Internet DRAFT - draft-garneij-ipv6-nd-m2m-issues
draft-garneij-ipv6-nd-m2m-issues
6man WG F. Garneij
Internet-Draft Ericsson
Intended status: Informational February 14, 2014
Expires: August 18, 2014
IPv6 Periodic RA Cellular Impact Investigation
draft-garneij-ipv6-nd-m2m-issues-00.txt
Abstract
The use of IPv6 in 3GPP cellular broadband for accessing the Internet
and other data services like VoLTE via smartphones has increased as a
result of EPS network deployments worldwide and new IPv6 capable
smartphones tablets, and netbook computers. The upcoming rise of
IoT/M2M is anticipated to bring billions of new devices into these
networks and the majority of these devices will be using only IPv6.
This document discusses the EPS network impact of IoT/M2M IPv6
connectivity specifically targeting the IPv6 Stateless Address Auto
Configuration (SLAAC), as specified in [RFC4861] and [RFC4862], which
currently is the only supported IPv6 address configuration mechanism
in 3GPP standards.
Status of this Memo
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This Internet-Draft will expire on August 18, 2014.
Copyright Notice
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document authors. All rights reserved.
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Table of Contents
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. The M2M Scenario and Neighbor Discovery Impact . . . . . . . . 4
3. Definition Of Terms . . . . . . . . . . . . . . . . . . . . . . 4
4. Analysis of Results . . . . . . . . . . . . . . . . . . . . . . 5
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Appendix A. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 6
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1. Background
Conceptually, IPv6 multicast messages are supposed to avoid broadcast
messages, but in practice, the multicast operation at many link
layers the mutlicast message is a broadcast. 3GPP links are cellular
links consuming expensive radio spectrum. Thus such radio networks
like to limit unnecessary signals in the network. IPv6 neighbor
discovery being the heart of IPv6 protocol, the document shows how it
can affect the cellular networks for M2M. M2M networks are usually
low bandwidth radio networks.
In 3GPP networks, mobility and connectivity is generated by the
arrangement of allocated radio resources and EPC node resources into
a PDN connection. The following list gives the logical functions
performed within the Evolved Packet System (EPS):
o Network Access Control Functions.
o Packet Routing and Transfer Functions
o Mobility Management Functions.
o Security Functions
o Radio Resource management functions
o Network Management Functions
For a User Equipment (UE) attached to a 3GPP network there are
procedures defined related to device mobility, EPS Mobility
Management (EMM) states and connectivity session, EPS Connectivity
Management (ECM) states as described in [TS.23401] Section 4.6. The
purpose of this document is to analyze the EPS resources impacted by
the procedures of the IPv6 Stateless Address Auto Configuration
(SLAAC), as specified in [RFC4861] and [RFC4862], as it is utilized
in 3GPP standards. Special attention is put on EPS control signaling
load and UE targeting packets generated by IPv6 periodic Router
Advertisements (unsolicited multicast Router Advertisements). In an
effort to adapt initial and periodic Router Advertisements in order
to preserve radio resources and UE power consumption while still
allowing for appropriate robustness and fast user-plane set-up time
even in bad radio conditions to the radio, 3GPP has defined specific
values and behavior for Router Advertisement in 3GPP TS 29.061
Section 11.2.1.3.4 IPv6 Router Configuration Variables.
Since in EPS, radio and network resources are not permanently
assigned to a specific UE there is a cost associated with the
allocation and release of resources and associated changes of states
in EPS nodes. It is desirable to reduce or avoid any additional
periodic packets that are not of any use to the application using the
3GPP derived UE connectivity. 2G and 3G radio resource allocation
have their own mechanisms with similar functionality but these are
not described or considered in this document.
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2. The M2M Scenario and Neighbor Discovery Impact
The analysis considers an IoT/M2M UE deployment scenario with less
frequent packet communications occurrences than would normally be
seen in a smartphone. Given an infrequent communication pattern the
current ECM state before a downlink packet is to be sent, UE ECM
state is with high probability going to be found in state IDLE.
Sending a packet to the UE while in ECM_IDLE state triggers UE Paging
followed by a UE Service Request and radio resource allocation.
These procedures are considered as among the heavier procedures in
EPS with regards to control signaling load and node state changes.
They are energy consuming in radio and in node processing power
utilized by the procedures. It is also likely that other devices
with different communications usage patterns like smartphones may
compete over network resources causing the procedure to be repeated
on order to complete. It should be noted that in addition to
establishing connectivity, security functions create node state that
are used in the UE Service Request procedure to provide
authentication, ciphering and integrity protection.
The use case to be analyzed considers the following network
dimensioning for a single P-GW node based on estimations and derived
from real world network deployment best practices:
o There are 10,000,000 simultaneous IPv6 PDN connections to IoT/M2M
devices. No dedicated bearers. Communication direction for IoT/
M2M service is from network to UE infrequent (e.g. twice a day or
less). GTP-U is used between P-GW and S-GW as described in
TS.23401 of 3GPP specification
o EPS Connectivity Management (ECM) state is ECM_IDLE, paging will
be done
o Tracking Area (TA) contains 100 base stations (eNodeB)
o MME UE Tracking Area Identifier (TAI) list containing 10 TA which
gives 10 * 100 eNodeB = 1000 eNodeB for a UE TAI list
o Calculation: periodic Router Advertisement interval is 18900 s
(5,25h)
The analysis focus on the connectivity state changes and resource
allocation are related to 1) Packet Routing and Transfer Functions 2)
Mobility Management Functions 3) Radio Resource Management Functions
3. Definition Of Terms
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].
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3GPP
Third Generation Partnership Project. Throughout the document,
the term "3GPP networks" refers to architectures standardized by
3GPP, in Second, Third, and Fourth Generation releases: 99, 4, and
5, as well as future releases.
EPS
Evolved packet System
eNodeB
The eNodeB is a base station entity that supports the Long-Term
Evolution (LTE) air interface.
MME
Mobility Management Entity
UE
User Equipment or host terminal
M2M
Machine to Machine Communication networks and related standards.
M2M includes industrial networks and communication.
4. Analysis of Results
If the periodic router advertisements are allowed in the network, the
measurement result shows that approximately 529 PPS(RA) can be sent
to the eNodeB from the Edge Router/Gateway device(PDN GW). And there
is ~100 to ~1000 state changes per second for MME, eNodeB, UE in the
network.
It has been shown that a single downlink packet consumes energy and
bandwidth and ties up resources in the EPS network and UE. It is
desirable to free up the 3GPP networks from periodic signaling
traffic (in this case IPv6 ND) so that the bandwith can be used for
packets that have business values.
5. Acknowledgements
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
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[6LOWPAN-ND]
Shelby, Z., Chakrabarti, S., Nordmark, E., and C. Bormann,
"ND Optimizations for 6LoWPAN", RFC 6775, November 2012.
[ND] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6", RFC 4861,
September 2007.
6.2. Informative References
[IPV6] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6), Specification", RFC 2460, December 1998.
[AUTOCONF]
Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Autoconfiguration", RFC 4862, September 2007.
[3GPP] Korhonen, J., "IPv6 in 3rd Generation Partnership Project
(3GPP) Evolved Packet System (EPS)", RFC 6459,
January 2012.
Appendix A.
Author's Address
Fredrik Garneij
Ericsson
Sweden
Email: fredrik.garneij@ericsson.com
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