Internet DRAFT - draft-ietf-v6ops-cpe-lan-pd
draft-ietf-v6ops-cpe-lan-pd
Internet Engineering Task Force T. Winters
Internet-Draft QA Cafe
Intended status: Informational 27 February 2024
Expires: 30 August 2024
IPv6 CE Routers LAN Prefix Delegation
draft-ietf-v6ops-cpe-lan-pd-00
Abstract
This document defines requirements for IPv6 CE Routers to support
DHCPv6 Prefix Delegation for redistributing any unused prefix(es)
that were delegated to the IPv6 CE Router. This document updates RFC
7084.
Status of This Memo
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provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on 30 August 2024.
Copyright Notice
Copyright (c) 2024 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
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Please review these documents carefully, as they describe your rights
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. IPv6 End-User Network Architecture . . . . . . . . . . . . . 3
5. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. LAN Prefix Delegation Requirements . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
This document defines DHCPv6 Prefix Delegation in IPv6 CE Routers
([RFC7084]) in order to properly utilize the IPv6 prefixes assigned
by service providers. Many ISP will assign a prefix larger then /64
to the CE Router, as recommended in [RFC6177]. If an IPv6 CE Router
doesn't support IA_PD on the LAN it will not be able to assign any
prefixes beyond it's local interfaces. Limiting the usefulness of
assigning prefixes larger than /64 by the operator. Supporting IA_PD
on the LAN interfaces will allow for those unused prefixes to be
distributed into a network. Work is being done in the areas such as
Stub Networking Auto Configuration (SNAC) working group that depends
on IPv6 addresses being properly distibuted.
Two models, hierarchical prefix and flat, have been proposed in the
past for prefix sub-delegation beyond the IPv6 CE Router.
Hierarchical prefix delegation requires an IPv6 CE Router to sub
delegate IPv6 prefixes based on set of rules. If more then one
router uses hierarchical prefix delegation, a IPv6 prefix tree is
created. When no routing protocol is present to discover the network
topology it's possible to have unbalanced prefix delegation tree
which leads to running out of prefixes. For more information on
heirachical prefix delegation is contained in Section 8.5 of
CableLabs IPv6 eRouter Specifiction [eRouter]. A flat prefix
delegation requires the router provisioned with the initial prefix
then assign /64 prefixes to all other prefix request from routers
downstream. This is the default configuration is designed to be the
flat model to support zero configuration networking.
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The Home Networking working group producted solutions for prefix
delegation for home networks, including [RFC7695]. The Home
Networking solutions haven't been deployed by ISPs or IPv6 CE Routers
since the publication partially due to their complexity.
This document does not cover dealing with multi-provisioned networks
with more than one provider. Due to complexity of a solution that
will require routing, provisioning, and policy this is out of scope
of this document.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document also makes use of internal conceptual variables to
describe protocol behavior and external variables that an
implementation must allow system administrators to change. The
specific variable names, how their values change, and how their
settings influence protocol behavior are provided to demonstrate
protocol behavior. An implementation is not required to have them in
the exact form described here, as long as its external behavior is
consistent with that described in this document.
3. Terminology
The following terminology is defined for this document.
* IPv6 CE Router: A router intended for home or small-office use
that forwards packets not explicitly addressed to itself as
defined in [RFC7084].
* Internet Service Provider (ISP): An entity that provides access to
the Internet. In this document, a service provider specifically
offers Internet access using IPv6, and may also offer IPv4
Internet access. The service provider can provide such access
over a variety of different transport methods such as DSL, cable,
wireless, and others.
4. IPv6 End-User Network Architecture
The end-user network that has IPv6 Customer Edge Routers with routers
and hosts downstream. Figure 1 illustrates the model topology.
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+-----------+
| Service |
| Provider |
| Router |
+-----+-----+
|
|
| Customer
| Internet Connection
|
+-----v-----+
| IPv6 |
| CE |
| Router |
+-----+-----+
|
+----+-+-------+
| |
| |
+---+----+ +-----+------+
| IPv6 | | |
| Host | | Router |
| | | |
+--------+ +------------+
Figure 1: Example IPv6 End User Topology
5. Requirements
The IPv6 CE Router distributes configuration information obtained
during WAN interface provisioning to IPv6 hosts and routers.
Previously, a router based on [RFC7084] would only provide IPv6 hosts
with individual addresses; this update allows for addressing and
routing of IPv6 prefixes to both hosts and routers.
5.1. LAN Prefix Delegation Requirements
LPD-1: The IPv6 CE Router MUST support a DHCPv6 server capable of
IPv6 prefix assignment according to [RFC8415] (Identity
Association for Prefix Delegation (IA_PD) option).
LPD-2: The IPv6 CE Router MUST assign a prefix from the delegated
prefix to each of its LAN links. If not enough addresses are
available the IPv6 CE Router SHOULD log a system management
error.
LPD-3: The prefix assigned to a link MUST NOT change in the absence
of topology or configuration changes.
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LPD-4: After LAN link prefix assignment the IPv6 CE Router MUST make
the remaining IPv6 prefixes available to other routers via
Prefix Delegation.
LPD-5: The IPv6 CE Router MUST install a route to the assigned IA_PD
with a next-hop of the IPv6 node that was assigned the
prefix. The IPv6 CE Router MUST remove the route when IA_PD
lease expires.
LPD-6: By default, the IPv6 CE Router firewall MUST allow forwarding
of packets with an outer IPv6 header containing a source
address belonging to Delegated Prefixes, along with
reciprocal packets from the same flow, following the
recommendations of [RFC6092]
LPD-7: The IPv6 CE Router SHOULD by default provision IA_PD IA
prefixes with a prefix-length of 64.
6. Security Considerations
This document does not add any new security considerations beyond
those mentioned in Section 4 of [RFC8213] and Section 22 of
[RFC8415].
7. IANA Considerations
This document makes no request of IANA.
8. Acknowledgements
Thanks to the following people for their guidance and feedback:
Marion Dillon, Erik Auerswald, Esko Dijk, Tim Carlin, Richard
Patterson, Ted Lemon, Michael Richardson, Martin Huneki, Gabor
Lencse, Ole Troan.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC6092] Woodyatt, J., Ed., "Recommended Simple Security
Capabilities in Customer Premises Equipment (CPE) for
Providing Residential IPv6 Internet Service", RFC 6092,
DOI 10.17487/RFC6092, January 2011,
<https://www.rfc-editor.org/info/rfc6092>.
[RFC6177] Narten, T., Huston, G., and L. Roberts, "IPv6 Address
Assignment to End Sites", BCP 157, RFC 6177,
DOI 10.17487/RFC6177, March 2011,
<https://www.rfc-editor.org/info/rfc6177>.
[RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers", RFC 7084,
DOI 10.17487/RFC7084, November 2013,
<https://www.rfc-editor.org/info/rfc7084>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8213] Volz, B. and Y. Pal, "Security of Messages Exchanged
between Servers and Relay Agents", RFC 8213,
DOI 10.17487/RFC8213, August 2017,
<https://www.rfc-editor.org/info/rfc8213>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
9.2. Informative References
[RFC7695] Pfister, P., Paterson, B., and J. Arkko, "Distributed
Prefix Assignment Algorithm", RFC 7695,
DOI 10.17487/RFC7695, November 2015,
<https://www.rfc-editor.org/info/rfc7695>.
[eRouter] CableLabs, "IPv4 and IPv6 eRouter Specification Version
I21", February 2022,
<https://www.cablelabs.com/specifications/CM-SP-eRouter>.
Author's Address
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Timothy Winters
QA Cafe
100 Main Street, Suite #212
Dover, NH 03820
United States of America
Email: tim@qacafe.com
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