Deployment Considerations for Dual-Stack Lite
Author(s): Christian Jacquenet, Yiu Lee, Mohamed Boucadair, Roberta Maglione, Carl Williams
This document discusses the deployment issues and describes requirements for the deployment and operation of Dual-Stack Lite. This document describes the various deployment considerations and applicability of the Dual-Stack Lite architecture....
Softwire Y. Lee Internet-Draft Comcast Intended status: Informational R. Maglione Expires: July 21, 2013 Telecom Italia C. Williams MCSR Labs C. Jacquenet M. Boucadair France Telecom January 17, 2013 Deployment Considerations for Dual-Stack Lite draft-ietf-softwire-dslite-deployment-08 Abstract This document discusses the deployment issues and describes requirements for the deployment and operation of Dual-Stack Lite. This document describes the various deployment considerations and applicability of the Dual-Stack Lite architecture. 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 July 21, 2013. Copyright Notice Copyright (c) 2013 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 Lee, et al. Expires July 21, 2013 [Page 1] Internet-Draft Deployment Considerations for DS-Lite January 2013 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. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. AFTR Deployment Considerations . . . . . . . . . . . . . . . . 3 2.1. Interface Consideration . . . . . . . . . . . . . . . . . 3 2.2. MTU and Fragmentation Considerations . . . . . . . . . . . 4 2.3. Logging at the AFTR . . . . . . . . . . . . . . . . . . . 4 2.4. Blacklisting a Shared IPv4 Address . . . . . . . . . . . . 5 2.5. AFTR's Policies . . . . . . . . . . . . . . . . . . . . . 5 2.5.1. Outgoing Policy . . . . . . . . . . . . . . . . . . . 5 2.5.2. Incoming Policy . . . . . . . . . . . . . . . . . . . 6 2.6. AFTR Impacts on Accounting Process . . . . . . . . . . . . 6 2.7. Reliability Considerations of AFTR . . . . . . . . . . . . 7 2.8. Strategic Placement of AFTR . . . . . . . . . . . . . . . 8 2.9. AFTR Considerations for Geographically Aware Services . . 8 2.10. Impacts on QoS Policy . . . . . . . . . . . . . . . . . . 9 2.11. Port Forwarding Considerations . . . . . . . . . . . . . . 9 2.12. DS-Lite Tunnel Security . . . . . . . . . . . . . . . . . 10 2.13. IPv6-only Network Considerations . . . . . . . . . . . . . 10 3. B4 Deployment Considerations . . . . . . . . . . . . . . . . . 11 3.1. DNS Deployment Considerations . . . . . . . . . . . . . . 11 3.2. IPv4 Service Monitoring . . . . . . . . . . . . . . . . . 11 3.2.1. B4 Remote Management . . . . . . . . . . . . . . . . . 11 3.2.2. IPv4 Connectivity Check . . . . . . . . . . . . . . . 12 4. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Normative References . . . . . . . . . . . . . . . . . . . 12 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 Lee, et al. Expires July 21, 2013 [Page 2] Internet-Draft Deployment Considerations for DS-Lite January 2013 1. Overview Dual-stack Lite (DS-Lite) [RFC6333] is a transition technique that enable operators to multiplex public IPv4 addresses while provisioning only IPv6 to users. DS-Lite is designed to continue offering IPv4 services while operators upgrading their network incrementally to IPv6. DS-Lite combines IPv4-in-IPv6 softwire [RFC2473] and NAT44 [RFC3022] to enable more than one user to share a public IPv4 address. While Appendix A of [RFC6333] explains how to deploy DS-Lite within specific scenarios, the purpose of this document is to describe problems that arise when deploying DS-Lite and what guidance should be taken to mitigate those issues. The information is based on real deployment experience and compiled in one comprehensive document so that operators aren't required to search through various RFCs deciding which sections are applicable and impact their DS-Lite deployment. 2. AFTR Deployment Considerations 2.1. Interface Consideration Address Family Transition Router (AFTR) is a network element that deployed inside the operator's network. AFTR can be a standalone device or embedded into a router. AFTR is the IPv4-in-IPv6 tunnel termination point and the NAT44 device. It is deployed at the IPv4- IPv6 network border where the tunnel interface is IPv6 and the external NAT44 interface is IPv4. The B4 element [RFC6333] is a function implemented on a dual-stack capable node, either a host device or a home gateway that creates a tunnel to an AFTR. Although an operator can configure both softwire tunnel termination and interface for NAT44 functions on a single physical interface (yet logically separated), there are scenarios we recommend to configure two individual interfaces (i.e. one dedicated for IPv4 and one dedicated for IPv6) to segregate the functions. o The access network between the B4 and AFTR is an IPv6-only network and the network between AFTR and IPv4 network is either IPv4-only network. In this deployment scenario, the AFTR interface to the IPv6-only network and the interface to the IPv4 network should use two physical interfaces on AFTR. o Operators may use Operations Support System (OSS) tools (e.g., Multi Router Traffic Grapher) to collect interface data packet count information. If an operator wants to separate the softwire function and NAT44 function on different physical interfaces for Lee, et al. Expires July 21, 2013 [Page 3] Internet-Draft Deployment Considerations for DS-Lite January 2013 collecting data packet count and the AFTR does not support packet count for logical interfaces, they should use two physical interfaces on AFTR. 2.2. MTU and Fragmentation Considerations DS-Lite is part tunneling protocol. Tunneling introduces overhead to the packet and decreases the effective MTU size after encapsulation. The DS-lite users may experience problems with applications such as not being able to download Internet pages or transfer large files. Since fragmentation and reassembly is not optimal, the operator should do everything possible to eliminate the need for it. If the operator uses simple IPv4-in-IPv6 softwire [RFC2473], it is recommended that the MTU size of the IPv6 network between the B4 and the AFTR account for the additional overhead (40 bytes). If the access network MTU size is fixed and cannot be changed, the operator should be aware that the B4 element and the AFTR must support fragmentation as defined in [RFC6333]. The operator should also be aware that reassembly at Tunnel Exit-Point is resource intensive as a large number of B4 may terminate on the same AFTR. Scalability of the AFTR is advised in this scenario. 2.3. Logging at the AFTR Source-Specific Log is essential for back tracking specific users when a problem is identified with one of the AFTR's NAT-ed addresses. Source-specific log contains the B4 IPv6 source address, transport protocol, source port, and source IPv4 address after NAT-ed. Using the Source-specific log, operators can uniquely identify a specific user when a DS-Lite user experiences problem to access IPv4 network. To maximize IPv4 shared radio, an operator may configure a short timeout value for NAT44 entries. This will result a large numbers of log created by the AFTR. For operators who desire to aggregate the logs, they can configure AFTR to pre-allocate a range of ports to each user. This range of ports will be used in the NAT44 function and the AFTR will create one log entry for the whole port-range. This aggregation can significantly reduce the log size for Source- specific logging. Some operators may require to log both source and destination information for user's connections. This is called Destination- Specific Log. Destination-specific log contains the B4's IPv6 address, transport protocol, source port, source IPv4 address after NAT-ed, destination port and destination IPv4 address. Destination- specific log is session-based, the operators should be aware that they will not be able to aggregate log entries. When using destination-specific log, the operator must be careful of the large Lee, et al. Expires July 21, 2013 [Page 4] Internet-Draft Deployment Considerations for DS-Lite January 2013 number of log entries created by the AFTR. Some AFTR implementations may keep the logs in main memory. This may be CPU and memory resource intensive. We suggest the operators must configure the AFTR to periodically send logs to storage facility and then purge them from AFTR. 2.4. Blacklisting a Shared IPv4 Address AFTR is a NAT device. It enables multiple users to share a single public IPv4 address. [RFC6269] discusses some considerations when sharing an IPv4 address. When a public IPv4 address is blacklisted by a remote peer, this may affect multiple B4 elements sharing the same IPv4 address. Operators deploying DS-Lite should be aware that Internet hosts may rely solely on source IP address to identify an abusive household and may not be aware that a given single IPv4 address is actually shared by multiple households. A content provider may block services for a shared IPv4 address and this will impact all households sharing this particular IPv4 address. The operator may receive calls of service outage and will need to take appropriate actions. Such corrective actions include but not limited to notifying the content provider to combine the IPv4 address with transport (e.g., TCP) and application protocol (e.g., HTTP) to identify abusive household. [RFC6302]. [I-D.ietf-intarea-nat-reveal-analysis] analyzes different approaches to identify a user in a shared address environment. 2.5. AFTR's Policies There are two types of AFTR policies: o Outgoing Policies apply to packets originating from B4 to AFTR. These policies should be provisioned on the AFTR's IPv6 interface connected to the B4 elements. o Incoming Policies apply to packets originating from IPv4 network to B4s. These policies should be provisioned on the IPv4 Interface connected to the IPv4 network. 2.5.1. Outgoing Policy Outgoing policies may include Access Control List (ACL) and Qualify of Service (QoS) settings. These policies control the packets from B4 elements to the AFTR. For example, the operator may configure the AFTR only to accept B4's connections originated from specific IPv6 prefixes configured in the AFTR. More discussion of this use case can be found in Section 2.12. An operator may configure the AFTR to give priority to the packets marked by certain DSCP values [RFC2475]. Furthermore, an AFTR may also apply outgoing policy to limit the rate Lee, et al. Expires July 21, 2013 [Page 5] Internet-Draft Deployment Considerations for DS-Lite January 2013 of port allocation for a single B4's IPv6 address. Some operators offer different service level agreements (SLA) to users to meet their requirements. Some users may require more ports and some may require different service priority. In this deployment scenario, the operator can implement outgoing policies specified to a user's B4 element or a group of B4 elements sharing the same policies. 2.5.2. Incoming Policy Similar to Outgoing Policy, Incoming Policy may also include ACL and QoS settings. Outgoing Policy controls packets coming from IPv4 network to the B4 elements. Incoming packets are normally treated equally, so these policies are globally applied. For example, an operator wants to use a pre-defined DSCP value to signal the IPv6 access network to apply certain traffic policies. In this deployment scenario, the operator can configure the AFTR to mark the incoming packets with the pre-defined DSCP value. This policy will apply to all incoming packets from the IPv4 network. 2.6. AFTR Impacts on Accounting Process This section discusses IPv4 and IPv6 traffic accounting in DS-Lite environment. In a typical broadband access scenario (e.g. DSL or Cable), the B4 element is embedded in the Residential Gateway and the edge router (e.g., Broadband Network Gateway or Cable Modem Termination System) is the IPv6 edge router. The edge router is usually responsible for IPv6 accounting and the user management functions such as authentication, authorization and accounting (AAA). However, given the fact that IPv4 traffic is encapsulated in an IPv6 packet at the B4 and only decapsulated at the ATFR, the edge router will require additional function to associate IPv4 accounting information to the B4 IPv6 address. If DS-lite is the only application using IPv4-in-IPv6 protocol in the IPv6 access network, the operator can configure the edge router to check the IPv6 Next Header field in the IPv6 header and identify the protocol type (i.e. 0x04) and collect IPv4 accounting information. Alternatively, AFTR may perform accounting for IPv4 traffic. However, operators must be aware that this will introduce some challenges especially in DSL deployment. In DSL deployment, the AAA transaction normally happens between the edge router (i.e., Broadband Network Gateway) and AAA server. [RFC6333] does not require the AFTR to interact with the AAA server or edge router. Thus, AFTR may not have the AAA parameters (e.g., Account Session ID) associated to users to generate IPv4 accounting record. The accounting process at the AFTR is only necessary if the operator requires separating per Lee, et al. Expires July 21, 2013 [Page 6] Internet-Draft Deployment Considerations for DS-Lite January 2013 user accounting records for IPv4 and IPv6 traffic. If the per user IPv6 accounting records, collected by the edge router, are sufficient, and the additional complexity of enabling IPv4 accounting at the ATFR is not required. It is important to notice that, since the IPv4 traffic is encapsulated in IPv6 packets, the data collected by the edge router for IPv6 traffic already contain the total amount of traffic (i.e. IPv4 and IPv6). Even if detailed accounting records collection for IPv4 traffic may not be required, it would be useful for an operator in some scenarios to have information the edge router generates that for the IPv6 traffic and can be used to identify the AFTR who is handling the IPv4 traffic for that user. This can be achieved by adding additional information to the IPv6 accounting records. For example: operators can use RADIUS attribute information specified in [RFC6519] or a new attribute to be specified in Internet Protocol Detailed Record (IPDR). 2.7. Reliability Considerations of AFTR For robustness, reliability and load distribution purposes, operators may deploy multiple AFTRs. In such case, the same IPv6 prefixes and algorithm to build the tunneling mechanisms will be configured on those AFTRs. In [RFC6333] A.3 mentions High Availability (HA) is the operator's responsibility. Since DS-lite is a stateful mechanism, all requirements for load-balancing and failover mechanism apply. There are many ways to implement HA in stateful mechanism, most common are Cold Standby mode and Hot Standby mode. More discussion on deploying of these two modes for NAT can be found in [I-D.xu-behave-stateful-nat-standby] In Cold Standby mode the AFTR states are not replicated from the Primary AFTR to the Backup AFTR. When the Primary AFTR fails, all the existing established sessions will be flushed out. The internal hosts are required to re-establish sessions with the external hosts. In Hot Standby mode the user's states are replicated on-the-fly from the Primary AFTR to the Backup AFTR. When the Primary AFTR fails, the Backup AFTR will take over all the existing established sessions. In this mode the internal hosts are not required to re-establish sessions with the external hosts. For operators, the decision to use Cold Standby mode or Hot Standby mode depends on the trade-off between capital cost and operational cost. Cold Standby mode does not require a Backup Standby AFTR to synchronize user states. This simplifies the operational model. When the Primary AFTR went down, any AFTR with extra capacity could take over. Hot Standby mode provides a smoother failover experience to users, the cost for the operators is more careful failover planning. For most deployment scenarios, we believe that Cold Lee, et al. Expires July 21, 2013 [Page 7] Internet-Draft Deployment Considerations for DS-Lite January 2013 Standby mode should be sufficient enough and thus recommended. 2.8. Strategic Placement of AFTR In DS-Lite environment, AFTR is the logical next-hop router of the B4 elements to access IPv4 network, so the placement of the AFTR will affect the traffic flows in the access network and overall network design. In general, there are two placement models to deploy AFTR. Model One is to deploy the AFTR in the edge of the network to cover a small region. Model Two is to deploy the AFTR in the core of network to cover a large region. When an operator considers where to deploy the AFTR, it must make trade-offs. AFTR in Model One serves fewer B4 elements, thus, it requires less powerful AFTR. Moreover, the traffic flows are more evenly distributed to the AFTRs. However, it requires deploying more AFTRs to cover the entire network. Often the operation cost increases proportionally with to the number of network equipment. AFTR in Model Two covers a larger area, thus, it serves more B4 elements. The operator could deploy only few AFTRs to support the entire user base. However, this model requires more powerful AFTR to sustain the load at peak hours. Since AFTR would support B4 elements from different regions, AFTR would be deployed closer to the core network. DS-Lite framework can be incrementally deployed. An operator may consider to start with Model Two. When the demand increases, the operator could push the AFTR closer to the edge, which would effectively become Model One. 2.9. AFTR Considerations for Geographically Aware Services By centralizing public IPv4 addresses in AFTR, remote services can no longer rely on an IPv4 address and IPv4 routing information to derive a user's geographical information. For example, the IPv6 access network and the AFTR may be in two different cities. If the remote services rely on the IPv4 address to locate a user, they may have thought the user was in a different city. [RFC6269] Section 7 describe the problem in more details. Applications could explicitly ask users to enter location information such as postal code or telephone number before offering geographical service. In contrast, applications could use HELD [RFC5985] to get the location information from the Location Information Server and give this information to the remote peer. [RFC6280] describes an architecture to enable location- based services. However to mitigate the impact, we recommend operators to deploy AFTR as close to users as possible. Lee, et al. Expires July 21, 2013 [Page 8] Internet-Draft Deployment Considerations for DS-Lite January 2013 2.10. Impacts on QoS Policy This section describes the application of [RFC2983] to DS-Lite deployment model. Operators must ensure that the QoS policy that is in place operates properly within the DS-Lite deployment. In this regard, operators commonly use DSCP [RFC2475] to classify and prioritize different types of traffic in their networks. DS-Lite tunnel can be seen as a particular case of uniform conceptual tunnel model described in section 3.1 of [RFC2983]. The uniform model views an IP tunnel as just a necessary mechanism to forward traffic to its destination, but the tunnel has no significant impact on traffic conditioning. In this model, any packet has exactly one DSCP Field that is used for traffic conditioning at any point and it is the field in the outermost IP header. In DS-Lite model this is the Traffic Class field in IPv6 header. According to [RFC2983] implementations of this model copy the DSCP value to the outer IP header at encapsulation and copy the outer header's DSCP value to the inner IP header at decapsulation. Operators should use this model by provisioning the network such that the AFTR copies the DSCP value in the IPv4 header to the Traffic Class field in the IPv6 header after the encapsulation for the downstream traffic. Similarly the B4 copies the DSCP value in the IPv4 header to the Traffic Class field to the IPv6 header after the encapsulation for the upstream traffic. Traffic identification and classification can be done by examining the outer IPv6 header in the IPv6 access network. 2.11. Port Forwarding Considerations Some applications behind the B4 element require the B4 element to accept incoming requests. If the remote application wants to communicate to the application behind the B4 element, the remote application must know both the NAT-ed IPv4 address used by the B4 element and the IPv4 destination port. Some applications use Universal Plug and Play (UPnP) (e.g., popular gaming consoles) or ICE [RFC5245] to request incoming ports. Some applications rely on Application Level Gateway (ALG) or manual port configuration to reserve a port in the NAT. For the DS-Lite deployment scenario whereby the B4 does not own a dedicated public IPv4 address or all the available ports, the operator will manage port-forwarding in the serving AFTR. Operators may use Port Control Protocol (PCP) [I-D.ietf-pcp-base] as guidance to provide port-forwarding service. Operators will deploy PCP client in the B4 elements. PCP permits PCP server to be deployed in a standalone server. However, we recommend the operators to consider deploying the PCP server in the AFTR. This will ease the overhead to design a global configuration for PCP server for many AFTRs because each PCP server will be dedicated to Lee, et al. Expires July 21, 2013 [Page 9] Internet-Draft Deployment Considerations for DS-Lite January 2013 the collocated AFTR. When sharing an IPv4 address, not all the ports are available to a user. Some restricted ports (i.e., 0-1023) are well-known such as TCP port 25 and 80. Many users may want to be provisioned with the restricted ports. For fairness, we recommend operators to configure the AFTR not to allocate the restricted ports to regular DS-Lite users. This operation model ensures that DS-lite users will have uniform configuration, which can simplify provisioning and operation. For users who want to use the restricted ports, operators can consider to provision a full IPv4 address to those users. If an operator still want to provision restricted ports to specific users, it may require to implement static user's configuration in the AFTR to match the B4's IPv6 address to the NAT rules. Alternatively, the B4 element may dynamically allocate the ports and the AFTR authenticates the user's request using PCP [I-D.ietf-pcp-base]. 2.12. DS-Lite Tunnel Security [RFC6333] Section 11 describes security issues associated to DS-Lite mechanism. To restrict the service offered by AFTR only to registered users, an operator can implement Outgoing Policy on the AFTR's tunnel interface to accept only the IPv6 prefixes defined in the policy. For static provisioning, the operator will need to know in advance the IPv6 prefixes provisioned to the users for the softwire in order to configure the policy. To simplify operation, operators should configure the AFTRs in the same region with the same IPv6 prefixes Outgoing Policy. The AFTRs will accept both regular connections and failover connections from the B4 elements in the same service region. 2.13. IPv6-only Network Considerations In environments where the operator wants to deploy AFTR in the IPv6- only network, the AFTR nodes may not have direct IPv4 connectivity. In this scenario the operator extends the IPv6-only boundary to the border of the network and only the border routers have IPv4 connectivity. For both scalability and performance purposes, AFTR is located in the IPv6-only network closer to B4 elements. In this scenario the AFTR has only IPv6 connectivity and must be able to send and receive IPv4 packets. Enhancements to the DS-Lite AFTR are required to achieve this. [I-D.boucadair-softwire-dslite-v6only] describes such issues and enhancements to DS-Lite in IPv6-only deployments. Lee, et al. Expires July 21, 2013 [Page 10] Internet-Draft Deployment Considerations for DS-Lite January 2013 3. B4 Deployment Considerations In order to configure the IPv4-in-IPv6 tunnel, the B4 element needs the IPv6 address of the AFTR element. This IPv6 address can be configured using a variety of methods, ranging from an out-of-band mechanism, manual configuration, DHCPv6 option to RADIUS. If an operator uses DHCPv6 to provision the B4, the B4 element must implement the DHCPv6 option defined in [RFC6334]. If an operator uses RADIUS to provision the B4, the B4 element must implement [RFC6519]. 3.1. DNS Deployment Considerations [RFC6333] recommends the B4 element should send DNS queries to an external recursive resolver over IPv6. The B4 element should implement proxy resolver that will proxy DNS query from IPv4 transport to the DNS server in the IPv6 network. [RFC6333] does not describe the DNS proxy behavior. In deployment, the operator must ensure that the DNS proxy implementation must follow [RFC5625]. This is important especially for operators who have deployed or consider to deploy DNSSEC [RFC4035]. Some operators may want to give clients behind the B4's element an IPv4 address of an external DNS recursive resolver. The B4 element will treat the DNS packets as normal IP packets and forward over the softwire. Note that there is no effective way to provision an IPv4 DNS address to the B4 over IPv6, operators who use this DNS deployment model must be aware that it is undefined how to provision an IPv4 DNS address over an IPv6 network, so it will introduce additional complexity in B4 provisioning. Moreover, this will increase load to AFTR by creating entries in the NAT table for DNS sessions. Operators may deploy a local DNS caching resolver in AFTR to reduce the load in the NAT table. Nonetheless, this DNS model is not covered in [RFC6333] and is not recommended. 3.2. IPv4 Service Monitoring 3.2.1. B4 Remote Management B4 is connected to IPv6 access network to offer IPv4 services. When users experience IPv4 connectivity issue, operators must be able to remotely access (e.g. TR-069) the B4 element to verify its B4's configuration and status. Operators should access B4 elements using native IPv6. Operators should not access B4 over the softwire. Lee, et al. Expires July 21, 2013 [Page 11] Internet-Draft Deployment Considerations for DS-Lite January 2013 3.2.2. IPv4 Connectivity Check DS-Lite framework provides IPv4 services over IPv6 access network. Operators and users must be able to check the IPv4 connectivity from the B4 element to its AFTR using PING and IPv4 Traceroute. AFTR should be configured with an IPv4 address to enable PING test and Traceroute test. Operators should assign the same IPv4 address (i.e., 192.0.0.2/32) to all AFTRs. IANA allocates 192.0.0.0/29 [RFC6333] Section 5.7 that can be used for this purpose. 4. Security Considerations This document does not present any new security issues. [RFC6333] discusses DS-Lite related security issues. 5. Acknowledgement Thanks to Mr. Nejc Skoberne and Dr. Maoke Chen for their thorough review and helpful comments. We also want to thank Mr. Hu Jie for sharing his DS-Lite deployment experience to us. He gave us recommendations what his company learned while testing DS-Lite in the production network. 6. IANA Considerations This memo includes no request to IANA. 7. References 7.1. Normative References [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC6333, August 2011. [RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite", RFC6334, August 2011. [RFC6519] Maglione, R. and A. Durand, "RADIUS Extensions for Dual- Stack Lite", RFC6519, February 2012. Lee, et al. Expires July 21, 2013 [Page 12] Internet-Draft Deployment Considerations for DS-Lite January 2013 7.2. Informative References [I-D.boucadair-softwire-dslite-v6only] Boucadair, M., Jacquenet, C., Grimault, J., Kassi-Lahlou, M., Levis, P., Cheng, D., and Y. Lee, "Deploying Dual- Stack Lite in IPv6 Network", draft-boucadair-softwire-dslite-v6only-01 (work in progress), April 2011. [I-D.ietf-intarea-nat-reveal-analysis] Boucadair, M., Touch, J., Levis, P., and R. Penno, "Analysis of Solution Candidates to Reveal a Host Identifier (HOST_ID) in Shared Address Deployments", draft-ietf-intarea-nat-reveal-analysis-04 (work in progress), August 2012. [I-D.ietf-pcp-base] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", draft-ietf-pcp-base-29 (work in progress), November 2012. [I-D.xu-behave-stateful-nat-standby] Xu, X., Boucadair, M., Lee, Y., and G. Chen, "Redundancy Requirements and Framework for Stateful Network Address Translators (NAT)", draft-xu-behave-stateful-nat-standby-06 (work in progress), October 2010. [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 Specification", RFC2473, December 1998. [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., and W. Weiss, "An Architecture for Differentiated Services", RFC2475, December 1998. [RFC2983] Black, D., "Differentiated Services and Tunnels", RFC2983, October 2000. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC3022, January 2001. [RFC4035] Arends, R., Austein, R., Larson, M., Massey, D., and S. Rose, "Protocol Modifications for the DNS Security Extensions", RFC4035, March 2005. [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Lee, et al. Expires July 21, 2013 [Page 13] Internet-Draft Deployment Considerations for DS-Lite January 2013 Traversal for Offer/Answer Protocols", RFC5245, April 2010. [RFC5625] Bellis, R., "DNS Proxy Implementation Guidelines", BCP 152, RFC5625, August 2009. [RFC5985] Barnes, M., "HTTP-Enabled Location Delivery (HELD)", RFC5985, September 2010. [RFC6269] Ford, M., Boucadair, M., Durand, A., Levis, P., and P. Roberts, "Issues with IP Address Sharing", RFC6269, June 2011. [RFC6280] Barnes, R., Lepinski, M., Cooper, A., Morris, J., Tschofenig, H., and H. Schulzrinne, "An Architecture for Location and Location Privacy in Internet Applications", BCP 160, RFC6280, July 2011. [RFC6302] Durand, A., Gashinsky, I., Lee, D., and S. Sheppard, "Logging Recommendations for Internet-Facing Servers", BCP 162, RFC6302, June 2011. Authors' Addresses Yiu L. Lee Comcast One Comcast Center Philadelphia, PA 19103 U.S.A. Email: email@example.com URI: http://www.comcast.com Roberta Maglione Telecom Italia Via Reiss Romoli 274 Torino 10148 Italy Email: firstname.lastname@example.org URI: Lee, et al. Expires July 21, 2013 [Page 14] Internet-Draft Deployment Considerations for DS-Lite January 2013 Carl Williams MCSR Labs U.S.A. Email: email@example.com Christian Jacquenet France Telecom Rennes France Email: firstname.lastname@example.org Mohamed Boucadair France Telecom Rennes France Email: email@example.com Lee, et al. Expires July 21, 2013 [Page 15]