Internet DRAFT - draft-hong-lwig-sleepmode-control
draft-hong-lwig-sleepmode-control
Network Working Group Y. Hong
Internet-Draft ETRI
Intended status: Informational J. Youn
Expires: May 11, 2014 DONG-EUI Univ.
November 07, 2013
Sleep node control mechanism for Constrained networks
draft-hong-lwig-sleepmode-control-00
Abstract
This document describes the mechanism of sleep mode control. The
router which manages a network can control IPv6 sleepy nodes and
deliver the packets from/to exterior networks. The IPv6 router can
keep the IPv6 sleepy node as sleep state and handle the packets from/
to the IPv6 sleepy nodes. Also, this document describes the
mechanism of sleep mode control using synchronization information.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Related Work and Background . . . . . . . . . . . . . . . . . 3
4. Sleep mode control mechanism . . . . . . . . . . . . . . . . 3
4.1. Sleep mode request/response . . . . . . . . . . . . . . . 4
4.2. Sleep mode advertisement by Router . . . . . . . . . . . 5
4.3. Sleep mode control by using synchronization information . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
In order to minimize the use of the battery of devices which are not
always connected to a power source, the devices become asleep (sleep
mode) for a long time and wake up to communicate (active mode) for a
short time. To keep the exact time of sleep mode/active mode of the
devices, the network usually utilizes the synchronization information
of a Base Station or an Access Point. Although the devices
switchover between active mode and sleep mode, the protocol in PHY/
MAC layer knows the transit time in advance through the
synchronization information.
The goals for power management may be different by the conditions of
device and environment. The general strategies for power management
of various conditions are depicted as always-on, always-off, and low-
power [I-D.arkko-lwig-cellular]. A constrained node, creating
constrained node networks, may occasionally go into sleep mode
according to strategies of using power for communication
[I-D.ietf-lwig-terminology]. In [I-D.ietf-lwig-terminology], a
device is divided into four classes according to energy limitation of
a device. Here, the constrained nodes classed such as class E1 and
E2 in classes of energy limitation may occasionally go into sleepy
mode. Thus, in constrained node networks, there can exist the end-
to-end communications between a sleep mode node and a non-sleep mode
node.
Recently, the power management issues arise in not only PHY/MAC layer
but also above network layer. In network/transport/application
layer, it is assumed that the network devices are always connected
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and ready to communicate. But, as various smart object devices
become connected to the Internet and power management to save battery
of devices is required.
2. Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
3. Related Work and Background
Power saving in wireless networks is mainly accomplished in PHY/MAC
layer. The basic idea of power saving in PHY/MAC layer is to
minimize the time of transmission/receipt. In IEEE 802.11 WLAN, the
feature of power saving is Power Save Mode (PSM) that is available
for nodes existing in an infrastructure based IEEE 802.11 WLAN. PSM
is based on a synchronous sleep scheduling policy, in which wireless
nodes are able to alternate between an active mode and a sleep mode
[PowerMgmt].
Recently, the consideration of power saving is moved to network
layer, too. In 6lowpan, the Neighbor Discovery operations must
consider the low-power wireless personal area networks such as IEEE
802.15.4. Because the usage of multicast signaling raises severe
energy consumption, the Neighbor Discovery optimization for 6lowpan
has limited the usage of multicast signaling [I-D.ietf-6lowpan-nd].
In application layer, the CoAP has two functions such as proxy and
cache. The proxy function in the CoAP can cache and service requests
for sleepy servers. Thus, a client sends a CoAP request to a proxy
on behalf of an origin server of sleep mode and then it respond
directly to the client through the proxy. Otherwise if the proxy has
an invalid representation of the resource in its cache, the proxy has
to attempt to get the valid resource from an origin server of sleep
mode. The attempt may or may not be successful according to the
state of the origin server [I-D.ietf-core-coap].
4. Sleep mode control mechanism
Figure 1 shows the environment where the sleep mode control mechanism
is used. In the constrained network, one or more sleepy nodes are
connected to the router which manages the constrained network and the
router is connected to external network.
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+---------------+
+---------------+ | | +--------------------+
|+------+ +------+ | | +------+ +----------+ |
||Sleepy|--|Router|---+ +---|Router|--|Non-Sleepy| |
|| node | +------+ | | +------+ | node | |
|+------+ | | | | | | +----------+ |
| | | | Internet | | | |
|+------+ | | | | | | +----------+ |
||Sleepy|---+ | | | | +---|Non-Sleepy| |
|| node | | | | | | node | |
|+------+ | | | | +----------+ |
+---------------+ | | +--------------------+
Constrained +---------------+ General
networks networks
Figure 1: Environment where sleep mode control mechanism is used
4.1. Sleep mode request/response
If a sleepy host wants to enter to sleep mode, it sends a request
message to the router. The router which receives the request message
records the status of the sleepy node as sleep mode. And then, the
router sends a response message to confirm the request. If the
sleepy node receives the request message, it enters sleep mode. The
router which manages the constrained network sends the status of the
sleepy node to the corresponding nodes if the sleepy node is
communicating. So, the corresponding nodes immediately know the
status of the sleepy node. Figure 2 depicts this procedure.
Constrained netwokr General network
+-------------------------+ +----------------------------+
| +------+ +------+ +------+ +------------+ |
| |Sleepy|-----------|Router| |Router|--------| Non-Sleepy | |
| | node | | |-----| | | node | |
| +------+ +------+ +------+ +------------+ |
+-------------------------+ +----------------------------+
| | | |
| Sleep mode REQ | | |
|------------------->| | |
| | | |
| Host info -> Sleep mode | |
| | | |
| Sleep mode ACK | | |
|<-------------------| | |
| | | |
Sleep mode | | |
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| | Sleeping | |
| |Host Notice | |
| |----------->| |
| | | Sleeping Host |
| | | Notice |
| | |------------------->|
| | | |
Figure 2: Procedure of sleep mode request/response
4.2. Sleep mode advertisement by Router
If some conditions are satisfied or events are triggered, a router in
a constrained network sends a sleep mode advertisement message to
sleepy nodes. The sleep mode advertisement message includes the
start time and finish time of sleep mode. If sleepy nodes receive
the advertisement message, they enter sleep mode. Some cases, the
sleepy nodes may responds to the advertisement message. After the
router change the status of sleepy node to sleep mode and deliver the
status information of sleepy nodes to corresponding nodes if there
are corresponding nodes that are communicating to the sleepy nodes.
So, the corresponding nodes immediately know the status of the sleepy
nodes. Figure 3 depicts this procedure.
Constrained netwokr General network
+-------------------------+ +----------------------------+
| +------+ +------+ +------+ +------------+ |
| |Sleepy|-----------|Router| |Router|--------| Non-Sleepy | |
| | node | | |-----| | | node | |
| +------+ +------+ +------+ +------------+ |
+-------------------------+ +----------------------------+
| | | |
| Sleep mode Adv. | | |
|<-------------------| | |
| | | |
| (Sleep mode ACK) | | |
|------------------->| | |
| | | |
Sleep mode | | |
| | | |
| Host info -> Sleep mode | |
| | | |
| | Sleeping | |
| |Host Notice | |
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| |----------->| |
| | | Sleeping Host |
| | | Notice |
| | |------------------->|
| | | |
Figure 3: Procedure of sleep mode advertisement
If corresponding nodes sends packets to sleepy nodes, the router
which manages a constrained network retrieves sleeping node list. If
the target node is not included in the sleeping node list, the router
handles the packets as normal process. If the target node is
included in the sleeping node list, the router responds to the
corresponding nodes and informs that the target node is in sleep
mode. Figure 4 depicts this procedure.
Constrained netwokr General network
+-------------------------+ +----------------------------+
| +------+ +------+ +------+ +------------+ |
| |Sleepy|-----------|Router| |Router|--------| Non-Sleepy | |
| | node | | |-----| | | node | |
| +------+ +------+ +------+ +------------+ |
+-------------------------+ +----------------------------+
| | | |
| | | Pakcet to |
| | | Sleepy node |
| | |<-------------------|
| | Packet to | |
| |Sleepy node | |
| |<-----------| |
| Retrieve Sleeping node list | |
| | | |
| (if in the list) | | |
| Packet to | | |
| Sleepy node | | |
|<-------------------| (if not) | |
| | Sleeping | |
| |Host Notice | |
| |----------->| |
| | | Sleeping Host |
| | | Notice |
| | |------------------->|
| | | |
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Figure 4: Procedure of the handling of packets from external network
4.3. Sleep mode control by using synchronization information
Generally, Base station or Access Point is used to synchronize the
network entities. By using the synchronization information, the
network keeps the exact time of sleep mode/active mode of the network
entities. This synchronization information can be also used to
provide sleep mode control. Figure 5 shows the case where
synchronization information is used to provide sleep mode control.
In Figure 5, the base station offers the synchronization information
and this synchronization information is delivered to a router by
using Layer 2 or Layer 3 message or cross-layer mechanism. After the
router receives the synchronization information, it knows the sleep
mode status of sleepy nodes. If there are corresponding nodes that
are communicating to the sleepy nodes, the router delivers the status
information of sleepy nodes to the corresponding nodes.
Constrained netwokr General network
+--------------------+ +--------------------------+
| +------+ +------+ +-------+ +------+ +------------+ |
| |Sleepy|------|Router| | BS | |Router|------| Non-Sleepy | |
| | node | | |---| or AP |--| | | node | |
| +------+ +------+ +-------+ +------+ +------------+ |
+--------------------+ +--------------------------+
| | | | |
| |Sync. Info.| | |
| |<----------| | |
| Sync. Info. | | | |
|<-------------| | | |
| | | | |
| | Sleeping | | |
| |Host Notice| | |
| |---------->|--------->| |
| | | | Sleeping Host |
| | | | Notice |
| | | |----------------->|
| | | | |
Figure 5: Procedure of sleep mode control by using synchronization
information
5. Security Considerations
TBD.
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6. IANA Considerations
TBD
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
7.2. Informative References
[I-D.arkko-lwig-cellular]
Arkko, J., Eriksson, A., and A. Keranen, "Building Power-
Efficient CoAP Devices for Cellular Networks", ID draft-
arkko-lwig-cellular-00, February 2013.
[I-D.ietf-6lowpan-nd]
Shelby, Z., Chakrabartiy, S., and E. Nordmark, "Neighbor
Discovery Optimization for Low Power and Lossy Networks
(6LoWPAN)", ID draft-ietf-6lowpan-nd-21, August 2012.
[I-D.ietf-core-coap]
Shelby, Z., Hartke, K., and C. Bormann, "Constrained
Application Protocol (CoAP)", ID draft-ietf-core-coap-18,
June 2013.
[I-D.ietf-lwig-terminology]
Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained Node Networks", ID draft-ietf-lwig-
terminology-05, July 2013.
[PowerMgmt]
Klues, K., "Power Management in Wireless Networks",
Report, for Advanced Topics in Networking: Wireless and
Mobile Networking by R. Jain, Wash. Univ. in St. Louis, ,
2006.
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Authors' Addresses
Yong-Geun Hong
ETRI
218 Gajeong-ro Yuseung-Gu
Daejeon 305-700
Korea
Phone: +82 42 860 6557
Email: yghong@etri.re.kr
JooSang Youn
DONG-EUI Univ.
Busan
Korea
Phone: +82 51 890 1993
Email: joosang.youn@gmail.com
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