A Framework for Multicast in Network Virtualization Overlays
The information below is for an old version of the document.
This is an older version of an Internet-Draft that was ultimately published as RFC 8293.
|Authors||Anoop Ghanwani , Linda Dunbar , Mike McBride , Vinay Bannai , Ramki Krishnan|
|Last updated||2017-10-02 (Latest revision 2017-06-23)|
|RFC stream||Internet Engineering Task Force (IETF)|
GENART Last Call review by Christer Holmberg Ready with Nits
TSVART Last Call review by Colin Perkins Ready with Issues
|Additional resources||Mailing list discussion|
|Stream||WG state||Submitted to IESG for Publication|
|Document shepherd||Sam Aldrin|
|Shepherd write-up||Show Last changed 2017-06-23|
|IESG||IESG state||IESG Evaluation|
Needs a YES.
|Responsible AD||Alia Atlas|
|Send notices to||"Matthew Bocci" <email@example.com>, "Sam Aldrin" <firstname.lastname@example.org>|
|IANA||IANA review state||IANA OK - No Actions Needed|
NVO3 working group A. Ghanwani Internet Draft Dell Intended status: Informational L. Dunbar Expires: November 8, 2017 M. McBride Huawei V. Bannai Google R. Krishnan Dell June 23, 2017 A Framework for Multicast in Network Virtualization Overlays draft-ietf-nvo3-mcast-framework-09 Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html This Internet-Draft will expire on November 8, 2016. Ghanwani et al. Expires November 2017 [Page 1] Internet-Draft A framework for multicast in NVO3 February 2016 Copyright Notice Copyright (c) 2017 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://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. Abstract This document discusses a framework of supporting multicast traffic in a network that uses Network Virtualization Overlays (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. Table of Contents 1. Introduction...................................................3 1.1. Infrastructure multicast..................................3 1.2. Application-specific multicast............................4 1.3. Terminology clarification.................................4 2. Acronyms.......................................................4 3. Multicast mechanisms in networks that use NVO3.................5 3.1. No multicast support......................................6 3.2. Replication at the source NVE.............................6 3.3. Replication at a multicast service node...................9 3.4. IP multicast in the underlay.............................10 3.5. Other schemes............................................12 4. Simultaneous use of more than one mechanism...................12 5. Other issues..................................................12 5.1. Multicast-agnostic NVEs..................................12 5.2. Multicast membership management for DC with VMs..........13 6. Summary.......................................................14 7. Security Considerations.......................................14 8. IANA Considerations...........................................14 Ghanwani et al. Expires November 2017 [Page 2] Internet-Draft A framework for multicast in NVO3 February 2016 9. References....................................................14 9.1. Normative References.....................................14 9.2. Informative References...................................15 10. Acknowledgments..............................................16 1. Introduction Network virtualization using Overlays over Layer 3 (NVO3) is a technology that is used to address issues that arise in building large, multitenant data centers 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). Both infrastructure multicast and application- specific multicast are considered. It describes the various mechanisms and considerations that can be used for delivering such traffic in networks that use NVO3. The reader is assumed to be familiar with the terminology as defined in the NVO3 Framework document [RFC7365] and NVO3 Architecture document [RFC8014]. 1.1. Infrastructure multicast Infrastructure multicast is a capability needed by networking services, such as Address Resolution Protocol (ARP), Neighbor Discovery (ND), Dynamic Host Configuration Protocol (DHCP), multicast Domain Name Server (mDNS), etc.. RFC3819 Section 5 and 6 have detailed description for some of the infrastructure multicast [RFC3819]. It is possible to provide solutions for these that do not involve multicast in the underlay network. In the case of ARP/ND, a network virtualization authority (NVA) can be used for distributing the mappings of IP address to MAC address to all network virtualization edges (NVEs). The NVEs can then trap ARP Request/ND Neighbor Solicitation messages from the TSs that are attached to it and respond to them, thereby eliminating the need to for broadcast/multicast of such messages. In the case of DHCP, the NVE can be configured to forward these messages using a helper function. 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. Ghanwani et al. Expires November 2017 [Page 3] Internet-Draft A framework for multicast in NVO3 February 2016 1.2. Application-specific multicast Application-specific multicast traffic are originated and consumed by user applications. The Application-specific multicast, which can be either Source-Specific Multicast (SSM) or Any-Source Multicast (ASM)[RFC3569], has the following characteristics: 1. Receiver hosts are expected to subscribe to multicast content using protocols such as IGMP [RFC3376] (IPv4) or MLD (IPv6). Multicast sources and listeners participant in these protocols using addresses that are in the Tenant System address domain. 2. The list of multicast listeners for each multicast group is not known in advance. Therefore, it may not be possible for an NVA to get the list of participants for each multicast group ahead of time. 1.3. Terminology clarification 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. 2. Acronyms 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 Ghanwani et al. Expires November 2017 [Page 4] Internet-Draft A framework for multicast in NVO3 February 2016 SSM: Source-Specific Multicast TS: Tenant system VM: Virtual Machine VN: Virtual Network VTEP: VxLAN Tunnel End Points 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 Virtual eXtensible Local Area Network (VXLAN) [RFC7348,VXLAN-GPE], Network Virtualization Using Generic Routing Encapsulation (NVGRE) [RFC7637], , Geneve [Geneve], Generic UDP Encapsulation (GUE) [GUE], etc. What makes NVO3 different from any other network is that some NVEs, especially the NVE implemented on server, might not support PIM or other native multicast mechanisms. They might just encapsulate the 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 data centers [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. Ghanwani et al. Expires November 2017 [Page 5] Internet-Draft A framework for multicast in NVO3 February 2016 These methods are briefly mentioned in the NVO3 Framework [RFC7365] and NVO3 architecture [RFC8014] document. This document provides more details about the basic mechanisms underlying each of these methods and discusses the issues and tradeoffs 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. 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 the NVEs to determine the mapping of a given Tenant System's (TS's) MAC/IP address to its NVE. 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 by use of a helper function in the NVE. 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 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 Ghanwani et al. Expires November 2017 [Page 6] Internet-Draft A framework for multicast in NVO3 February 2016 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 virtual network (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: Using LISP-signal-free does not necessarily mean the head-end (i.e. NVE) must do replication. If the mapping database (i.e. NVA) indicates that packets are encapsulated to multicast RLOCs, then there is no replication happening at the NVE. The receiver-sites registration is achieved by egress NVEs performing the IGMP/MLD snooping to maintain 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 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 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 multi-homing 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 choose any one of the egress NVEs for the data frames destined towards the 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. This also creates an issue with the forwarding performance of the NVE. Ghanwani et al. Expires November 2017 [Page 7] Internet-Draft A framework for multicast in NVO3 February 2016 Note that this method is similar to what was used in Virtual Private LAN Service (VPLS) [RFC4762] prior to support of Multi-Protocol Label Switching (MPLS) multicast [RFC7117]. While there are some similarities between MPLS Virtual Private Network (VPN) and NVO3, there are some key differences: - The Customer Edge (CE) to Provider Edge (PE) attachment in VPNs is somewhat static, whereas in a DC that allows VMs to migrate anywhere, the TS attachment to NVE is much more dynamic. - 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, [RFC6513] "Multicast VPN" 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 excessive wastage of bandwidth in the provider's network. In a DC environment, a typical server/hypervisor based virtual switch may only support 10's VMs (as of this writing). A subnet with N VMs may be, in the worst case, spread across N vSwitches. Using "MPLS VPN multicast" approach in such a scenario would require the creation of a Multicast group in the core for this VN to reach all N NVEs. If only 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 considerable wastage of bandwidth. Therefore, the Multicast VPN solution may not scale in DC environment with dynamic attachment of Virtual Networks to NVEs and greater number of NVEs for each virtual network. Ghanwani et al. Expires November 2017 [Page 8] Internet-Draft A framework for multicast in NVO3 February 2016 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)LANE specification [LANE]. The MSN is similar to the RP in PIM SM, but different in that the user data traffic are carried by the NVO3 tunnels. The following are the possible ways for the MSN to get the membership information for each multicast group: - 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 messages sent out by the MSN to an NVE is encapsulated with the MSN address in the outer source address field and the address of the NVE in the outer destination address field. The encapsulated IGMP/MLD query messages also has a VNID for a virtual network (VN) that TSs belong in the outer header and a multicast address in the inner destination address field. Upon receiving the encapsulated IGMP/MLD query message, the NVE establishes a mapping "MSN address" <-> "multicast address", decapsulates the received encapsulated IGMP/MLD message, and multicast the decapsulated query message to TSs that belong to the VN under the NVE. A IGMP/MLD report message sent by a TS includes the multicast address and the address of the TS. With the proper "MSN Address" <-> "Multicast-Address" mapping, the NVEs can encapsulate all multicast data frames to the "Multicast-Address" with the address of the MSN in the outer destination address field. - The MSN can obtain the membership information from the NVEs that have the capability to establish multicast groups by snooping native IGMP/MLD messages (p.s. the communication must be specific Ghanwani et al. Expires November 2017 [Page 9] Internet-Draft A framework for multicast in NVO3 February 2016 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 Multicast Service Node. 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 sub-optimality 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 Protocol Independent Multicast (PIM), or 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: - The NVE only supports the basic IGMP/MLD snooping function, let the TSs routers handling the application specific multicast. This scheme doesn't utilize the underlay IP multicast protocols. - The NVE can act as a pseudo multicast router for the directly attached VMs and support proper mapping of IGMP/MLD's messages to the messages needed by the underlay IP multicast protocols. Ghanwani et al. Expires November 2017 [Page 10] Internet-Draft A framework for multicast in NVO3 February 2016 With this method, there are none of the issues with the methods described in Sections 3.2. With PIM Sparse Mode (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 implementaion. RFC6831 [RFC6831] has good description of using SSM as an alternative to BIDIR if the VTEP/NVE devices have a way to learn of each other's IP address so that they could join all SSM SPT's 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, plus a separate group for each multicast address (used for multicast applications) within a tenant. Additional considerations are 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 which 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 sub-optimal delivery (even if a particular tenant within the group of tenants doesn't have a presence on one of the NVEs which another one does, the former's 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 which is to completely decouple the overlay and physical network design allowing complete freedom of placement of VMs anywhere within the data center. Ghanwani et al. Expires November 2017 [Page 11] Internet-Draft A framework for multicast in NVO3 February 2016 Multicast schemes such as BIER (Bit Indexed Explicit Replication) [BIER-ARCH] 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 (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. Ghanwani et al. Expires November 2017 [Page 12] Internet-Draft A framework for multicast in NVO3 February 2016 By default, TSs 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 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 DA being 22.214.171.124 (destination address of IGMP report) to TSs' router and MSN. This process is similar to "Source Replication" described in Section 3.2, except the NVEs only replicate the message to TSs' router and MSN. 5.2. Multicast membership management for DC with VMs For data centers 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. Ghanwani et al. Expires November 2017 [Page 13] Internet-Draft A framework for multicast in NVO3 February 2016 6. 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 co-existence may be a consideration. It also highlights some of the requirements for supporting multicast applications in an NVO3 network. 7. Security Considerations This draft does not introduce any new security considerations beyond what is described n NVO3 Architecture (RFC8014). 8. IANA Considerations This document requires no IANA actions. RFC Editor: Please remove this section before publication. 9. References 9.1. Normative References [RFC3376] Cain B. et al., "Internet Group Management Protocol, Version 3", October 2002. [RFC6513] Rosen, E. et al., "Multicast in MPLS/BGP IP VPNs", February 2012. [RFC7364] Narten, T. et al., "Problem statement: Overlays for network virtualization", October 2014. [RFC7365] Lasserre, M. et al., "Framework for data center (DC) network virtualization", October 2014. [RFC8014] Narten, T. et al.," An Architecture for Overlay Networks (NVO3)", RFC8014, Dec. 2016. Ghanwani et al. Expires November 2017 [Page 14] Internet-Draft A framework for multicast in NVO3 February 2016 9.2. Informative References [RFC3569] S. Bhattacharyya, Ed., "An Overview of Source-Specific Multicast (SSM)", July 2003. [RFC3819] P. Harn et al., "Advice for Internet Subnetwork Designers", July 2004. [RFC4762] Lasserre, M., and Kompella, V. (Eds.), "Virtual Private LAN Service (VPLS) using Label Distribution Protocol (LDP) signaling," January 2007. [RFC6831] Farinacci, D. et al., "The Locator/ID Seperation Protocol (LISP) for Multicast Environments", Jan, 2013. [RFC7117] Aggarwal, R. et al., "Multicast in VPLS," February 2014. [RFC7348] Mahalingam, M. et al., " Virtual eXtensible Local Area Network (VXLAN): A Framework for Overlaying Virtualized Layer 2 Networks over Layer 3 Networks", August 2014. [RFC7637] Garg P. and Wang, Y. (Eds.), "NVGRE: Network Vvirtualization using Generic Routing Encapsulation", September 2015. [BIER-ARCH] Wijnands, IJ. (Ed.) et al., "Multicast using Bit Index Explicit Replication," <draft-ietf-bier-architecture-03>, January 2016. [DC-MC] McBride, M. and Lui, H., "Multicast in the data center overview," <draft-mcbride-armd-mcast-overview-02>, work in progress, July 2012. [EDGE-REP] Marques P. et al., "Edge multicast replication for BGP IP VPNs," <draft-marques-l3vpn-mcast-edge-01>, work in progress, June 2012. Ghanwani et al. Expires November 2017 [Page 15] Internet-Draft A framework for multicast in NVO3 February 2016 [Geneve] Gross, J. and Ganga, I. (Eds.), "Geneve: Generic Network Virtualization Encapsulation", <draft-ietf-nvo3-geneve- 01>, work in progress, January 2016. [GUE] Herbert, T. et al., "Generic UDP Encapsulation", <draft- ietf-nvo3-gue-02>, work in progress, December 2015. [ISIS-Multicast] Yong, L. et al., "ISIS Protocol Extension for Building Distribution Trees", <draft-yong-isis-ext-4-distribution- tree-03>, work in progress, October 2014. [LANE] "LAN emulation over ATM," The ATM Forum, af-lane-0021.000, January 1995. [LISP-Signal-Free] Moreno, V. and Farinacci, D., "Signal-Free LISP Multicast", <draft-ietf-lisp-signal-free-multicast-01>, work in progress, April 2016. [VXLAN-GPE] Kreeger, L. and Elzur, U. (Eds.), "Generic Protocol Extension for VXLAN", <draft-ietf-nvo3-vxlan-gpe-02>, work in progress, April 2016. 10. 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. This document was prepared using 2-Word-v2.0.template.dot. Ghanwani et al. Expires November 2017 [Page 16] Internet-Draft A framework for multicast in NVO3 February 2016 Authors' Addresses Anoop Ghanwani Dell Email: email@example.com Linda Dunbar Huawei Technologies 5340 Legacy Drive, Suite 1750 Plano, TX 75024, USA Phone: (469) 277 5840 Email: firstname.lastname@example.org Mike McBride Huawei Technologies Email: email@example.com Vinay Bannai Google Email: firstname.lastname@example.org Ram Krishnan Dell Email: email@example.com Ghanwani et al. Expires November 2017 [Page 17]