Network Working Group Z. Chen Internet-Draft China Telecom Intended status: Standards Track D. Lopez Expires: September 6, 2012 Telefonica I+D T. Tsou Huawei Technologies (USA) C. Zhou Huawei Technologies March 05, 2012 DC Migration to IPv6 draft-lopez-v6ops-dc-ipv6-00 Abstract This document describes the issues, possible solutions, and opportunities in Data Center (DC) migration from IPv4 to IPv6. It focuses on the DC infrastructure itself, its operation, and the aspects related to DC interconnection through IPv6. It does not consider the particular mechanisms for making Internet services provided by applications hosted in the DC available through IPv6 beyond the specific aspects related to how their deployed on the DC infrastructure. Apart from facilitating the migration procedure itself, the mechanisms outlined here are intended to make this migration as transparent as possible (if not completely transparent) to applications and services running on the DC infrastructure, as well as to take advantage of IPv6 features to simplify DC operations, internally and across the Internet. 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 September 6, 2012. Chen, et al. Expires September 6, 2012 [Page 1] Internet-Draft DC Migration to IPv6 March 2012 Copyright Notice Copyright (c) 2012 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Maturity Levels . . . . . . . . . . . . . . . . . . . . . . . 5 3. Proposed Solution . . . . . . . . . . . . . . . . . . . . . . 6 4. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Chen, et al. Expires September 6, 2012 [Page 2] Internet-Draft DC Migration to IPv6 March 2012 1. Introduction The need for considering the aspects related to IPv4-to-IPv6 migration for all devices and services connected to the Internet has been widely mentioned elsewhere, and it is not our intention to make an additional call on it. Just let us note that many of those services are already or will soon be located in datacenters (DC), what makes considering the issues associated to DC infrastructure migration a key aspect both for these infrastructures themselves, and for providing a simpler and clear path to service migration. All issues discussed here are related to DC infrastructure migration, and are intended to be orthogonal to whatever particular mechanisms for making the services hosted in the DC available through IPv6 beyond the specific aspects related to their deployment on the infrastructure. Those general mechanisms to service migration have been discussed in depth elsewhere and are considered to be orthogonal to the goal of this discussion. Though it is obvious that their applicability in many cases would depend on the characteristics of the supporting DC infrastructure, the migration procedures are intended to keep services as independent as possible of these processes. Furthermore, the combination of the regularity and controlled management in a DC interconnection fabric with IPv6 universal end-to- end addressing should translate in simpler and faster VM migrations, either intra- or inter-DC, and even inter-provider. The diagram in Figure 1 depicts a generalized interconnection schema in a DC. Chen, et al. Expires September 6, 2012 [Page 3] Internet-Draft DC Migration to IPv6 March 2012 | | +-----+-----+ +-----+-----+ | Gateway | | Gateway | Internet Access +-----+-----+ +-----+-----+ | | +---+-----------+ | | +---+---+ +---+---+ | Core0 | | CoreN | Core +---+---+ +---+---+ / \ / / / \-----\ / / /---/ \ / +--------+ +--------+ +/-------+ | +/-------+ | | Aggr01 | +-----| AggrN1 | + Aggregation +---+---+/ +--------+/ / \ / \ / \ / \ +-----+ +-----+ +-----+ +-----+ | T11 |... | T1x | | T21 |... | T2y | Access +-----+ +-----+ +-----+ +-----+ | HyV | | HyV | | HyV | | HyV | Physical Servers +:::::+ +:::::+ +:::::+ +:::::+ | VMs | | VMs | | VMs | | VMs | Virtual Machines +-----+ +-----+ +-----+ +-----+ . . . . . . . . . . . . . . . . +-----+ +-----+ +-----+ +-----+ | HyV | | HyV | | HyV | | HyV | +:::::+ +:::::+ +:::::+ +:::::+ | VMs | | VMs | | VMs | | VMs | +-----+ +-----+ +-----+ +-----+ Figure 1: DC Interconnnection Schema o Hypervisors provide connection services (among others) to virtual machines running on physical servers. o Access elements provide connectivity directly to/from physical servers. The access elements are typically placed either top-of- rack (ToR) or end-of-row(EoR). o Aggregation elements group several (many) physical racks to achieve local integration and provide as much structure as possible to data paths. o Core elements connect all aggregation elements acting as the DC backbone. Chen, et al. Expires September 6, 2012 [Page 4] Internet-Draft DC Migration to IPv6 March 2012 o One or several gateways connecting the DC to the Internet and/or other DCs through dedicated links. In many actual deployments, depending on DC size and design decisions, many of these elements may be combined (core and gateways are provider by the same routers, or hypervisors act as access elements), but this layered schema is the one that best accommodates the different options to use L2 or L3 at any of the different DC interconnection layers, and will help us in the discussion along the document. 2. Maturity Levels Three main maturity levels can be considered when analyzing IPv6 deployment in the DC infrastructure, all compatible with the availability of services running in the DC through IPv6: 1. Intra-DC IPv4 infrastructure, with gateway routers (or even application gateways when services require so) connecting to the IPv6 and IPv4 Internet. DC network scheme and addressing do not require any important change, if any. Even at this level, some implicit advantages of IPv6 application come into play, even if they can only be applied at the ingress elements: * Flow labels can be applied to enhance load-balancing. * During VM migration, Mobile IP mechanisms can be applied to keep service availability during the transient state. * VM migration among DCs are simplified in what relates to address management. 2. Intra-DC IPv6 infrastructure, including inter-DC links. IPv6 is deployed up to whatever the layer in the interconnection scheme where L3 is applied to packet forwarding, and gateway routers run 64NAT (or an equivalent mechanism) to connect to the IPv4 Internet, or rely on Internet providers to do so. While the previous level can be considered a degenerate case of this when L3 forwarding is only applied at the external gateways, it is important to note that this can only be the case if all L3 packet forwarding mechanisms are IPv6-based, including those applied to data paths (SAN, for example) or internal management interfaces. At this level, the advantages outlined above on flow labels and Mobile IP mechanisms are applicable to any L3-based mechanism. Itra- as well as inter-DC, they will translate into enhanced VM mobility, more effective load balancing, and higher service Chen, et al. Expires September 6, 2012 [Page 5] Internet-Draft DC Migration to IPv6 March 2012 availability. Furthermore, the simpler integration provided by IPv6 to and from the L2 flat space to the structured L3 one can be applied to achieve simpler deployments, as well as alleviating encapsulation and fragmentation issues when traversing between L2 and L3 spaces. With an appropriate prefix management, automatic address assingment, discovery, and renumbering can be applied not only to public service interfaces, but most notably to data and management paths. Other potential advantages include the application of multicast scopes to limit broadcast floods, and the usage of specific security headers to enhance tenant differentiation. 3. Pervasive IPv6 infrastructure, including full IPv6 hypervisors, which perform the appropriate tunneling or NAT if required by internal applications running IPv4. At this level, individual services could directly take advantage of the features provided by the IPv6 address space and protocols, and probably this would imply the usual paradigm of the hypervisor acting as a virtual L2 switch could be extended. Independent service mobility could be one of the additional functions facilitated at this level. Since current deployments and technology best practices are at level 1, i.e. IPv4-only DC infrastructures with mostly IPv4 Internet Service access, we will concentrate on the issues regarding this first maturity level in this memo. Future documents or versions of this document will address in detail the aspects related to higher maturity levels. Nevertheless, a great part of the technology proposed in this document could also be applied in these higher IPv6 migration levels. 3. Proposed Solution In the network topology of DC, the aggregation level provides traffic aggregation function for the access level models (e.g., switches). For the "Core-Edge" DC network, Firewall (FW) is deployed as the security edge of the whole service domain and provides safe access control of this service domain from other function domains. In addition, some application optimization devices and security devices (e.g.,Load Balance, SSL VPN, IPS and etc.) may be deployed in the aggregation level to alleviate the burden of the server and to guarantee deep security. Figure 2 provides a typical Internet facing application scheme for the Data Center. Chen, et al. Expires September 6, 2012 [Page 6] Internet-Draft DC Migration to IPv6 March 2012 +---------------------+ | Internet | +---------+-----------+ | +--+--+ | FW | +--+--+ | +--+--+ | LB | +--+--+ _ / \_ / \ +--+--+ +--+--+ | Web | ... | Web | +--+--+ +--+--+ | \ __ _ _/ | | / \ | +--+--+ +--+--+ |Cache| | DB | +-----+ +-----+ Figure 2: Data Center Application Scheme In the first maturity level of Data Center migration mentioned above, LB or some other boxes could be upgraded to support the data transmission. There may be two ways to achieve this at the edge of the DC: Encapsulation and NAT. In the encapsulation case, the LB function carries the IPv6 traffic over IPv4 using an encapsulation (IPv6-in-IPv4). In the NAT case, there are already some technologies to solve this problem. For example, DNS and NAT device could be concatenated for IPv4/IPv6 translation, if IPv6 host needs to visit IPv4 servers. However, this may require the concatenation of multiple network devices, which means the NAT tables needs to be synchronized at different devices. In this document, we propose a simplified IPv4/IPv6 translation model, which could be implemented in LB device. The mapping information of IPv4 and IPv6 will be generated automatically based on the information of LB. The host IP address will be translated without the port translation. Chen, et al. Expires September 6, 2012 [Page 7] Internet-Draft DC Migration to IPv6 March 2012 +----------+------------------------------+ |Dual Stack| IPv4-only +----------+ | | | +----|Web Server| | | +------|------+ / +----------+ | +----------+ | | | | / | | Internet +-----|---+Load-Balancer+-- \ | +----------+ | | | | \ +----------+ | | +------|------+ +----|Web Server| | | | +----------+ | +----------+------------------------------+ Figure 3: Dual Stack LB mechanism As shown in Figure 3,the LB (load-balancer) can be considered dividing into two parts: dual-stack part which is facing the internet, IPv4 only part which contains the tradition LB function.The IPv4 DC is allocated an IPv6 prefix which is for the VSIPv6 (Virtual Service IPv6 Address). We suggest that the IPv6 prefix is not the well-known prefix in order to avoid the IPv4 routings of the services in different DCs spread to the IPv6 network. The VSIPv4 (Virtual Service IPv4 Address) is embedded in VSIPv6 using the allocated IPv6 prefix. In this way, the LB has the stateless IP address mapping between VSIPv6 and VSIPv4, and the synchronization is not need between LB and DNS64 server. The dual-stack part of the LB has a private IPv4 address pool. When IPv6 packets come from internet to DC, the dual-stack part does the one-on-one SIP (source IP address) mapping between IPv4 private address and IPv6 SIP. Because there will be too many UDP/TCP sessions between the DC and Internet, the IP addresses binding tables between IPv6 and IPv4 are not session-based, but SIP-based. Thus, the dual-stack part of LB builds IP binding stateful tables for the host IPv6 address and private IPv4 address of the pool. When the following IPv6 packets of the host come from Internet to the LB, the dual stack part does the IP address translation for the packets. Thus, the IPv6 packets were translated to IPv4 packets and sent to the IPv4 only part of the LB. 4. Procedures Figure 4 gives a diagram illustrating an exemplary data flow between an IPv6 host, a load balancer, and an IPv4-only DC system. Chen, et al. Expires September 6, 2012 [Page 8] Internet-Draft DC Migration to IPv6 March 2012 +----------+------------------------------+ |Dual Stack| IPv4-only +----------+ | | | +----|Web Server| | | +------|------+ / +----------+ | +-----+ +--------+ | | | | / | |IPv6 |--|Internet|-----|---+Load-Balancer+-- \ | |Host | | | | | | | \ +----------+ | +-----+ +--------+ | +------|------+ +----|Web Server| | | | | | +----------+ | | +------|---+------------------------------+ | |(1)Allocating IPv6 prefix for the | |services in DC | |(2)Services in DC generating their | |virtual service IPv6 address based | |on the allocated IPv6 prefix, and | |announcing their VSIPv6 to the DNS | |Servers | |---+ | | |(3)Private IPv4 address pool |(4) First IPv6 packet to |---+ configured in LB | visit IPv6 service | |-------------------------->| | |(5)LB creates one-to-one IP binding | |table of host IPv6 address and pri- | |vate IPv4 address, and makes address | |translation based on the binding | |table and VSIP mapping rule | |(IPv4 packet) |(6)Following packets |---------------------------------> |-------------------------->| | |(7)Address translation based on | |the binding table and VSIP mapping | |rule (IPv4 packet) | |---------------------------------> |(9)Address translation |(8)Response (IPv4 packet) |based on the binding table |<------------------------------ |and VSIP mapping rule. | |Sends the IPv6 packets | |<-----------------------| Figure 4: Procedures of the solution 5. Security Considerations Come later. Chen, et al. Expires September 6, 2012 [Page 9] Internet-Draft DC Migration to IPv6 March 2012 6. IANA Considerations None. Authors' Addresses Zhonghua Chen China Telecom P.R.China Phone: Email: 18918588897@189.cn Diego R. Lopez Telefonica I+D Don Ramon de la Cruz, 84 Madrid 28006 Spain Phone: +34 913 129 041 Email: diego@tid.es Tina Tsou Huawei Technologies (USA) 2330 Central Expressway Santa Clara, CA 95050 USA Phone: +1 408 330 4424 Email: Tina.Tsou.Zouting@huawei.com Cathy Zhou Huawei Technologies Bantian, Longgang District Shenzhen 518129 P.R. China Phone: Email: cathy.zhou@huawei.com Chen, et al. Expires September 6, 2012 [Page 10]