each of the event channels at neighboring nodes then in turn forwards the event to their neighbors. This process continues until all nodes have received the message.
- the general technique just referred to is known as flooding.
- the routing controller executes a routing algorithm to compute routes by reading the networking capacity graph from the local NCG database. It is triggered by an event that is pushed by the NCG repository when the networking capacity graph changes.
- the routing algorithm computes a set of routes for each one of the configured traffic classes, and writes them into the local route repository. Since the route repository, the NCG, and the event channel have well-defined interfaces, any routing algorithm from a large class of routing algorithms can be plugged into the framework. In particular, any routing algorithm applicable to multirate circuit switching can be applied. Moreover, the algorithm could be changed dynamically while the system is running.
- the route computation algorithm is changed by loading a new dynamic library on the fly.
- the networking capacity graph repository provides APIs for reading and writing aspects of the networking capacity graph.
- the write operations allow for adding and removing nodes and links to the networking capacity graph. They also allow for writing the schedulable region and statistics of the operating point for each link in the networking capacity graph. All the write operations trigger an event to be pushed to the event channel controller, so that all interested parties are alerted to the change in the networking capacity graph.
- the read operations allow for reading the set of nodes, the set of links attached to a node, and the schedulable region and operating point statistics of a link.
- the route repository provides interfaces for reading and writing routes. It also provides an interface for clearing all routes.
- Routes are categorized based on source- destination pair and traffic class. Multiple routes may exist for each category. The organization of these routes may take one of many forms. For example, the routes may be ordered according to some criterion such as path length. The criterion would be determined by the route computation algorithm. Alternatively, the paths could be organized as a probability distribution, with each path assigned a probability by the route computation algorithm.
- all controllers belonging to a given GOC are placed in the same process of the same computer. This will minimize the communication overhead between these controllers. These controllers were grouped together as they perform tightly coupled functions. It is possible to split controllers belonging to single GOC, and execute them on different computers, or on the same computer but on different processes. It is generally more efficient for the neighbor discovery controller of a S-GOC to be located on the control computer of the switch that the S-GOC represents, and the neighbor discovery controller of a C-GOC to be located on the computer it represents. The reason for this is that the placement of the NDC controllers is important to their function, which is to detect their neighbors.
- a switch controller is located on a computer other than the control computer, then it would require some means of communicating with the ATM switch, either through a proxy on the control computer or via virtual circuits. The latter solution could make the topology discovery mechanism complicated. Similarly, if a NIC controller is located on a computer other than the one it controls, then it would need some mechanism to communicate with that computer.
- connection controller is a software entity that accepts requests for ATM connections between specified source and destination nodes with quality of service. Given a request, the connection controller can read the route repository for a route between the source and destination with the specified quality of service. If there is a route between the specified nodes satisfying the requested quality of service, the route repository will return such a route. Then, the connection controller can use that route to identify the switches along the route and hence communicate with those switches to setup virtual circuit segments on those switches. As a result, a virtual circuit between the source and the destination nodes emerges. The means by which the connection controller communicates with the switches is not relevant here. Connection Re-routing
- the present invention is suitable for handling connection re-routing.
- an existing connection is abruptly lost due to an ATM switch failure or an ATM link failure.
- Such failures will be detected by one or more neighbor discovery controllers and distributed to all nodes via the event channel.
- Any software entity desiring to receive an alert message indicating the change of topology may register with the NCG event channel in order to receive such an alert message.
- the software entity e.g., a connection controller
- the software entity e.g., a connection controller
- the software entity e.g., a connection controller
- the software entity e.g., a connection controller
- the software entity e.g., a connection controller
- the call would have been re-routed around the failed ATM switches and/or links.
- Similar action can be taken to reroute an affected virtual paths. In case there is no route between the source and destination nodes after the failure, then re-routing would not be possible.
- the present invention is suitable for visualizing the networking capacity graph of an ATM network.
- the management system can register itself with the event channel controller to receive updates, just like a NCG controller. Such updates can be used to visual the networking capacity graph in real-time on a graphical user interface (GUI).
- GUI graphical user interface
- the present invention is also suitable for a collection of management agents to monitor the health of their neighbors. In this way, if one or more management agents crash or otherwise cease to be operational, neighboring agents can detect the failure.
- the present invention aids this monitoring by providing the agents with a list of neighboring nodes.
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Publication number | Priority date | Publication date | Assignee | Title |
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FR2836617A1 (en) * | 2002-02-28 | 2003-08-29 | Cit Alcatel | Orbiting satellite communications time variable resource assignment having planning using base station interval graphs which research communications links finding disjoint node paths. |
EP1639734A2 (en) * | 2003-06-06 | 2006-03-29 | Intellambda Systems, Inc. | Optical network topology databases and optical network operations |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US5649108A (en) * | 1993-11-30 | 1997-07-15 | Nec Corporation | Combined progressive and source routing control for connection-oriented communications networks |
US5729685A (en) * | 1993-06-29 | 1998-03-17 | Bay Networks, Inc. | Apparatus for determining the topology of an ATM network or the like Via communication of topology information between a central manager and switches in the network over a virtual service path |
-
2000
- 2000-10-06 AU AU78677/00A patent/AU7867700A/en not_active Abandoned
- 2000-10-06 WO PCT/US2000/027663 patent/WO2001026308A2/en active Application Filing
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5729685A (en) * | 1993-06-29 | 1998-03-17 | Bay Networks, Inc. | Apparatus for determining the topology of an ATM network or the like Via communication of topology information between a central manager and switches in the network over a virtual service path |
US5649108A (en) * | 1993-11-30 | 1997-07-15 | Nec Corporation | Combined progressive and source routing control for connection-oriented communications networks |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2836617A1 (en) * | 2002-02-28 | 2003-08-29 | Cit Alcatel | Orbiting satellite communications time variable resource assignment having planning using base station interval graphs which research communications links finding disjoint node paths. |
EP1341321A1 (en) * | 2002-02-28 | 2003-09-03 | Alcatel | Method for allocating resources variable in time for assuring continu services and use of this method to the planification of a telecommunication system |
EP1639734A2 (en) * | 2003-06-06 | 2006-03-29 | Intellambda Systems, Inc. | Optical network topology databases and optical network operations |
EP1639734A4 (en) * | 2003-06-06 | 2010-12-01 | Intellambda Systems Inc | Optical network topology databases and optical network operations |
Also Published As
Publication number | Publication date |
---|---|
WO2001026308A9 (en) | 2001-12-06 |
AU7867700A (en) | 2001-05-10 |
WO2001026308A3 (en) | 2001-11-08 |
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