draft-ietf-bier-mld-03.txt   draft-ietf-bier-mld-04.txt 
Network Working Group P. Pfister Network Working Group P. Pfister
Internet-Draft IJ. Wijnands Internet-Draft IJ. Wijnands
Intended status: Standards Track S. Venaas Intended status: Standards Track S. Venaas
Expires: May 7, 2020 Cisco Systems Expires: September 7, 2020 Cisco Systems
C. Wang C. Wang
Z. Zhang Z. Zhang
ZTE Corporation ZTE Corporation
M. Stenberg M. Stenberg
November 4, 2019 March 6, 2020
BIER Ingress Multicast Flow Overlay using Multicast Listener Discovery BIER Ingress Multicast Flow Overlay using Multicast Listener Discovery
Protocols Protocols
draft-ietf-bier-mld-03 draft-ietf-bier-mld-04
Abstract Abstract
This document specifies the ingress part of a multicast flow overlay This document specifies the ingress part of a multicast flow overlay
for BIER networks. Using existing multicast listener discovery for BIER networks. Using existing multicast listener discovery
protocols, it enables multicast membership information sharing from protocols, it enables multicast membership information sharing from
egress routers, acting as listeners, toward ingress routers, acting egress routers, acting as listeners, toward ingress routers, acting
as queriers. Ingress routers keep per-egress-router state, used to as queriers. Ingress routers keep per-egress-router state, used to
construct the BIER bit mask associated with IP multicast packets construct the BIER bit mask associated with IP multicast packets
entering the BIER domain. entering the BIER domain.
skipping to change at page 1, line 43 skipping to change at page 1, line 43
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
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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
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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 May 7, 2020. This Internet-Draft will expire on September 7, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2020 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
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
skipping to change at page 2, line 29 skipping to change at page 2, line 29
3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Applicability Statement . . . . . . . . . . . . . . . . . . . 4 4. Applicability Statement . . . . . . . . . . . . . . . . . . . 4
5. Querier and Listener Specifications . . . . . . . . . . . . . 4 5. Querier and Listener Specifications . . . . . . . . . . . . . 4
5.1. Configuration Parameters . . . . . . . . . . . . . . . . 5 5.1. Configuration Parameters . . . . . . . . . . . . . . . . 5
5.2. MLDv2 instances. . . . . . . . . . . . . . . . . . . . . 6 5.2. MLDv2 instances. . . . . . . . . . . . . . . . . . . . . 6
5.2.1. Sending Queries . . . . . . . . . . . . . . . . . . . 6 5.2.1. Sending Queries . . . . . . . . . . . . . . . . . . . 6
5.2.2. Sending Reports . . . . . . . . . . . . . . . . . . . 6 5.2.2. Sending Reports . . . . . . . . . . . . . . . . . . . 6
5.2.3. Receiving Queries . . . . . . . . . . . . . . . . . . 7 5.2.3. Receiving Queries . . . . . . . . . . . . . . . . . . 7
5.2.4. Receiving Reports . . . . . . . . . . . . . . . . . . 8 5.2.4. Receiving Reports . . . . . . . . . . . . . . . . . . 8
5.3. Packet Forwarding . . . . . . . . . . . . . . . . . . . . 8 5.3. Packet Forwarding . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. BIER MLD/IGMP Extension Type . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 9 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.2. Informative References . . . . . . . . . . . . . . . . . 10 10.1. Normative References . . . . . . . . . . . . . . . . . . 10
Appendix A. BIER Use Case in Data Centers . . . . . . . . . . . 11 10.2. Informative References . . . . . . . . . . . . . . . . . 11
A.1. Convention and Terminology . . . . . . . . . . . . . . . 12 Appendix A. BIER Use Case in Data Centers . . . . . . . . . . . 12
A.2. BIER in data centers . . . . . . . . . . . . . . . . . . 13 A.1. Convention and Terminology . . . . . . . . . . . . . . . 13
A.3. A BIER MLD solution for Virtual Network information . . . 13 A.2. BIER in data centers . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 A.3. A BIER MLD solution for Virtual Network information . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
The Bit Index Explicit Replication (BIER - [RFC8279]) forwarding The Bit Index Explicit Replication (BIER - [RFC8279]) forwarding
technique enables IP multicast transport across a BIER domain. When technique enables IP multicast transport across a BIER domain. When
receiving or originating a packet, ingress routers have to construct receiving or originating a packet, ingress routers have to construct
a bit mask indicating which BIER egress routers located within the a bit mask indicating which BIER egress routers located within the
same BIER domain will receive the packet. A stateless approach would same BIER domain will receive the packet. A stateless approach would
consist of forwarding all incoming packets toward all egress routers, consist of forwarding all incoming packets toward all egress routers,
which would in turn make a forwarding decision based on local which would in turn make a forwarding decision based on local
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This document specifies how to use the Multicast Listener Discovery This document specifies how to use the Multicast Listener Discovery
protocol version 2 [RFC3810] (resp. the Internet Group Management protocol version 2 [RFC3810] (resp. the Internet Group Management
protocol version 3 [RFC3376]) as the ingress part of a BIER multicast protocol version 3 [RFC3376]) as the ingress part of a BIER multicast
flow overlay (BIER layering is described in [RFC8279]) for IPv6 flow overlay (BIER layering is described in [RFC8279]) for IPv6
(resp. IPv4). It enables multicast membership information sharing (resp. IPv4). It enables multicast membership information sharing
from egress routers, acting as listeners, toward ingress routers, from egress routers, acting as listeners, toward ingress routers,
acting as queriers. Ingress routers keep per-egress-router state, acting as queriers. Ingress routers keep per-egress-router state,
used to construct the BIER bit mask associated with IP multicast used to construct the BIER bit mask associated with IP multicast
packets entering the BIER domain. packets entering the BIER domain.
This document makes use of an extension to MLDv2 and IGMPv3 specified This document defines an MLDv2 and IGMPv3 extension type, using the
in [I-D.venaas-pim-igmp-mld-extension] that allows for providing BIER extension scheme defined in [I-D.venaas-pim-igmp-mld-extension], that
specific information about the message originator. allows for providing BIER specific information about the message
originator.
This specification is applicable to both IP version 4 and version 6. This specification is applicable to both IP version 4 and version 6.
It therefore specifies two separate mechanisms operating It therefore specifies two separate mechanisms operating
independently. For the sake of simplicity, the rest of this document independently. For the sake of simplicity, the rest of this document
uses IPv6 terminology. It can be applied to IPv4 by replacing uses IPv6 terminology. It can be applied to IPv4 by replacing
'MLDv2' with 'IGMPv3', and following specific requirements when 'MLDv2' with 'IGMPv3', and following specific requirements when
explicitly stated. explicitly stated.
2. Terminology 2. Terminology
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o With the IP destination address set to the 'all BMLD Nodes' group o With the IP destination address set to the 'all BMLD Nodes' group
address. address.
o With the IP source address set to the BFR-Prefix of the sender. o With the IP source address set to the BFR-Prefix of the sender.
o With a TTL value large enough such that the packet can be received o With a TTL value large enough such that the packet can be received
by all BMLD Nodes, depending on the underlying BIER layer (whether by all BMLD Nodes, depending on the underlying BIER layer (whether
it decrements the IP TTL or not) and the size of the network. The it decrements the IP TTL or not) and the size of the network. The
default value is 64. default value is 64.
o The extension defined in [I-D.venaas-pim-igmp-mld-extension] MUST o The extension defined in Section 6 MUST be included, specifying
be included, specifying the Sub-domain-id, BFR-id and BFR-Prefix the Sub-domain-id, BFR-id and BFR-Prefix of the sender. This
of the sender. This information may be useful for logging and information may be useful for logging and debugging.
debugging.
5.2.2. Sending Reports 5.2.2. Sending Reports
BMLD Reports are IP packets sent over BIER by BMLD Listeners: BMLD Reports are IP packets sent over BIER by BMLD Listeners:
o Toward all BMLD Queriers (i.e., providing to the BIER layer the o Toward all BMLD Queriers (i.e., providing to the BIER layer the
BFR-ids of all BMLD Queriers). BFR-ids of all BMLD Queriers).
o Without the IPv6 router alert option [RFC2711] in the hop-by-hop o Without the IPv6 router alert option [RFC2711] in the hop-by-hop
extension header [RFC8200] (or the IPv4 router alert option extension header [RFC8200] (or the IPv4 router alert option
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o With the IP destination address set to the 'all BMLD Queriers' o With the IP destination address set to the 'all BMLD Queriers'
group address. group address.
o With the IP source address set to the BFR-Prefix of the sender. o With the IP source address set to the BFR-Prefix of the sender.
o With a TTL value large enough such that the packet can be received o With a TTL value large enough such that the packet can be received
by all BMLD Queriers, depending on the underlying BIER layer by all BMLD Queriers, depending on the underlying BIER layer
(whether it decrements the IP TTL or not) and the size of the (whether it decrements the IP TTL or not) and the size of the
network. The default value is 64. network. The default value is 64.
o The extension defined in [I-D.venaas-pim-igmp-mld-extension] MUST o The extension defined in Section 6 MUST be included, specifying
be included, specifying the Sub-domain-id, BFR-id and BFR-Prefix the Sub-domain-id, BFR-id and BFR-Prefix of the sender. This
of the sender. This information is used to create the necessary information is used to create the necessary forwarding state for
forwarding state for requested flows, and may be useful for requested flows, and may be useful for logging and debugging.
logging and debugging.
Since the reports may contain a large number of records, they may Since the reports may contain a large number of records, they may
become larger than the maximum BIER payload that can be delivered to become larger than the maximum BIER payload that can be delivered to
all the BMLD Queriers. Hence an implementation will need to either all the BMLD Queriers. Hence an implementation will need to either
use a small default maximum size, allow configuration of a maximum use a small default maximum size, allow configuration of a maximum
size, or rely on MTU discovery. MTU discovery may be done for a sub- size, or rely on MTU discovery. MTU discovery may be done for a sub-
domain using BIER MTU Discovery [I-D.venaas-bier-mtud] or for the set domain using BIER MTU Discovery [I-D.venaas-bier-mtud] or for the set
of BMLD Queriers using Path MTU Discovery of BMLD Queriers using Path MTU Discovery
[I-D.ietf-bier-path-mtu-discovery]. [I-D.ietf-bier-path-mtu-discovery].
5.2.3. Receiving Queries 5.2.3. Receiving Queries
BMLD Queriers and Listeners MUST check the destination address of all BMLD Queriers and Listeners MUST check the destination address of all
the IP packets that are received or forwarded over BIER whenever the IP packets that are received or forwarded over BIER whenever
their own BIER bit is set in the packet. If the destination address their own BIER bit is set in the packet. If the destination address
is equal to the 'all BMLD Nodes' group address the packet is is equal to the 'all BMLD Nodes' group address the packet is
processed as specified in this section. processed as specified in this section.
If the IPv6 (resp. IPv4) packet contains an ICMPv6 (resp. IGMP) If the IPv6 (resp. IPv4) packet contains an ICMPv6 (resp. IGMP)
message of type 'Multicast Listener Query' (resp. of type 'Membership message of type 'Multicast Listener Query' (resp. of type 'Membership
Query'), and include the extension defined in Query'), and include the extension defined in Section 6), it is
[I-D.venaas-pim-igmp-mld-extension]), it is processed by the MLDv2 processed by the MLDv2 (resp. IGMPv3) instance run by the BMLD
(resp. IGMPv3) instance run by the BMLD Querier. It MUST be dropped Querier. It MUST be dropped otherwise.
otherwise.
During the MLDv2 processing, the packet MUST NOT be checked against During the MLDv2 processing, the packet MUST NOT be checked against
the MLDv2 consistency conditions (i.e., the presence of the router the MLDv2 consistency conditions (i.e., the presence of the router
alert option, the TTL equaling 1 and, for IPv6 only, the source alert option, the TTL equaling 1 and, for IPv6 only, the source
address being link-local). address being link-local).
5.2.4. Receiving Reports 5.2.4. Receiving Reports
BMLD Queriers MUST check the destination address of all the IP BMLD Queriers MUST check the destination address of all the IP
packets that are received or forwarded over BIER whenever their own packets that are received or forwarded over BIER whenever their own
BIER bit is set. If the destination address is equal to the 'all BIER bit is set. If the destination address is equal to the 'all
BMLD Queriers' the packet is processed as specified in this section. BMLD Queriers' the packet is processed as specified in this section.
If the IPv6 (resp. IPv4) packet contains an ICMPv6 (resp. IGMP) If the IPv6 (resp. IPv4) packet contains an ICMPv6 (resp. IGMP)
message of type 'Multicast Listener Report Message v2' (resp. message of type 'Multicast Listener Report Message v2' (resp.
'Version 3 Membership Report'), and include the extension defined in 'Version 3 Membership Report'), and include the extension defined in
[I-D.venaas-pim-igmp-mld-extension]), it is processed by the MLDv2 Section 6), it is processed by the MLDv2 (resp. IGMPv3) instance run
(resp. IGMPv3) instance run by the BMLD Querier. It MUST be dropped by the BMLD Querier. It MUST be dropped otherwise.
otherwise.
During the MLDv2 processing, the packet MUST NOT be checked against During the MLDv2 processing, the packet MUST NOT be checked against
the MLDv2 consistency conditions (i.e., the presence of the router the MLDv2 consistency conditions (i.e., the presence of the router
alert option, the TTL equaling 1 and, for IPv6 only, the source alert option, the TTL equaling 1 and, for IPv6 only, the source
address being link-local). address being link-local).
5.3. Packet Forwarding 5.3. Packet Forwarding
BMLD Queriers configure the BIER Layer using the information obtained BMLD Queriers configure the BIER Layer using the information obtained
using BMLD, and the extension [I-D.venaas-pim-igmp-mld-extension]), using BMLD, and the extension Section 6), to track membership state,
to track membership state, including the Sub-domain-id, BFR-id and including the Sub-domain-id, BFR-id and BFR-Prefix of the members.
BFR-Prefix of the members.
More specifically, the membership state associated with each BMLD More specifically, the membership state associated with each BMLD
Listener is provided to the BIER layer such that whenever a multicast Listener is provided to the BIER layer such that whenever a multicast
packet enters the BIER domain, if that packet matches the membership packet enters the BIER domain, if that packet matches the membership
information from a BMLD Listener, its Sub-domain-id and BFR-id is information from a BMLD Listener, its Sub-domain-id and BFR-id is
added to the set of Sub-domains and BFR-ids the packet should be added to the set of Sub-domains and BFR-ids the packet should be
forwarded to by the BIER-Layer. forwarded to by the BIER-Layer.
6. Security Considerations 6. BIER MLD/IGMP Extension Type
A new MLD/IGMP extension type adds BIER specific information to IGMP/
MLD messages, using the extension scheme defined in
[I-D.venaas-pim-igmp-mld-extension]). The BIER specific information
is the same as the PTA tunnel identifier in [RFC8556] and is shown in
Figure 1. Note that, as defined in the MLD (resp. IGMP), existing
implementations are supposed to ignore this additional data.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Ext Type TBD | Sub-domain ID | BFR-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFR-Prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BFR-Prefix |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: MLD/IGMP Extension Type for BIER
o Ext Type: Assigned by IANA, identifying this BIER extension.
o Sub-domain-id: A single octet containing a BIER sub-domain-id (see
[[RFC8279]]). This indicates the BIER sub-domain of the router
originating the message.
o BFR-id: A two-octet field containing the BFR-id, in the specified
sub-domain, of the router originating the message.
o BFR-prefix: The BFR-prefix (see [[RFC8279]]) of the router that is
originating the message. The BFR-prefix will either be a /32 IPv4
address or a /128 IPv6 address.
7. Security Considerations
BMLD makes use of IP MLDv2 messages transported over BIER in order to BMLD makes use of IP MLDv2 messages transported over BIER in order to
configure the BIER Layer of BFIRs. BMLD messages MUST be secured, configure the BIER Layer of BFIRs. BMLD messages MUST be secured,
either by relying on physical or link-layer security, by securing the either by relying on physical or link-layer security, by securing the
IP packets (e.g., using IPSec [RFC4301]), or by relying on security IP packets (e.g., using IPSec [RFC4301]), or by relying on security
features provided by the BIER Layer. features provided by the BIER Layer.
Whenever an attacker would be able to spoof the identity of a router, Whenever an attacker would be able to spoof the identity of a router,
it could: it could:
o Redirect undesired traffic toward the spoofed router by o Redirect undesired traffic toward the spoofed router by
subscribing to undesired multicast traffic. subscribing to undesired multicast traffic.
o Prevent desired multicast traffic from reaching the spoofed router o Prevent desired multicast traffic from reaching the spoofed router
by unsubscribing to some desired multicast traffic. by unsubscribing to some desired multicast traffic.
7. IANA Considerations 8. IANA Considerations
This specification does not require any action from IANA. This document requests that IANA assigns a new type called BIER
information in the registry defined in
[I-D.venaas-pim-igmp-mld-extension].
8. Acknowledgements 9. Acknowledgements
Comments concerning this document are very welcome. Comments concerning this document are very welcome.
9. References 10. References
9.1. Normative References 10.1. Normative References
[I-D.ietf-bier-path-mtu-discovery] [I-D.ietf-bier-path-mtu-discovery]
Mirsky, G., Przygienda, T., and A. Dolganow, "Path Maximum Mirsky, G., Przygienda, T., and A. Dolganow, "Path Maximum
Transmission Unit Discovery (PMTUD) for Bit Index Explicit Transmission Unit Discovery (PMTUD) for Bit Index Explicit
Replication (BIER) Layer", draft-ietf-bier-path-mtu- Replication (BIER) Layer", draft-ietf-bier-path-mtu-
discovery-06 (work in progress), June 2019. discovery-07 (work in progress), November 2019.
[I-D.venaas-bier-mtud] [I-D.venaas-bier-mtud]
Venaas, S., Wijnands, I., Ginsberg, L., and M. Sivakumar, Venaas, S., Wijnands, I., Ginsberg, L., and M. Sivakumar,
"BIER MTU Discovery", draft-venaas-bier-mtud-02 (work in "BIER MTU Discovery", draft-venaas-bier-mtud-02 (work in
progress), October 2018. progress), October 2018.
[I-D.venaas-pim-igmp-mld-extension] [I-D.venaas-pim-igmp-mld-extension]
Sivakumar, M., Venaas, S., and Z. Zhang, "IGMPv3/MLDv2 Sivakumar, M., Venaas, S., and Z. Zhang, "IGMPv3/MLDv2
Message Extension", draft-venaas-pim-igmp-mld-extension-00 Message Extension", draft-venaas-pim-igmp-mld-extension-00
(work in progress), November 2019. (work in progress), November 2019.
skipping to change at page 10, line 20 skipping to change at page 11, line 15
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A., [RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279, Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017, DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>. <https://www.rfc-editor.org/info/rfc8279>.
9.2. Informative References 10.2. Informative References
[RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", [RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option",
RFC 2711, DOI 10.17487/RFC2711, October 1999, RFC 2711, DOI 10.17487/RFC2711, October 1999,
<https://www.rfc-editor.org/info/rfc2711>. <https://www.rfc-editor.org/info/rfc2711>.
[RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 [RFC3306] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6
Multicast Addresses", RFC 3306, DOI 10.17487/RFC3306, Multicast Addresses", RFC 3306, DOI 10.17487/RFC3306,
August 2002, <https://www.rfc-editor.org/info/rfc3306>. August 2002, <https://www.rfc-editor.org/info/rfc3306>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
skipping to change at page 11, line 16 skipping to change at page 12, line 10
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
2016, <https://www.rfc-editor.org/info/rfc7761>. 2016, <https://www.rfc-editor.org/info/rfc7761>.
[RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", STD 86, RFC 8200, (IPv6) Specification", STD 86, RFC 8200,
DOI 10.17487/RFC8200, July 2017, DOI 10.17487/RFC8200, July 2017,
<https://www.rfc-editor.org/info/rfc8200>. <https://www.rfc-editor.org/info/rfc8200>.
[RFC8556] Rosen, E., Ed., Sivakumar, M., Przygienda, T., Aldrin, S.,
and A. Dolganow, "Multicast VPN Using Bit Index Explicit
Replication (BIER)", RFC 8556, DOI 10.17487/RFC8556, April
2019, <https://www.rfc-editor.org/info/rfc8556>.
Appendix A. BIER Use Case in Data Centers Appendix A. BIER Use Case in Data Centers
In current data center virtualization, virtual eXtensible Local Area In current data center virtualization, virtual eXtensible Local Area
Network (VXLAN) [RFC7348] is a kind of network virtualization overlay Network (VXLAN) [RFC7348] is a kind of network virtualization overlay
technology which is overlaid between NVEs and is intended for multi- technology which is overlaid between NVEs and is intended for multi-
tenancy data center networks, whose reference architecture is tenancy data center networks, whose reference architecture is
illustrated as per Figure 1. illustrated as per Figure 2.
+--------+ +--------+ +--------+ +--------+
| Tenant +--+ +----| Tenant | | Tenant +--+ +----| Tenant |
| System | | (') | System | | System | | (') | System |
+--------+ | ................ ( ) +--------+ +--------+ | ................ ( ) +--------+
| +-+--+ . . +--+-+ (_) | +-+--+ . . +--+-+ (_)
| | NVE|--. .--| NVE| | | | NVE|--. .--| NVE| |
+--| | . . | |---+ +--| | . . | |---+
+-+--+ . . +--+-+ +-+--+ . . +--+-+
/ . . / . .
/ . L3 Overlay . +--+-++--------+ / . L3 Overlay . +--+-++--------+
+--------+ / . Network . | NVE|| Tenant | +--------+ / . Network . | NVE|| Tenant |
| Tenant +--+ . .--| || System | | Tenant +--+ . .--| || System |
| System | . . +--+-++--------+ | System | . . +--+-++--------+
+--------+ ................ +--------+ ................
Figure 1: NVO3 Architecture Figure 2: NVO3 Architecture
And there are two kinds of most common methods about how to forward And there are two kinds of most common methods about how to forward
BUM packets in this virtualization overlay network. One is using PIM BUM packets in this virtualization overlay network. One is using PIM
as underlay multicast routing protocol to build explicit multicast as underlay multicast routing protocol to build explicit multicast
distribution tree, such as PIM-SM [RFC7761] or PIM-BIDIR [RFC5015] distribution tree, such as PIM-SM [RFC7761] or PIM-BIDIR [RFC5015]
multicast routing protocol. Then, when BUM packets arrive at NVE, it multicast routing protocol. Then, when BUM packets arrive at NVE, it
requires NVE to have a mapping between the VXLAN Network Identifier requires NVE to have a mapping between the VXLAN Network Identifier
and the IP multicast group. According to the mapping, NVE can and the IP multicast group. According to the mapping, NVE can
encapsulate BUM packets in a multicast packet which group address is encapsulate BUM packets in a multicast packet which group address is
the mapping IP multicast group address and steer them through the mapping IP multicast group address and steer them through
 End of changes. 23 change blocks. 
48 lines changed or deleted 88 lines changed or added

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