module ietf-dslite { yang-version 1.1; namespace "urn:ietf:params:xml:ns:yang:ietf-dslite"; prefix dslite; 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: Editor: Mohamed Boucadair Editor: Christian Jacquenet Editor: Senthil Sivakumar "; description "This module is a YANG module for DS-Lite AFTR and 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). This version of this YANG module is part of RFC XXXX; see the RFC itself for full legal notices."; revision 2017-12-12 { description "Initial revision."; reference "RFC XXXX: A YANG Data Module for Dual-Stack Lite (DS-Lite)"; } /* * Features */ feature b4 { description "The B4 element is a function implemented on a dual-stack-capable node, either a directly connected device or a CPE, that creates a tunnel to an AFTR."; reference "Section 5 of RFC 6333."; } feature aftr { description "An AFTR element is the combination of an IPv4-in-IPv6 tunnel endpoint and an IPv4-IPv4 NAT implemented on the same node."; reference "Section 6 of RFC 6333."; } /* * Augments */ augment "/if:interfaces/if:interface" { when "if:type = 'ianaift:tunnel'"; description "Augments Interface module with DS-Lite parameters. IANA interface types are maintained at this registry: https://www.iana.org/assignments/ianaiftype-mib/ianaiftype-mib. tunnel (131), -- Encapsulation interface"; leaf ipv6-address { type inet:ipv6-address; description "IPv6 address of the local DS-Lite endpoint (AFTR or B4)."; reference "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf ipv4-address { type inet:ipv4-address; description "IPv4 address of the local DS-Lite AFTR or B4. 192.0.0.1 is reserved for the AFTR element, while 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 "RFC 6333: Dual-Stack Lite Broadband Deployments Following IPv4 Exhaustion"; } leaf aftr-ipv6-addr { if-feature b4; type inet:ipv6-address; description "Indicates the AFTR's IPv6 address to be used by a B4 element."; 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/B4 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" { when "/nat:nat/nat:instances/nat:instance/nat:type='nat:napt44'" + " and /nat:nat/nat:instances/nat:instance/" + "nat:per-interface-binding='dslite'"; if-feature aftr; description "Augments the NAPT44 module with AFTR parameters."; 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 a subscriber mask (subscriber-mask-v6). 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 user device (e.g., CPE). The AFTR uses the subscriber-mask-v6 to determine whether two IPv6 addresses belong to the same CPE (e.g., if the subscriber-mask-v6 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"; 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" { when "/nat:nat/nat:instances/nat:instance/nat:type='nat:napt44'" + " and /nat:nat/nat:instances/nat:instance/" + "nat:per-interface-binding='dslite'"; if-feature aftr; description "Augments the NAPT44 mapping table with DS-Lite specifics."; container b4-ipv6-address { description "Records the IPv6 address used by a B4 element and the last time that address changed."; leaf address { type inet:ipv6-address; description "Corresponds to the IPv6 address used by a 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: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: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: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" { if-feature aftr; description "Indicates the number of active softwires."; leaf active-softwires{ type yang:gauge32; description "The number of currently active softwires on the AFTR instance."; } } /* * Notifications */ notification b4-address-change-limit-policy-violation { if-feature aftr; 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."; } } }