draft-ietf-softwire-dslite-yang-09.txt   draft-ietf-softwire-dslite-yang-10.txt 
Network Working Group M. Boucadair Network Working Group M. Boucadair
Internet-Draft C. Jacquenet Internet-Draft C. Jacquenet
Intended status: Standards Track Orange Intended status: Standards Track Orange
Expires: May 17, 2018 S. Sivakumar Expires: May 20, 2018 S. Sivakumar
Cisco Systems Cisco Systems
November 13, 2017 November 16, 2017
YANG Data Modules for Dual-Stack Lite (DS-Lite) A YANG Data Module for Dual-Stack Lite (DS-Lite)
draft-ietf-softwire-dslite-yang-09 draft-ietf-softwire-dslite-yang-10
Abstract Abstract
This document defines YANG modules for the DS-Lite Address Family This document defines a YANG module for the DS-Lite Address Family
Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements. Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Please update these statements with the RFC number to be assigned to Please update these statements with the RFC number to be assigned to
this document: this document:
o "This version of this YANG module is part of RFC XXXX;" 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 "RFC XXXX: A YANG Data Module for Dual-Stack Lite (DS-Lite)";
o "reference: RFC XXXX" o "reference: RFC XXXX"
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 17, 2018. This Internet-Draft will expire on May 20, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. DS-Lite YANG Modules: An Overview . . . . . . . . . . . . . . 4 2. DS-Lite YANG Module: An Overview . . . . . . . . . . . . . . 4
3. DS-Lite AFTR YANG Module . . . . . . . . . . . . . . . . . . 7 3. DS-Lite YANG Module . . . . . . . . . . . . . . . . . . . . . 6
4. DS-Lite B4 YANG Module . . . . . . . . . . . . . . . . . . . 14 4. Security Considerations . . . . . . . . . . . . . . . . . . . 14
5. Security Considerations . . . . . . . . . . . . . . . . . . . 16 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.1. Normative references . . . . . . . . . . . . . . . . . . 16
8.1. Normative references . . . . . . . . . . . . . . . . . . 18 7.2. Informative references . . . . . . . . . . . . . . . . . 17
8.2. Informative references . . . . . . . . . . . . . . . . . 19 Appendix A. B4 Example . . . . . . . . . . . . . . . . . . . . . 18
Appendix A. B4 Example . . . . . . . . . . . . . . . . . . . . . 21 Appendix B. AFTR Examples . . . . . . . . . . . . . . . . . . . 18
Appendix B. AFTR Examples . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction 1. Introduction
This document defines data models for DS-Lite [RFC6333], using the This document defines a data model for DS-Lite [RFC6333], using the
YANG data modeling language [RFC7950]. Both the Address Family YANG data modeling language [RFC7950]. Both the Address Family
Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements Transition Router (AFTR) and Basic Bridging BroadBand (B4) elements
are covered by this specification. are covered by this specification.
As a reminder, Figure 1 illustrates an overview of the DS-Lite As a reminder, Figure 1 illustrates an overview of the DS-Lite
architecture that involves AFTR and B4 elements. architecture that involves AFTR and B4 elements.
+-----------+ +-----------+
| Host | | Host |
+-----+-----+ +-----+-----+
skipping to change at page 4, line 22 skipping to change at page 4, line 22
This document makes use of the terms defined in Section 3 of This document makes use of the terms defined in Section 3 of
[RFC6333]. [RFC6333].
The terminology for describing YANG data modules is defined in The terminology for describing YANG data modules is defined in
[RFC7950]. [RFC7950].
The meaning of the symbols in tree diagrams is defined in The meaning of the symbols in tree diagrams is defined in
[I-D.ietf-netmod-yang-tree-diagrams]. [I-D.ietf-netmod-yang-tree-diagrams].
2. DS-Lite YANG Modules: An Overview 2. DS-Lite YANG Module: An Overview
As shown in Figure 1: As shown in Figure 1:
o The AFTR element is a combination of an IPv4-in-IPv6 tunnel and a o The AFTR element is a combination of an IPv4-in-IPv6 tunnel and a
NAPT function (Section 2.2 of [RFC3022]). NAPT function (Section 2.2 of [RFC3022]).
o The B4 element is an IPv4-in-IPv6 tunnel. o The B4 element is an IPv4-in-IPv6 tunnel.
Therefore, the AFTR YANG module is designed to augment both the Therefore, the DS-Lite YANG module is designed to augment both the
Interfaces YANG module [RFC7223] and the NAT YANG module Interfaces YANG module [RFC7223] and the NAT YANG module
[I-D.ietf-opsawg-nat-yang] with DS-Lite specific features. The B4 [I-D.ietf-opsawg-nat-yang] with DS-Lite specific features.
YANG module augments the interfaces YANG module.
Concretely, the AFTR YANG module (Figure 2) augments the Interfaces The YANG "feature" statement is used to distinguish which of the DS-
YANG module with the following: Lite elements ('aftr' or 'b4') is relevant for a specific data node.
o An IPv6 address used by the AFTR for sending and receiving IPv4- Concretely, the DS-Lite YANG module (Figure 2) augments the
in-IPv6 packets (aftr-ipv6-address). Interfaces YANG module with the following:
o An IPv4 address that is used by the AFTR for troubleshooting o An IPv6 address used by the tunnel endpoint (AFTR or B4) for
purposes (aftr-ipv4-address). sending and receiving IPv4-in-IPv6 packets (ipv6-address).
o The tunnel MTU, used to avoid fragmentation (tunnel-mtu). o An IPv4 address that is used by the tunnel endpoint (AFTR or B4)
for troubleshooting purposes (ipv4-address).
o A policy to instruct the AFTR whether it must preserve DSCP o An IPv6 address used by a B4 element to reach its AFTR (aftr-
marking when encapsulating/decapsulating packets (v6-v4-dscp- ipv6-addr).
preservation).
In addition, the AFTR YANG module augments the NAT YANG module o The tunnel MTU used to avoid fragmentation (tunnel-mtu).
o A policy to instruct the tunnel endpoint (AFTR or B4) whether it
must preserve DSCP marking when encapsulating/decapsulating
packets (v6-v4-dscp-preservation).
In addition, the DS-Lite YANG module augments the NAT YANG module
(policy, in particular) with the following: (policy, in particular) with the following:
o A policy to limit the number of DS-Lite softwires per subscriber o A policy to limit the number of DS-Lite softwires per subscriber
(max-softwire-per-subscriber). (max-softwire-per-subscriber).
o A policy to instruct the AFTR whether a state can be automatically o A policy to instruct the AFTR whether a state can be automatically
migrated (state-migrate). migrated (state-migrate).
o Further, in order to prevent a denial-of-service by frequently o Further, in order to prevent a denial-of-service by frequently
changing the source IPv6 address, 'b4-address-change-limit' is changing the source IPv6 address, 'b4-address-change-limit' is
used to rate-lmite such changes. used to rate-lmite such changes.
o An instruction to rewrite the TCP Maximum Segment Size (MSS) o An instruction to rewrite the TCP Maximum Segment Size (MSS)
option (mss-clamping) to avoid TCP fragmentation. option (mss-clamping) to avoid TCP fragmentation.
Given that the NAPT table of the AFTR element is extended to include Given that the NAPT table of the AFTR element is extended to include
the source IPv6 address of incoming packets, the AFTR YANG module the source IPv6 address of incoming packets, the DS-Lite YANG module
augments the NAPT44 mapping-entry with the following: augments the NAPT44 mapping-entry with the following:
o b4-ipv6-address which is used to record the source IPv6 address of 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 a packet received from a B4 element. This IPv6 address is
required to disambiguate between the overlapping IPv4 address required to disambiguate between the overlapping IPv4 address
space of subscribers. space of subscribers.
o The value of the Traffic Class field in the IPv6 header as 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 received from a B4 element (v6-dscp): This information is used to
preserve DSCP marking when encapsulating/decapsulationg at the preserve DSCP marking when encapsulating/decapsulationg at the
skipping to change at page 6, line 5 skipping to change at page 6, line 9
packet upstream. packet upstream.
Access Control List (ACL) and Quality of Service (QoS) policies Access Control List (ACL) and Quality of Service (QoS) policies
discussed in Section 2.5 of [RFC6908] are out of scope. A YANG 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]. module for ACLs is documented in [I-D.ietf-netmod-acl-model].
Likewise, PCP-related considerations discussed in Section 8.5 of Likewise, PCP-related considerations discussed in Section 8.5 of
[RFC6333] are out of scope. A YANG module for PCP is documented in [RFC6333] are out of scope. A YANG module for PCP is documented in
[I-D.boucadair-pcp-yang]. [I-D.boucadair-pcp-yang].
module: ietf-dslite-aftr module: ietf-dslite
augment /if:interfaces/if:interface: augment /if:interfaces/if:interface:
+--rw aftr-ipv6-address? inet:ipv6-address +--rw ipv6-address? inet:ipv6-address {aftr or b4}?
+--rw aftr-ipv4-address? inet:ipv4-address +--rw ipv4-address? inet:ipv4-address {aftr or b4}?
+--rw tunnel-mtu? uint16 +--rw aftr-ipv6-addr? inet:ipv6-address {b4}?
+--rw v6-v4-dscp-preservation? boolean +--rw tunnel-mtu? uint16 {aftr or b4}?
+--rw v6-v4-dscp-preservation? boolean {aftr or b4}?
augment /nat:nat/nat:instances/nat:instance/nat:policy: augment /nat:nat/nat:instances/nat:instance/nat:policy:
+--rw max-softwires-per-subscriber? uint8 +--rw max-softwires-per-subscriber? uint8 {aftr}?
+--rw state-migrate? boolean +--rw state-migrate? boolean {aftr}?
+--rw b4-address-change-limit? uint32 +--rw b4-address-change-limit? uint32 {aftr}?
+--rw mss-clamping +--rw mss-clamping {aftr}?
+--rw enable? boolean +--rw enable? boolean
+--rw mss-value? uint16 +--rw mss-value? uint16
augment /nat:nat/nat:instances/nat:instance/nat:mapping-table/nat:mapping-entry: augment /nat:nat/nat:instances/nat:instance/nat:mapping-table/nat:mapping-entry:
+--rw b4-ipv6-address +--rw b4-ipv6-address {aftr}?
| +--rw address? inet:ipv6-address | +--rw address? inet:ipv6-address
| +--rw last-address-change? yang:date-and-time | +--rw last-address-change? yang:date-and-time
+--rw v6-dscp? uint8 +--rw v6-dscp? uint8 {aftr}?
+--rw internal-v4-dscp? uint8 +--rw internal-v4-dscp? uint8 {aftr}?
+--rw external-v4-dscp? uint8 +--rw external-v4-dscp? uint8 {aftr}?
augment /nat:nat/nat:instances/nat:instance/nat:statistics/nat:mappings-statistics: augment /nat:nat/nat:instances/nat:instance/nat:statistics/nat:mappings-statistics:
+--ro active-softwires? yang:gauge32 +--ro active-softwires? yang:gauge32 {aftr}?
notifications: notifications:
+---n b4-address-change-limit-policy-violation +---n b4-address-change-limit-policy-violation {aftr}?
+--ro id -> /nat:nat/instances/instance/id +--ro id -> /nat:nat/instances/instance/id
+--ro policy-id -> /nat:nat/instances/instance/policy/id +--ro policy-id -> /nat:nat/instances/instance/policy/id
+--ro address inet:ipv6-address +--ro address inet:ipv6-address
Figure 2: YANG Module for DS-Lite AFTR Figure 2: YANG Module for DS-Lite
Examples to illustrate the use of this module are provided in Examples to illustrate the use of this module are provided in
Appendix B. Appendix A and 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).
o An instruction whether DSCP marking is to be preserved when 3. DS-Lite YANG Module
encapsulating an IPv4 packet in an IPv6 packet (v6-v4-dscp-
preservation).
module: ietf-dslite-b4 <CODE BEGINS> file "ietf-dslite@2017-11-15.yang"
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 module ietf-dslite {
yang-version 1.1;
An example to illustrate the use of this module is provided in namespace "urn:ietf:params:xml:ns:yang:ietf-dslite";
Appendix A. 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; }
3. DS-Lite AFTR YANG Module organization "IETF Softwire Working Group";
<CODE BEGINS> file "ietf-dslite-aftr@2017-11-14.yang" contact
module ietf-dslite-aftr { "WG Web: <https://datatracker.ietf.org/wg/softwire/>
yang-version 1.1; WG List: <mailto:softwires@ietf.org>
namespace "urn:ietf:params:xml:ns:yang:ietf-dslite-aftr"; Editor: Mohamed Boucadair
prefix dslite-aftr; <mailto:mohamed.boucadair@orange.com>
import ietf-inet-types { prefix inet; } Editor: Christian Jacquenet
import ietf-interfaces { prefix if; } <mailto:christian.jacquenet@orange.com>
import iana-if-type { prefix ianaift; }
import ietf-nat {prefix nat;}
import ietf-yang-types { prefix yang; }
organization "IETF Softwire Working Group"; Editor: Senthil Sivakumar
<mailto:ssenthil@cisco.com>";
contact description
"This module is a YANG module for DS-Lite AFTR and B4
implementations.
"WG Web: <https://datatracker.ietf.org/wg/softwire/> Copyright (c) 2017 IETF Trust and the persons identified as
WG List: <mailto:softwires@ietf.org> authors of the code. All rights reserved.
WG Chair: Ian Farrer Redistribution and use in source and binary forms, with or
<mailto:ianfarrer@gmx.com> 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).
WG Chair: Yong Cui This version of this YANG module is part of RFC XXXX; see
<mailto:cuiyong@tsinghua.edu.cn> the RFC itself for full legal notices.";
Editor: Mohamed Boucadair revision 2017-11-15 {
<mailto:mohamed.boucadair@orange.com> description
"Initial revision.";
reference
"RFC XXXX: A YANG Data Module for Dual-Stack Lite (DS-Lite)";
}
Editor: Christian Jacquenet /*
<mailto:christian.jacquenet@orange.com> * Features
*/
Editor: Senthil Sivakumar feature b4 {
<mailto:ssenthil@cisco.com>"; 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 description
"This module is a YANG module for DS-Lite AFTR "An AFTR element is the combination of an IPv4-in-IPv6 tunnel
implementations. endpoint and an IPv4-IPv4 NAT implemented on the same node.";
reference
"Section 6 of RFC 6333.";
}
Copyright (c) 2017 IETF Trust and the persons identified as /*
authors of the code. All rights reserved. * Augments
*/
Redistribution and use in source and binary forms, with or augment "/if:interfaces/if:interface" {
without modification, is permitted pursuant to, and subject when "if:type = 'ianaift:tunnel'";
to the license terms contained in, the Simplified BSD License description
set forth in Section 4.c of the IETF Trust's Legal Provisions "Augments Interface module with AFTR parameters.
Relating to IETF Documents IANA interface types are maintained at this registry:
(http://trustee.ietf.org/license-info). https://www.iana.org/assignments/ianaiftype-mib/ianaiftype-mib.
This version of this YANG module is part of RFC XXXX; see tunnel (131), -- Encapsulation interface";
the RFC itself for full legal notices.";
revision 2017-11-14 { leaf ipv6-address {
description if-feature "aftr or b4";
"Initial revision."; type inet:ipv6-address;
reference description
"RFC XXXX: YANG Data Modules for Dual-Stack Lite (DS-Lite)"; "IPv6 address of the local DS-Lite endpoint (AFTR or B4).";
} reference
"RFC 6333: Dual-Stack Lite Broadband Deployments Following
IPv4 Exhaustion";
}
augment "/if:interfaces/if:interface" { leaf ipv4-address {
when "if:type = 'ianaift:tunnel'"; if-feature "aftr or b4";
description type inet:ipv4-address;
"Augments Interface module with AFTR parameters. description
IANA interface types are maintained at this registry: "IPv4 address of the local DS-Lite AFTR or B4.
https://www.iana.org/assignments/ianaiftype-mib/ianaiftype-mib.
tunnel (131), -- Encapsulation interface"; 192.0.0.1 is reserved for the AFTR element, while
192.0.0.0/29 is reserved for the B4 element.
leaf aftr-ipv6-address { This address can be used to report ICMP problems and will
type inet:ipv6-address; appear in traceroute outputs.";
description reference
"IPv6 address of the DS-Lite AFTR."; "RFC 6333: Dual-Stack Lite Broadband Deployments Following
reference IPv4 Exhaustion";
"RFC 6333: Dual-Stack Lite Broadband Deployments Following }
IPv4 Exhaustion";
}
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. 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";
}
This address can be used to report ICMP problems and will leaf tunnel-mtu {
appear in traceroute outputs."; if-feature "aftr or b4";
reference type uint16;
"RFC 6333: Dual-Stack Lite Broadband Deployments Following description
IPv4 Exhaustion"; "Configures a tunnel MTU.
}
leaf tunnel-mtu { [RFC6908] specifies that since fragmentation and reassembly
type uint16; is not optimal, the operator should do everything possible
description to eliminate the need for it. If the operator uses simple
"Configures a tunnel MTU. IPv4-in-IPv6 softwire, it is recommended that the MTU size
[RFC6908] specifies that since fragmentation and reassembly of the IPv6 network between the B4 and the AFTR accounts for
is not optimal, the operator should do everything possible the additional overhead (40 bytes).";
to eliminate the need for it. If the operator uses simple reference
IPv4-in-IPv6 softwire, it is recommended that the MTU size "RFC 6908: Deployment Considerations for Dual-Stack Lite";
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 { leaf v6-v4-dscp-preservation {
type boolean; if-feature "aftr or b4";
description type boolean;
"Copies the DSCP value from the IPv6 header and vice versa. description
"Copies the DSCP value from the IPv6 header and vice versa.
According to Section 2.10 of [RFC6908], operators should According to Section 2.10 of [RFC6908], operators should
use this model by provisioning the network such that the AFTR use this model by provisioning the network such that the
copies the DSCP value in the IPv4 header to the Traffic Class AFTR/B4 copies the DSCP value in the IPv4 header to
field in the IPv6 header, after the encapsulation for the Traffic Class field in the IPv6 header, after the
the downstream traffic."; encapsulation for the downstream traffic.";
reference reference
"Section 2.10 of RFC 6908."; "Section 2.10 of RFC 6908.";
} }
} }
augment "/nat:nat/nat:instances/nat:instance/nat:policy" { augment "/nat:nat/nat:instances/nat:instance/nat:policy" {
description when "/nat:nat/nat:instances/nat:instance/nat:type='napt44'" +
"Augments the NAPT44 module with AFTR parameters."; " 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 { leaf max-softwires-per-subscriber {
type uint8; type uint8;
default 1; default 1;
description description
"Configures the maximum softwires per subscriber feature. "Configures the maximum softwires per subscriber feature.
A subscriber is uniquely identified by means A subscriber is uniquely identified by means
of subscriber-mask. of a subscriber mask (subscriber-mask-v6).
This policy aims to prevent a misbehaving subscriber from This policy aims to prevent a misbehaving subscriber from
mounting several DS-Lite softwires that would consume mounting several DS-Lite softwires that would consume
additional AFTR resources (e.g., get more external ports additional AFTR resources (e.g., get more external ports
if the quota were enforced on a per-softwire basis, if the quota were enforced on a per-softwire basis,
consume extra processing due to a large number of active consume extra processing due to a large number of active
softwires)."; softwires).";
reference reference
"Section 4 of RFC 7785."; "Section 4 of RFC 7785.";
} }
leaf state-migrate { leaf state-migrate {
type boolean; type boolean;
default true; default true;
description description
"State migration is enabled by default. "State migration is enabled by default.
In the event a new IPv6 address is assigned to the B4 element, 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 the AFTR should migrate existing state to be bound to the new
IPv6 address. This operation ensures that traffic destined to IPv6 address. This operation ensures that traffic destined to
the previous B4's IPv6 address will be redirected to the newer the previous B4's IPv6 address will be redirected to the newer
B4's IPv6 address. The destination IPv6 address for tunneling B4's IPv6 address. The destination IPv6 address for tunneling
return traffic from the AFTR should be the last seen as the B4's return traffic from the AFTR should be the last seen as the
IPv6 source address from the CPE. B4's IPv6 source address from the user device (e.g., CPE).
The AFTR uses the subscriber-mask to determine whether two The AFTR uses the subscriber-mask-v6 to determine whether two
IPv6 addresses belong to the same CPE (e.g., if the IPv6 addresses belong to the same CPE (e.g., if the
subscriber-mask is set to 56, the AFTR concludes that 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 2001:db8:100:100::1 and 2001:db8:100:100::2 belong to the same
CPE assigned with 2001:db8:100:100::/56)."; CPE assigned with 2001:db8:100:100::/56).";
reference reference
"RFC 7785: Recommendations for Prefix Binding in the Context "RFC 7785: Recommendations for Prefix Binding in the Context
of Softwire Dual-Stack Lite"; of Softwire Dual-Stack Lite";
} }
leaf b4-address-change-limit { leaf b4-address-change-limit {
type uint32; type uint32;
units "seconds"; units "seconds";
default '1800'; default '1800';
description description
"Minimum number of seconds between successive B4's IPv6 address "Minimum number of seconds between successive B4's IPv6 address
change from the same prefix. change from the same prefix.
Changing the source B4's IPv6 address may be used as an attack 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 vector. Packets with a new B4's IPv6 address from the same
prefix should be rate-limited. prefix should be rate-limited.
It is recommended to set this rate limit to 30 minutes; other It is recommended to set this rate limit to 30 minutes; other
values can be set on a per-deployment basis."; values can be set on a per-deployment basis.";
reference reference
"RFC 7785: Recommendations for Prefix Binding in the Context "RFC 7785: Recommendations for Prefix Binding in the Context
of Softwire Dual-Stack Lite"; of Softwire Dual-Stack Lite";
} }
container mss-clamping { container mss-clamping {
description description
"MSS rewriting configuration to avoid IPv6 fragmentation."; "MSS rewriting configuration to avoid IPv6 fragmentation.";
leaf enable { leaf enable {
type boolean; type boolean;
description description
"Enable/disable MSS rewriting feature."; "Enable/disable MSS rewriting feature.";
} }
leaf mss-value { leaf mss-value {
type uint16; type uint16;
units "octets"; units "octets";
description description
"Sets the MSS value to be used for MSS rewriting."; "Sets the MSS value to be used for MSS rewriting.";
} }
}
} }
}
augment "/nat:nat/nat:instances/nat:instance/"+ augment "/nat:nat/nat:instances/nat:instance/"+
"nat:mapping-table/nat:mapping-entry"{ "nat:mapping-table/nat:mapping-entry"{
description when "/nat:nat/nat:instances/nat:instance/nat:type='napt44'" +
"Augments the NAPT44 mapping table with DS-Lite specifics."; " 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 { container b4-ipv6-address {
description description
"Records the IPv6 address used by the B4 element and the last "Records the IPv6 address used by the B4 element and the last
time that address changed."; time that address changed.";
leaf address { leaf address {
type inet:ipv6-address; type inet:ipv6-address;
description description
"Corresponds to the IPv6 address used by the B4 element."; "Corresponds to the IPv6 address used by the B4 element.";
reference reference
"RFC 6333: Dual-Stack Lite Broadband Deployments Following "RFC 6333: Dual-Stack Lite Broadband Deployments Following
IPv4 Exhaustion"; IPv4 Exhaustion";
} }
leaf last-address-change { leaf last-address-change {
type yang:date-and-time; type yang:date-and-time;
description description
"Records the last time when the address changed."; "Records the last time when the address changed.";
} }
} }
leaf v6-dscp { leaf v6-dscp {
when "/if:interfaces/if:interface/" + when "/if:interfaces/if:interface/" +
"dslite-aftr:v6-v4-dscp-preservation='true'"; "dslite:v6-v4-dscp-preservation='true'";
type uint8; type uint8;
description description
"DSCP value used at the softwire level (i.e., IPv6 header)."; "DSCP value used at the softwire level (i.e., IPv6 header).";
} }
leaf internal-v4-dscp { leaf internal-v4-dscp {
when "/if:interfaces/if:interface/" + when "/if:interfaces/if:interface/" +
"dslite-aftr:v6-v4-dscp-preservation='true'"; "dslite:v6-v4-dscp-preservation='true'";
type uint8; type uint8;
description description
"DSCP value of the encapsulated IPv4 packet."; "DSCP value of the encapsulated IPv4 packet.";
} }
leaf external-v4-dscp { leaf external-v4-dscp {
when "/if:interfaces/if:interface/" + when "/if:interfaces/if:interface/" +
"dslite-aftr:v6-v4-dscp-preservation='true'"; "dslite:v6-v4-dscp-preservation='true'";
type uint8; type uint8;
description description
"DSCP value of the translated IPv4 packet as marked by "DSCP value of the translated IPv4 packet as marked by
the AFTR."; the AFTR.";
} }
} }
augment "/nat:nat/nat:instances/nat:instance/nat:statistics/" + augment "/nat:nat/nat:instances/nat:instance/nat:statistics/" +
"nat:mappings-statistics" { "nat:mappings-statistics" {
description if-feature aftr;
"Indicates the number of active softwires."; description
"Indicates the number of active softwires.";
leaf active-softwires{ leaf active-softwires{
type yang:gauge32; type yang:gauge32;
description description
"The number of currently active softwires on the AFTR "The number of currently active softwires on the AFTR
instance."; instance.";
}
} }
}
/* /*
* Notifications * Notifications
*/ */
notification b4-address-change-limit-policy-violation { notification b4-address-change-limit-policy-violation {
description if-feature aftr;
"Generates notifications when a B4 unsuccessfully attempts description
to change IPv6 address in a time shorter than the value of "Generates notifications when a B4 unsuccessfully attempts
b4-address-change-limit. 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.";
}
}
}
<CODE ENDS>
4. DS-Lite B4 YANG Module
<CODE BEGINS> 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: <https://datatracker.ietf.org/wg/softwire/>
WG List: <mailto:softwires@ietf.org>
WG Chair: Ian Farrer
<mailto:ianfarrer@gmx.com>
WG Chair: Yong Cui
<mailto:cuiyong@tsinghua.edu.cn>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Editor: Christian Jacquenet
<mailto:christian.jacquenet@orange.com>
Editor: Senthil Sivakumar
<mailto:ssenthil@cisco.com>";
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).
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
"RFC 6333: Dual-Stack Lite Broadband Deployments Following
IPv4 Exhaustion";
}
leaf tunnel-mtu { Notifications are rate-limited (notify-interval).";
type uint16;
description
"Configures a tunnel MTU.
[RFC6908] specifies that since fragmentation and reassembly is leaf id {
not optimal, the operator should do everything possible to type leafref {
eliminate the need for it. If the operator uses simple path "/nat:nat/nat:instances/nat:instance/nat:id";
IPv4-in-IPv6 softwire, it is recommended that the MTU size of }
the IPv6 network between the B4 and the AFTR accounts for mandatory true;
the additional overhead (40 bytes)."; description
reference "NAT instance identifier.";
"RFC 6908: Deployment Considerations for Dual-Stack Lite"; }
}
leaf v6-v4-dscp-preservation { leaf policy-id {
type boolean; type leafref {
description path "/nat:nat/nat:instances/nat:instance/nat:policy/nat:id";
"Copies the DSCP value from the IPv6 header and vice versa. }
mandatory true;
description
"Policy Identifier.";
}
Operators should use this model by provisioning the network such leaf address {
that the AFTR copies the DSCP value in the IPv4 header to type inet:ipv6-address;
the Traffic Class field in the IPv6 header, after the mandatory true;
encapsulation for the downstream traffic."; description
reference "B4's IPv6 address.";
"Section 2.10 of RFC 6908."; }
}
} }
} }
<CODE ENDS> <CODE ENDS>
5. Security Considerations 4. Security Considerations
The YANG module defined in this document is designed to be accessed The YANG module defined in this document is designed to be accessed
via network management protocols such as NETCONF [RFC6241] or via network management protocols such as NETCONF [RFC6241] or
RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport RESTCONF [RFC8040]. The lowest NETCONF layer is the secure transport
layer, and the mandatory-to-implement secure transport is Secure layer, and the mandatory-to-implement secure transport is Secure
Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the Shell (SSH) [RFC6242]. The lowest RESTCONF layer is HTTPS, and the
mandatory-to-implement secure transport is TLS [RFC5246]. mandatory-to-implement secure transport is TLS [RFC5246].
The NETCONF access control model [RFC6536] provides the means to The NETCONF access control model [RFC6536] provides the means to
restrict access for particular NETCONF or RESTCONF users to a restrict access for particular NETCONF or RESTCONF users to a
skipping to change at page 17, line 42 skipping to change at page 15, line 23
o Set 'v6-v4-dscp-preservation' to 'false" may lead to a service o Set 'v6-v4-dscp-preservation' to 'false" may lead to a service
degradation if some policies are applied on the network based on degradation if some policies are applied on the network based on
the DSCP value. the DSCP value.
Additional security considerations are discussed in Additional security considerations are discussed in
[I-D.ietf-opsawg-nat-yang]. [I-D.ietf-opsawg-nat-yang].
Security considerations related to DS-Lite are discussed in Security considerations related to DS-Lite are discussed in
[RFC6333]. [RFC6333].
6. IANA Considerations 5. IANA Considerations
This document requests IANA to register the following URIs in the This document requests IANA to register the following URI in the
"IETF XML Registry" [RFC3688]: "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-dslite-aftr URI: urn:ietf:params:xml:ns:yang:ietf-dslite
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. Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace. XML: N/A; the requested URI is an XML namespace.
This document requests IANA to register the following YANG modules in This document requests IANA to register the following YANG module in
the "YANG Module Names" registry [RFC7950]. the "YANG Module Names" registry [RFC7950].
name: ietf-dslite-aftr name: ietf-dslite
namespace: urn:ietf:params:xml:ns:yang:ietf-dslite-aftr namespace: urn:ietf:params:xml:ns:yang:ietf-dslite
prefix: dslite-aftr prefix: dslite-aftr
reference: RFC XXXX reference: RFC XXXX
name: ietf-dslite-b4 6. Acknowledgements
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 Thanks to Qin Wu for identifying a compiling error. Mahesh
Jethanandani provided an early yangdoctors review; many thanks to Jethanandani provided an early yangdoctors review; many thanks to
him. him.
Many thanks to Ian Farrer for the review and comments. Many thanks to Ian Farrer for the review and comments.
8. References 7. References
8.1. Normative references 7.1. Normative references
[I-D.ietf-opsawg-nat-yang] [I-D.ietf-opsawg-nat-yang]
Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula, Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula,
S., and Q. Wu, "A YANG Data Model for Network Address S., and Q. Wu, "A YANG Data Model for Network Address
Translation (NAT) and Network Prefix Translation (NPT)", Translation (NAT) and Network Prefix Translation (NPT)",
draft-ietf-opsawg-nat-yang-08 (work in progress), November draft-ietf-opsawg-nat-yang-08 (work in progress), November
2017. 2017.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004, DOI 10.17487/RFC3688, January 2004,
skipping to change at page 19, line 45 skipping to change at page 17, line 13
<https://www.rfc-editor.org/info/rfc7223>. <https://www.rfc-editor.org/info/rfc7223>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016, RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>. <https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017, Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>. <https://www.rfc-editor.org/info/rfc8040>.
8.2. Informative references 7.2. Informative references
[I-D.boucadair-pcp-yang] [I-D.boucadair-pcp-yang]
Boucadair, M., Jacquenet, C., Sivakumar, S., and S. Boucadair, M., Jacquenet, C., Sivakumar, S., and S.
Vinapamula, "YANG Modules for the Port Control Protocol Vinapamula, "YANG Modules for the Port Control Protocol
(PCP)", draft-boucadair-pcp-yang-05 (work in progress), (PCP)", draft-boucadair-pcp-yang-05 (work in progress),
October 2017. October 2017.
[I-D.ietf-netmod-acl-model] [I-D.ietf-netmod-acl-model]
Jethanandani, M., Huang, L., Agarwal, S., and D. Blair, Jethanandani, M., Huang, L., Agarwal, S., and D. Blair,
"Network Access Control List (ACL) YANG Data Model", "Network Access Control List (ACL) YANG Data Model",
skipping to change at page 21, line 15 skipping to change at page 18, line 15
Appendix A. B4 Example Appendix A. B4 Example
The following example shows a B4 element (2001:db8:0:1::1) that is 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 configured with an AFTR element (2001:db8:0:2::1). The B4 element is
also instructed to preserve the DSCP marking. also instructed to preserve the DSCP marking.
<interface> <interface>
<name>myB4</name> <name>myB4</name>
<type>ianaift:tunnel</type> <type>ianaift:tunnel</type>
<enabled>true</enabled> <enabled>true</enabled>
<b4-ipv6-address>2001:db8:0:1::1</b4-ipv6-address> <ipv6-address>2001:db8:0:1::1</ipv6-address>
<aftr-ipv6-addr>2001:db8:0:2::1</aftr-ipv6-addr> <aftr-ipv6-addr>2001:db8:0:2::1</aftr-ipv6-addr>
<v6-v4-dscp-preservation>true</v6-v4-dscp-preservation> <v6-v4-dscp-preservation>true</v6-v4-dscp-preservation>
</interface> </interface>
Appendix B. AFTR Examples Appendix B. AFTR Examples
The following example shows an AFTR that is reachable at The following example shows an AFTR that is reachable at
2001:db8:0:2::1. Also, this XML snippet indicates that the AFTR is 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 provided with an IPv4 address (192.0.0.1) to be used for
troubleshooting purposes such as reporting problems to B4s. troubleshooting purposes such as reporting problems to B4s.
Note that a subscriber is identified by a subscriber-mask ([RFC7785]) Note that a subscriber is identified by a subscriber mask ([RFC7785])
that can be configured by means of [I-D.ietf-opsawg-nat-yang]. that can be configured by means of [I-D.ietf-opsawg-nat-yang].
<interface> <interface>
<name>myAFTR</name> <name>myAFTR</name>
<type>ianaift:tunnel</type> <type>ianaift:tunnel</type>
<enabled>true</enabled> <enabled>true</enabled>
<aftr-ipv6-address>2001:db8:0:2::1</aftr-ipv6-address> <ipv6-address>2001:db8:0:2::1</ipv6-address>
<aftr-ipv4-address>192.0.0.1</aftr-ipv4-address> <ipv4-address>192.0.0.1</ipv4-address>
</interface> </interface>
The following shows an XML excerpt depicting a dynamic UDP mapping 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 entry maintained by a DS-Lite AFTR for a packet received from the B4
element introduced in Appendix A. Concretely, this UDP packet element introduced in Appendix A. Concretely, this UDP packet
received with a source IPv6 address (2001:db8:0:1::1), a source IPv4 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 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 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 port number (15000). The remaining lifetime of this mapping is 300
seconds. seconds.
 End of changes. 105 change blocks. 
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