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A NOVEL TECHNIQUE TO ACCELERATE CONVERGENCE OF LOW-POWER AND LOSSY NETWORKS UNDER POWER OUTAGE OCCURRENCE

IP.com Disclosure Number: IPCOM000250490D
Publication Date: 2017-Jul-25
Document File: 5 page(s) / 257K

Publishing Venue

The IP.com Prior Art Database

Related People

Dapeng Zhu: AUTHOR [+4]

Abstract

A node recognizes a power outage notification (PON). If the PON is sent by the node's parents, the node may quickly reselect novel parents. This may accelerate network convergence and avoid relaying a power restore notification (PRN) received from the removed parents along an invalid path. A downward route maintainer (e.g., nodes working in routing protocol for low-power and lossy networks (RPL) storing mode, field area routers (FAR), etc.) recognizes the PON and checks the routing table. If there are routes to the PON sender, the downward route maintainer may delete the downward route entry to the sender and report a no-path destination advertisement object message for a route poison reverse.

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Copyright 2017 Cisco Systems, Inc. 1

A NOVEL TECHNIQUE TO ACCELERATE CONVERGENCE OF LOW-POWER AND LOSSY NETWORKS UNDER POWER OUTAGE OCCURRENCE

AUTHORS: Dapeng Zhu

Yuping Wang Rui Huang

Xiaopu Zhang

CISCO SYSTEMS, INC.

ABSTRACT

A node recognizes a power outage notification (PON). If the PON is sent by the

node’s parents, the node may quickly reselect novel parents. This may accelerate network

convergence and avoid relaying a power restore notification (PRN) received from the

removed parents along an invalid path. A downward route maintainer (e.g., nodes working

in routing protocol for low-power and lossy networks (RPL) storing mode, field area

routers (FAR), etc.) recognizes the PON and checks the routing table. If there are routes to

the PON sender, the downward route maintainer may delete the downward route entry to

the sender and report a no-path destination advertisement object message for a route poison

reverse.

DETAILED DESCRIPTION

Low-power and lossy networks (LLNs) face several communication challenges

when a power outage occurs:

1) When a LLN device, as the preferred parent of some other devices, loses its

power, the LLN device fails to forward packets from its children devices to the LLN edge

router. Furthermore, data collected by the children devices cannot reach the Field Area

Router (FAR) until they reselect their parents. Because the process of reselecting parents

normally lasts dozens of minutes, the data with expired retransmitting times are dropped

during the power outage period.

As illustrated in Figure 1 below, three subnets are named A, B and C (the subnets

split based on spatial position rather than network address). Subnets A and B have a higher

rank than C, and packets from C to FAR must travel through A or B. Nodes a1/a2, b1/b2,

Copyright 2017 Cisco Systems, Inc. 2

and c1/c2 are edge nodes. Node c1 has preferred parent a1 and backup parent b1. Node c2

has preferred parent a2 and backup parent b2.

Figure 1

When a power outage occurs on subnet A, communications between C and FAR

via A are interrupted, and will not recover until route path FAR-A-C switches to FAR-B-

Copyright 2017 Cisco Systems, Inc. 3

C. This personal area network (PAN) migration process typically requires a large amount

of time.

When a power outage occurs on subnet C, there are two general scenarios: one

involving RPL non-storing mode, and one involving RPL storing mode. In RPL non-

storing mode, FAR may still forward packets to subnet C while C is suffering from the

power outage, because FAR determines whether C is reachable according to a downward

route table that is based on the destination advertisement object (DAO) message received

from devices in subnet C. Unfortunately, the downward route entries have long lifetimes,

and therefore FAR cannot consider that subnet C is unreachable until the lifetime(s) has

decreased to zero.

In the RPL storing mode, FAR directly forward packets to subnet C when C is

suffering from the power outage (because these pac...