Network Working Group M. Boucadair Internet-Draft C. Jacquenet Intended status: Standards Track Orange Expires: May 17, 2018 S. Sivakumar Cisco Systems November 13, 2017 YANG Data Modules for Dual-Stack Lite (DS-Lite) draft-ietf-softwire-dslite-yang-09 Abstract This document defines YANG modules for the DS-Lite Address Family Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements. Editorial Note (To be removed by RFC Editor) Please update these statements with the RFC number to be assigned to this document: o "This version of this YANG module is part of RFC XXXX;" o "RFC XXXX: YANG Data Modules for Dual-Stack Lite (DS-Lite)"; o "reference: RFC XXXX" 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 https://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 17, 2018. Boucadair, et al. Expires May 17, 2018 [Page 1] Internet-Draft DS-Lite YANG Modules November 2017 Copyright Notice Copyright (c) 2017 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 (https://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 . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 2. DS-Lite YANG Modules: An Overview . . . . . . . . . . . . . . 4 3. DS-Lite AFTR YANG Module . . . . . . . . . . . . . . . . . . 7 4. DS-Lite B4 YANG Module . . . . . . . . . . . . . . . . . . . 14 5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1. Normative references . . . . . . . . . . . . . . . . . . 18 8.2. Informative references . . . . . . . . . . . . . . . . . 19 Appendix A. B4 Example . . . . . . . . . . . . . . . . . . . . . 21 Appendix B. AFTR Examples . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 1. Introduction This document defines data models for DS-Lite [RFC6333], using the YANG data modeling language [RFC7950]. Both the Address Family Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements are covered by this specification. As a reminder, Figure 1 illustrates an overview of the DS-Lite architecture that involves AFTR and B4 elements. Boucadair, et al. Expires May 17, 2018 [Page 2] Internet-Draft DS-Lite YANG Modules November 2017 +-----------+ | Host | +-----+-----+ |192.0.2.1 | | |192.0.2.2 +---------|---------+ | | | | Home router | |+--------+--------+| || B4 || |+--------+--------+| +--------|||--------+ |||2001:db8:0:1::1 ||| |||<-IPv4-in-IPv6 softwire ||| -------|||------- / ||| \ | ISP core network | \ ||| / -------|||------- ||| |||2001:db8:0:2::1 +--------|||--------+ | AFTR | |+--------+--------+| || Concentrator || |+--------+--------+| | |NAT| | | +-+-+ | +---------|---------+ |198.51.100.1 | --------|-------- / | \ | Internet | \ | / --------|-------- | |203.0.113.1 +-----+-----+ | IPv4 Host | +-----------+ Figure 1: DS-Lite Base Architecture Boucadair, et al. Expires May 17, 2018 [Page 3] Internet-Draft DS-Lite YANG Modules November 2017 DS-Lite deployment considerations are discussed in [RFC6908]. This document follows the guidelines of [RFC6087], uses the common YANG types defined in [RFC6991], and adopts the Network Management Datastore Architecture (NMDA). 1.1. Terminology This document makes use of the terms defined in Section 3 of [RFC6333]. The terminology for describing YANG data modules is defined in [RFC7950]. The meaning of the symbols in tree diagrams is defined in [I-D.ietf-netmod-yang-tree-diagrams]. 2. DS-Lite YANG Modules: An Overview As shown in Figure 1: o The AFTR element is a combination of an IPv4-in-IPv6 tunnel and a NAPT function (Section 2.2 of [RFC3022]). o The B4 element is an IPv4-in-IPv6 tunnel. Therefore, the AFTR YANG module is designed to augment both the Interfaces YANG module [RFC7223] and the NAT YANG module [I-D.ietf-opsawg-nat-yang] with DS-Lite specific features. The B4 YANG module augments the interfaces YANG module. Concretely, the AFTR YANG module (Figure 2) augments the Interfaces YANG module with the following: o An IPv6 address used by the AFTR for sending and receiving IPv4- in-IPv6 packets (aftr-ipv6-address). o An IPv4 address that is used by the AFTR for troubleshooting purposes (aftr-ipv4-address). o The tunnel MTU, used to avoid fragmentation (tunnel-mtu). o A policy to instruct the AFTR whether it must preserve DSCP marking when encapsulating/decapsulating packets (v6-v4-dscp- preservation). In addition, the AFTR YANG module augments the NAT YANG module (policy, in particular) with the following: Boucadair, et al. Expires May 17, 2018 [Page 4] Internet-Draft DS-Lite YANG Modules November 2017 o A policy to limit the number of DS-Lite softwires per subscriber (max-softwire-per-subscriber). o A policy to instruct the AFTR whether a state can be automatically migrated (state-migrate). o Further, in order to prevent a denial-of-service by frequently changing the source IPv6 address, 'b4-address-change-limit' is used to rate-lmite such changes. o An instruction to rewrite the TCP Maximum Segment Size (MSS) option (mss-clamping) to avoid TCP fragmentation. Given that the NAPT table of the AFTR element is extended to include the source IPv6 address of incoming packets, the AFTR YANG module augments the NAPT44 mapping-entry with the following: o b4-ipv6-address which is used to record the source IPv6 address of a packet received from a B4 element. This IPv6 address is required to disambiguate between the overlapping IPv4 address space of subscribers. o The value of the Traffic Class field in the IPv6 header as received from a B4 element (v6-dscp): This information is used to preserve DSCP marking when encapsulating/decapsulationg at the AFTR. o The IPv4 DSCP marking of the IPv4 packet received from a B4 element (internal-v4-dscp): This information can be used by the AFTR for setting the DSCP of packets relayed to a B4 element. o The IPv4 DSCP marking as set by the AFTR in its external interface (external-v4-dscp): An AFTR can be instructed to preserve the same marking or to set it to another value when forwarding an IPv4 packet upstream. Access Control List (ACL) and Quality of Service (QoS) policies discussed in Section 2.5 of [RFC6908] are out of scope. A YANG module for ACLs is documented in [I-D.ietf-netmod-acl-model]. Likewise, PCP-related considerations discussed in Section 8.5 of [RFC6333] are out of scope. A YANG module for PCP is documented in [I-D.boucadair-pcp-yang]. Boucadair, et al. Expires May 17, 2018 [Page 5] Internet-Draft DS-Lite YANG Modules November 2017 module: ietf-dslite-aftr augment /if:interfaces/if:interface: +--rw aftr-ipv6-address? inet:ipv6-address +--rw aftr-ipv4-address? inet:ipv4-address +--rw tunnel-mtu? uint16 +--rw v6-v4-dscp-preservation? boolean augment /nat:nat/nat:instances/nat:instance/nat:policy: +--rw max-softwires-per-subscriber? uint8 +--rw state-migrate? boolean +--rw b4-address-change-limit? uint32 +--rw mss-clamping +--rw enable? boolean +--rw mss-value? uint16 augment /nat:nat/nat:instances/nat:instance/nat:mapping-table/nat:mapping-entry: +--rw b4-ipv6-address | +--rw address? inet:ipv6-address | +--rw last-address-change? yang:date-and-time +--rw v6-dscp? uint8 +--rw internal-v4-dscp? uint8 +--rw external-v4-dscp? uint8 augment /nat:nat/nat:instances/nat:instance/nat:statistics/nat:mappings-statistics: +--ro active-softwires? yang:gauge32 notifications: +---n b4-address-change-limit-policy-violation +--ro id -> /nat:nat/instances/instance/id +--ro policy-id -> /nat:nat/instances/instance/policy/id +--ro address inet:ipv6-address Figure 2: YANG Module for DS-Lite AFTR Examples to illustrate the use of this module are provided in Appendix B. The B4 YANG module (Figure 3) augments the Interfaces YANG module with the following: o An IPv6 address used by a B4 element for sending and receiving IPv4-in-IPv6 packets (b4-ipv6-address). o The IPv6 address of the AFTR to use by a B4 element (aftr- ipv6-addr). o An IPv4 address that is used by a B4 element for troubleshooting purposes (b4-ipv4-address). o The tunnel MTU at the B4 side to avoid fragmentation (tunnel-mtu). Boucadair, et al. Expires May 17, 2018 [Page 6] Internet-Draft DS-Lite YANG Modules November 2017 o An instruction whether DSCP marking is to be preserved when encapsulating an IPv4 packet in an IPv6 packet (v6-v4-dscp- preservation). module: ietf-dslite-b4 augment /if:interfaces/if:interface: +--rw b4-ipv6-address? inet:ipv6-address +--rw aftr-ipv6-addr? inet:ipv6-address +--rw b4-ipv4-address? inet:ipv4-address +--rw tunnel-mtu? uint16 +--rw v6-v4-dscp-preservation? boolean Figure 3: YANG Module for DS-Lite B4 An example to illustrate the use of this module is provided in Appendix A. 3. DS-Lite AFTR YANG Module file "ietf-dslite-aftr@2017-11-14.yang" module ietf-dslite-aftr { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-dslite-aftr"; prefix dslite-aftr; import ietf-inet-types { prefix inet; } import ietf-interfaces { prefix if; } import iana-if-type { prefix ianaift; } import ietf-nat {prefix nat;} import ietf-yang-types { prefix yang; } organization "IETF Softwire Working Group"; contact "WG Web: WG List: WG Chair: Ian Farrer WG Chair: Yong Cui Editor: Mohamed Boucadair Boucadair, et al. Expires May 17, 2018 [Page 7] Internet-Draft DS-Lite YANG Modules November 2017 Editor: Christian Jacquenet Editor: Senthil Sivakumar "; description "This module is a YANG module for DS-Lite AFTR implementations. Copyright (c) 2017 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2017-11-14 { description "Initial revision."; reference "RFC XXXX: YANG Data Modules for Dual-Stack Lite (DS-Lite)"; } augment "/if:interfaces/if:interface" { when "if:type = 'ianaift:tunnel'"; description "Augments Interface module with AFTR parameters. IANA interface types are maintained at this registry: https://www.iana.org/assignments/ianaiftype-mib/ianaiftype-mib. tunnel (131), -- Encapsulation interface"; leaf aftr-ipv6-address { type inet:ipv6-address; description "IPv6 address of the DS-Lite AFTR."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } Boucadair, et al. Expires May 17, 2018 [Page 8] Internet-Draft DS-Lite YANG Modules November 2017 leaf aftr-ipv4-address { type inet:ipv4-address; default "192.0.0.1"; description "IPv4 address of the DS-Lite AFTR. 192.0.0.1 is reserved for the AFTR element. This address can be used to report ICMP problems and will appear in traceroute outputs."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf tunnel-mtu { type uint16; description "Configures a tunnel MTU. [RFC6908] specifies that 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, it is recommended that the MTU size of the IPv6 network between the B4 and the AFTR accounts for the additional overhead (40 bytes)."; reference "RFC 6908: Deployment Considerations for Dual-Stack Lite"; } leaf v6-v4-dscp-preservation { type boolean; description "Copies the DSCP value from the IPv6 header and vice versa. According to Section 2.10 of [RFC6908], 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."; reference "Section 2.10 of RFC 6908."; } } augment "/nat:nat/nat:instances/nat:instance/nat:policy" { description "Augments the NAPT44 module with AFTR parameters."; Boucadair, et al. Expires May 17, 2018 [Page 9] Internet-Draft DS-Lite YANG Modules November 2017 leaf max-softwires-per-subscriber { type uint8; default 1; description "Configures the maximum softwires per subscriber feature. A subscriber is uniquely identified by means of subscriber-mask. This policy aims to prevent a misbehaving subscriber from mounting several DS-Lite softwires that would consume additional AFTR resources (e.g., get more external ports if the quota were enforced on a per-softwire basis, consume extra processing due to a large number of active softwires)."; reference "Section 4 of RFC 7785."; } leaf state-migrate { type boolean; default true; description "State migration is enabled by default. In the event a new IPv6 address is assigned to the B4 element, the AFTR should migrate existing state to be bound to the new IPv6 address. This operation ensures that traffic destined to the previous B4's IPv6 address will be redirected to the newer B4's IPv6 address. The destination IPv6 address for tunneling return traffic from the AFTR should be the last seen as the B4's IPv6 source address from the CPE. The AFTR uses the subscriber-mask to determine whether two IPv6 addresses belong to the same CPE (e.g., if the subscriber-mask is set to 56, the AFTR concludes that 2001:db8:100:100::1 and 2001:db8:100:100::2 belong to the same CPE assigned with 2001:db8:100:100::/56)."; reference "RFC 7785: Recommendations for Prefix Binding in the Context of Softwire Dual-Stack Lite"; } leaf b4-address-change-limit { type uint32; units "seconds"; Boucadair, et al. Expires May 17, 2018 [Page 10] Internet-Draft DS-Lite YANG Modules November 2017 default '1800'; description "Minimum number of seconds between successive B4's IPv6 address change from the same prefix. Changing the source B4's IPv6 address may be used as an attack vector. Packets with a new B4's IPv6 address from the same prefix should be rate-limited. It is recommended to set this rate limit to 30 minutes; other values can be set on a per-deployment basis."; reference "RFC 7785: Recommendations for Prefix Binding in the Context of Softwire Dual-Stack Lite"; } container mss-clamping { description "MSS rewriting configuration to avoid IPv6 fragmentation."; leaf enable { type boolean; description "Enable/disable MSS rewriting feature."; } leaf mss-value { type uint16; units "octets"; description "Sets the MSS value to be used for MSS rewriting."; } } } augment "/nat:nat/nat:instances/nat:instance/"+ "nat:mapping-table/nat:mapping-entry"{ description "Augments the NAPT44 mapping table with DS-Lite specifics."; container b4-ipv6-address { description "Records the IPv6 address used by the B4 element and the last time that address changed."; leaf address { type inet:ipv6-address; Boucadair, et al. Expires May 17, 2018 [Page 11] Internet-Draft DS-Lite YANG Modules November 2017 description "Corresponds to the IPv6 address used by the B4 element."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf last-address-change { type yang:date-and-time; description "Records the last time when the address changed."; } } leaf v6-dscp { when "/if:interfaces/if:interface/" + "dslite-aftr:v6-v4-dscp-preservation='true'"; type uint8; description "DSCP value used at the softwire level (i.e., IPv6 header)."; } leaf internal-v4-dscp { when "/if:interfaces/if:interface/" + "dslite-aftr:v6-v4-dscp-preservation='true'"; type uint8; description "DSCP value of the encapsulated IPv4 packet."; } leaf external-v4-dscp { when "/if:interfaces/if:interface/" + "dslite-aftr:v6-v4-dscp-preservation='true'"; type uint8; description "DSCP value of the translated IPv4 packet as marked by the AFTR."; } } augment "/nat:nat/nat:instances/nat:instance/nat:statistics/" + "nat:mappings-statistics" { description "Indicates the number of active softwires."; leaf active-softwires{ type yang:gauge32; description Boucadair, et al. Expires May 17, 2018 [Page 12] Internet-Draft DS-Lite YANG Modules November 2017 "The number of currently active softwires on the AFTR instance."; } } /* * Notifications */ notification b4-address-change-limit-policy-violation { description "Generates notifications when a B4 unsuccessfully attempts to change IPv6 address in a time shorter than the value of b4-address-change-limit. Notifications are rate-limited (notify-interval)."; leaf id { type leafref { path "/nat:nat/nat:instances/nat:instance/nat:id"; } mandatory true; description "NAT instance identifier."; } leaf policy-id { type leafref { path "/nat:nat/nat:instances/nat:instance/nat:policy/nat:id"; } mandatory true; description "Policy Identifier."; } leaf address { type inet:ipv6-address; mandatory true; description "B4's IPv6 address."; } } } Boucadair, et al. Expires May 17, 2018 [Page 13] Internet-Draft DS-Lite YANG Modules November 2017 4. DS-Lite B4 YANG Module file "ietf-dslite-b4@2017-11-13.yang" module ietf-dslite-b4 { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-dslite-b4"; prefix dslite-b4; import ietf-inet-types { prefix inet; } import ietf-interfaces { prefix if; } import iana-if-type { prefix ianaift; } organization "IETF Softwire Working Group"; contact "WG Web: WG List: WG Chair: Ian Farrer WG Chair: Yong Cui Editor: Mohamed Boucadair Editor: Christian Jacquenet Editor: Senthil Sivakumar "; description "This module is a YANG module for DS-Lite B4 implementations. Copyright (c) 2017 IETF Trust and the persons identified as authors of the code. All rights reserved. Redistribution and use in source and binary forms, with or without modification, is permitted pursuant to, and subject to the license terms contained in, the Simplified BSD License set forth in Section 4.c of the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info). Boucadair, et al. Expires May 17, 2018 [Page 14] Internet-Draft DS-Lite YANG Modules November 2017 This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2017-11-13 { description "Initial revision."; reference "RFC XXXX: YANG Data Modules for Dual-Stack Lite (DS-Lite)"; } augment "/if:interfaces/if:interface" { when "if:type = 'ianaift:tunnel'"; description "Augments Interface module with B4 parameters. IANA interface types are maintained at this registry: https://www.iana.org/assignments/ianaiftype-mib/ianaiftype-mib. tunnel (131), -- Encapsulation interface"; leaf b4-ipv6-address { type inet:ipv6-address; description "The IPv6 address used by the B4 element."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf aftr-ipv6-addr { type inet:ipv6-address; description "The AFTR's IPv6 address."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf b4-ipv4-address { type inet:ipv4-address; default "192.0.0.2"; description "IPv4 address of the DS-Lite B4. 192.0.0.0/29 is reserved for the B4 element. This address can be used to report ICMP problems and will appear in traceroute outputs."; reference Boucadair, et al. Expires May 17, 2018 [Page 15] Internet-Draft DS-Lite YANG Modules November 2017 "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf tunnel-mtu { type uint16; description "Configures a tunnel MTU. [RFC6908] specifies that 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, it is recommended that the MTU size of the IPv6 network between the B4 and the AFTR accounts for the additional overhead (40 bytes)."; reference "RFC 6908: Deployment Considerations for Dual-Stack Lite"; } leaf v6-v4-dscp-preservation { type boolean; description "Copies the DSCP value from the IPv6 header and vice versa. 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."; reference "Section 2.10 of RFC 6908."; } } } 5. Security Considerations The YANG module defined in this document is designed to be accessed via network management protocols such as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport layer, and the mandatory-to-implement secure transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC5246]. The NETCONF access control model [RFC6536] provides the means to restrict access for particular NETCONF or RESTCONF users to a preconfigured subset of all available NETCONF or RESTCONF protocol operations and content. Boucadair, et al. Expires May 17, 2018 [Page 16] Internet-Draft DS-Lite YANG Modules November 2017 All data nodes defined in the YANG module which can be created, modified and deleted (i.e., config true, which is the default) are considered sensitive. Write operations (e.g., edit-config) applied to these data nodes without proper protection can negatively affect network operations. An attacker who is able to access to the B4/AFTR can undertake various attacks, such as: o Set the value of 'aftr-ipv6-addr' on the B4 to point to an illegitimate AFTR so that it can intercept all the traffic sent by a B4. Illegitimately intercepting users' traffic is a attack with severe implications on privacy. o Set the MTU to a low value which may increase the number of fragments ('tunnel-mtu' for both B4 and AFTR). o Set 'max-softwire-per-subscriber' to an arbitrary high value, which will be exploited by a misbehaving user to grab more resources (by mounting as many softwires as required to get more external IP addresses/ports) or to perform a Denial-of-Service on the AFTR by mounting a massive number of softwires. o Set 'state-migrate' to 'false' on the AFTR. This action may lead to a service degradation for the users. o Set 'b4-address-change-limit" to an arbitrary low value can ease DoS attacks based on frequent change of B4 IPv6 address. o Set 'v6-v4-dscp-preservation' to 'false" may lead to a service degradation if some policies are applied on the network based on the DSCP value. Additional security considerations are discussed in [I-D.ietf-opsawg-nat-yang]. Security considerations related to DS-Lite are discussed in [RFC6333]. 6. IANA Considerations This document requests IANA to register the following URIs in the "IETF XML Registry" [RFC3688]: Boucadair, et al. Expires May 17, 2018 [Page 17] Internet-Draft DS-Lite YANG Modules November 2017 URI: urn:ietf:params:xml:ns:yang:ietf-dslite-aftr Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. URI: urn:ietf:params:xml:ns:yang:ietf-dslite-b4 Registrant Contact: The IESG. XML: N/A; the requested URI is an XML namespace. This document requests IANA to register the following YANG modules in the "YANG Module Names" registry [RFC7950]. name: ietf-dslite-aftr namespace: urn:ietf:params:xml:ns:yang:ietf-dslite-aftr prefix: dslite-aftr reference: RFC XXXX name: ietf-dslite-b4 namespace: urn:ietf:params:xml:ns:yang:ietf-dslite-b4 prefix: dslite-b4 reference: RFC XXXX 7. Acknowledgements Thanks to Qin Wu for identifying a compiling error. Mahesh Jethanandani provided an early yangdoctors review; many thanks to him. Many thanks to Ian Farrer for the review and comments. 8. References 8.1. Normative references [I-D.ietf-opsawg-nat-yang] Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula, S., and Q. Wu, "A YANG Data Model for Network Address Translation (NAT) and Network Prefix Translation (NPT)", draft-ietf-opsawg-nat-yang-08 (work in progress), November 2017. [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, January 2004, . Boucadair, et al. Expires May 17, 2018 [Page 18] Internet-Draft DS-Lite YANG Modules November 2017 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, August 2008, . [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011, . [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011, . [RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual- Stack Lite Broadband Deployments Following IPv4 Exhaustion", RFC 6333, DOI 10.17487/RFC6333, August 2011, . [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, DOI 10.17487/RFC6536, March 2012, . [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, July 2013, . [RFC7223] Bjorklund, M., "A YANG Data Model for Interface Management", RFC 7223, DOI 10.17487/RFC7223, May 2014, . [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, August 2016, . [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, . 8.2. Informative references [I-D.boucadair-pcp-yang] Boucadair, M., Jacquenet, C., Sivakumar, S., and S. Vinapamula, "YANG Modules for the Port Control Protocol (PCP)", draft-boucadair-pcp-yang-05 (work in progress), October 2017. Boucadair, et al. Expires May 17, 2018 [Page 19] Internet-Draft DS-Lite YANG Modules November 2017 [I-D.ietf-netmod-acl-model] Jethanandani, M., Huang, L., Agarwal, S., and D. Blair, "Network Access Control List (ACL) YANG Data Model", draft-ietf-netmod-acl-model-14 (work in progress), October 2017. [I-D.ietf-netmod-yang-tree-diagrams] Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft- ietf-netmod-yang-tree-diagrams-02 (work in progress), October 2017. [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network Address Translator (Traditional NAT)", RFC 3022, DOI 10.17487/RFC3022, January 2001, . [RFC6087] Bierman, A., "Guidelines for Authors and Reviewers of YANG Data Model Documents", RFC 6087, DOI 10.17487/RFC6087, January 2011, . [RFC6908] Lee, Y., Maglione, R., Williams, C., Jacquenet, C., and M. Boucadair, "Deployment Considerations for Dual-Stack Lite", RFC 6908, DOI 10.17487/RFC6908, March 2013, . [RFC7785] Vinapamula, S. and M. Boucadair, "Recommendations for Prefix Binding in the Context of Softwire Dual-Stack Lite", RFC 7785, DOI 10.17487/RFC7785, February 2016, . Boucadair, et al. Expires May 17, 2018 [Page 20] Internet-Draft DS-Lite YANG Modules November 2017 Appendix A. B4 Example The following example shows a B4 element (2001:db8:0:1::1) that is configured with an AFTR element (2001:db8:0:2::1). The B4 element is also instructed to preserve the DSCP marking. myB4 ianaift:tunnel true 2001:db8:0:1::1 2001:db8:0:2::1 true Appendix B. AFTR Examples The following example shows an AFTR that is reachable at 2001:db8:0:2::1. Also, this XML snippet indicates that the AFTR is provided with an IPv4 address (192.0.0.1) to be used for troubleshooting purposes such as reporting problems to B4s. Note that a subscriber is identified by a subscriber-mask ([RFC7785]) that can be configured by means of [I-D.ietf-opsawg-nat-yang]. myAFTR ianaift:tunnel true 2001:db8:0:2::1 192.0.0.1 The following shows an XML excerpt depicting a dynamic UDP mapping entry maintained by a DS-Lite AFTR for a packet received from the B4 element introduced in Appendix A. Concretely, this UDP packet received with a source IPv6 address (2001:db8:0:1::1), a source IPv4 address (192.0.2.1), and source port number (1568) is translated into a UDP packet having a source IPv4 address (198.51.100.1) and source port number (15000). The remaining lifetime of this mapping is 300 seconds. Boucadair, et al. Expires May 17, 2018 [Page 21] Internet-Draft DS-Lite YANG Modules November 2017 15 dynamic-explicit 17
2001:db8:0:1::1
192.0.2.1 1568 198.51.100.1 15000 300
Authors' Addresses Mohamed Boucadair Orange Rennes 35000 France EMail: mohamed.boucadair@orange.com Boucadair, et al. Expires May 17, 2018 [Page 22] Internet-Draft DS-Lite YANG Modules November 2017 Christian Jacquenet Orange Rennes 35000 France EMail: christian.jacquenet@orange.com Senthil Sivakumar Cisco Systems 7100-8 Kit Creek Road Research Triangle Park, North Carolina 27709 USA Phone: +1 919 392 5158 EMail: ssenthil@cisco.com Boucadair, et al. Expires May 17, 2018 [Page 23]