Virtual trees routing protocol for an ATM-based mobile network

A method for dynamically updating routing paths for cells traveling in a wireless communications network, said communications network including a plurality of switching nodes and said cells being routed according to destination-rooted virtual path identifier (VPI) trees, said method comprising the steps of:

• detecting a trigger condition at a node i in said communications network indicative of a requirement to update one or more of said VPI trees, said trigger condition being a congested link in said communications network;
• updating route structures and route states of said VPI trees in said communications network in response to said trigger condition;
• and
• determining a candidate set of said VPI trees for redirection, said candidate set including "empty" VPIs, wherein an empty VPI has no assigned virtual channel identifiers (VCIs) thereon, said step of determining further including the substeps of:
• creating a set of all VPIs using said congested link;
• referencing a record of connections at said node i having been admitted with quality of service (QoS) guarantees to thereby rule out any non-empty VPIs.;
• communicating with a root node of each potentially empty VPI to determine if a best-effort connection without QoS guarantees has been admitted on said VPI.

A method for dynamically updating routing paths for cells traveling in a wireless communications network, said communications network including a plurality of switching nodes and said cells being routed according to destination-rooted virtual path identifier (VPI) trees, said method comprising the steps of:

• detecting a trigger condition at a node i in said communications network indicative of a requirement to update one or more of said VPI trees wherein said trigger condition is the addition of a link in said network to replace a previously failed link;
• updating route structures and route states of said VPI trees in said communications network in response to said trigger condition;
• determining a set of VPIs that were inactivated by a selective freeze procedure when said the link failure occurred;
• activating said set of VPIs previously inactivated;
• updating a data table at node i to indicate that a VPI from said set of VPIs previously inactivated is active;
• sending selective unfreeze messages in a chained fashion to neighbor nodes downstream of a selected VPI in said communications network, wherein each node informs a root node of its activation;
• and
• updating a data table at said root node to reflect new activation of said set of VPIs and thereby incorporate the restored link in said network.

A method for dynamically updating routing paths for cells traveling in a wireless communications network, said communications network including a plurality of switching nodes and said cells being routed according to destination-rooted virtual path identifier (VPI) trees, said method comprising the steps of:

• detecting a trigger condition at a node i in said communications network indicative of a requirement to update one or more of said VPI trees, wherein said trigger condition is the addition of a link in said network between two ports not previously connected;
• updating route structures and route states of said VPI trees in said communications network in response to said trigger condition;
• selecting a set of empty VPIs that pass through other links in said network;
• and
• redirecting said other links onto the new link being added.

A method for dynamically updating routing paths for cells traveling in a wireless communications network, said communications network including a plurality of switching nodes and said cells being routed according to destination-rooted virtual path identifier (VPI) trees, said method comprising the steps of:

• detecting a trigger condition at a node i in said communications network indicative of a requirement to update one or more of said VPI trees, wherein said trigger condition is the addition of said node i into said network;
• updating route structures and route states of said VPI trees in said communications network in response to said trigger condition;
• communicating with neighbor nodes in said network to determine a set of VPI trees to join as a leaf node;
• and
• joining said set of VPI trees as a leaf node.