Multicast IP zones for fast spanning tree convergence in wide-area packet network systems

• US 20030058857A1
• Filed: 09/24/2001
• Published: 03/27/2003
• Est. Priority Date: 09/24/2001
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Maher, John W., Harrington, Patrick L.
• Granted Patent: US 7,009,972 B2
• Time in Patent Office: Days
• US Class Current: 370/390
• CPC Class Codes: H04L 12/185 with management of multicast group membership
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04L 45/484 using multiple routing trees

Abstract

System and methods for confining multicast routing trees to within single zones of a multi-zone communication systems, thereby enabling faster convergence of the trees relative to trees spanning multiple zones. Separate multicast routing trees are established using different multicast addresses in a source zone and one or more listening zones. Packets for a call distributed by routers (104, 116) of a packet network within the source zone via a source zone multicast address are received by a source zone packet duplicator (132). The source zone packet duplicator forwards the packets, via routers (116, 118, 120, 122) of the packet network using unicast routing, to various listening zone packet duplicators (136, 138). The listening zone packet duplicators, upon receiving the packets, separately distribute the packets within their respective zones via the packet network using different multicast addresses of the listening zones. The source zone and listening zones may be redefined during the call as the source changes or moves to different zones.

Claims

1. In a communication system organized into a plurality of participating zones for a call, a method comprising:

distributing one or more packets for the call, within a source zone of the participating zones, via a source zone multicast routing tree;

receiving the packets by a host associated with the source zone;

forwarding the packets by the host associated with the source zone to one or more hosts associated with listening zones of the participating zones;

receiving the packets by the hosts associated with the listening zones; and

separately re-distributing the packets within the listening zones via one or more separate listening zone multicast routing trees.

2. The method of claim 1, wherein the host associated with the source zone comprises a source zone packet duplicator, and wherein the hosts associated with the listening zones comprise listening zone packet duplicators.

3. The method of claim 1 comprising, prior to the step of distributing:

joining, by one or more recipient devices including at least the source zone packet duplicator, a multicast address associated with the source zone, defining a source zone multicast address;

establishing, by one or more network devices, the source zone multicast routing tree logically interconnecting the recipient devices having joined the source zone multicast address; and

sending, from a communication source in the source zone to the one or more network devices, one or more packets addressed to the source zone multicast address.

4. The method of claim 3, wherein the step of distributing comprises delivering, by the network devices to the recipient devices, the one or more packets addressed to the source zone multicast address.

5. The method of claim 3 further comprising the steps of:

determining that the call has ended;

leaving, by the recipient devices, the source zone multicast address; and

de-establishing, by the one or more network devices, the source zone multicast routing tree.

6. The method of claim 3 further comprising the steps of:

redefining the source zone and listening zones, thereby defining a former source zone packet duplicator and a new source zone packet duplicator, a former source zone multicast address and a new source zone multicast address;

leaving, by the former source zone packet duplicator, the former source zone multicast address; and

joining, by the new source zone packet duplicator, the new source zone multicast address.

7. The method of claim 6, wherein the step of re-defining the source zone and listening zones is accomplished in response to payload for the call becoming sourced in the new source zone.

8. The method of claim 1, wherein the step of forwarding comprises:

sending, from the first host to one or more network devices, one or more packets addressed to the secondary hosts; and

routing the packets from the one or more network devices to the secondary hosts.

9. The method of claim 8, comprising:

receiving, by the first host, unicast addresses of the secondary hosts, the step of sending comprising sending the one or packets to the unicast addresses.

10. The method of claim 1 comprising, prior to the step of separately redistributing:

joining, by recipient devices in different ones of the listening zones, different listening zone multicast addresses; and

establishing, by one or more network devices, the separate listening zone multicast routing trees logically interconnecting the recipient devices in the different listening zones having joined the different listening zone multicast addresses.

11. The method of claim 10, wherein the step of separately re-distributing comprises

separately sending, from the secondary hosts associated with the different listening zones to one or more network devices, one or more packets addressed to the different listening zone multicast addresses;

and

delivering, by the network devices to the recipient devices in the different listening zones, the one or more packets addressed to the different listening zone multicast addresses.

12. The method of claim 10 further comprising the steps of:

determining that the call has ended;

leaving, by the recipient devices in the different zones, the different listening zone multicast addresses; and

de-establishing, by the one or more network devices, the separate listening zone multicast routing trees.

13. A method comprising the steps of:

receiving, from a communication source, a request for a call;

identifying a plurality of participating zones for the call, the participating zones defining a source zone and one or more listening zones;

instructing a source zone packet duplicator to begin a call source sequence, whereby the source zone packet duplicator receives payload for the call sourced in the source zone;

instructing the source zone packet duplicator to forward the payload to one or more listening zones packet duplicators associated with the one or more listening zones; and

instructing the one or more listening zone packet duplicators to begin a call listen sequence, whereby the listening zone packet duplicators receive payload forwarded by the source zone packet duplicator and distribute the payload within their respective zones.

14. The method of claim 13, performed by one or more zone controllers associated with the participating zones.

15. The method of claim 14, further comprising the zone controllers identifying a source zone multicast address to be used for distributing payload for the call within the source zone, and one or more listening zone multicast addresses for separately distributing payload within the listening zones.

16. The method of claim 15, wherein the step of instructing the source zone packet duplicator to begin a call source sequence comprises instructing the source zone packet duplicator to join the source zone multicast group address.

17. The method of claim 15, wherein the step of instructing the listening zone packet duplicators to begin a call listen sequence comprises instructing the listening zone packet duplicators, upon receiving the payload forwarded from the source zone packet duplicator, to distribute the payload within their respective zones via the listening zone multicast addresses.

18. A communication system comprising:

a plurality of communication devices participating in a call, the communication devices being distributed among a plurality of participating zones;

a packet network for routing one or more packets for the call, within a source zone of the participating zones, via a source zone multicast address, from the source zone to one or more listening zones of the participating zones via respective unicast addresses, and within the listening zones, via one or more separate listening zone multicast addresses;

a source zone packet duplicator for receiving packets within the source zone and forwarding the packets to the packet network, for routing to the listening zones via the unicast addresses;

one or more listening zone packet duplicators for receiving the packets forwarded from the source zone and sending the packets to the packet network, for routing within the listening zones via the separate listening zone multicast addresses.