Network Working Group M. Boucadair
Internet-Draft C. Jacquenet
Intended status: Standards Track Orange
Expires: May 16, 2018 S. Sivakumar
Cisco Systems
November 12, 2017
YANG Data Modules for Dual-Stack Lite (DS-Lite)
draft-ietf-softwire-dslite-yang-08
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 16, 2018.
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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
1.2. Tree Diagrams . . . . . . . . . . . . . . . . . . . . . . 4
2. DS-Lite YANG Modules: An Overview . . . . . . . . . . . . . . 4
3. DS-Lite AFTR YANG Module . . . . . . . . . . . . . . . . . . 7
4. DS-Lite B4 YANG Module . . . . . . . . . . . . . . . . . . . 12
5. Security Considerations . . . . . . . . . . . . . . . . . . . 15
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 17
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.1. Normative references . . . . . . . . . . . . . . . . . . 17
8.2. Informative references . . . . . . . . . . . . . . . . . 18
Appendix A. B4 Example . . . . . . . . . . . . . . . . . . . . . 19
Appendix B. AFTR Examples . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
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.
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+-----------+
| 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
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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].
1.2. Tree Diagrams
The meaning of the symbols in these diagrams is as follows:
o Brackets "[" and "]" enclose list keys.
o Curly braces "{" and "}" contain names of optional features that
make the corresponding node conditional.
o Abbreviations before data node names: "rw" means configuration
(read-write), "ro" state data (read-only).
o Symbols after data node names: "?" means an optional node, "!" a
container with presence, and "*" denotes a "list" or "leaf-list".
o Parentheses enclose choice and case nodes, and case nodes are also
marked with a colon (":").
o Ellipsis ("...") stands for contents of subtrees that are not
shown.
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.
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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 limit the number of DS-Lite softwires per subscriber
(max-softwire-per-subscriber).
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:
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.
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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].
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 max-softwire-per-subscriber? uint8
+--rw v6-v4-dscp-preservation? boolean
augment /nat:nat/nat:instances/nat:instance/nat:policy:
+--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? inet:ipv6-address
+--rw v6-dscp? uint8
+--rw internal-v4-dscp? uint8
+--rw external-v4-dscp? uint8
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).
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o The tunnel MTU at the B4 side to avoid fragmentation (tunnel-mtu).
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
<CODE BEGINS> file "ietf-dslite-aftr@2017-11-13.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;}
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
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<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 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 2017-11-13 {
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 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";
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}
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 max-softwire-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
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"Section 4 of RFC 7785.";
}
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.";
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";
}
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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"{
description
"Augments the NAPT44 mapping table with DS-Lite specifics.";
leaf b4-ipv6-address {
type inet:ipv6-address;
description
"Corresponds to the IPv6 address used by the B4 element.";
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reference
"RFC 6333: Dual-Stack Lite Broadband Deployments Following
IPv4 Exhaustion";
}
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.";
}
}
}
<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";
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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:
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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 {
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).";
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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.";
}
}
}
<CODE ENDS>
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.
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).
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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]:
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
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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-06 (work in progress), October
2017.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>.
[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,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[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,
<https://www.rfc-editor.org/info/rfc6333>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536,
DOI 10.17487/RFC6536, March 2012,
<https://www.rfc-editor.org/info/rfc6536>.
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[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC7223] Bjorklund, M., "A YANG Data Model for Interface
Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
<https://www.rfc-editor.org/info/rfc7223>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
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.
[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.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022,
DOI 10.17487/RFC3022, January 2001,
<https://www.rfc-editor.org/info/rfc3022>.
[RFC6087] Bierman, A., "Guidelines for Authors and Reviewers of YANG
Data Model Documents", RFC 6087, DOI 10.17487/RFC6087,
January 2011, <https://www.rfc-editor.org/info/rfc6087>.
[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,
<https://www.rfc-editor.org/info/rfc6908>.
[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,
<https://www.rfc-editor.org/info/rfc7785>.
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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.
<interface>
<name>myB4</name>
<type>ianaift:tunnel</type>
<enabled>true</enabled>
<b4-ipv6-address>2001:db8:0:1::1</b4-ipv6-address>
<aftr-ipv6-addr>2001:db8:0:2::1</aftr-ipv6-addr>
<v6-v4-dscp-preservation>true</v6-v4-dscp-preservation>
</interface>
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.
Moreover, the AFTR is instructed to limit the number of softwires per
subscriber to '1'.
Note that a subscriber is identified by a subscriber-mask ([RFC7785])
that can be configured by means of [I-D.ietf-opsawg-nat-yang].
<interface>
<name>myAFTR</name>
<type>ianaift:tunnel</type>
<enabled>true</enabled>
<aftr-ipv6-address>2001:db8:0:2::1</aftr-ipv6-address>
<aftr-ipv4-address>192.0.0.1</aftr-ipv4-address>
<max-softwire-per-subscriber>1</max-softwire-per-subscriber>
</interface>
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.
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<mapping-entry>
<index>15</index>
<type>
dynamic-explicit
</type>
<transport-protocol>
17
</transport-protocol>
<b4-ipv6-address>
2001:db8:0:1::1
</b4-ipv6-address>
<internal-src-address>
192.0.2.1
</internal-src-address>
<internal-src-port>
<start-port-number>
1568
</start-port-number>
</internal-src-port>
<external-src-address>
198.51.100.1
</external-src-address>
<external-src-port>
<start-port-number>
15000
</start-port-number>
</external-src-port>
<lifetime>
300
</lifetime>
</mapping-entry>
Authors' Addresses
Mohamed Boucadair
Orange
Rennes 35000
France
EMail: mohamed.boucadair@orange.com
Christian Jacquenet
Orange
Rennes 35000
France
EMail: christian.jacquenet@orange.com
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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
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