draft-ietf-mboned-ieee802-mcast-problems-09.txt   draft-ietf-mboned-ieee802-mcast-problems-10.txt 
Internet Area C. Perkins Internet Area C. Perkins
Internet-Draft Internet-Draft
Intended status: Informational M. McBride Intended status: Informational M. McBride
Expires: March 29, 2020 Futurewei Expires: May 7, 2020 Futurewei
D. Stanley D. Stanley
HPE HPE
W. Kumari W. Kumari
Google Google
JC. Zuniga JC. Zuniga
SIGFOX SIGFOX
September 26, 2019 November 4, 2019
Multicast Considerations over IEEE 802 Wireless Media Multicast Considerations over IEEE 802 Wireless Media
draft-ietf-mboned-ieee802-mcast-problems-09 draft-ietf-mboned-ieee802-mcast-problems-10
Abstract Abstract
Well-known issues with multicast have prevented the deployment of Well-known issues with multicast have prevented the deployment of
multicast in 802.11 and other local-area wireless environments. This multicast in 802.11 and other local-area wireless environments. This
document offers guidance on known limitations and problems with document offers guidance on known limitations and problems with
wireless Layer-2 multicast. Also described are certain multicast wireless (primarily 802.11) Layer-2 multicast. Also described are
enhancement features that have been specified by the IETF and by IEEE certain multicast enhancement features that have been specified by
802 for wireless media, as well as some operational choices that can the IETF and by IEEE 802 for wireless media, as well as some
be taken to improve the performance of the network. Finally, some operational choices that can be taken to improve the performance of
recommendations are provided about the usage and combination of these the network. Finally, some recommendations are provided about the
features and operational choices. usage and combination of these features and operational choices.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on March 29, 2020. This Internet-Draft will expire on May 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 28 skipping to change at page 2, line 28
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Identified multicast issues . . . . . . . . . . . . . . . . . 5 3. Identified multicast issues . . . . . . . . . . . . . . . . . 5
3.1. Issues at Layer 2 and Below . . . . . . . . . . . . . . . 5 3.1. Issues at Layer 2 and Below . . . . . . . . . . . . . . . 5
3.1.1. Multicast reliability . . . . . . . . . . . . . . . . 5 3.1.1. Multicast reliability . . . . . . . . . . . . . . . . 5
3.1.2. Lower and Variable Data Rate . . . . . . . . . . . . 6 3.1.2. Lower and Variable Data Rate . . . . . . . . . . . . 6
3.1.3. High Interference . . . . . . . . . . . . . . . . . . 7 3.1.3. Capacity and Impact on Interference . . . . . . . . . 7
3.1.4. Power-save Effects on Multicast . . . . . . . . . . . 7 3.1.4. Power-save Effects on Multicast . . . . . . . . . . . 7
3.2. Issues at Layer 3 and Above . . . . . . . . . . . . . . . 7 3.2. Issues at Layer 3 and Above . . . . . . . . . . . . . . . 7
3.2.1. IPv4 issues . . . . . . . . . . . . . . . . . . . . . 8 3.2.1. IPv4 issues . . . . . . . . . . . . . . . . . . . . . 8
3.2.2. IPv6 issues . . . . . . . . . . . . . . . . . . . . . 8 3.2.2. IPv6 issues . . . . . . . . . . . . . . . . . . . . . 8
3.2.3. MLD issues . . . . . . . . . . . . . . . . . . . . . 9 3.2.3. MLD issues . . . . . . . . . . . . . . . . . . . . . 9
3.2.4. Spurious Neighbor Discovery . . . . . . . . . . . . . 9 3.2.4. Spurious Neighbor Discovery . . . . . . . . . . . . . 9
4. Multicast protocol optimizations . . . . . . . . . . . . . . 10 4. Multicast protocol optimizations . . . . . . . . . . . . . . 10
4.1. Proxy ARP in 802.11-2012 . . . . . . . . . . . . . . . . 10 4.1. Proxy ARP in 802.11-2012 . . . . . . . . . . . . . . . . 10
4.2. IPv6 Address Registration and Proxy Neighbor Discovery . 11 4.2. IPv6 Address Registration and Proxy Neighbor Discovery . 11
4.3. Buffering to Improve Battery Life . . . . . . . . . . . . 12 4.3. Buffering to Improve Battery Life . . . . . . . . . . . . 12
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5.2. Mitigating Spurious Service Discovery Messages . . . . . 18 5.2. Mitigating Spurious Service Discovery Messages . . . . . 18
6. Multicast Considerations for Other Wireless Media . . . . . . 18 6. Multicast Considerations for Other Wireless Media . . . . . . 18
7. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 19 7. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 19
8. Discussion Items . . . . . . . . . . . . . . . . . . . . . . 19 8. Discussion Items . . . . . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20 9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 20
12. Informative References . . . . . . . . . . . . . . . . . . . 20 12. Informative References . . . . . . . . . . . . . . . . . . . 20
Appendix A. Changes in this draft between revisions 06 versus 07 24 Appendix A. Changes in this draft between revisions 06 versus 07 24
Appendix B. Changes in this draft between revisions 05 versus 06 24 Appendix B. Changes in this draft between revisions 05 versus 06 24
Appendix C. Changes in this draft between revisions 04 versus 05 24 Appendix C. Changes in this draft between revisions 04 versus 05 25
Appendix D. Changes in this draft between revisions 03 versus 04 25 Appendix D. Changes in this draft between revisions 03 versus 04 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction 1. Introduction
Well-known issues with multicast have prevented the deployment of Well-known issues with multicast have prevented the deployment of
multicast in 802.11 [dot11] and other local-area wireless multicast in 802.11 [dot11] and other local-area wireless
environments, as described in [mc-props], [mc-prob-stmt]. environments, as described in [mc-props], [mc-prob-stmt].
Performance issues have been observed when multicast packet Performance issues have been observed when multicast packet
transmissions of IETF protocols are used over IEEE 802 wireless transmissions of IETF protocols are used over IEEE 802 wireless
media. Even though enhancements for multicast transmissions have media. Even though enhancements for multicast transmissions have
been designed at both IETF and IEEE 802, incompatibilities still been designed at both IETF and IEEE 802, incompatibilities still
exist between specifications, implementations and configuration exist between specifications, implementations and configuration
choices. choices.
Many IETF protocols depend on multicast/broadcast for delivery of Many IETF protocols depend on multicast/broadcast for delivery of
control messages to multiple receivers. Multicast is used for control messages to multiple receivers. Multicast allows sending
various purposes such as neighbor discovery, network flooding, data to multiple interested recipients without the source needing to
address resolution, as well minimizing media occupancy for the send duplicate data to each recipient. With broadcast traffic, data
transmission of data that is intended for multiple receivers. In is sent to every device regardless of their interest in the data.
addition to protocol use of broadcast/multicast for control messages, Multicast is used for various purposes such as neighbor discovery,
more applications, such as push to talk in hospitals, or video in network flooding, address resolution, as well minimizing media
enterprises, universities, and homes, are sending multicast IP to end occupancy for the transmission of data that is intended for multiple
user devices, which are increasingly using Wi-Fi for their receivers. In addition to protocol use of broadcast/multicast for
connectivity. control messages, more applications, such as push to talk in
hospitals, or video in enterprises, universities, and homes, are
sending multicast IP to end user devices, which are increasingly
using Wi-Fi for their connectivity.
IETF protocols typically rely on network protocol layering in order IETF protocols typically rely on network protocol layering in order
to reduce or eliminate any dependence of higher level protocols on to reduce or eliminate any dependence of higher level protocols on
the specific nature of the MAC layer protocols or the physical media. the specific nature of the MAC layer protocols or the physical media.
In the case of multicast transmissions, higher level protocols have In the case of multicast transmissions, higher level protocols have
traditionally been designed as if transmitting a packet to an IP traditionally been designed as if transmitting a packet to an IP
address had the same cost in interference and network media access, address had the same cost in interference and network media access,
regardless of whether the destination IP address is a unicast address regardless of whether the destination IP address is a unicast address
or a multicast or broadcast address. This model was reasonable for or a multicast or broadcast address. This model was reasonable for
networks where the physical medium was wired, like Ethernet. networks where the physical medium was wired, like Ethernet.
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needs to be provided in order to make them more reliable. IPv6 needs to be provided in order to make them more reliable. IPv6
neighbor discovery saturating the Wi-Fi link is only part of the neighbor discovery saturating the Wi-Fi link is only part of the
problem. Wi-Fi traffic classes may help. This document is intended problem. Wi-Fi traffic classes may help. This document is intended
to help make the determination about what problems should be solved to help make the determination about what problems should be solved
by the IETF and what problems should be solved by the IEEE (see by the IETF and what problems should be solved by the IEEE (see
Section 8). Section 8).
This document details various problems caused by multicast This document details various problems caused by multicast
transmission over wireless networks, including high packet error transmission over wireless networks, including high packet error
rates, no acknowledgements, and low data rate. It also explains some rates, no acknowledgements, and low data rate. It also explains some
enhancements that have been designed at the IETF and IEEE 802 to enhancements that have been designed at the IETF and IEEE 802.11 to
ameliorate the effects of multicast traffic. Recommendations are ameliorate the effects of multicast traffic. Recommendations are
also provided to implementors about how to use and combine these also provided to implementors about how to use and combine these
enhancements. Some advice about the operational choices that can be enhancements. Some advice about the operational choices that can be
taken is also included. It is likely that this document will also be taken is also included. It is likely that this document will also be
considered relevant to designers of future IEEE wireless considered relevant to designers of future IEEE wireless
specifications. specifications.
2. Terminology 2. Terminology
This document uses the following definitions: This document uses the following definitions:
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3.1. Issues at Layer 2 and Below 3.1. Issues at Layer 2 and Below
In this section some of the issues related to the use of multicast In this section some of the issues related to the use of multicast
transmissions over IEEE 802 wireless technologies are described. transmissions over IEEE 802 wireless technologies are described.
3.1.1. Multicast reliability 3.1.1. Multicast reliability
Multicast traffic is typically much less reliable than unicast Multicast traffic is typically much less reliable than unicast
traffic. Since multicast makes point-to-multipoint communications, traffic. Since multicast makes point-to-multipoint communications,
multiple acknowledgements would be needed to guarantee reception at multiple acknowledgements would be needed to guarantee reception at
all recipients. Since typically there are no ACKs for multicast all recipients. Since there are no ACKs for multicast packets, it is
packets, it is not possible for the Access Point (AP) to know whether not possible for the Access Point (AP) to know whether or not a
or not a retransmission is needed. Even in the wired Internet, this retransmission is needed. Even in the wired Internet, this
characteristic often causes undesirably high error rates. This has characteristic often causes undesirably high error rates. This has
contributed to the relatively slow uptake of multicast applications contributed to the relatively slow uptake of multicast applications
even though the protocols have long been available. The situation even though the protocols have long been available. The situation
for wireless links is much worse, and is quite sensitive to the for wireless links is much worse, and is quite sensitive to the
presence of background traffic. Consequently, there can be a high presence of background traffic. Consequently, there can be a high
packet error rate (PER) due to lack of retransmission, and because packet error rate (PER) due to lack of retransmission, and because
the sender never backs off. It is not uncommon for there to be a the sender never backs off. It is not uncommon for there to be a
packet loss rate of 5% or more, which is particularly troublesome for packet loss rate of 5% or more, which is particularly troublesome for
video and other environments where high data rates and high video and other environments where high data rates and high
reliability are required. reliability are required.
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impact the ability for QoS solutions to effectively reserve bandwidth impact the ability for QoS solutions to effectively reserve bandwidth
and provide admission control. and provide admission control.
For wireless stations associated with an Access Point, the power For wireless stations associated with an Access Point, the power
necessary for good reception can vary from station to station. For necessary for good reception can vary from station to station. For
unicast, the goal is to minimize power requirements while maximizing unicast, the goal is to minimize power requirements while maximizing
the data rate to the destination. For multicast, the goal is simply the data rate to the destination. For multicast, the goal is simply
to maximize the number of receivers that will correctly receive the to maximize the number of receivers that will correctly receive the
multicast packet; generally the Access Point has to use a much lower multicast packet; generally the Access Point has to use a much lower
data rate at a power level high enough for even the farthest station data rate at a power level high enough for even the farthest station
to receive the packet, for example as briefly mentioned in [RFC5757]. to receive the packet, for example as briefly mentioned in section 2
Consequently, the data rate of a video stream, for instance, would be of [RFC5757]. Consequently, the data rate of a video stream, for
constrained by the environmental considerations of the least reliable instance, would be constrained by the environmental considerations of
receiver associated with the Access Point. the least reliable receiver associated with the Access Point.
Because more robust modulation and coding schemes (MCSs) have longer Because more robust modulation and coding schemes (MCSs) have longer
range but also lower data rate, multicast / broadcast traffic is range but also lower data rate, multicast / broadcast traffic is
generally transmitted at the slowest rate of all the connected generally transmitted at the slowest rate of all the connected
devices. This is also known as the basic rate. The amount of devices. This is also known as the basic rate. The amount of
additional interference depends on the specific wireless technology. additional interference depends on the specific wireless technology.
In fact, backward compatibility and multi-stream implementations mean In fact, backward compatibility and multi-stream implementations mean
that the maximum unicast rates are currently up to a few Gbps, so that the maximum unicast rates are currently up to a few Gbps, so
there can be more than 3 orders of magnitude difference in the there can be more than 3 orders of magnitude difference in the
transmission rate between multicast / broadcast versus optimal transmission rate between multicast / broadcast versus optimal
unicast forwarding. Some techiques employed to increase spectral unicast forwarding. Some techiques employed to increase spectral
efficiency, such as spatial multiplexing in mimo systems, are not efficiency, such as spatial multiplexing in MIMO systems, are not
available with more than one intended reciever; it is not the case available with more than one intended receiver; it is not the case
that backwards compatibility is the only factor responsible for lower that backwards compatibility is the only factor responsible for lower
multicast transmission rates. multicast transmission rates.
Wired multicast also affects wireless LANs when the AP extends the Wired multicast also affects wireless LANs when the AP extends the
wired segment; in that case, multicast / broadcast frames on the wired segment; in that case, multicast / broadcast frames on the
wired LAN side are copied to WLAN. Since broadcast messages are wired LAN side are copied to the Wireless Local Area Network (WLAN).
transmitted at the most robust MCS, many large frames are sent at a
slow rate over the air.
3.1.3. High Interference Since broadcast messages are transmitted at the most robust MCS, many
large frames are sent at a slow rate over the air.
3.1.3. Capacity and Impact on Interference
Transmissions at a lower rate require longer occupancy of the Transmissions at a lower rate require longer occupancy of the
wireless medium and thus take away from the airtime of other wireless medium and thus take away from the airtime of other
communications and degrade the overall capacity. Furthermore, communications and degrade the overall capacity. Furthermore,
transmission at higher power, as is required to reach all multicast transmission at higher power, as is required to reach all multicast
STAs associated to the AP, proportionately increases the area of STAs associated to the AP, proportionately increases the area of
interference. interference.
3.1.4. Power-save Effects on Multicast 3.1.4. Power-save Effects on Multicast
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o On-demand routing o On-demand routing
o Backbone construction o Backbone construction
o Other L3 protocols (non-IP) o Other L3 protocols (non-IP)
User Datagram Protocol (UDP) is the most common transport layer User Datagram Protocol (UDP) is the most common transport layer
protocol for multicast applications. By itself, UDP is not reliable protocol for multicast applications. By itself, UDP is not reliable
-- messages may be lost or delivered out of order. -- messages may be lost or delivered out of order.
3.2.1. IPv4 issues 3.2.1. IPv4 issues
The following list contains some representative multicast protocols The following list contains some representative discovery protocols
that are used with IPv4. that are used with IPv4.
o ARP o ARP
o DHCP o DHCP
o mDNS [RFC6762] o mDNS [RFC6762]
o uPnP [RFC6970] o uPnP [RFC6970]
After initial configuration, ARP and DHCP occur much less commonly, After initial configuration, ARP and DHCP occur much less commonly,
but service discovery can occur at any time. Some widely-deployed but service discovery can occur at any time. Some widely-deployed
service discovery protocols (e.g., for finding a printer) utilize service discovery protocols (e.g., for finding a printer) utilize
mDNS (i.e., multicast). It's often the first service that operators mDNS (i.e., multicast). It's often the first service that operators
drop. Even if multicast snooping is utilized, many devices can drop. Even if multicast snooping is utilized, many devices can
register at once and cause serious network degradation. register at once and cause serious network degradation.
3.2.2. IPv6 issues 3.2.2. IPv6 issues
IPv6 makes extensive use of multicast, including the following: IPv6 makes extensive use of multicast, including the following:
o DHCPv6 o DHCPv6
o Protocol Independent Multicast (PIM)
o IPv6 Neighbor Discovery Protocol (NDP) [RFC4861] o IPv6 Neighbor Discovery Protocol (NDP) [RFC4861]
o multicast DNS (mDNS) o multicast DNS (mDNS)
o Route Discovery o Route Discovery
o Decentralized Address Assignment o Decentralized Address Assignment
o Geographic routing o Geographic routing
IPv6 NDP Neighbor Solicitation (NS) messages used in Duplicate IPv6 NDP Neighbor Solicitation (NS) messages used in Duplicate
Address Detection (DAD) and Address Lookup make use of Link-Scope Address Detection (DAD) and Address Lookup make use of Link-Scope
multicast. In contrast to IPv4, an IPv6 node will typically use multicast. In contrast to IPv4, an IPv6 node will typically use
multiple addresses, and may change them often for privacy reasons. multiple addresses, and may change them often for privacy reasons.
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4. Multicast protocol optimizations 4. Multicast protocol optimizations
This section lists some optimizations that have been specified in This section lists some optimizations that have been specified in
IEEE 802 and IETF that are aimed at reducing or eliminating the IEEE 802 and IETF that are aimed at reducing or eliminating the
issues discussed in Section 3. issues discussed in Section 3.
4.1. Proxy ARP in 802.11-2012 4.1. Proxy ARP in 802.11-2012
The AP knows the MAC address and IP address for all associated STAs. The AP knows the MAC address and IP address for all associated STAs.
In this way, the AP acts as the central "manager" for all the 802.11 In this way, the AP acts as the central "manager" for all the 802.11
STAs in its BSS. Proxy ARP is easy to implement at the AP, and STAs in its basic service set (BSS). Proxy ARP is easy to implement
offers the following advantages: at the AP, and offers the following advantages:
o Reduced broadcast traffic (transmitted at low MCS) on the wireless o Reduced broadcast traffic (transmitted at low MCS) on the wireless
medium medium
o STA benefits from extended power save in sleep mode, as ARP o STA benefits from extended power save in sleep mode, as ARP
requests for STA's IP address are handled instead by the AP. requests for STA's IP address are handled instead by the AP.
o ARP frames are kept off the wireless medium. o ARP frames are kept off the wireless medium.
o No changes are needed to STA implementation. o No changes are needed to STA implementation.
Here is the specification language as described in clause 10.23.13 of Here is the specification language as described in clause 10.23.13 of
[dot11-proxyarp]: [dot11-proxyarp]:
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The 6lo Working Group has specified an update [RFC8505] to RFC6775. The 6lo Working Group has specified an update [RFC8505] to RFC6775.
Wireless devices can register their address to a Backbone Router Wireless devices can register their address to a Backbone Router
[I-D.ietf-6lo-backbone-router], which proxies for the registered [I-D.ietf-6lo-backbone-router], which proxies for the registered
addresses with the IPv6 NDP running on a high speed aggregating addresses with the IPv6 NDP running on a high speed aggregating
backbone. The update also enables a proxy registration mechanism on backbone. The update also enables a proxy registration mechanism on
behalf of the registered node, e.g. by a 6LoWPAN router to which the behalf of the registered node, e.g. by a 6LoWPAN router to which the
mobile node is attached. mobile node is attached.
The general idea behind the backbone router concept is that broadcast The general idea behind the backbone router concept is that broadcast
and multicast messaging should be tightly controlled in a variety of and multicast messaging should be tightly controlled in a variety of
Wireless Local Area Networks (WLANs) and Wireless Personal Area WLANs and Wireless Personal Area Networks (WPANs). Connectivity to a
Networks (WPANs). Connectivity to a particular link that provides particular link that provides the subnet should be left to Layer-3.
the subnet should be left to Layer-3. The model for the Backbone The model for the Backbone Router operation is represented in
Router operation is represented in Figure 1. Figure 1.
| |
+-----+ +-----+
| | Gateway (default) router | | Gateway (default) router
| | | |
+-----+ +-----+
| |
| Backbone Link | Backbone Link
+--------------------+------------------+ +--------------------+------------------+
| | | | | |
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Similar considerations hold for most other wireless media. A brief Similar considerations hold for most other wireless media. A brief
introduction is provided in [RFC5757] for the following: introduction is provided in [RFC5757] for the following:
o 802.16 WIMAX o 802.16 WIMAX
o 3GPP/3GPP2 o 3GPP/3GPP2
o DVB-H / DVB-IPDC o DVB-H / DVB-IPDC
o TV Broadcast and Satellite Networks o TV Broadcast and Satellite Networks
7. Recommendations 7. Recommendations
This section will provide some recommendations about the usage and This section provides some recommendations about the usage and
combinations of the multicast enhancements described in Section 4 and combinations of the multicast enhancements described in Section 4 and
Section 5. Section 5.
Future protocol documents utilizing multicast signaling should be Future protocol documents utilizing multicast signaling should be
carefully scrutinized if the protocol is likely to be used over carefully scrutinized if the protocol is likely to be used over
wireless media. wireless media.
Proxy methods should be encouraged to conserve network bandwidth and Proxy methods should be encouraged to conserve network bandwidth and
power utilization by low-power devices. The device can use a unicast power utilization by low-power devices. The device can use a unicast
message to its proxy, and then the proxy can take care of any needed message to its proxy, and then the proxy can take care of any needed
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Multicast signaling for wireless devices should be done in a way Multicast signaling for wireless devices should be done in a way
compatible with low duty-cycle operation. compatible with low duty-cycle operation.
8. Discussion Items 8. Discussion Items
This section suggests two discussion items for further resolution. This section suggests two discussion items for further resolution.
The IETF should determine guidelines by which it may be decided that The IETF should determine guidelines by which it may be decided that
multicast packets are to be sent wired. For example, 802.1ak works multicast packets are to be sent wired. For example, 802.1ak works
on ethernet and Wi-Fi. 802.1ak has been pulled into 802.1Q as of on ethernet and Wi-Fi. 802.1ak has been pulled into 802.1Q as of
802.1Q-2011. 802.1Q-2014 can be found here: 802.1Q-2011. If a generic solution is not found, guidelines for
http://www.ieee802.org/1/pages/802.1Q-2014.html. If a generic multicast over Wi-Fi should be established.
solution is not found, guidelines for multicast over Wi-Fi should be
established.
Reliable registration to Layer-2 multicast groups and a reliable Reliable registration to Layer-2 multicast groups and a reliable
multicast operation at Layer-2 might provide a generic solution. multicast operation at Layer-2 might provide a generic solution.
There is no need to support 2^24 groups to get solicited node There is no need to support 2^24 groups to get solicited node
multicast working: it is possible to simply select a number of multicast working: it is possible to simply select a number of
trailing bits that make sense for a given network size to limit the trailing bits that make sense for a given network size to limit the
number of unwanted deliveries to reasonable levels. IEEE 802.1, number of unwanted deliveries to reasonable levels. IEEE 802.1,
802.11, and 802.15 should be encouraged to revisit L2 multicast 802.11, and 802.15 should be encouraged to revisit L2 multicast
issues. In reality, Wi-Fi provides a broadcast service, not a issues. In reality, Wi-Fi provides a broadcast service, not a
multicast service. On the physical medium, all frames are broadcast multicast service. On the physical medium, all frames are broadcast
except in very unusual cases in which special beamforming except in very unusual cases in which special beamforming
transmitters are used. Unicast offers the advantage of being much transmitters are used. Unicast offers the advantage of being much
faster (2 orders of magnitude) and much more reliable (L2 ARQ). faster (2 orders of magnitude) and much more reliable (L2 ARQ).
9. Security Considerations 9. Security Considerations
This document does not introduce or modify any security mechanisms. This document does not introduce or modify any security mechanisms.
Multicast is made more secure in a variety of ways. [RFC4601], for
instance, mandates the use of IPsec to ensure authentication of the
link-local messages in the Protocol Independent Multicast - Sparse
Mode (PIM-SM) routing protocol. [RFC5796]specifies mechanisms to
authenticate the PIM-SM link-local messages using the IP security
(IPsec) Encapsulating Security Payload (ESP) or (optionally) the
Authentication Header (AH).
As noted in [group_key], the unreliable nature of multicast As noted in [group_key], the unreliable nature of multicast
transmission over wireless media can cause subtle problems with transmission over wireless media can cause subtle problems with
multicast group key management and updates. Quoting from that multicast group key management and updates. When WPA (TKIP) or WPA2
website, "... most clients are able to get connected and surf the (AES-CCMP) encryption is in use, AP to client (From DS) multicasts
web, check email, etc. even when From DS multicasts are broken. So a have to be encrypted with a separate encryption key that is known to
lot of people don't realize they have multicast problems on their all of the clients (this is called the Group Key). Quoting further
network..." from that website, "... most clients are able to get connected and
surf the web, check email, etc. even when From DS multicasts are
broken. So a lot of people don't realize they have multicast
problems on their network..."
10. IANA Considerations 10. IANA Considerations
This document does not request any IANA actions. This document does not request any IANA actions.
11. Acknowledgements 11. Acknowledgements
This document has benefitted from discussions with the following This document has benefitted from discussions with the following
people, in alphabetical order: Mikael Abrahamsson, Bill Atwood, people, in alphabetical order: Mikael Abrahamsson, Bill Atwood,
Stuart Cheshire, Donald Eastlake, Toerless Eckert, Jake Holland, Joel Stuart Cheshire, Donald Eastlake, Toerless Eckert, Jake Holland, Joel
skipping to change at page 21, line 30 skipping to change at page 21, line 34
[dot11-proxyarp] [dot11-proxyarp]
Hiertz, G., Mestanov, F., and B. Hart, "Proxy ARP in Hiertz, G., Mestanov, F., and B. Hart, "Proxy ARP in
802.11ax", September 2015, 802.11ax", September 2015,
<https://mentor.ieee.org/802.11/dcn/15/11-15-1015-01-00ax- <https://mentor.ieee.org/802.11/dcn/15/11-15-1015-01-00ax-
proxy-arp-in-802-11ax.pptx>. proxy-arp-in-802-11ax.pptx>.
[dot11aa] "IEEE 802 Wireless", "Part 11: Wireless LAN Medium Access [dot11aa] "IEEE 802 Wireless", "Part 11: Wireless LAN Medium Access
Control (MAC) and Physical Layer (PHY) Specifications Control (MAC) and Physical Layer (PHY) Specifications
Amendment 2: MAC Enhancements for Robust Audio Video Amendment 2: MAC Enhancements for Robust Audio Video
Streaming", March 2012, Streaming", March 2012,
<http://standards.ieee.org/findstds/standard/802.11aa- <https://standards.ieee.org/standard/802_11aa-2012.html>.
2012.pdf>.
[group_key] [group_key]
Spiff, ""Why do some WiFi routers block multicast packets Spiff, "Why do some WiFi routers block multicast packets
going from wired to wireless?"", Jan 2017, going from wired to wireless?", Jan 2017,
<https://superuser.com/questions/730288/why-do-some-wifi- <https://superuser.com/questions/730288/why-do-some-wifi-
routers-block-multicast-packets-going-from-wired-to- routers-block-multicast-packets-going-from-wired-to-
wireless>. wireless>.
[I-D.ietf-6lo-backbone-router] [I-D.ietf-6lo-backbone-router]
Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6 Thubert, P., Perkins, C., and E. Levy-Abegnoli, "IPv6
Backbone Router", draft-ietf-6lo-backbone-router-13 (work Backbone Router", draft-ietf-6lo-backbone-router-13 (work
in progress), September 2019. in progress), September 2019.
[I-D.ietf-6tisch-architecture] [I-D.ietf-6tisch-architecture]
Thubert, P., "An Architecture for IPv6 over the TSCH mode Thubert, P., "An Architecture for IPv6 over the TSCH mode
of IEEE 802.15.4", draft-ietf-6tisch-architecture-26 (work of IEEE 802.15.4", draft-ietf-6tisch-architecture-28 (work
in progress), August 2019. in progress), October 2019.
[I-D.ietf-mboned-driad-amt-discovery] [I-D.ietf-mboned-driad-amt-discovery]
Holland, J., "DNS Reverse IP AMT Discovery", draft-ietf- Holland, J., "DNS Reverse IP AMT Discovery", draft-ietf-
mboned-driad-amt-discovery-08 (work in progress), June mboned-driad-amt-discovery-09 (work in progress), October
2019. 2019.
[ietf_802-11] [ietf_802-11]
Stanley, D., "IEEE 802.11 multicast capabilities", Nov Stanley, D., "IEEE 802.11 multicast capabilities", Nov
2015, <https://mentor.ieee.org/802.11/ 2015, <https://mentor.ieee.org/802.11/
dcn/15/11-15-1261-03-0arc-multicast-performance- dcn/15/11-15-1261-03-0arc-multicast-performance-
optimization-features-overview-for-ietf-nov-2015.ppt>. optimization-features-overview-for-ietf-nov-2015.ppt>.
[mc-ack-mux] [mc-ack-mux]
Tanaka, Y., Sakai, E., Morioka, Y., Mori, M., Hiertz, G., Tanaka, Y., Sakai, E., Morioka, Y., Mori, M., Hiertz, G.,
skipping to change at page 23, line 5 skipping to change at page 23, line 5
Discovery for IP Version 6 (IPv6)", RFC 2461, Discovery for IP Version 6 (IPv6)", RFC 2461,
DOI 10.17487/RFC2461, December 1998, DOI 10.17487/RFC2461, December 1998,
<https://www.rfc-editor.org/info/rfc2461>. <https://www.rfc-editor.org/info/rfc2461>.
[RFC4541] Christensen, M., Kimball, K., and F. Solensky, [RFC4541] Christensen, M., Kimball, K., and F. Solensky,
"Considerations for Internet Group Management Protocol "Considerations for Internet Group Management Protocol
(IGMP) and Multicast Listener Discovery (MLD) Snooping (IGMP) and Multicast Listener Discovery (MLD) Snooping
Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006, Switches", RFC 4541, DOI 10.17487/RFC4541, May 2006,
<https://www.rfc-editor.org/info/rfc4541>. <https://www.rfc-editor.org/info/rfc4541>.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006,
<https://www.rfc-editor.org/info/rfc4601>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007, DOI 10.17487/RFC4862, September 2007,
<https://www.rfc-editor.org/info/rfc4862>. <https://www.rfc-editor.org/info/rfc4862>.
[RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast [RFC5757] Schmidt, T., Waehlisch, M., and G. Fairhurst, "Multicast
Mobility in Mobile IP Version 6 (MIPv6): Problem Statement Mobility in Mobile IP Version 6 (MIPv6): Problem Statement
and Brief Survey", RFC 5757, DOI 10.17487/RFC5757, and Brief Survey", RFC 5757, DOI 10.17487/RFC5757,
February 2010, <https://www.rfc-editor.org/info/rfc5757>. February 2010, <https://www.rfc-editor.org/info/rfc5757>.
[RFC5796] Atwood, W., Islam, S., and M. Siami, "Authentication and
Confidentiality in Protocol Independent Multicast Sparse
Mode (PIM-SM) Link-Local Messages", RFC 5796,
DOI 10.17487/RFC5796, March 2010,
<https://www.rfc-editor.org/info/rfc5796>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6 [RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282, Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011, DOI 10.17487/RFC6282, September 2011,
<https://www.rfc-editor.org/info/rfc6282>. <https://www.rfc-editor.org/info/rfc6282>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013, DOI 10.17487/RFC6762, February 2013,
<https://www.rfc-editor.org/info/rfc6762>. <https://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service [RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
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