draft-ietf-v6ops-unique-ipv6-prefix-per-host-02.txt   draft-ietf-v6ops-unique-ipv6-prefix-per-host-03.txt 
v6ops J. Brzozowski v6ops J. Brzozowski
Internet-Draft Comcast Cable Internet-Draft Comcast Cable
Intended status: Best Current Practice G. Van De Velde Intended status: Best Current Practice G. Van De Velde
Expires: September 14, 2017 Nokia Expires: November 18, 2017 Nokia
March 13, 2017 May 17, 2017
Unique IPv6 Prefix Per Host Unique IPv6 Prefix Per Host
draft-ietf-v6ops-unique-ipv6-prefix-per-host-02 draft-ietf-v6ops-unique-ipv6-prefix-per-host-03
Abstract Abstract
In some IPv6 environments the need has arisen for hosts to be able to In some IPv6 environments, the need has arisen for hosts to be able
utilise a unique IPv6 prefix even though the link or media may be to utilize a unique IPv6 prefix, even though the link or media may be
shared. Typically hosts (subscribers) on a shared network, either shared. Typically hosts (subscribers) on a shared network, either
wired or wireless, such as Ethernet, WiFi, etc., will acquire unique wired or wireless, such as Ethernet, WiFi, etc., will acquire unique
IPv6 addresses from a common IPv6 prefix that is allocated or IPv6 addresses from a common IPv6 prefix that is allocated or
assigned for use on a specific link. assigned for use on a specific link.
In most deployments today IPv6 address assignment from a single IPv6 In most deployments today, IPv6 address assignment from a single IPv6
prefix on a shared network is done by either using IPv6 stateless prefix on a shared network is done by either using IPv6 stateless
address auto-configuration (SLAAC) and/or stateful DHCPv6. While address auto-configuration (SLAAC) and/or stateful DHCPv6. While
this is still viable and operates as designed there are some large this is still viable and operates as designed, there are some large
scale environments where this concept introduces significant scale environments where this concept introduces significant
performance challenges and implications, specifically related to IPv6 performance challenges and implications, specifically related to IPv6
router and neighbor discovery. router and neighbor discovery.
This document outlines an approach utilising existing IPv6 protocols This document outlines an approach utilising existing IPv6 protocols
to allow hosts to be assigned a unique IPv6 prefix (instead of a to allow hosts to be assigned a unique IPv6 prefix (instead of a
unique IPv6 address from a shared IPv6 prefix). Benefits of a unique unique IPv6 address from a shared IPv6 prefix). Benefits of unique
IPv6 prefix compared to a unique IPv6 address from the service IPv6 prefix over a unique IPv6 address from the service provider
provider are going from improved subscriber isolation to enhanced include improved subscriber isolation and enhanced subscriber
subscriber management. management.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 14, 2017. This Internet-Draft will expire on November 18, 2017.
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
(http://trustee.ietf.org/license-info) in effect on the date of (http://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
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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
2. Motivation and Scope of Applicability . . . . . . . . . . . . 3 2. Motivation and Scope of Applicability . . . . . . . . . . . . 3
3. Design Principles . . . . . . . . . . . . . . . . . . . . . . 4 3. Design Principles . . . . . . . . . . . . . . . . . . . . . . 4
4. IPv6 Unique Prefix Assignment . . . . . . . . . . . . . . . . 4 4. IPv6 Unique Prefix Assignment . . . . . . . . . . . . . . . . 4
5. IPv6 Neighbourship Discovery Best Practices . . . . . . . . . 5 5. IPv6 Neighbor Discovery Best Practices . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
9. Normative References . . . . . . . . . . . . . . . . . . . . 7 9. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
The concepts in this document are originally developed as part of a The concepts in this document are originally developed as part of a
large scale, production deployment of IPv6 support for a provider large scale, production deployment of IPv6 support for a provider
managed shared network service. In this document IPv6 support does managed shared network service. In this document IPv6 support does
not preclude support for IPv4, however, the primary objectives for not preclude support for IPv4; however, the primary objectives for
this work was to make it so that user equipment (UE) were capable of this work was to make it so that user equipment (UE) were capable of
an IPv6 only experience from a network operators perspective. In the an IPv6 only experience from a network operators perspective. In the
context of this document, UE can be a 'regular' end-user-equipment, context of this document, UE can be 'regular' end-user-equipment, as
as well as a server in a datacentre, assuming a shared network (wired well as a server in a datacentre, assuming a shared network (wired or
or wireless). wireless).
Details of IPv4 support are out of scope for this document. This Details of IPv4 support are out of scope for this document. This
document will also, in general, outline the requirements that must be document will also, in general, outline the requirements that must be
satified by UE to allow for an IPv6 only experience. satified by UE to allow for an IPv6 only experience.
In most deployments today User Equipment (UE) IPv6 address assignment In most current deployments, User Equipment (UE) IPv6 address
is commonly done using either IPv6 SLAAC RFC4862 [RFC4862] and/or assignment is commonly done using either IPv6 SLAAC RFC4862 [RFC4862]
DHCP IA_NA RFC3315 [RFC3315]. During the time when this approach was and/or DHCP IA_NA RFC3315 [RFC3315]. During the time when this
developed and subsequently deployed it has been observed that some approach was developed and subsequently deployed, it has been
operating systems do not support the use of DHCPv6 for the observed that some operating systems do not support the use of DHCPv6
acquisition of IA_NA per RFC7934 [RFC7934]. As such the use of IPv6 for the acquisition of IA_NA per RFC7934 [RFC7934]. As such the use
SLAAC based subscriber and address management for provider managed of IPv6 SLAAC based subscriber and address management for provider
shared network services is the recommended technology of choice as it managed shared network services is the recommended technology of
does not exclude any known IPv6 implementation. In addition an choice, as it does not exclude any known IPv6 implementation. In
IA_NA-only network is not recommended per RFC 7934 RFC7934 [RFC7934] addition an IA_NA-only network is not recommended per RFC 7934
section 8. This document will detail the mechanics involved for IPv6 RFC7934 [RFC7934] section 8. This document will detail the mechanics
SLAAC based address and subscriber management coupled with stateless involved for IPv6 SLAAC based address and subscriber management
DHCPv6, where beneficial. coupled with stateless DHCPv6, where beneficial.
This document will focus upon the process for UEs to obtain a unique This document will focus upon the process for UEs to obtain a unique
IPv6 prefix. IPv6 prefix.
2. Motivation and Scope of Applicability 2. Motivation and Scope of Applicability
The motivation for this work falls into the following categories: The motivation for this work falls into the following categories:
o Deployment advice for IPv6 that will allow stable and secure IPv6 o Deployment advice for IPv6 that will allow stable and secure IPv6
only experience, even if IPv4 support is present only experience, even if IPv4 support is present
o Ensure support for IPv6 is efficient and does not impact the o Ensure support for IPv6 is efficient and does not impact the
performance of the underlying network and in turn the customer performance of the underlying network and in turn the customer
experience experience
o Allow for the greatest flexibility across host implementation to o Allow for the greatest flexibility across host implementation to
allow for the widest range of addressing and configuration allow for the widest range of addressing and configuration
mechanisms to be employed. The goal here is the ensure that the mechanisms to be employed. The goal here is to ensure that the
widest population of UE implementations can leverage the widest population of UE implementations can leverage the
availability of IPv6 availability of IPv6
o Lay the technological foundation for future work related to the o Lay the technological foundation for future work related to the
use of IPv6 over shared media requiring optimized subscriber use of IPv6 over shared media requiring optimized subscriber
management management
o Two devices (subscriber/hosts), both attached to the same provider o Two devices (subscriber/hosts), both attached to the same provider
managed shared network should only be able to communicate through managed shared network should only be able to communicate through
the provider managed First Hop Router the provider managed First Hop Router
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o Provide guidelines regarding best common practices around IPv6 o Provide guidelines regarding best common practices around IPv6
neighborship discovery and IPv6 address managent settings between neighborship discovery and IPv6 address managent settings between
the First Hop router and directly connected hosts/subscribers. the First Hop router and directly connected hosts/subscribers.
3. Design Principles 3. Design Principles
The First Hop router discussed in this document is the L3-Edge router The First Hop router discussed in this document is the L3-Edge router
responsible for the communication with the devices (hosts and responsible for the communication with the devices (hosts and
subscribers) directly connected to a provider managed shared network, subscribers) directly connected to a provider managed shared network,
and to transport traffic between the directly connected devices and and to transport traffic between the directly connected devices and
between directy connected devices and remote devices. between directly connected devices and remote devices.
The work detailed in this document is focussed to provide details The work detailed in this document is focused on providing details
regarding best common practices of the IPv6 neighborship discovery regarding best common practices of the IPv6 neighbor discovery and
and related IPv6 address management settings between the First Hop related IPv6 address management settings between the First Hop router
router and directly connected hosts/subscribers. The documented Best and directly connected hosts/subscribers. The documented Best
Current Practice helps a service provider to better manage the shared Current Practice helps a service provider to better manage the shared
provider managed network on behalf of the connected devices. provider managed network on behalf of the connected devices.
The Best Current Practice documented in this note is to provide The Best Current Practice documented in this note is to provide a
hosts/subscribers devices connected to the provider managed shared unique IPv6 prefix to hosts/subscribers devices connected to the
network with a unique IPv6 prefix while at the same functioning as provider managed shared network. Each unique IPv6 prefix can
control-plane anchor point to make sure that each subscriber is function as control-plane anchor point to make sure that each
receiving the expected subscriber policy and service levels subscriber is receiving expected subscriber policy and service levels
(throughput, QoS, security, parental-control, subscriber mobility (throughput, QoS, security, parental-control, subscriber mobility
management, etc.). management, etc.).
4. IPv6 Unique Prefix Assignment 4. IPv6 Unique Prefix Assignment
When a UE connects to the shared provider managed network and is When a UE connects to the shared provider managed network and is
attached it will initiate IP configuration phase. During this phase attached, it will initiate IP configuration phase. During this phase
the UE will from an IPv6 perspective attempt to learn the default the UE will, from an IPv6 perspective, attempt to learn the default
IPv6 gateway, the IPv6 prefix information, the DNS information IPv6 gateway, the IPv6 prefix information, the DNS information
RFC6106 [RFC6106], and the remaining information required to RFC6106 [RFC6106], and the remaining information required to
establish globally routable IPv6 connectivity. For that purpose the establish globally routable IPv6 connectivity. For that purpose, the
the UE/subscriber sends a RS (Router Solicitation) message. the UE/subscriber sends a RS (Router Solicitation) message.
The First Hop Router receives this UE/subscriber RS message and The First Hop Router receives this UE/subscriber RS message and
starts the process to compose the response to the UE/subscriber starts the process to compose the response to the UE/subscriber
originated RS message. The First Hop Provider Router will answer originated RS message. The First Hop Provider Router will answer
using a unicast RA (Router Advertisement) to the UE/subscriber. This using a unicast RA (Router Advertisement) to the UE/subscriber. This
RA contains a few important parameters for the EU/subscriber to RA contains two important parameters for the EU/subscriber to
consume: (1) a /64 prefix and (2) flags. The /64 prefix can be consume: (1) a /64 prefix and (2) flags. The /64 prefix can be
derived from a locally managed pool or aggregate IPv6 block assigned derived from a locally managed pool or aggregate IPv6 block assigned
to the First Hop Provider Router or from a centrally allocated pool. to the First Hop Provider Router or from a centrally allocated pool.
The flags indicate to the UE/subscriber to use SLAAC and/or DHCPv6 The flags indicate to the UE/subscriber to use SLAAC and/or DHCPv6
for address assignment, it may indicate if the autoconfigured address for address assignment; it may indicate if the autoconfigured address
is on/off-link and if 'Other' information (e.g. DNS server address) is on/off-link and if 'Other' information (e.g. DNS server address)
needs to be requested. needs to be requested.
The IPv6 RA flags used for best common practice in IPv6 SLAAC based The IPv6 RA flags used for best common practice in IPv6 SLAAC based
Provider managed shared networks are: Provider managed shared networks are:
o M-flag = 0 (UE/subscriber address is not managed through DHCPv6), o M-flag = 0 (UE/subscriber address is not managed through DHCPv6),
this flag may be set to 1 in the future if/when DHCPv6 prefix this flag may be set to 1 in the future if/when DHCPv6 prefix
delegation support is desired) delegation support is desired)
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including the use of privacy IPv6 addressing. including the use of privacy IPv6 addressing.
The architected result of designing the RA as documented above is The architected result of designing the RA as documented above is
that each UE/subscriber gets its own unique /64 IPv6 prefix for which that each UE/subscriber gets its own unique /64 IPv6 prefix for which
it can use SLAAC or any other method to select its /128 unique it can use SLAAC or any other method to select its /128 unique
address. In addition it will use stateless DHCPv6 to get the IPv6 address. In addition it will use stateless DHCPv6 to get the IPv6
address of the DNS server, however it SHOULD NOT use stateful DHCPv6 address of the DNS server, however it SHOULD NOT use stateful DHCPv6
to receive a service provider managed IPv6 address. If the UE/ to receive a service provider managed IPv6 address. If the UE/
subscriber desires to send anything external including other UE/ subscriber desires to send anything external including other UE/
subscriber devices (assuming device to device communications is subscriber devices (assuming device to device communications is
enabled and supported), then due to the L-bit set it SHOULD send this enabled and supported), then, due to the L-bit set, it SHOULD send
traffic to the First Hop Provider Router. this traffic to the First Hop Provider Router.
Now that the UE/subscriber received the RA and the associated flags, After the UE/subscriber received the RA, and the associated flags, it
it will assign itself a 128 bit IPv6 address using SLAAC. Since the will assign itself a 128 bit IPv6 address using SLAAC. Since the
address is composed by the UE/subscriber device itself it will need address is composed by the UE/subscriber device itself, it will need
to verify that the address is unique on the shared network. The UE/ to verify that the address is unique on the shared network. The UE/
subscriber will for that purpose perform Duplicate Address Detection subscriber will for that purpose, perform Duplicate Address Detection
algorithm. This will occur for each address the UE attempts to algorithm. This will occur for each address the UE attempts to
utilize on the shared provider managed network. utilize on the shared provider managed network.
5. IPv6 Neighbourship Discovery Best Practices 5. IPv6 Neighbor Discovery Best Practices
An operational consideration when using IPv6 address assignment using An operational consideration when using IPv6 address assignment using
IPv6 SLAAC is that after the onboarding procedure the UE/subscriber IPv6 SLAAC is that after the onboarding procedure, the UE/subscriber
will have a prefix with certain preferred and valid lifetimes. The will have a prefix with certain preferred and valid lifetimes. The
First Hop Provider Router extends these lifetimes by sending an First Hop Provider Router extends these lifetimes by sending an
unsolicited RA, the applicable MaxRtrAdvInterval on the first hop unsolicited RA, the applicable MaxRtrAdvInterval on the first hop
router MUST therefore be lower than the preferred lifetime. As a router MUST therefore be lower than the preferred lifetime. One
consequence of this process is that the First Hop Router never knows consequence of this process is that the First Hop Router never knows
when a UE/subscriber stops using addresses from a prefix and when a UE/subscriber stops using addresses from a prefix and
additional procedures are required to help the First Hop Router to additional procedures are required to help the First Hop Router to
gain this information. When using stateful DHCPv6 IA_NA for IPv6 UE/ gain this information. When using stateful DHCPv6 IA_NA for IPv6 UE/
subscriber address assignment this uncertainty on the First Hop subscriber address assignment, this uncertainty on the First Hop
Router is not of impact due to the stateful nature of DHCPv6 IA_NA Router is not of impact due to the stateful nature of DHCPv6 IA_NA
address assignment. address assignment.
Following is reference table of the key IPv6 router discovery and Following is a reference table of the key IPv6 router discovery and
neighbor discovery timers for provider managed shared networks: neighbor discovery timers for provider managed shared networks:
o IPv6 Router Advertisement Interval = 300s o IPv6 Router Advertisement Interval = 300s
o IPv6 Router LifeTime = 3600s o IPv6 Router LifeTime = 3600s
o Reachable time = 30s o Reachable time = 30s
o IPv6 Valid Lifetime = 3600s o IPv6 Valid Lifetime = 3600s
o IPv6 Preferred Lifetime = 1800s o IPv6 Preferred Lifetime = 1800s
o Retransmit timer = 0s o Retransmit timer = 0s
The stateless nature of the UE/subscriber IPv6 SLAAC connectivity The stateless nature of the UE/subscriber IPv6 SLAAC connectivity
model provides value to make sure that the UE/subscriber context is model provides a consideration to make regarding resource consumption
timely removed from the First Hop Router to avoid ongoing resource (i.e. memory, neighbor state) on the First Hop Router. To reduce
depletion in the case of non-permanent UE, such as in the case of undesired resource consumption on the First Hop Router the desire is
WiFi hotspots. A possible solution is to use a subscriber inactivity to remove UE/subscriber context in the case of non-permanent UE, such
timer which after tracking a pre-defined (currently unspecified) # of as in the case of WiFi hotspots as quickly as possible. A possible
minutes deletes the subscriber context on the First Hop Router. solution is to use a subscriber inactivity timer which, after
tracking a pre-defined (currently unspecified) number of minutes,
deletes the subscriber context on the First Hop Router.
When employing stateless IPv6 address assignment a number of widely When employing stateless IPv6 address assignment, a number of widely
deployed operating systems will attempt to utilize RFC 4941 RFC4941 deployed operating systems will attempt to utilize RFC 4941 RFC4941
[RFC4941] temporary 'private' addresses. [RFC4941] temporary 'private' addresses.
Similarly, when using this technology in a datacentre, the UE server Similarly, when using this technology in a datacentre, the UE server
may need to use several addresses from the same /64, for example may need to use several addresses from the same /64, for example
because is using multiple virtual hosts, containers, etc. in the because is using multiple virtual hosts, containers, etc. in the
bridged virtual switch. This can lead to the consequence that a UE bridged virtual switch. This can lead to the consequence that a UE
has multiple /128 addresses from the same IPv6 prefix. The First Hop has multiple /128 addresses from the same IPv6 prefix. The First Hop
Provider Router MUST be able to handle the presence and use of Provider Router MUST be able to handle the presence and use of
multiple globally routable IPv6 addresses. multiple globally routable IPv6 addresses.
For accounting purposes the First Hop Provider Router must be able to For accounting purposes, the First Hop Provider Router must be able
send usage statistics per UE/subscriber using Radius attributes. to send usage statistics per UE/subscriber using Radius attributes.
6. IANA Considerations 6. IANA Considerations
No IANA considerations are defined at this time. No IANA considerations are defined at this time.
7. Security Considerations 7. Security Considerations
No additional security considerations are made in this document. No additional security considerations are made in this document.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank the following, in alphabetical order, The authors would like to thank the following, in alphabetical order,
for their contributions: for their contributions:
Tim Chown, Lorenzo Colitti, Killian Desmedt, Brad Hilgenfeld, Wim Tim Chown, Lorenzo Colitti, Killian Desmedt, Brad Hilgenfeld, Wim
Henderickx, Erik Kline, Thomas Lynn, Jordi Palet, Phil Sanderson, Henderickx, Erik Kline, Warren Kumari, Thomas Lynn, Jordi Palet, Phil
Colleen Szymanik, Eric Vyncke, Sanjay Wadhwa Sanderson, Colleen Szymanik, Eric Vyncke, Sanjay Wadhwa
9. Normative References 9. Normative References
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>. 2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless [RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, Address Autoconfiguration", RFC 4862,
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