wdiff rfc8293v1.txt rfc8293.txt

Internet Engineering Task Force (IETF) A. Ghanwani
Request for Comments: 8293 Dell
Category: Informational L. Dunbar
ISSN: 2070-1721 M. McBride
Huawei
V. Bannai
Google
R. Krishnan
Dell
December 2017

A Framework for Multicast in Network Virtualization Overlays over Layer 3

Abstract

This document provides a framework of for supporting multicast traffic
in a network that uses Network Virtualization Overlays over Layer 3 (NVO3).
Both infrastructure multicast and application-specific multicast are
discussed. It describes the various mechanisms that can be used for
delivering such traffic as well as the data plane and control plane
considerations for each of the mechanisms.

Status of This Memo

This document is not an Internet Standards Track specification; it is
published for informational purposes.

This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.

Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8293.

This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.

Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Infrastructure Multicast . . . . . . . . . . . . . . . . 3
1.2. Application-Specific Multicast . . . . . . . . . . . . . 3
2. Abbreviations and Terminology and Abbreviations . . . . . . . . . . . . . . . . 3
3. Multicast Mechanisms in Networks That Use NVO3 . . . . . . . 4
3.1. No Multicast Support . . . . . . . . . . . . . . . . . . 5
3.2. Replication at the Source NVE . . . . . . . . . . . . . . 6
3.3. Replication at a Multicast Service Node . . . . . . . . . 8
3.4. IP Multicast in the Underlay . . . . . . . . . . . . . . 9
3.5. Other Schemes . . . . . . . . . . . . . . . . . . . . . . 10 11
4. Simultaneous Use of More Than One Mechanism . . . . . . . . . 11
5. Other Issues . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Multicast-Agnostic NVEs . . . . . . . . . . . . . . . . . 11
5.2. Multicast Membership Management for DC with VMs . . . . . 11 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 12
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
8. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15

1. Introduction

Network Virtualization using Overlays over Layer 3 (NVO3) [RFC7365] is a technology
that is used to address issues that arise in building large, multi-tenant multi-
tenant data centers (DCs) that make extensive use of server
virtualization [RFC7364].

This document provides a framework for supporting multicast traffic
in a network that uses Network Virtualization using Overlays over
Layer 3 (NVO3). NVO3. Both infrastructure multicast and application-
specific
application-specific multicast are considered. It describes the various
mechanisms
mechanisms, and the considerations of each of them, that can be used
for delivering such traffic in networks that use NVO3.

The reader is assumed to be familiar with the terminology and
concepts as defined in the NVO3 Framework document [RFC7365] and NVO3
Architecture
document [RFC8014]. [RFC8014] documents.

1.1. Infrastructure Multicast

Infrastructure multicast is a capability needed by refers to networking
services, services that require
multicast or broadcast delivery, such as Address Resolution Protocol
(ARP), Neighbor Discovery (ND), Dynamic Host Configuration Protocol
(DHCP), multicast Domain Name Server (mDNS), and so on [RFC3819]. etc., some of which are
described in Sections 5 and 8
have detailed descriptions for some 6 of the infrastructure multicast RFC 3819 [RFC3819]. It is possible
to provide solutions for these services that do not involve multicast
in the underlay network. In For example, in the case of ARP/ND, a
Network Virtualization Authority (NVA) can be used for distributing
to all the Network Virtualization Edges (NVEs) the mappings of
the IP address to the Media Access Control (MAC) address. The NVEs address mappings to all
of the Network Virtualization Edges (NVEs). An NVE can then trap ARP
Request / and/or ND Neighbor Solicitation messages from the Tenant
Systems (TSs) that are attached to it and respond to them, thereby
eliminating the need to for the broadcast/multicast of such messages.
In the case of DHCP, the NVE can be configured to forward these
messages using a helper function. the DHCP relay function [RFC2131].

Of course, it is possible to support all of these infrastructure
multicast protocols natively if the underlay provides multicast
transport. However, even in the presence of multicast transport, it
may be beneficial to use the optimizations mentioned above to reduce
the amount of such traffic in the network.

1.2. Application-Specific Multicast

Application-specific multicast traffic is originated refers to multicast traffic
that originates and is consumed by user applications. The application-specific multicast, which can Several such
applications are described elsewhere [DC-MC]. Application-specific
multicast may be either Source-Specific Multicast (SSM) or Any-Source
Multicast (ASM)
[RFC3569], [RFC3569] and has the following characteristics:

1. Receiver hosts are expected to subscribe to multicast content
using protocols such as IGMP [RFC3376] (IPv4) or Multicast
Listener Discovery (MLD) [RFC2710] (IPv6). Multicast sources and
listeners participate in these protocols using addresses that are
in the Tenant System TS address domain.

2. The list set of multicast listeners for each multicast group is may not
be known in advance. Therefore, it may not be possible or
practical for an NVA to get the list of participants for each
multicast group ahead of time.

2. Abbreviations and Terminology and Abbreviations

In this document, the terms host, Tenant System (TS), and Virtual
Machine (VM) are used interchangeably to represent an end station
that originates or consumes data packets.

ASM: Any-Source Multicast

IGMP: Internet Group Management Protocol

LISP: Locator/ID Separation Protocol

MSN: Multicast Service Node

RLOC: Routing Locator

NVA: Network Virtualization Authority

NVE: Network Virtualization Edge

NVGRE: Network Virtualization using GRE

PIM: Protocol-Independent Multicast

SSM: Source-Specific Multicast

TS: Tenant System

VM: Virtual Machine

VN: Virtual Network

VTEP: VXLAN Tunnel End Point

VXLAN: Virtual eXtensible LAN

3. Multicast Mechanisms in Networks That Use NVO3

In NVO3 environments, traffic between NVEs is transported using an
encapsulation such as VXLAN [RFC7348] [VXLAN-GPE], Network
Virtualization using Generic Routing Encapsulation (NVGRE) [RFC7637],
Geneve [Geneve], Generic UDP Encapsulation [GUE], etc.

What makes networks using NVO3 different from any other network networks is that
some NVEs, especially the NVE NVEs implemented on the server, in servers, might not support PIM
or other native
regular multicast mechanisms. They might just encapsulate protocols such as PIM. Instead, the only
capability they may support would be that of encapsulating data
packets from VMs with an outer unicast header. Therefore, it is
important for networks using NVO3 to have mechanisms to support
multicast as a network capability for NVEs, to map multicast traffic
from VMs (users/applications) to an equivalent multicast capability
inside the NVE, or to figure out the outer destination address if NVE
does not support native multicast (e.g., PIM) or IGMP.

Besides the need to support ARP and ND, there are several
applications that require the support of multicast and/or broadcast
in DCs [DC-MC].

With NVO3, there are many possible ways that multicast may be handled
in such networks. We discuss some of the attributes of the following
four methods:

1. No multicast support

2. Replication at the source NVE

3. Replication at a multicast service node

4. IP multicast in the underlay

These methods are briefly mentioned in the NVO3 Framework [RFC7365]
and NVO3 Architecture [RFC8014] documents. This document provides
more details about the basic mechanisms underlying each of these
methods and discusses the issues and trade-offs of each.

We note that other methods are also possible, such as [EDGE-REP], but
we focus on the above four because they are the most common.

It is worth noting that when selecting a multicast replication
strategy, mechanism, it is
useful to consider the interaction with impact of these on any multicast congestion
control mechanisms that applications may be using to obtain the
desired system dynamics. In addition, for multicast, we follow the same rules for Explicit
Congestion Notification (ECN) as any non- would apply to multicast traffic would, and we are in conformance with the
appropriate encapsulation document being
encapsulated, as for unicast traffic [RFC6040].

3.1. No Multicast Support

In this scenario, there is no support whatsoever for multicast
traffic when using the overlay. This method can only work if the
following conditions are met:

1. All of the application traffic in the network is unicast traffic,
and the only multicast/broadcast traffic is from ARP/ND
protocols.

2. An NVA is used by all of the NVEs to determine the mapping of a
given TS's MAC/IP MAC and IP address to its NVE. the NVE that it is attached to.
In other words, there is no data-plane learning. Address
resolution requests via ARP/ND that are issued by the TSs must be
resolved by the NVE that they are attached to.

With this approach, it is not possible to support application-
specific multicast. However, certain multicast/broadcast
applications such as DHCP can be supported without multicast; for example, DHCP,
which can be supported by use of a helper DHCP relay function in the NVE. [RFC2131].

The main drawback of this approach, even for unicast traffic, is that
it is not possible to initiate communication with a TS for which a
mapping to an NVE does not already exist in at the NVA. This is a
problem in the case where the NVE is implemented in a physical switch
and the TS is a physical end station that has not registered with the
NVA.

3.2. Replication at the Source NVE

With this method, the overlay attempts to provide a multicast service
without requiring any specific support from the underlay, other than
that of a unicast service. A multicast or broadcast transmission is
achieved by replicating the packet at the source NVE and making
copies, one for each destination NVE that the multicast packet must
be sent to.

For this mechanism to work, the source NVE must know, a priori, the
IP addresses of all destination NVEs that need to receive the packet.
For the purpose of ARP/ND, this would involve knowing the IP
addresses of all the NVEs that have TSs in the VN of the TS that
generated the request.

For the support of application-specific multicast traffic, a method
similar to that of receiver-sites registration for a particular
multicast group, described in [LISP-Signal-Free], can be used. The
registrations from different receiver sites can be merged at the NVA,
which can construct a multicast replication list inclusive of all
NVEs to which receivers for a particular multicast group are
attached. The replication list for each specific multicast group is
maintained by the NVA. Note that using signal-free LISP receiver-sites registration
does not necessarily mean the head end
(i.e., NVE) source NVE must do replication. If the mapping database (i.e., NVA)
NVA indicates that multicast packets are encapsulated to multicast RLOCs,
service nodes, then there is would be no replication happening at the NVE.

The receiver-sites registration is achieved by egress NVEs performing
the
IGMP/MLD snooping to maintain the state for which attached TSs have
subscribed to a given IP multicast group. When the members of a
multicast group are outside the NVO3 domain, it is necessary for NVO3
gateways to keep track of the remote members of each multicast group.
The NVEs and NVO3 gateways then communicate with the multicast groups
that are of interest to the NVA. If the membership is not
communicated to the NVA, and if it is necessary to prevent hosts TSs
attached to an NVE that have not subscribed to a multicast group from
receiving the multicast traffic, the NVE would need to maintain
multicast group membership information.

In the absence of IGMP/MLD snooping, the traffic would be delivered
to all TSs that are part of the VN.

In multihoming environments, i.e., in those where a TS is attached to
more than one NVE, the NVA would be expected to provide information
to all of the NVEs under its control about all of the NVEs to which
such a TS is attached. The ingress NVE can then choose any one of
those NVEs as the egress NVEs NVE for the data frames destined towards the
multi-homed TS.

This method requires multiple copies of the same packet to all NVEs
that participate in the VN. If, for example, a tenant subnet is
spread across 50 NVEs, the packet would have to be replicated 50
times at the source NVE. Obviously, this approach creates more
traffic to the network that can cause congestion when the network
load is high. This also creates an issue with the forwarding
performance of the NVE.

Note that this method is similar to what was used in Virtual Private
LAN Service (VPLS) [RFC4762] prior to support of Multiprotocol Label
Switching (MPLS) multicast [RFC7117]. While there are some
similarities between MPLS Virtual Private Network (VPN) and NVO3,
there are some key differences:

o The attachment from Customer Edge (CE) to Provider Edge (PE) in
VPNs is somewhat static, whereas in a DC that allows VMs to
migrate anywhere, the TS attachment to NVE is much more dynamic.

o The number of PEs to which a single VPN customer is attached in an
MPLS VPN environment is normally far less than the number of NVEs
to which a VN's VMs are attached in a DC.

When a VPN customer has multiple multicast groups, "Multicast VPN"
[RFC6513] combines all those multicast groups within each VPN client
to one single multicast group in the MPLS (or VPN) core. The result
is that messages from any of the multicast groups belonging to one
VPN customer will reach all the PE nodes of the client. In other
words, any messages belonging to any multicast groups under customer
X will reach all PEs of the customer X. When the customer X is
attached to only a handful of PEs, the use of this approach does not
result in an excessive waste of bandwidth in the provider's network.

In a DC environment, a typical server/hypervisor-based hypervisor-based virtual switch may
only support on the order of 10's of VMs (as of this writing). A
subnet with N VMs may be, in the worst case, spread across N virtual
switches (vSwitches). Using an "MPLS VPN multicast" approach in such
a scenario would require the creation of a multicast group in the
core in order for the VN to reach all N NVEs. If only a small
percentage of this client's VMs participate in application-specific
multicast, a great number of NVEs will receive multicast traffic that
is not forwarded to any of their attached VMs, resulting in a
considerable waste of bandwidth.

Therefore, the multicast VPN solution may not scale in a DC
environment with the dynamic attachment of VNs to NVEs and a greater
number of NVEs for each VN.

3.3. Replication at a Multicast Service Node

With this method, all multicast packets would be sent using a unicast
tunnel encapsulation from the ingress NVE to a Multicast Service Node
(MSN). The MSN, in turn, would create multiple copies of the packet
and would deliver a copy, using a unicast tunnel encapsulation, to
each of the NVEs that are part of the multicast group for which the
packet is intended.

This mechanism is similar to that used by the Asynchronous Transfer
Mode (ATM) Forum's LAN Emulation (LANE) specification [LANE]. The
MSN is similar to the Rendezvous Point (RP) in Protocol Independent
Multicast - Sparse Mode (PIM-SM), but different in that the user data
traffic is carried by the NVO3 tunnels.

The following are the possible ways for the MSN to get the membership
information for each multicast group:

o The MSN can obtain this membership information from the IGMP/MLD
report messages sent by TSs in response to IGMP/MLD query messages
from the MSN. The IGMP/MLD query messages are sent from the MSN
to the NVEs, which then forward the query messages to TSs attached
to them. An IGMP/MLD query message sent out by the MSN to an NVE
is encapsulated with the MSN address in the outer IP source
address field and the address of the NVE in the outer IP
destination address field. The An encapsulated IGMP/MLD query messages message
also has a VNID
for a virtual network (VN) identifier (corresponding to the
VN that the TSs belong to) in the outer header and a multicast
address in the inner IP destination address field. Upon receiving
the encapsulated IGMP/MLD query message, the NVE establishes a
mapping for "MSN address" <-> to "multicast address", decapsulates the
received encapsulated IGMP/MLD message, and multicasts the
decapsulated query message to the TSs that belong to the VN under the
attached to that NVE. An IGMP/MLD report message sent by a TS
includes the multicast address and the address of the TS. With
the proper "MSN address" <-> to "multicast address" mapping, the NVEs
can encapsulate all multicast data frames to containing the
"multicast address" with the address of the MSN in the outer IP
destination address field.

o The MSN can obtain the membership information from the NVEs that
have the capability to establish multicast groups by snooping
native IGMP/MLD messages (note that the communication must be
specific to the multicast addresses) or by having the NVA obtain
the information from the NVEs and in turn have MSN communicate
with the NVA. This approach requires additional protocol between
MSN and NVEs.

Unlike the method described in Section 3.2, there is no performance
impact at the ingress NVE, nor are there any issues with multiple
copies of the same packet from the source NVE to the MSN. However,
there remain issues with multiple copies of the same packet on links
that are common to the paths from the MSN to each of the egress NVEs.
Additional issues that are introduced with this method include the
availability of the MSN, methods to scale the services offered by the
MSN, and the suboptimality of the delivery paths.

Finally, the IP address of the source NVE must be preserved in packet
copies created at the multicast service node if data-plane learning
is in use. This could create problems if IP source address Reverse
Path Forwarding (RPF) checks are in use.

3.4. IP Multicast in the Underlay

In this method, the underlay supports IP multicast and the ingress
NVE encapsulates the packet with the appropriate IP multicast address
in the tunnel encapsulation header for delivery to the desired set of
NVEs. The protocol in the underlay could be any variant of PIM, or a
protocol-dependent multicast, such as [ISIS-Multicast].

If an NVE connects to its attached TSs via a Layer 2 network, there
are multiple ways for NVEs to support the application-specific
multicast:

o The NVE only supports the basic IGMP/MLD snooping function, let while
the TSs routers handling "TS routers" handle the application-specific multicast. This
scheme doesn't utilize the underlay IP multicast protocols.
Instead routers, which are themselves TSs attached to the NVE,
would handle multicast protocols for the application-specific
multicast. We refer to such routers as TS routers.

o The NVE can act as a pseudomulticast pseudo multicast router for the directly
attached VMs TSs and support proper the mapping of IGMP/MLD's IGMP/MLD messages to the
messages needed by the underlay IP multicast protocols.

With this method, there are none of the issues with the methods
described in Section 3.2. Sections 3.2 and 3.3 with respect to scaling and
congestion. Instead, there are other issues described below.

With PIM-SM, the number of flows required would be (n*g), where n is
the number of source NVEs that source packets for the group, and g is
the number of groups. Bidirectional PIM (BIDIR-PIM) would offer
better scalability with the number of flows required being g.
Unfortunately, many vendors still do not fully support BIDIR or have
limitations on its implementation. [RFC6831] has a good description describes the use of using
SSM as an alternative to BIDIR if BIDIR, provided that the VTEP/NVE devices NVEs have a way to
learn of each other's IP addresses so that they could can join all of the
SSM Shortest Path Trees (SPTs) to create/maintain an underlay SSM IP
multicast tunnel solution.

In the absence of any additional mechanism (e.g., using an NVA for
address resolution), for optimal delivery, there would have to be a
separate group for each tenant VN for infrastructure multicast plus a
separate group for each application-specific multicast address (used for multicast applications) within
a tenant.

Additional considerations are

An additional consideration is that only the lower 23 bits of the IP
address (regardless of whether IPv4 or IPv6 is in use) are mapped to
the outer MAC address, and if there is equipment that prunes
multicasts at Layer 2, there will be some aliasing.

Finally, a mechanism to efficiently provision such addresses for each
group would be required.

There are additional optimizations that are possible, but they come
with their own restrictions. For example, a set of tenants may be
restricted to some subset of NVEs, and they could all share the same
outer IP multicast group address. This, however, introduces a
problem of suboptimal delivery (even if a particular tenant within
the group of tenants doesn't have a presence on one of the NVEs that
another one does, the multicast packets would still be delivered to
that NVE). It also introduces an additional network management
burden to optimize which tenants should be part of the same tenant
group (based on the NVEs they share), which somewhat dilutes the
value proposition of NVO3 (to completely decouple the overlay and
physical network design allowing complete freedom of placement of VMs
anywhere within the DC).

Multicast schemes such as Bit Indexed Explicit Replication (BIER)
[RFC8279] may be able to provide optimizations by allowing the
underlay network to provide optimum multicast delivery without
requiring routers in the core of the network to maintain per-
multicast group state.

3.5. Other Schemes

There are still other mechanisms that may be used that attempt to
combine some of the advantages of the above methods by offering
multiple replication points, each with a limited degree of
replication [EDGE-REP]. Such schemes offer a trade-off between the
amount of replication at an intermediate node (e.g., router) versus
performing all of the replication at the source NVE or all of the
replication at a multicast service node.

4. Simultaneous Use of More Than One Mechanism

While the mechanisms discussed in the previous section have been
discussed individually, it is possible for implementations to rely on
more than one of these. For example, the method of Section 3.1 could
be used for minimizing ARP/ND, while at the same time, multicast
applications may be supported by one, or a combination, of the other
methods. For small multicast groups, the methods of source NVE
replication or the use of a multicast service node may be attractive,
while for larger multicast groups, the use of multicast in the
underlay may be preferable.

5. Other Issues

5.1. Multicast-Agnostic NVEs

Some hypervisor-based NVEs do not process or recognize IGMP/MLD
frames, i.e., those NVEs simply encapsulate the IGMP/MLD messages in
the same way as they do for regular data frames.

By default, TSs a TS router periodically sends IGMP/MLD query messages to
all the hosts in the subnet to trigger the hosts that are interested
in the multicast stream to send back IGMP/MLD reports. In order for
the MSN to get the updated multicast group information, the MSN can
also send the IGMP/MLD query message comprising a client-specific
multicast address encapsulated in an overlay header to all of the
NVEs to which the TSs in the VN are attached.

However, the MSN may not always be aware of the client-specific
multicast addresses. In order to perform multicast filtering, the
MSN has to snoop the IGMP/MLD messages between TSs and their
corresponding routers to maintain the multicast membership. In order
for the MSN to snoop the IGMP/MLD messages between TSs and their
router, the NVA needs to configure the NVE to send copies of the
IGMP/MLD messages to the MSN in addition to the default behavior of
sending them to the TSs' routers; e.g., the NVA has to inform the
NVEs to encapsulate data frames with the Destination Address (DA)
being 224.0.0.2 (DA of IGMP report) to the TSs' router and MSN.

This process is similar to "Source Replication" described in
Section 3.2, except the NVEs only replicate the message to the TSs'
router and MSN.

5.2. Multicast Membership Management for DC with VMs

For DCs with virtualized servers, VMs can be added, deleted, or moved
very easily. When VMs are added, deleted, or moved, the NVEs to
which the VMs are attached are changed.

When a VM is deleted from an NVE or a new VM is added to an NVE, the
VM management system should notify the MSN to send the IGMP/MLD query
messages to the relevant NVEs (as described in Section 3.3) so that
the multicast membership can be updated promptly.

Otherwise, if there are changes of VMs attachment to NVEs (within the
duration of the configured default time interval that the TSs routers
use for IGMP/MLD queries), multicast data may not reach the VM(s)
that moved.

6. Security Considerations

This document does not introduce any new security considerations
beyond what is described in the NVO3 Architecture document [RFC8014].

7. IANA Considerations

This document does not require any IANA actions.

8. Summary

This document has identified various mechanisms for supporting
application-specific multicast in networks that use NVO3. It
highlights the basics of each mechanism and some of the issues with
them. As solutions are developed, the protocols would need to
consider the use of these mechanisms, and coexistence may be a
consideration. It also highlights some of the requirements for
supporting multicast applications in an NVO3 network.

9. References

9.1. Normative References

[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version
3", RFC 3376, DOI 10.17487/RFC3376, October 2002,
<https://www.rfc-editor.org/info/rfc3376>.

[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
2012, <https://www.rfc-editor.org/info/rfc6513>.

[RFC7364] Narten, T., Ed., Gray, E., Ed., Black, D., Fang, L.,
Kreeger, L., and M. Napierala, "Problem Statement:
Overlays for Network Virtualization", RFC 7364,
DOI 10.17487/RFC7364, October 2014,
<https://www.rfc-editor.org/info/rfc7364>.

[RFC7365] Lasserre, M., Balus, F., Morin, T., Bitar, N., and Y.
Rekhter, "Framework for Data Center (DC) Network
Virtualization", RFC 7365, DOI 10.17487/RFC7365, October
2014, <https://www.rfc-editor.org/info/rfc7365>.

[RFC8014] Black, D., Hudson, J., Kreeger, L., Lasserre, M., and T.
Narten, "An Architecture for Data-Center Network
Virtualization over Layer 3 (NVO3)", RFC 8014,
DOI 10.17487/RFC8014, December 2016,
<https://www.rfc-editor.org/info/rfc8014>.

9.2. Informative References

[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997,
<https://www.rfc-editor.org/info/rfc2131>.

[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710,
DOI 10.17487/RFC2710, October 1999,
<https://www.rfc-editor.org/info/rfc2710>.

[RFC3569] Bhattacharyya, S., Ed., "An Overview of Source-Specific
Multicast (SSM)", RFC 3569, DOI 10.17487/RFC3569, July
2003, <https://www.rfc-editor.org/info/rfc3569>.

[RFC3819] Karn, P., Ed., Bormann, C., Fairhurst, G., Grossman, D.,
Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L.
Wood, "Advice for Internet Subnetwork Designers", BCP 89,
RFC 3819, DOI 10.17487/RFC3819, July 2004,
<https://www.rfc-editor.org/info/rfc3819>.

[RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private
LAN Service (VPLS) Using Label Distribution Protocol (LDP)
Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007,
<https://www.rfc-editor.org/info/rfc4762>.

[RFC6040] Briscoe, B., "Tunnelling of Explicit Congestion
Notification", RFC 6040, DOI 10.17487/RFC6040, November
2010, <https://www.rfc-editor.org/info/rfc6040>.

[RFC6831] Farinacci, D., Meyer, D., Zwiebel, J., and S. Venaas, "The
Locator/ID Separation Protocol (LISP) for Multicast
Environments", RFC 6831, DOI 10.17487/RFC6831, January
2013, <https://www.rfc-editor.org/info/rfc6831>.

[RFC7117] Aggarwal, R., Ed., Kamite, Y., Fang, L., Rekhter, Y., and
C. Kodeboniya, "Multicast in Virtual Private LAN Service
(VPLS)", RFC 7117, DOI 10.17487/RFC7117, February 2014,
<https://www.rfc-editor.org/info/rfc7117>.

[RFC7348] Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3
Networks", RFC 7348, DOI 10.17487/RFC7348, August 2014,
<https://www.rfc-editor.org/info/rfc7348>.

[RFC7637] Garg, P., Ed. and Y. Wang, Ed., "NVGRE: Network
Virtualization Using Generic Routing Encapsulation",
RFC 7637, DOI 10.17487/RFC7637, September 2015,
<https://www.rfc-editor.org/info/rfc7637>.

[RFC8279] Wijnands, IJ., Ed., Rosen, E., Ed., Dolganow, A.,
Przygienda, T., and S. Aldrin, "Multicast Using Bit Index
Explicit Replication (BIER)", RFC 8279,
DOI 10.17487/RFC8279, November 2017,
<https://www.rfc-editor.org/info/rfc8279>.

[DC-MC] McBride, M. and H. Liu, "Multicast in the Data Center
Overview", Work in Progress, draft-mcbride-armd-mcast-
overview-02, July 2012.

[EDGE-REP]
Marques, P., Fang, L., Winkworth, D., Cai, Y., and P.
Lapukhov, "Edge multicast replication for BGP IP VPNs.",
Work in Progress, draft-marques-l3vpn-mcast-edge-01, June
2012.

[Geneve] Gross, J., Ganga, I., and T. Sridhar, "Geneve: Generic
Network Virtualization Encapsulation", Work in Progress,
draft-ietf-nvo3-geneve-05, September 2017.

[GUE] Herbert, T., Yong, L., and O. Zia, "Generic UDP
Encapsulation", Work in Progress, draft-ietf-nvo3-gue-05,
October 2016. draft-ietf-intarea-gue-
04, May 2017.

[ISIS-Multicast]
Yong, L., Weiguo, H., Eastlake, D., Qu, A., Hudson, J.,
and U. Chunduri, "IS-IS Protocol Extension For Building
Distribution Trees", Work in Progress, draft-yong-isis-
ext-4-distribution-tree-03, October 2014.

[LANE] ATM Forum, "LAN Emulation Over ATM: Version 1.0", ATM
Forum Technical Committee, af-lane-0021.000, January 1995.

[LISP-Signal-Free]
Moreno, V. and D. Farinacci, "Signal-Free LISP Multicast",
Work in Progress, draft-ietf-lisp-signal-free-multicast-
07, November 2017.

[VXLAN-GPE]
Maino, F., Kreeger, L., and U. Elzur, "Generic Protocol
Extension for VXLAN", Work in Progress, draft-ietf-nvo3-
vxlan-gpe-05, October 2017.

Acknowledgments

Many thanks are due to Dino Farinacci, Erik Nordmark, Lucy Yong,
Nicolas Bouliane, Saumya Dikshit, Joe Touch, Olufemi Komolafe, and
Matthew Bocci for their valuable comments and suggestions.

Authors' Addresses

Anoop Ghanwani
Dell

Email: anoop@alumni.duke.edu

Linda Dunbar
Huawei Technologies
5340 Legacy Drive, Suite 1750
Plano, TX 75024
United States of America

Phone: (469) 277 5840
Email: ldunbar@huawei.com
Mike McBride
Huawei Technologies

Email: mmcbride7@gmail.com

Vinay Bannai
Google

Email: vbannai@gmail.com

Ram Krishnan
Dell

Email: ramkri123@gmail.com