US 7,609,694 B2 · Multicast communications system with mechanism for updating multicast trees · patentgrep

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Abstract

A multicast communications system that updates multicast trees in a reliable way to prevent transmitted packets from being dropped or reversed before they reach their destinations. When a transmitting device sending multicast packets has moved from an initial access point to a new access point, a trigger data generator produces and sends trigger data to a network control server. This trigger data includes a sequence number of a particular packet as a trigger condition that initiates a change from an initial multicast tree to a new multicast tree. A trigger data distributor then sends the trigger data to both the initial and new access points. In packet routing devices, an update processor maintains the initial multicast tree until a packet having the sequence number specified in the trigger data is received and forwarded. After that, the update processor replaces the initial multicast tree with the new multicast tree.

Claims25

Dependent claims

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast, and
a trigger data generator that produces trigger data and sends the trigger data together with a location registration request when the transmitting device has moved during a multicast session, the trigger data specifying a trigger condition that initiates a change from an initial multicast tree to a new multicast tree, the trigger data including the sequence number of a particular packet as the trigger condition;
(b) a network control server that handles the location registration request from the transmitting device and manages the multicast tree, the network control server comprising:
a trigger data distributor that receives the trigger data from the transmitting device and forwards the trigger data to the second access point where the transmitting device is visiting, as well as sending the trigger data in encapsulated form to the first access point to which the transmitting device has previously attached;
(c) a first packet routing device at the second access point, comprising:
a buffer that stores packets transmitted by the transmitting device during a period between reception of the trigger data and establishment of a new multicast tree and outputs the stored packets when the new multicast tree becomes ready;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated trigger data received and sends the decapsulated trigger data to the initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that finds the sequence number specified in the trigger data, maintains the initial multicast tree until a packet having the specified sequence number is received and forwarded, and replaces the initial multicast tree with the new multicast tree afterwards.

9 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast,
a trigger data generator that produces trigger data when the transmitting device has moved during a multicast session, the trigger data specifying a trigger condition that initiates a change from an initial multicast tree to a new multicast tree, the trigger data including the sequence number of a particular packet as the trigger condition, and
a trigger data distributor that sends the produced trigger data to the second access point where the transmitting device is visiting, as well as sending the produced trigger data in encapsulated form to the first access point to which the transmitting device has previously attached;
and
(b) a network control server that handles location registration of the transmitting device;
(c) a first packet routing device at the second access point, comprising:
a buffer that stores packets transmitted by the transmitting device during a period between reception of the trigger data and establishment of a new multicast tree and outputs the stored packets when the new multicast tree becomes ready;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated trigger data received and sends the decapsulated trigger data to the initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that finds the sequence number specified in the trigger data, maintains the initial multicast tree until a packet having the specified sequence number is received and forwarded, and replaces the initial multicast tree with the new multicast tree afterwards.

10 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast;
(b) a network control server comprising:
a command transmitter transmitting a pause-before-update command initiating a change from an initial multicast tree to a new multicast tree, as well as an anchor appointment command appointing an anchor that is positioned immediately below a root of the new multicast tree;
(c) a first routing device at an access point of the network to which the transmitting device attaches, the access routing device comprising:
an access routing controller that receives and forwards the pause-before-update command from the network control server to the initial multicast tree, produces trigger data including the sequence number of a particular packet as a trigger condition for switching to the new multicast tree, sends out the produced trigger data to the initial multicast tree, and holds outgoing packets of the transmitting device temporarily until an entry request is received in response to the trigger data that is sent;
(d) a second routing device next to the first routing device on the new multicast tree, comprising:
an anchor routing controller that, upon recognition of the second routing device as an anchor router from the anchor appointment command received from the network control server, receives and forwards an entry request from the new multicast tree to the first routing device, and receives and forwards packets from the first routing device to the new multicast tree;
and
(e) a third routing device, comprising:
an update processor that sends the entry request toward the first routing device in response to the pause-before-update command forwarded from the first routing device, and keeps the current multicast tree active until a packet with the sequence number specified in the trigger data is received and forwarded.

8 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast;
and
a trigger/address sender that produces trigger data and transmits the produced trigger data, together with an address of the second access point that the transmitting device is going to visit during a multicast session, the trigger data specifying a trigger condition that initiates a change from an initial multicast tree to a new multicast tree, the trigger data including the sequence number of a particular packet as the trigger condition;
(b) a network control server that handles location registration of the transmitting device and manages the multicast tree, the network control server comprising:
a trigger data distributor that receives the trigger data from the transmitting device and forwards the trigger data to the second access point where the transmitting device is visiting, as well as sending the trigger data in encapsulated form to the packet routing device at the first access point to which the transmitting device has previously attached;
(c) a first packet routing device at the second access point and at least one neighboring packet routing device thereof on a new multicast tree, the first packet routing device comprising:
an entry request handler that begins to wait for a multicast service entry request from the neighboring packet routing device in response to the trigger data from the network control server and upon receipt thereof, begins to route packets from the transmitting device to the new multicast tree;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated trigger data received and sends the decapsulated trigger data to the initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that finds the sequence number specified in the trigger data, maintains the initial multicast tree until a packet having the specified sequence number is received and forwarded, and replaces the initial multicast tree with the new multicast tree afterwards.

10 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast;
and
a multicast control data generator that produces multicast control data for building and controlling multicast trees and sends the multicast control data together with a location registration request when the transmitting device has moved during a multicast session;
(b) a network control server that handles the location registration request from the transmitting device and manages multicast trees, the network control server comprising:
a multicast control data distributor that receives the multicast control data from the transmitting device and forwards the multicast control data to the second access point where the transmitting device is visiting, as well as sending the multicast control data in encapsulated form to the first access point to which the transmitting device has previously attached;
(c) a first packet routing device at the second access point, comprising:
a buffer that stores packets transmitted by the transmitting device during a period between reception of the multicast control data and establishment of a new multicast tree and outputs the stored packets when the new multicast tree becomes ready;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated multicast control data received from the network control server and sends the decapsulated multicast control data to an initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that replaces the initial multicast tree with the new multicast tree according to the multicast control data.

10 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast;
a multicast control data generator that produces multicast control data for building and controlling multicast trees and sends the multicast control data together with a location registration request when the transmitting device has moved during a multicast session;
and
a multicast control data distributor that sends the produced multicast control data to the second access point where the transmitting device is visiting, as well as sending the produced multicast control data in encapsulated form to the first access point to which the transmitting device has previously attached;
(b) a network control server that handles location registration of the transmitting device;
(c) a first packet routing device at the second access point, comprising:
a buffer that stores packets transmitted by the transmitting device during a period between reception of the multicast control data and establishment of a new multicast tree and outputs the stored packets when the new multicast tree becomes ready;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated multicast control data received from the network control server and sends the decapsulated multicast control data to an initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that replaces the initial multicast tree with the new multicast tree according to the multicast control data.

10 more elements

A multicast communications system for multicasting packets through a multicast tree on a network, the system comprising:

(a) a transmitting device capable of moving from a first access point to a second access point in the network, the transmitting device comprising:
a multicast transmitter that transmits packets while adding a sequence number to each packet to be multicast, and
a multicast control data/address sender that produces multicast control data for building and controlling multicast trees and transmits beforehand the produced multicast control data, together with an address of the second access point that the transmitting device is going to visit during a multicast session;
(b) a network control server that handles location registration of the transmitting device and manages multicast trees, the network control server comprising:
a multicast control data distributor that receives the multicast control data from the transmitting device and forwards the multicast control data to the second access point where the transmitting device is visiting, as well as sending the multicast control data in encapsulated form to the first access point to which the transmitting device has previously attached;
(c) a first packet routing device at the second access point and at least one neighboring packet routing device thereof on a new multicast tree, the first packet routing device comprising:
an entry request handler that begins to wait for a multicast service entry request from the neighboring packet routing device in response to the multicast control data from the network control server and upon receipt thereof, begins to route packets from the transmitting device to the new multicast tree;
(d) a second packet routing device at the first access point, comprising:
a decapsulator that decapsulates the encapsulated multicast control data received from the transmitting device and sends the decapsulated multicast control data to an initial multicast tree;
and
(e) a third packet routing device on the initial multicast tree, comprising:
an update processor that replaces the initial multicast tree with the new multicast tree according to the multicast control data.

9 more elements

A method of multicasting packets over a multicast tree on a network, the method comprising:

transmitting multicast packets from a transmitting device to an access point of the network, while adding a sequence number to each multicast packet;
sending trigger data to an initial multicast tree, the trigger data specifying a trigger condition that initiates a change from the initial multicast tree to a new multicast tree;
preparing the new multicast tree at each routing device that has received the trigger data, depending on a current state of the initial multicast tree;
and
switching from the initial multicast tree to the new multicast tree at each routing device upon receipt of a multicast packet that meets the trigger condition specified by the trigger data.

2 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/853,126Filed 11 Sep 2007 · continuation
Priority: 25 Mar 2005
Published: US 2008/0002693 A13 Jan 2008
Granted: 27 Oct 2009
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04L 45/00
Routing or path finding of packets in data switching networks
H04L 12/1863
For broadcast or conference , e.g. multicast: comprising mechanisms for improved reliability, e.g. status reports
H04L 45/16
Routing or path finding of packets in data switching networks: multipoint routing
H04L 12/189
For broadcast or conference , e.g. multicast: in combination with wireless systems

Family

PCT/JP2005/005517Parent of this continuation · filed 25 Mar 2005
US 2008/0002693 A1Pre-grant publication · published 3 Jan 2008
US 7,609,694 B2This patent

From the US filing history. Foreign family members aren’t listed.

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