Network Working Group X. Xu Internet-Draft Huawei Technologies Intended status: Informational R. Raszuk Expires: May 30, 2016 Bloomberg LP C. Jacquenet Orange T. Boyes Bloomberg LP B. Fee Extreme Networks November 27, 2015 Virtual Subnet: A BGP/MPLS IP VPN-based Subnet Extension Solution draft-ietf-bess-virtual-subnet-06 Abstract This document describes a BGP/MPLS IP VPN-based subnet extension solution referred to as Virtual Subnet, which can be used for building Layer 3 network virtualization overlays within and/or between data centers. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on May 30, 2016. Copyright Notice Copyright (c) 2015 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 Xu, et al. Expires May 30, 2016 [Page 1] Internet-Draft Virtual Subnet November 2015 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 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Solution Description . . . . . . . . . . . . . . . . . . . . 4 3.1. Unicast . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1.1. Intra-subnet Unicast . . . . . . . . . . . . . . . . 4 3.1.2. Inter-subnet Unicast . . . . . . . . . . . . . . . . 6 3.2. Multicast . . . . . . . . . . . . . . . . . . . . . . . . 8 3.3. Host Discovery . . . . . . . . . . . . . . . . . . . . . 9 3.4. ARP/ND Proxy . . . . . . . . . . . . . . . . . . . . . . 9 3.5. Host Mobility . . . . . . . . . . . . . . . . . . . . . . 9 3.6. Forwarding Table Scalability on Data Center Switches . . 10 3.7. ARP/ND Cache Table Scalability on Default Gateways . . . 10 3.8. ARP/ND and Unknown Unicast Flood Avoidance . . . . . . . 10 3.9. Path Optimization . . . . . . . . . . . . . . . . . . . . 10 4. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . 11 4.1. Non-support of Non-IP Traffic . . . . . . . . . . . . . . 11 4.2. Non-support of IP Broadcast and Link-local Multicast . . 11 4.3. TTL and Traceroute . . . . . . . . . . . . . . . . . . . 11 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . 12 8.2. Informative References . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14 1. Introduction For business continuity purposes, Virtual Machine (VM) migration across data centers is commonly used in situations such as data center maintenance, migration, consolidation, expansion, or disaster avoidance. It's generally admitted that IP renumbering of servers (i.e., VMs) after the migration is usually complex and costly at the risk of extending the business downtime during the process of migration. To allow the migration of a VM from one data center to another without IP renumbering, the subnet on which the VM resides needs to be extended across these data centers. Xu, et al. Expires May 30, 2016 [Page 2] Internet-Draft Virtual Subnet November 2015 To achieve subnet extension across multiple cloud data centers in a scalable way, the following requirements and challenges must be considered: a. VPN Instance Space Scalability: In a modern cloud data center environment, thousands or even tens of thousands of tenants could be hosted over a shared network infrastructure. For security and performance isolation purposes, these tenants need to be isolated from one another. b. Forwarding Table Scalability: With the development of server virtualization technologies, it's not uncommon for a single cloud data center to contain millions of VMs. This number already implies a big challenge to the forwarding table scalability of data center switches. Provided multiple data centers of such scale were interconnected at Layer 2, this challenge would become even worse. c. ARP/ND Cache Table Scalability: [RFC6820] notes that the Address Resolution Protocol (ARP)/Neighbor Discovery (ND) cache tables maintained by default gateways within cloud data centers can raise scalability issues. Therefore, mastering the size of the ARP/ND cache tables is critical as the number of data centers to be connected increases. d. ARP/ND and Unknown Unicast Flooding: It's well-known that the flooding of ARP/ND broadcast/multicast messages as well as unknown unicast traffic within large Layer 2 networks is likely to affect network and host performance. When multiple data centers that each hosts millions of VMs are interconnected at Layer 2, the impact of such flooding would become even worse. As such, it becomes increasingly important to avoid the flooding of ARP/ND broadcast/multicast as well as unknown unicast traffic across data centers. e. Path Optimization: A subnet usually indicates a location in the network. However, when a subnet has been extended across multiple geographically-dispersed data center locations, the location semantics of such subnet is not retained any longer. As a result, traffic exchanged between a specific user and a server that would be located in different data centers, may first be forwarded through a third data center. This suboptimal routing would obviously result in an unnecessary consumption of the bandwidth resources between data centers. Furthermore, in the case where traditional VPLS technology [RFC4761] [RFC4762] is used for data center interconnect, return traffic from a server may be forwarded to a default gateway located in a different data center due to the configuration of a virtual router redundancy Xu, et al. Expires May 30, 2016 [Page 3] Internet-Draft Virtual Subnet November 2015 group. This suboptimal routing would also unnecessarily consume the bandwidth resources between data centers. This document describes a BGP/MPLS IP VPN-based subnet extension solution referred to as Virtual Subnet, which can be used for data center interconnection while addressing all of the aforementioned requirements and challenges. Here the BGP/MPLS IP VPN means both BGP/MPLS IPv4 VPN [RFC4364] and BGP/MPLS IPv6 VPN [RFC4659]. In addition, since Virtual Subnet is mainly built on proven technologies such as BGP/MPLS IP VPN and ARP/ND proxy [RFC0925][RFC1027][RFC4389], those service providers that provide Infrastructure as a Service (IaaS) cloud services can rely upon their existing BGP/MPLS IP VPN infrastructure and take advantage of their BGP/MPLS VPN operational experience to interconnect data centers. Although Virtual Subnet is described in this document as an approach for data center interconnection, it can be used within data centers as well. Note that the approach described in this document is not intended to achieve an exact emulation of Layer 2 connectivity and therefore it can only support a restricted Layer 2 connectivity service model with limitations that are discussed in Section 4. As for the discussion about where this service model can apply, it's outside the scope of this document. 2. Terminology This memo makes use of the terms defined in [RFC4364]. 3. Solution Description 3.1. Unicast 3.1.1. Intra-subnet Unicast Xu, et al. Expires May 30, 2016 [Page 4] Internet-Draft Virtual Subnet November 2015 +--------------------+ +------------------+ | | +------------------+ |VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24| | \ | | | | / | | +------+ \ ++---+-+ +-+---++/ +------+ | | |Host A+-----+ PE-1 | | PE-2 +----+Host B| | | +------+\ ++-+-+-+ +-+-+-++ /+------+ | | 192.0.2.2/24 | | | | | | 192.0.2.3/24 | | | | | | | | | | DC West | | | IP/MPLS Backbone | | | DC East | +------------------+ | | | | +------------------+ | +--------------------+ | | | VRF_A : V VRF_A : V +------------+---------+--------+ +------------+---------+--------+ | Prefix | Nexthop |Protocol| | Prefix | Nexthop |Protocol| +------------+---------+--------+ +------------+---------+--------+ |192.0.2.1/32|127.0.0.1| Direct | |192.0.2.1/32|127.0.0.1| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.2/32|192.0.2.2| Direct | |192.0.2.2/32| PE-1 | IBGP | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.3/32| PE-2 | IBGP | |192.0.2.3/32|192.0.2.3| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.0/24|192.0.2.1| Direct | |192.0.2.0/24|192.0.2.1| Direct | +------------+---------+--------+ +------------+---------+--------+ Figure 1: Intra-subnet Unicast Example As shown in Figure 1, two hosts (i.e., Hosts A and B) belonging to the same subnet (i.e., 192.0.2.0/24) are located in different data centers (i.e., DC West and DC East) respectively. PE routers (i.e., PE-1 and PE-2) that are used for interconnecting these two data centers create host routes for their own local hosts respectively and then advertise these routes by means of the BGP/MPLS IP VPN signaling. Meanwhile, an ARP proxy is enabled on Virtual Routing and Forwarding (VRF) attachment circuits of these PE routers. Let's now assume that host A sends an ARP request for host B before communicating with host B. Upon receiving the ARP request, PE-1 acting as an ARP proxy returns its own MAC address as a response. Host A then sends IP packets for host B to PE-1. PE-1 tunnels such packets towards PE-2 which in turn forwards them to host B. Thus, hosts A and B can communicate with each other as if they were located within the same subnet. Xu, et al. Expires May 30, 2016 [Page 5] Internet-Draft Virtual Subnet November 2015 3.1.2. Inter-subnet Unicast +--------------------+ +------------------+ | | +------------------+ |VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24| | \ | | | | / | | +------+ \ ++---+-+ +-+---++/ +------+ | | |Host A+-------+ PE-1 | | PE-2 +-+----+Host B| | | +------+\ ++-+-+-+ +-+-+-++ | /+------+ | | 192.0.2.2/24 | | | | | | | 192.0.2.3/24 | | GW=192.0.2.4 | | | | | | | GW=192.0.2.4 | | | | | | | | | +------+ | | | | | | | | +----+ GW +-- | | | | | | | | /+------+ | | | | | | | | 192.0.2.4/24 | | | | | | | | | | DC West | | | IP/MPLS Backbone | | | DC East | +------------------+ | | | | +------------------+ | +--------------------+ | | | VRF_A : V VRF_A : V +------------+---------+--------+ +------------+---------+--------+ | Prefix | Nexthop |Protocol| | Prefix | Nexthop |Protocol| +------------+---------+--------+ +------------+---------+--------+ |192.0.2.1/32|127.0.0.1| Direct | |192.0.2.1/32|127.0.0.1| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.2/32|192.0.2.2| Direct | |192.0.2.2/32| PE-1 | IBGP | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.3/32| PE-2 | IBGP | |192.0.2.3/32|192.0.2.3| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.4/32| PE-2 | IBGP | |192.0.2.4/32|192.0.2.4| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.0/24|192.0.2.1| Direct | |192.0.2.0/24|192.0.2.1| Direct | +------------+---------+--------+ +------------+---------+--------+ | 0.0.0.0/0 | PE-2 | IBGP | | 0.0.0.0/0 |192.0.2.4| Static | +------------+---------+--------+ +------------+---------+--------+ Figure 2: Inter-subnet Unicast Example (1) As shown in Figure 2, only one data center (i.e., DC East) is deployed with a default gateway (i.e., GW). PE-2 that is connected to GW would either be configured with or learn from GW a default route with the next-hop being pointed at GW. Meanwhile, this route is distributed to other PE routers (i.e., PE-1) as per normal [RFC4364] operation. Assume host A sends an ARP request for its default gateway (i.e., 192.0.2.4) prior to communicating with a destination host outside of its subnet. Upon receiving this ARP request, PE-1 acting as an ARP proxy returns its own MAC address as a response. Host A then sends a packet for Host B to PE-1. PE-1 Xu, et al. Expires May 30, 2016 [Page 6] Internet-Draft Virtual Subnet November 2015 tunnels such packet towards PE-2 according to the default route learnt from PE-2, which in turn forwards that packet to GW. +--------------------+ +------------------+ | | +------------------+ |VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24| | \ | | | | / | | +------+ \ ++---+-+ +-+---++/ +------+ | | |Host A+----+--+ PE-1 | | PE-2 +-+----+Host B| | | +------+\ | ++-+-+-+ +-+-+-++ | /+------+ | | 192.0.2.2/24 | | | | | | | | 192.0.2.3/24 | | GW=192.0.2.4 | | | | | | | | GW=192.0.2.4 | | +------+ | | | | | | | | +------+ | |--+ GW-1 +----+ | | | | | | +----+ GW-2 +-- | | +------+\ | | | | | | /+------+ | | 192.0.2.4/24 | | | | | | 192.0.2.4/24 | | | | | | | | | | DC West | | | IP/MPLS Backbone | | | DC East | +------------------+ | | | | +------------------+ | +--------------------+ | | | VRF_A : V VRF_A : V +------------+---------+--------+ +------------+---------+--------+ | Prefix | Nexthop |Protocol| | Prefix | Nexthop |Protocol| +------------+---------+--------+ +------------+---------+--------+ |192.0.2.1/32|127.0.0.1| Direct | |192.0.2.1/32|127.0.0.1| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.2/32|192.0.2.2| Direct | |192.0.2.2/32| PE-1 | IBGP | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.3/32| PE-2 | IBGP | |192.0.2.3/32|192.0.2.3| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.4/32|192.0.2.4| Direct | |192.0.2.4/32|192.0.2.4| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.0/24|192.0.2.1| Direct | |192.0.2.0/24|192.0.2.1| Direct | +------------+---------+--------+ +------------+---------+--------+ | 0.0.0.0/0 |192.0.2.4| Static | | 0.0.0.0/0 |192.0.2.4| Static | +------------+---------+--------+ +------------+---------+--------+ Figure 3: Inter-subnet Unicast Example (2) As shown in Figure 3, in the case where each data center is deployed with a default gateway, hosts will get ARP responses directly from their local default gateways, rather than from their local PE routers when sending ARP requests for their default gateways. Xu, et al. Expires May 30, 2016 [Page 7] Internet-Draft Virtual Subnet November 2015 +------+ +------+ PE-3 +------+ +------------------+ | +------+ | +------------------+ |VPN_A:192.0.2.1/24| | | |VPN_A:192.0.2.1/24| | \ | | | | / | | +------+ \ ++---+-+ +-+---++/ +------+ | | |Host A+-------+ PE-1 | | PE-2 +------+Host B| | | +------+\ ++-+-+-+ +-+-+-++ /+------+ | | 192.0.2.2/24 | | | | | | 192.0.2.3/24 | | GW=192.0.2.1 | | | | | | GW=192.0.2.1 | | | | | | | | | | DC West | | | IP/MPLS Backbone | | | DC East | +------------------+ | | | | +------------------+ | +--------------------+ | | | VRF_A : V VRF_A : V +------------+---------+--------+ +------------+---------+--------+ | Prefix | Nexthop |Protocol| | Prefix | Nexthop |Protocol| +------------+---------+--------+ +------------+---------+--------+ |192.0.2.1/32|127.0.0.1| Direct | |192.0.2.1/32|127.0.0.1| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.2/32|192.0.2.2| Direct | |192.0.2.2/32| PE-1 | IBGP | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.3/32| PE-2 | IBGP | |192.0.2.3/32|192.0.2.3| Direct | +------------+---------+--------+ +------------+---------+--------+ |192.0.2.0/24|192.0.2.1| Direct | |192.0.2.0/24|192.0.2.1| Direct | +------------+---------+--------+ +------------+---------+--------+ | 0.0.0.0/0 | PE-3 | IBGP | | 0.0.0.0/0 | PE-3 | IBGP | +------------+---------+--------+ +------------+---------+--------+ Figure 4: Inter-subnet Unicast Example (3) Alternatively, as shown in Figure 4, PE routers themselves could be configured as default gateways for their locally connected hosts as long as these PE routers have routes to reach outside networks. 3.2. Multicast To support IP multicast between hosts of the same Virtual Subnet, MVPN technologies [RFC6513] could be used without any change. For example, PE routers attached to a given VPN join a default provider multicast distribution tree which is dedicated to that VPN. Ingress PE routers, upon receiving multicast packets from their local hosts, forward them towards remote PE routers through the corresponding default provider multicast distribution tree. Within this context, the IP multicast doesn't include link-local multicast. Xu, et al. Expires May 30, 2016 [Page 8] Internet-Draft Virtual Subnet November 2015 3.3. Host Discovery PE routers should be able to dynamically discover their local hosts and keep the list of these hosts up-to-date in a timely manner so as to ensure the availability and accuracy of the corresponding host routes originated from them. PE routers could accomplish local host discovery by some traditional host discovery mechanisms using ARP or ND protocols. 3.4. ARP/ND Proxy Acting as an ARP or ND proxy, a PE router should only respond to an ARP request or Neighbor Solicitation (NS) message for a target host when it has a best route for that target host in the associated VRF and the outgoing interface of that best route is different from the one over which the ARP request or NS message is received. In the scenario where a given VPN site (i.e., a data center) is multi-homed to more than one PE router via an Ethernet switch or an Ethernet network, the Virtual Router Redundancy Protocol (VRRP) [RFC5798] is usually enabled on these PE routers. In this case, only the PE router being elected as the VRRP Master is allowed to perform the ARP/ND proxy function. 3.5. Host Mobility During the VM migration process, the PE router to which the moving VM is now attached would create a host route for that host upon receiving a notification message of VM attachment (e.g., a gratuitous ARP or unsolicited NA message). The PE router to which the moving VM was previously attached would withdraw the corresponding host route when noticing the detachment of that VM. Meanwhile, the latter PE router could optionally broadcast a gratuitous ARP or send an unsolicited NA message on behalf of that host with source MAC address being one of its own. In this way, the ARP/ND entry of this host that moved and which has been cached on any local host would be updated accordingly. In the case where there is no explicit VM detachment notification mechanism, the PE router could also use the following trick to detect the VM detachment: upon learning a route update for a local host from a remote PE router for the first time, the PE router could immediately check whether that local host is still attached to it by some means (e.g., ARP/ND PING and/or ICMP PING). It is important to ensure that the same MAC and IP are associated to the default gateway active in each data center, as the VM would most likely continue to send packets to the same default gateway address after having migrated from one data center to another. One possible way to achieve this goal is to configure the same VRRP group on each location so as to ensure that the default Xu, et al. Expires May 30, 2016 [Page 9] Internet-Draft Virtual Subnet November 2015 gateway active in each data center shares the same virtual MAC and virtual IP addresses. 3.6. Forwarding Table Scalability on Data Center Switches In a Virtual Subnet environment, the MAC learning domain associated with a given Virtual Subnet which has been extended across multiple data centers is partitioned into segments and each segment is confined within a single data center. Therefore data center switches only need to learn local MAC addresses, rather than learning both local and remote MAC addresses. 3.7. ARP/ND Cache Table Scalability on Default Gateways When default gateway functions are implemented on PE routers as shown in Figure 4, the ARP/ND cache table on each PE router only needs to contain ARP/ND entries of local hosts. As a result, the ARP/ND cache table size would not grow as the number of data centers to be connected increases. 3.8. ARP/ND and Unknown Unicast Flood Avoidance In a Virtual Subnet environment, the flooding domain associated with a given Virtual Subnet that has been extended across multiple data centers, is partitioned into segments and each segment is confined within a single data center. Therefore, the performance impact on networks and servers imposed by the flooding of ARP/ND broadcast/ multicast and unknown unicast traffic is minimized. 3.9. Path Optimization Take the scenario shown in Figure 4 as an example, to optimize the forwarding path for the traffic between cloud users and cloud data centers, PE routers located in cloud data centers (i.e., PE-1 and PE- 2), which are also acting as default gateways, propagate host routes for their own local hosts respectively to remote PE routers which are attached to cloud user sites (i.e., PE-3). As such, traffic from cloud user sites to a given server on the Virtual Subnet which has been extended across data centers would be forwarded directly to the data center location where that server resides, since traffic is now forwarded according to the host route for that server, rather than the subnet route. Furthermore, for traffic coming from cloud data centers and forwarded to cloud user sites, each PE router acting as a default gateway would forward traffic according to the longest-match route in the corresponding VRF. As a result, traffic from data centers to cloud user sites is forwarded along an optimal path as well. Xu, et al. Expires May 30, 2016 [Page 10] Internet-Draft Virtual Subnet November 2015 4. Limitations 4.1. Non-support of Non-IP Traffic Although most traffic within and across data centers is IP traffic, there may still be a few legacy clustering applications which rely on non-IP communications (e.g., heartbeat messages between cluster nodes). Since Virtual Subnet is strictly based on L3 forwarding, those non-IP communications cannot be supported in the Virtual Subnet solution. In order to support those few non-IP traffic (if present) in the environment where the Virtual Subnet solution has been deployed, the approach following the idea of "route all IP traffic, bridge non-IP traffic" could be considered. In other words, all IP traffic including both intra- and inter-subnet, would be processed according to the Virtual Subnet design, while non-IP traffic would be forwarded according to a particular Layer 2 VPN approach. Such unified L2/L3 VPN approach requires ingress PE routers to classify packets received from hosts before distributing them to the corresponding L2 or L3 VPN forwarding processes. Note that more and more cluster vendors are offering clustering applications based on Layer 3 interconnection. 4.2. Non-support of IP Broadcast and Link-local Multicast As illustrated before, intra-subnet traffic is forwarded at Layer 3 in the Virtual Subnet solution. Therefore, IP broadcast and link- local multicast traffic cannot be supported by the Virtual Subnet solution. In order to support the IP broadcast and link-local multicast traffic in the environment where the Virtual Subnet solution has been deployed, the unified L2/L3 overlay approach as described in Section 4.1 could be considered as well. That is, IP broadcast and link-local multicast messages would be forwared at Layer 2 while routable IP traffic would be processed according to the Virtual Subnet design. 4.3. TTL and Traceroute As mentioned before, intra-subnet traffic is forwarded at Layer 3 in the Virtual Subnet context. Since it doesn't require any change to the Time To Live (TTL) handling mechanism of the BGP/MPLS IP VPN, when doing a traceroute operation on one host for another host (assuming that these two hosts are within the same subnet but are attached to different sites), the traceroute output would reflect the fact that these two hosts within the same subnet are actually connected via a Virtual Subnet, rather than a Layer 2 connection since the PE routers to which those two hosts are connected would be displayed in the traceroute output. In addition, for any other applications that generate intra-subnet traffic with TTL set to 1, Xu, et al. Expires May 30, 2016 [Page 11] Internet-Draft Virtual Subnet November 2015 these applications may not work properly in the Virtual Subnet context, unless special TTL processing for such context has been implemented (e.g., if the source and destination addresses of a packet whose TTL is set to 1 belong to the same extended subnet, neither ingress nor egress PE routers should decrement the TTL of such packet. Furthermore, the TTL of such packet should not be copied into the TTL of the transport tunnel and vice versa). 5. Acknowledgements Thanks to Susan Hares, Yongbing Fan, Dino Farinacci, Himanshu Shah, Nabil Bitar, Giles Heron, Ronald Bonica, Monique Morrow, Rajiv Asati, Eric Osborne, Thomas Morin, Martin Vigoureux, Pedro Roque Marque, Joe Touch and Wim Henderickx for their valuable comments and suggestions on this document. Thanks to Loa Andersson for his WG LC review on this document. Thanks to Alvaro Retana for his AD review on this document. Thanks to Ronald Bonica for his RtgDir review. Thanks to Donald Eastlake for his Sec-DIR review of this document. Thanks to Jouni Korhonen for the OPS-Dir review of this document. Thanks to Roni Even for the Gen-ART review of this document. Thanks to Sabrina Tanamal for the IANA review of this document. 6. IANA Considerations There is no requirement for any IANA action. 7. Security Considerations Since the BGP/MPLS IP VPN signaling is reused without any change, those security considerations as described in [RFC4364] are applicable to this document. Meanwhile, since security issues associated with the NDP are inherited due to the use of NDP proxy, those security considerations and recommendations as described in [RFC6583] are applicable to this document as well. 8. References 8.1. Normative References [RFC0925] Postel, J., "Multi-LAN address resolution", RFC 925, DOI 10.17487/RFC0925, October 1984, . [RFC1027] Carl-Mitchell, S. and J. Quarterman, "Using ARP to implement transparent subnet gateways", RFC 1027, DOI 10.17487/RFC1027, October 1987, . Xu, et al. Expires May 30, 2016 [Page 12] Internet-Draft Virtual Subnet November 2015 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 2006, . [RFC4389] Thaler, D., Talwar, M., and C. Patel, "Neighbor Discovery Proxies (ND Proxy)", RFC 4389, DOI 10.17487/RFC4389, April 2006, . 8.2. Informative References [RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur, "BGP-MPLS IP Virtual Private Network (VPN) Extension for IPv6 VPN", RFC 4659, DOI 10.17487/RFC4659, September 2006, . [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private LAN Service (VPLS) Using BGP for Auto-Discovery and Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, . [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, . [RFC5798] Nadas, S., Ed., "Virtual Router Redundancy Protocol (VRRP) Version 3 for IPv4 and IPv6", RFC 5798, DOI 10.17487/RFC5798, March 2010, . [RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/ BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February 2012, . [RFC6583] Gashinsky, I., Jaeggli, J., and W. Kumari, "Operational Neighbor Discovery Problems", RFC 6583, DOI 10.17487/RFC6583, March 2012, . [RFC6820] Narten, T., Karir, M., and I. Foo, "Address Resolution Problems in Large Data Center Networks", RFC 6820, DOI 10.17487/RFC6820, January 2013, . Xu, et al. Expires May 30, 2016 [Page 13] Internet-Draft Virtual Subnet November 2015 Authors' Addresses Xiaohu Xu Huawei Technologies No.156 Beiqing Rd Beijing 100095 CHINA Email: xuxiaohu@huawei.com Robert Raszuk Bloomberg LP 731 Lexington Ave New York City, NY 10022 USA Email: robert@raszuk.net Christian Jacquenet Orange 4 rue du Clos Courtel Cesson-Sevigne, 35512 FRANCE Email: christian.jacquenet@orange.com Truman Boyes Bloomberg LP Email: tboyes@bloomberg.net Brendan Fee Extreme Networks Email: bfee@extremenetworks.com Xu, et al. Expires May 30, 2016 [Page 14]