V6ops WG V. Kuarsingh, Ed. Internet-Draft Rogers Communications Intended status: Informational Y. Lee Expires: August 5, 2011 Comcast O. Vautrin Juniper Networks February 1, 2011 6to4 Provider Managed Tunnels draft-kuarsingh-v6ops-6to4-provider-managed-tunnel-01 Abstract 6to4 Provider Managed Tunnels (6to4-PMT) provides a framework which can help manage 6to4 [RFC3056] tunnels operating an an anycast [RFC3068] configuration. The 6to4-PMT framework is intended to serve as an option to service providers to help improve the experience of 6to4 operation when conditions of the network may provide sub-optimal performance or break normal 6to4 operation. 6to4-PMT provides a stable provider prefix and forwarding environment by utilizing existing 6to4 Relays with an added function of IPv6 Prefix Translation. This operation may be particularly important in NAT444 infrastructures where a customer endpoint may be assigned a non- RFC1918 address subject to a northbound Large Scale NAT [draft-nishitani-cgn-05] translator breaking the normal IPv4 return path. 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 August 5, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the Kuarsingh, et al. Expires August 5, 2011 [Page 1] Internet-Draft 6to4 Provider Managed Tunnels February 2011 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. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. 6to4 Provider Managed Tunnels . . . . . . . . . . . . . . . . 4 3.1. 6to4 Provider Managed Tunnel Model . . . . . . . . . . . . 4 3.2. Traffic Flow . . . . . . . . . . . . . . . . . . . . . . . 5 3.3. Prefix Translation . . . . . . . . . . . . . . . . . . . . 5 3.4. Translation State . . . . . . . . . . . . . . . . . . . . 6 4. Deployment Issues and Requirements . . . . . . . . . . . . . . 7 4.1. Customer Opt-out . . . . . . . . . . . . . . . . . . . . . 7 4.2. ISP Shared Space Interaction . . . . . . . . . . . . . . . 7 4.3. End to End Transparency . . . . . . . . . . . . . . . . . 8 4.4. Routing Requirements . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Kuarsingh, et al. Expires August 5, 2011 [Page 2] Internet-Draft 6to4 Provider Managed Tunnels February 2011 1. Introduction 6to4 [RFC3056] tunneling along with anycast operation [RFC3068] is widely deployed in modern host Operating Systems and off the shelf gateways sold throughout the retail and OEM channels. RFC3068 based 6to4 allows for tunneled IPv6 connectivity through IPv4 clouds, but due to the anycast nature of the ingress and egress flows, flows paths are difficult to determine and often change based on network conditions. The return path is uncontrolled by the local provider and can contribute to poor performance for IPv6, and can also act as a breakage point (i.e. mis-behaving relay/system). Additionally, consumer endpoints which are subject to northbound NAT44 operation, such as with NAT444, may be subject to broken IPv6 connectivity if non-RFC1918 addresses are used on the CPE. Providers which are actively deploying IPv6 networks and operate legacy IPv4 access environments may want to utilize the existing 6to4 behavior in deployed hardware and software as an interim option to reach the IPv6 internet in advance of being able to offer native IPv6. 6to4-PMT offers a provider the opportunity to utilize IPv6 Prefix Translation to provide deterministic and an unbroken path to and from the Internet for IPv6 based traffic. 6to4-PMT translates the prefix portion of the address from the 6to4 address to a provider assigned prefix which is used to represent the source. This translation will then provide a stable forward and return path for the 6to4 traffic by allowing the existing IPv6 routing and policy environment to control the traffic. 6to4-PMT is primarily intended to be used in a stateless manner to maintain many of the elements inherent in normal 6to4 operation. Alternatively, 6to4-PMT can be used in a stateful translation mode should the operator choose this option. 2. Motivation Providers endeavor to deploy IPv6 as soon as possible, so as to ensure uninterrupted connectivity to all Internet applications and content through the transition process. The IPv6 preparations within these organizations are often faced with both financial challenges and timing issues related to deploying IPv6 to the network edge and related transition technologies. Many of the new technologies addressing IPv4 to IPv6 transition will require the replacement of the customer CPE to support technologies like 6RD [RFC5969] which also require the replacement or upgrade of the customer endpoint device.. Provider initiated replacement of this equipment will take time due Kuarsingh, et al. Expires August 5, 2011 [Page 3] Internet-Draft 6to4 Provider Managed Tunnels February 2011 to the nature of such mass equipment refresh programs. Additionally, many providers also do not supply CPE related equipment and general lack of awareness in the consumer space may delay the upgrade of many in-home gateway and operating environments. Providers may still be motivated to provide a form of IPv6 connectivity to customers to mitigate potential issues related to IPv6-only deployments elsewhere on the Internet. Providers may also need to mitigate issues of default 6to4 operation in these existing home devices. After IPv4 run out, IPv6 content and addressed endpoints may grow rapidly in number and in some cases, IPv4 may not be a connection option for some web based content providers or the remote hosts (IPv6 Only). 6to4-PMT allows a provider to help mitigate such challenges by leveraging a protocol which is already found on many CPE home gateways, while maintaining operator control of access to the IPv6 Internet. It is intended for use when better options, such as 6RD or native IPv6, are not yet viable. The 6to4-PMT operation can also be used immediately with existing OS and gateway functionality (in the wild) without the initial replacement of consumer equipment. The default 6to4 operation on most consumer grade OSs and gateways will allow for IPv6 connectivity over the IPv4 access network. Once native IPv6 is available to the endpoint, the 6to4-PMT operation is no longer needed. If 6to4-PMT operation was used to mitigate default 6to4 operation in a NAT444 environment, then native IPv6 addresses will take precedence based on IPv6 address selection [RFC3484]. 3. 6to4 Provider Managed Tunnels 3.1. 6to4 Provider Managed Tunnel Model The 6to4 managed tunnel model behaves like a standard 6to4 service between the customer IPv6 host or gateway and the 6ot4-PMT Relay (within the provider domain). The 6to4-PMT Relay shares properties with 6RD [RFC5969] by decapsulating and forwarding embedded IPv6 flows, within an IPv4 packet, to the IPv6 Internet. The model provides an additional function which translates the source 6to4 prefix to a provider assigned prefix which is not found in 6RD [RFC5969] or traditional 6to4 operation. The 6to4-PMT Relay is intended to provide a stateless (or stateful) mapping of the 6to4 prefix to a provider supplied prefix by mapping the embedded IPv4 address in the 6to4 prefix to the provider prefix. Kuarsingh, et al. Expires August 5, 2011 [Page 4] Internet-Draft 6to4 Provider Managed Tunnels February 2011 | 6to4-PMT Operation | +-----+ 6to4 Tunnel +--------+ +------+ IPv6 +----+ | CPE |-------------|6to4 BR |--| PT66 |--------- |Host| +-----+ IPv4 +--------+ +------+ Provider +----+ Network Prefix Unified or Separate Functions/Platforms Figure 1: 6to4-PMT Functional Model This mode of operation is seen as beneficial when compared to broken 6to4 paths and or environments where 6to4 operation may be functional but highly degraded. 3.2. Traffic Flow Traffic in the 6to4-PMT model is intended to be controlled by the operators IPv6 peering operations. Egress traffic is managed through outgoing routing policy, and incoming traffic is influenced by the operator assigned prefix advertisements. The routing model is as predictable as native IPv6 traffic and legacy IPv4 based traffic. Figure 1 provides a view of the routing topology needed to support this relay environment. The diagram references PrefixA as 2002::/16 and PrefixB as the example 2001:db8::/32. | 6to4 IPv4 Path | Native IPv6 Path | ----------- ----------- ------------- / IPv4 Net \ / IPv6 Net \ / IPv6 Internet \ +------+ +--------+ +-------+ +---------+ | CPE | PrefixA |6to4-PMT| PrefixB |Peering| |IPv6 HOST| +------+ +--------+ +-------+ +---------+ \ / \ / \ / ---------- ------------ -------------- IPv4 6to4 IPv6 Provider IPv6 Prefix Anycast Prefix Advertisement Figure 2: 6to4-PMT Flow Model Traffic between two 6to4 enabled devices would use the IPv4 path for communication according to RFC3056. 3.3. Prefix Translation The IPv6 Prefix Translation is a key part of the system as a whole. The 6to4-PMT framework is a combination of two concepts: 6to4 Kuarsingh, et al. Expires August 5, 2011 [Page 5] Internet-Draft 6to4 Provider Managed Tunnels February 2011 [RFC3056] and IPv6 Prefix Translation. IPv6 Prefix Translation has some similarities to concepts discussed in [draft-mrw-nat66]. The only change in this particular case is that the provider would build specific rules on the translator to map the 6to4 prefix to an appropriate provider assigned prefix. The provider can use any prefix mapping strategy they so choose, but the simpler the better. Simple direct bit mapping can be used such as in Figure 2, or more advanced forms of translation can used to achieve higher address compression. Figure 2 shows a 6to4 Prefix with a Subnet-ID of "0000" mapped to a provider globally unique prefix (2001:db8::/32). With this simple form of translation, there is support for only one Subnet-ID per provider assigned prefix. In characterization of deployed OSs and gateways, a subnet-id of "0000" is the most common default case. Pre-Relayed Packet [Provider Access Network Side] 0 16 32 48 64 80 96 112 128 Bits | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | 2002 : 0C98 : 2C01 : 0000 : xxxx : xxxx : xxxx : xxxx | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | | | | | | | ---- ---- | | | | | | | | | | | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | 2001 : 0db8 : 0c98 : 2c01 : xxxx : xxxx : xxxx : xxxx | ---- | ---- | ---- | ---- | ---- | ---- | ---- | ---- | Post-Relayed Packet [Internet Side] Figure 3: 6to4-PMT Prefix Mapping Additional prefix compression techniques can be used such as those described in [draft-tremblay-pt66ac]. These techniques would allow for a more flexible implementation potentially supporting more Subnet-IDs per provider prefix. 3.4. Translation State It is preferred that the overall system use deterministic prefix translation mappings such that stateless operation can be implemented. This allows the provider to place N number of relays within the network without the need to manage translation state. If stateful is chosen, the operation would need to validate state and routing requirements particular to that type of deployment full Kuarsingh, et al. Expires August 5, 2011 [Page 6] Internet-Draft 6to4 Provider Managed Tunnels February 2011 deployment considerations for this type of deployment are not within this scope of this document. 4. Deployment Issues and Requirements 4.1. Customer Opt-out A provider enabling this function should provide a method to allow customers to opt-out of such a service should the customer choose to maintain normal 6to4 operation irrespective of degraded performance. Since the 6to4-PMT system is targeted at customers who are relatively unaware of IPv6 and IPv4, and normally run network equipment with a default configuration, an opt-out strategy is recommended. This method provides the 6to4-PMT operation for non-IPv6 savvy customers whose equipment may turn on 6to4 automatically. Customers who are aware of IPv6 operation can request an opt-out, or more appropriately use an automated mechanism to opt-out of the 6to4- PMT operation. One automated opt-out strategy can include the use of Subnet-Id triggers (well known IDs which are determined by policy in the relay to not be translated). Other policy based strategies can be employed by the provider to enable opt-out. Capable customers can also disable anycast based 6to4 entirely and use traditional 6to4 or other tunneling mechanisms if they are so capable. This is not considered the normal case, and most endpoints with auto-6to4 operation will be subject to 6to4-PMT operation operation since most users are unaware of it's existence. 6to4-PMT is targeted as an option for stable IPv6 connectivity for average consumers. 4.2. ISP Shared Space Interaction 6to4-PMT operation can also be used to mitigate a known problem with 6to4 when ISP Shared Space [draft-weil-shared-transition-space-request-01] or public but non- routed IPv4 space is used. Public but un-routed address space would cause many deployed OSs and network equipment to potentially auto- enable 6to4 operation even without a valid return path. This use case is considered highly likely based on points made in [draft-weil-shared-transition-space-request] and in reports such as [wide-tr-kato-as112-rep-01] Such hosts, in normal cases, would send 6to4 traffic to the IPv6 Internet via the IPv4 anycast relay, which would in fact provide broken IPv6 connectivity since the return path is based on an address Kuarsingh, et al. Expires August 5, 2011 [Page 7] Internet-Draft 6to4 Provider Managed Tunnels February 2011 that is not routed or assigned to the source Network. The use of 6to4-PMT would help reverse these effects by translating the 6to4 prefix to a provided assigned prefix, masking this automatic and undesired behavior. It is conceivable that 6to4-PMT can also used to help provide 6to4 operation with the use of ISP Shared Space. 4.3. End to End Transparency 6to4-PMT mode operation removes the traditional end to end transparency of 6to4. Remote hosts would connect to a translated IPv6 address versus the original 6to4 based prefix. This can be seen as a disadvantage to the 6to4-PMT system. This lack of transparency should also be contrasted with the normal operating state of 6to4 which provides uncontrolled and often high latency prone connectivity. The lack of transparency is however a better form of operation when extreme poor performance or broken connectivity is considered as the alternative. 4.4. Routing Requirements The provider would need to advertise the anycast IP range within the IPv4 routing environment (service customers of interest) to attract the 6to4 upstream traffic. To control this environment and make sure all northbound traffic lands on a provider BR, the operator may filter the anycast range form being advertised form customer endpoints. The provider would not be able to control route advertisements inside the customer domain, but this use case is out of scope. It is likely in this case the end network/customer understands IPv6 operation and is maintaining their own environment. The provider would also likely want to advertise the 2002::/16 range within their own network to help bridge within their own network (Native IPv6 to 6to4-IPv6 based endpoint). 5. IANA Considerations No IANA considerations are defined at this time. 6. Security Considerations 6to4-PMT operation would be subject to the same security concerns as normal 6to4 operation and with the operation of tunnels. Considerations may also include operation modes related to Prefix Translation. Additional considerations may be found after real Kuarsingh, et al. Expires August 5, 2011 [Page 8] Internet-Draft 6to4 Provider Managed Tunnels February 2011 deployment data is gathered or further analysis is made. 7. Acknowledgements Thanks to the following people for their textual contributions and/or guidance on 6to4 deployment considerations: Dan Wing, Scott Beuker, JF Tremblay, John Brzozowski and Chris Donley 8. References 8.1. Normative References [RFC3056] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via IPv4 Clouds", RFC 3056, February 2001. [RFC3068] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers", RFC 3068, June 2001. 8.2. Informative References [I-D.mrw-nat66] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix Translation", draft-mrw-nat66-07 (work in progress), January 2011. [I-D.tremblay-pt66ac] Tremblay, J. and S. Beuker, "Addressing bit compression for stateless IPv6 prefix translation", draft-tremblay-pt66ac-00 (work in progress), November 2010. [I-D.weil-shared-transition-space-request] Weil, J., Kuarsingh, V., Donley, C., Liljenstolpe, C., and M. Azinger, "IANA Reserved IPv4 Prefix for Shared Transition Space", draft-weil-shared-transition-space-request-01 (work in progress), November 2010. [RFC3484] Draves, R., "Default Address Selection for Internet Protocol version 6 (IPv6)", RFC 3484, February 2003. [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) -- Protocol Specification", RFC 5969, August 2010. Kuarsingh, et al. Expires August 5, 2011 [Page 9] Internet-Draft 6to4 Provider Managed Tunnels February 2011 Authors' Addresses Victor Kuarsingh (editor) Rogers Communications 8200 Dixie Road Brampton, Ontario L6T 0C1 Canada Email: victor.kuarsingh@rci.rogers.com URI: http://www.rogers.com Yiu L. Lee Comcast One Comcast Center Philadelphia, PA 19103 U.S.A. Email: yiu_lee@cable.comcast.com URI: http://www.comcast.com Olivier Vautrin Juniper Networks 1194 N Mathilda Avenue Sunnyvale, CA 94089 U.S.A. Email: olivier@juniper.net URI: http://www.juniper.net Kuarsingh, et al. Expires August 5, 2011 [Page 10]