# US 11,909,543 B2 · Multicast-only thin DODAG in low power and lossy network

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- Number: US 11,909,543 B2
- Document ID: US11909543B2
- Status: Granted
- Kind: B2
- Application number: 17/727,348
- Filed: 2022-04-22
- Published: 2022-08-04
- Granted: 2024-02-20
- Earliest claimed: 2020-04-09
- Assignees: Cisco Technology, Inc.
- Applicants: Cisco Technology, Inc.
- Inventors: Pascal Thubert; Huimin She; Feiliang Wang; Yinfang Wang
- Web page: https://patentgrep.com/patent/US11909543B2

## CPC

- H04L 12/1881: {with schedule organisation, e.g. priority, sequence management}
- H04L 12/18: for broadcast or conference {, e.g. multicast}
- H04L 45/16: Multipoint routing
- H04L 45/48: Routing tree calculation
- H04L 49/201: Multicast operation; Broadcast operation
- H04L 65/611: for multicast or broadcast (systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06)
- H04L 65/80: Responding to QoS
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

In one embodiment, a method comprises: generating, by a constrained low power and lossy network (LLN) device that is localized within a subregion of an LLN, a thin destination oriented directed acyclic graph (DODAG) having up to a prescribed limit of attached LLN devices at each hop of the thin DODAG based on generating a DODAG information object (DIO) message specifying an instruction for limiting attachment at each hop of the thin DODAG to the prescribed limit; and causing, by the constrained LLN device, multicast-only transmissions via the thin DODAG based on inserting into the DIO message a multicast-only transmission mode via the thin DODAG and outputting the DIO message, the DIO message causing each neighboring LLN device to selectively attach to the constrained LLN device as an attached child LLN device based on the instruction and execute the multicast-only transmissions via the thin DODAG.

## Claims

### Claim 1

A method comprising:
generating, by a network device, a destination oriented directed acyclic graph (DODAG) that is rooted by the network device, the generating of the DODAG based on outputting an instruction implementing multicast communication in the DODAG; and
multicasting, by the network device, a targeted packet that is destined for at least one targeted member device of the DODAG, the targeted packet causing sequential unicast communications in the DODAG,
wherein the targeted packet causes a router device in the DODAG to establish a unicast route for reaching the destination device within a prescribed limited number of hops, and
wherein the targeted packet is a unicast packet specifying a destination address encapsulated within a multicast packet specifying a multicast address, the at least one targeted member device operating as a destination device and processing the unicast packet in response to detecting the destination address associated with the destination device.

### Claim 2 (depends on 1)

The method of claim 1, further comprising:
receiving from the targeted member device an advertisement message that enables the network device to reach the destination device via a next-hop network device; and
causing unicast transmission to the destination device for up to a limited state lifetime interval, based on receiving the advertisement message.

### Claim 3 (depends on 2)

The method of claim 2, wherein the limited state lifetime interval is based on a prescribed schedule specified by the network device.

### Claim 4

An apparatus implemented as a physical machine, the apparatus comprising:
non-transitory machine readable media configured for storing executable machine readable code, wherein the apparatus is implemented as network device;
a device interface circuit; and
a processor circuit configured for executing the machine readable code, and when executing the machine readable code operable for:
generating a destination oriented directed acyclic graph (DODAG) that is rooted by the network device, the generating of the DODAG based on outputting an instruction implementing multicast communication in the DODAG, and
multicasting a targeted packet that is destined for at least one targeted member device of the DODAG, the targeted packet causing sequential unicast communications in the DODAG,
wherein the targeted packet causes a router device in the DODAG to establish a unicast route for reaching the destination device within a prescribed limited number of hops, and
wherein the targeted packet is a unicast packet specifying a destination address encapsulated within a multicast packet specifying a multicast address, the at least one targeted member device operating as a destination device and processing the unicast packet in response to detecting the destination address associated with the destination device.

### Claim 5 (depends on 4)

The apparatus of claim 4, wherein the processor circuit is configured for:
receiving from the targeted member device an advertisement message that enables the network device to reach the destination device via a next-hop network device; and
causing unicast transmission to the destination device for up to a limited state lifetime interval, based on receiving the advertisement message.

### Claim 6 (depends on 5)

The apparatus of claim 5, wherein the limited state lifetime interval is based on a prescribed schedule specified by the network device.

### Claim 7

One or more non-transitory tangible media encoded with logic for execution by a machine and when executed by the machine operable for:
generating, by the machine implemented as a network device, a destination oriented directed acyclic graph (DODAG) that is rooted by the network device, the generating of the DODAG based on outputting an instruction implementing multicast communication in the DODAG; and
multicasting a targeted packet that is destined for at least one targeted member device of the DODAG, the targeted packet causing sequential unicast communications in the DODAG,
wherein the targeted packet causes a router device in the DODAG to establish a unicast route for reaching the destination device within a prescribed limited number of hops, and
wherein the targeted packet is a unicast packet specifying a destination address encapsulated within a multicast packet specifying a multicast address, the at least one targeted member device operating as a destination device and processing the unicast packet in response to detecting the destination address associated with the destination device.

### Claim 8 (depends on 7)

The or more non-transitory tangible media of claim 7, further operable for:
receiving from the targeted member device an advertisement message that enables the network device to reach the destination device via a next-hop network device; and
causing unicast transmission to the destination device for up to a limited state lifetime interval, based on receiving the advertisement message.