3com Corporation

Alexander Or

Haim Rochberger

Ken Benstead

Sarit Shani Natanson

Arcady Chernyak

Michael Gorokhovsky

Kenneth Benstead

A method of performing flow control in a PNNI network wherein a node that becomes congested advertises this fact to the network thus eliminating additional call requests and other messages that it cannot handle due to the current load. The method utilizes the Maximum Cell Rate (MCR) and Available Cell Rate (ACR) parameters provided for in the PNNI standard. When the congestion level on a local node exceeds a predetermined threshold, a PTSE with MCR set to zero and ACR set to zero is advertised to the network. The PTSE causes nodes (originating nodes in particular) to not consider that node in route calculations. When the congestion level recedes on the local node, another PTSE is generated with the original MCR and ACR that existed before the congestion occurred causing the resumption of call request messages to be forwarded to the network.

Method of local flow control in an asynchronous transfer mode network utilizing PNNI routing protocol

A method of triggering reroutes in an ATM network based on a call optimization value being reduced beyond a predefined threshold. The method utilizes a signaling element in the SETUP message called a PNNI optimization reservation signaling element that includes an optimization type, value and percentage. A switch accumulates the optimization value and passes this value to the next node along the path. In addition, the hardware in the node is configured to measure and monitor the optimization value. The optimization value is monitored for changes that exceed the predefined optimization percentage. When this is detected, the software calculates a reroute. If the new route is better than the current route and is within the optimization percentage constraints, a reroute is performed using the newly calculated route. The reroute procedure provided by the ATM Forum can be used to implement the reroute.

Method of triggering reroutes in an asynchronous transfer mode network

An apparatus for and method of enabling the debugging and testing of complex multilevel PNNI based ATM networks. The invention has applications in networks wherein one or more nodes implement only the Minimum Function PNNI implementation and wherein these modes must operate correctly in a PNNI hierarchy environment. A plurality of PTSEs representing simulated virtual portions of an ATM network are injected into a node under test. The PTSEs represent hierarchical portions of ATM networks that are difficult or impossible to implement. The virtual portions of the networks may or may not have been able to be created using real physical network elements. The method includes first generating the injection file containing all the PTSEs to be simulated and then injecting this file into the node under test. The injection process includes reading the ASCII file, parsing the contents and constructing the topology database by processing the binary version of the contents using already existing PNNI processing routines in the switch.

Apparatus for and method of testing a hierarchical PNNI based ATM network

A system of building a hierarchy in a PNNI based ATM network utilizing one or more proxy SVCC-based RCC entities. The invention separates the routing, signaling, etc. functions from the functions required to be performed by the peer group leader and the logical group node. A dedicated computing platform is connected to the network but does not perform functions related to routing, signaling, etc. Rather, it is dedicated to running peer group leader and logical group node functions, including complex node representation (summarization calculations) of the child peer group. The dedicated computer has PVCs connecting it to one or more entities that are termed 'proxy SRCC' nodes. The proxy SRCC nodes perform the SRCC functionality on behalf of the dedicated computer. When the border nodes in the peer group run the Hello FSM over outside links they each advertise the closest proxy SRCC entity, which is themselves. The border nodes on the other side of the outside link are operative to then generate an uplink with the advertised address of the proxy SRCC. The logical group nodes then establish RCC SVCCs to one of the proxy SRCCs. The PNNI routing messages are relayed from the proxy SRCC to the dedicated computer peer group leader/logical group node via a previously established PVC.

Building a hierarchy in an asynchronous transfer mode PNNI network utilizing proxy SVCC-based RCC entities

A method of performing source routing when a node is in the overload state. A node in the overload state cannot perform routing functions in response to a SETUP message for destinations other than its directly connected neighbors. Instead, the node forwards the SETUP request to one of its directly connected neighbors. The neighboring node chosen must be able to support the overload routing feature, the link between the two nodes must be in the FULL state and the node chosen must not itself be in the overload state. The neighboring node chosen to calculate the source route receives a ROUTE REQUEST message encapsulating the information received from the source user. The neighboring node chosen then calculates the source route as if it was the node connected to the source user, i.e., the node in the overload state. The route, once calculated, is sent to the requesting node in the overload state.

Method of source routing in an asynchronous transfer mode network when a node is in an overload state

A method of permitting older networks based on E-IISP routing to operate in newer PNNI based networks. The invention combines the PNNI and E-IISP routing schemes and permits their simultaneous execution in the same ATM network. The E-IISP routing scheme is modified so as to operate in unison with the minimal PNNI implementation configured on each node. The Hello protocol and associated Finite State Machine (FSM) are utilized to determine whether a remote node is in the same peer group. If it is determined that both nodes are in the same peer group, the ports on either side of the link are configured as standard PNNI type ports. If it is determined that the two nodes are from different peer groups, the ports on either of the link are configured as E-IISP type ports. Foreign address information is then exchanged between the two nodes thus permitting border nodes to learn about other peer groups from their respective remote nodes. Relatively large networks can be constructed that do not have any hierarchy as in networks running the full PNNI standard. Via the Hello protocol, changes made to links between nodes will be detected immediately and the port configuration modified appropriately.

Method of combining PNNI and E-IISP in an asynchronous transfer mode network

Two solutions are provided for optimizing the algorithm used by the local node in calculating the route to a destination node. A first method optimizes the route calculation by associating a port/link information with the PTSEs received by the node. The association is made using the first PTSE to arrive from an originating node. The routing algorithm is then steered to begin routing to a destination using the associated port/link. A second method optimizes the route calculation by utilizing a special PTSE termed a ROUTE.sub.-- PTSE into which is placed the route the PTSE takes upon being flooded from the creating node to the local node. When routing, the local node traverses the DTL already existing in the ROUTE.sub.-- PTSE received from a particular originating node that is the current destination node.

Growing community of inventors

Nesher, Israel

Alexander Or