Network Working Group R. Penno Internet-Draft J. Medved Intended status: Informational Juniper Networks Expires: December 18, 2010 June 16, 2010 ALTO and IPv4/IPv6 Co-existence and Transition draft-penno-alto-ipv4v6-00 Abstract IPv4/IPv6 co-existence and transition is topic or great discussion and interest. In order to deal with IPv4 depletion ISPs have some techniques at their disposal such as Carrier Grade NAT , DS-Lite and 6rd. As this techniques get deployed, they change the topology of the network by creating gateways or overlays which in the end affect how ALTO might work. This draft discusses such impacts and possible solutions. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 [RFC2119]. 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 December 18, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. Penno & Medved Expires December 18, 2010 [Page 1] Internet-Draft ALTO and IPv4/IPv6 June 2010 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. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Landscape . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 5. Carrier Grade NAT . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Assumptions . . . . . . . . . . . . . . . . . . . . . . . . 5 5.2. Endpoint Property Service . . . . . . . . . . . . . . . . . 6 5.3. Endpoint Cost Service . . . . . . . . . . . . . . . . . . . 6 5.4. ALTO Server in ISP's Public Network . . . . . . . . . . . . 6 5.5. ALTO Server in ISP's Private Network . . . . . . . . . . . 6 6. Softwires . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7. ALTO and CDNs . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1. Same Administrator Domain . . . . . . . . . . . . . . . . . 7 7.2. Different Administrator Domains . . . . . . . . . . . . . . 7 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8 9. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 8 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 11.1. Normative References . . . . . . . . . . . . . . . . . . . 8 11.2. Informative References . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Penno & Medved Expires December 18, 2010 [Page 2] Internet-Draft ALTO and IPv4/IPv6 June 2010 1. Introduction IPv4/IPv6 co-existence and transition is topic or great discussion and interest. In order to deal with IPv4 depletion ISPs have some techniques at their disposal, one of which, Carrier Grade NAT, is probably the most popular due to the fact it requires no changes in the infrastructure or end hosts. Other techniques based on Softwires such as DS-Lite help with IPv4 depletion IPv6 introduction. 6rd helps IPv6 introduction and leverages existing IPv4 access networks. As this techniques get deployed, they change the topology of the network by creating gateways or overlays which in the end affect how ALTO might work. This draft discussed such impacts and possible solutions. 2. Scope This document discusses how the issues that IPv4/IPv6 co-existence and transition brings to ALTO and how to possibly solve them. This draft is a work in progress and will be updates based on feedback and discussions. 3. Terminology The reader should be familiar with terminology introduced by RFC 2663 [RFC2663], RFC 4787 [RFC4787], NAT64 [I-D.ietf-behave-v6v4-xlate], DS-Lite [I-D.ietf-softwire-dual-stack-lite] and Carrier Grade NAT [I-D.nishitani-cgn] 4. Landscape During the co-existence period there will be three address 'families' on the Internet: private IPv4, public IPv4 and IPv6. The same host could be using one or more IP address from each of the families and certainly different hosts within a home or enterprise could be accessing the network using different address families. In this context, ALTO clients and servers still need to a consistent and deterministic view of the network. But this co-existence brings some pitfalls that should be avoided, for example: o An ALTO Client with only a public IPv4 has no use of a cost map that contains private IPv4 addresses. o An ALTO Client with only an IPv6 address has no use for a IPv4 cost map, whether private or public. Penno & Medved Expires December 18, 2010 [Page 3] Internet-Draft ALTO and IPv4/IPv6 June 2010 Furthermore, with NAT migrating from the user CPE to the network and the creation of overlays, the impact on the network and cost maps and the associated placement of the ALTO Server needs to be evaluated. In the next sections we will discuss some of these scenarios, their implications and possible solutions. 5. Carrier Grade NAT In the case of CGN, a NAT device is deployed in the edge of the network instead of (or in addition to ) the NAT at the CPE. In this scenario the placement of the ALTO Server and Client(s) becomes specially important. If the Alto Server in on the private network, the network and cost maps built from such data are not of use to clients on the Internet or on the ISP's public network. If on the other hand the ALTO Server is on the ISP's public network and the ALTO Clients reside on end hosts (P2P case), the cost between endpoints becomes the cost between CGN boxes. Penno & Medved Expires December 18, 2010 [Page 4] Internet-Draft ALTO and IPv4/IPv6 June 2010 (preamble) ISP Private ISP Public Internet ,-. ,-. ,-. +---+ / \ / \ ; : |CPE| / \ / \ ; : +---+ ; +-----+ ; +-----+ ; : ; | | ; | | ; : ; | CGN |; | BR | ; : +---+ | | || | | | | |CPE| | +-----+| +-----+ ; : +---+ ; | ; | ; : ; : ; : | | | +-----+ +-----+| | +---+ | | | | || | |CPE| | | CGN | | BR || | +---+ | | | | || | . | +-----+ +-----+| | | | | | | | | | | | | | | | | : ; : ; | | : +-----+: +-----+: ; +---+ __________ | || | | : ; |CPE|()_________)| CGN || | BR | | | +---+ : | |: | | : ; : +-----+ : +-----+ : ; : ; : ; : ; \ / \ / : ; \ / \ / : ; `-' `-' `-' (postamble) 5.1. Assumptions The following assumptions are common for all Alto Server - CGN interworking use cases: o In absence of failures, any given CPE always uses the same CGN. All sessions from the CPE pass through that CGN. o The assignment of CPEs to CGN is determined by a policy specified by the provider. The assignment does not change while both the CPE and the CGN are alive o A Content Origin Server will typically reside in a public network, since all its clients will connect to it at Port 80, which can not be translated by the NAT. Penno & Medved Expires December 18, 2010 [Page 5] Internet-Draft ALTO and IPv4/IPv6 June 2010 5.2. Endpoint Property Service The Endpoint Property Lookup query allows an ALTO Client to lookup properties of Endpoints known to the ALTO Server. In the case where the ALTO Server is on the ISP's public network, the 'pid' property remains as is since a public IPv4 address belongs to a PID. On the other hand, properties that are different across endpoints such as bandwidth and access type need modification. In other to make use of this service to query properties associated exclusively with an endpoint, the query would need to be extended to include a public transport port associated with the private IP address. This stems from the fact that many private IPv4 addresses are mapped to the same public IPv4 address. 5.3. Endpoint Cost Service The endpoint cost service does not need modification. The cost might have different semantics but the query can be used as specified in the ALTO protocol. 5.4. ALTO Server in ISP's Public Network In this case the network and cost map are built based on NAT pool addresses configured at each CGN. If the architecture is distributed such that the cost from endpoints to the CGN does not vary significantly, the ALTO Service should not be impacted. In fact, having an anchor point such as a CGN might present some advantages such as a natural mapping between PID and CGN and deterministic traffic flow and therefore cost map. 5.5. ALTO Server in ISP's Private Network If the ALTO Server and associated network and cost maps are based on the private network they might provide more fine granular guidance but such maps could not be used by outside parties. One way to solve this problem is to have another ALTO Server on the public side and provide two network and cost maps to clients. 6. Softwires Softwires create a overlay on top of the current IP infrastructure. Everything between the Softwire Initiator and Concentrator is seen as a 'single-hop' or virtual link from the network users point of view. Therefore, the network and cost maps should be built similar to the CGN case where the ALTO Server is place in the ISP's public network. Penno & Medved Expires December 18, 2010 [Page 6] Internet-Draft ALTO and IPv4/IPv6 June 2010 In the case of 6rd which is based on stateless IP anycast operation, there is no way to know a priori which border relay will be used by a CPE. This makes computation of network maps and consequently cost maps problematic. DS-Lite requires NAPT44 and therefore traffic from and endhost is expected to flow drought the same NAPT device consistently. IP anycast could be used with DS-Lite as well but NAPT44 requires traffic flows to be more deterministic. 7. ALTO and CDNs For CDN use cases, we have to differentiate whether the CDN is in the same administrative domain as the CPE's Network Provider or not. 7.1. Same Administrator Domain The network provider may want to place cache nodes as close to the CPE as possible, i.e., in the private network. Alto Server HTTP Redirector / DNS Redirector all in the private network. We are optimizing the traffic through the private network, choosing a cache node in the private network which is the closest to the CPE. Assume the Cache Node also goes though its own CGN, so we must optimize the whole path CPE->Cache->CGN->Origin Server. CPE->Cache->CGN can be optimized by the private network Redirector using private network's Alto Server Network Maps. For CGN->Origin Server optimization we need Network Maps from a public network Alto Server - this is likely a similar situation as we had in the multi- domain CDN case (the interesting part is that the model seems to be similar to the multi-domain model, yet this is a single domain case, but the public/private split makes it look like multi-domain. 7.2. Different Administrator Domains In this case the CDN cache nodes will also reside in a public network, and all traffic between the CPE and either the Origin Server and/or the cache node will go through the CGN. Since the assignment of CPEs to the CGN is static, we can only optimize traffic in the public network by selecting a cache node that is closest to the CPE's CGN. This would work with both HTTP redirection and DNS redirection as described in ALTO and CDNs [I-D.penno-alto-cdn]. The Alto Server in the public network would provide network maps to either an HTTP Penno & Medved Expires December 18, 2010 [Page 7] Internet-Draft ALTO and IPv4/IPv6 June 2010 Redirector or a DNS Redirectors, which would choose a cache node closest to the CPE's CGN. Neither the Alto Server nor the HTTP Redirector nor the DNS Redirector is aware of the private network and that the CPE is behind a NAT. (Note that this would work pretty much the same as CPE-based NATs today.) 8. IANA Considerations This document makes no request of IANA. Note to RFC Editor: this section may be removed on publication as an RFC. 9. Security Considerations 10. Acknowledgements TBD 11. References 11.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 11.2. Informative References [I-D.ietf-alto-protocol] Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", draft-ietf-alto-protocol-04 (work in progress), May 2010. [I-D.ietf-behave-v6v4-xlate] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation Algorithm", draft-ietf-behave-v6v4-xlate-20 (work in progress), May 2010. [I-D.ietf-behave-v6v4-xlate-stateful] Bagnulo, M., Matthews, P., and I. Beijnum, "Stateful NAT64: Network Address and Protocol Translation from IPv6 Clients to IPv4 Servers", draft-ietf-behave-v6v4-xlate-stateful-11 (work in progress), March 2010. Penno & Medved Expires December 18, 2010 [Page 8] Internet-Draft ALTO and IPv4/IPv6 June 2010 [I-D.ietf-softwire-dual-stack-lite] Durand, A., Droms, R., Haberman, B., Woodyatt, J., Lee, Y., and R. Bush, "Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion", draft-ietf-softwire-dual-stack-lite-04 (work in progress), March 2010. [I-D.nishitani-cgn] Yamagata, I., Nishitani, T., Miyakawa, S., Nakagawa, A., and H. Ashida, "Common requirements for IP address sharing schemes", draft-nishitani-cgn-04 (work in progress), March 2010. [I-D.penno-alto-cdn] Penno, R., Raghunath, S., Medved, J., Bakshi, M., Alimi, R., and S. Previdi, "ALTO and Content Delivery Networks", draft-penno-alto-cdn-00 (work in progress), June 2010. [RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address Translator (NAT) Terminology and Considerations", RFC 2663, August 1999. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, January 2001. [RFC3568] Barbir, A., Cain, B., Nair, R., and O. Spatscheck, "Known Content Network (CN) Request-Routing Mechanisms", RFC 3568, July 2003. [RFC4787] Audet, F. and C. Jennings, "Network Address Translation (NAT) Behavioral Requirements for Unicast UDP", BCP 127, RFC 4787, January 2007. [RFC5632] Griffiths, C., Livingood, J., Popkin, L., Woundy, R., and Y. Yang, "Comcast's ISP Experiences in a Proactive Network Provider Participation for P2P (P4P) Technical Trial", RFC 5632, September 2009. Penno & Medved Expires December 18, 2010 [Page 9] Internet-Draft ALTO and IPv4/IPv6 June 2010 Authors' Addresses Reinaldo Penno Juniper Networks 1194 N Mathilda Avenue Sunnyvale USA Email: rpenno@juniper.net Jan Medved Juniper Networks 1194 N Mathilda Avenue Sunnyvale USA Email: jmedved@juniper.net Penno & Medved Expires December 18, 2010 [Page 10]