IPv6 Enterprise Network Analysis - IP Layer 3 Focus
draft-ietf-v6ops-ent-analysis-07
The information below is for an old version of the document that is already published as an RFC.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 4852.
|
|
|---|---|---|---|
| Authors | David Green , Steve Klynsma , Yanick Pouffary , Jim Bound , Tim Chown | ||
| Last updated | 2020-01-21 (Latest revision 2006-12-11) | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | Informational | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | (None) | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 4852 (Informational) | |
| Action Holders |
(None)
|
||
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | David Kessens | ||
| Send notices to | townsley@cisco.com |
draft-ietf-v6ops-ent-analysis-07
IPv6 Operations WG Jim Bound
Internet-Draft Yanick Pouffary
Expires June 8, 2007 Hewlett-Packard
Steve Klynsma
MITRE
Tim Chown
University of Southampton
Dave Green
Command Information
December 8, 2007
IPv6 Enterprise Network Analysis - IP Layer 3 Focus
<draft-ietf-v6ops-ent-analysis-07.txt>
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
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This document analyzes the transition to IPv6 in enterprise
networks focusing on IP Layer 3. These networks are characterized
as a network that has multiple internal links, one or more router
connections, to one or more Providers, and is managed by a network
operations entity. The analysis will focus on a base set of
transition notational networks and requirements expanded from a
previous Enterprise Scenarios document. Discussion is provided on a
focused set of transition analysis required for the enterprise to
transition to IPv6, assuming a Dual-IP layer (IPv4 and IPv6)
network and node environment, within the enterprise. Then a set of
transition mechanisms are recommended for each notational network.
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Table of Contents:
1. Introduction................................................4
2. Terminology.................................................7
3. Enterprise Matrix Analysis for Transition...................8
4. Wide-Scale Dual-Stack Deployment Analysis..................12
4.1 Staged Dual-Stack Deployment...............................12
4.2 Routing Capability Analysis for Dual-IP Deployment.........13
4.2.1 IPv6 Routing Capability..................................13
4.2.2 IPv6 Routing Non-Capability..............................14
4.2.2.1 Tunnel IPv6 over the IPv4 infrastructure...............14
4.2.2.2 Deploy a parallel IPv6 infrastructure..................14
4.3 Remote IPv6 access to the enterprise.......................15
4.4 Other considerations.......................................15
5. Sparse Dual-Stack Deployment Analysis......................16
5.1 Internal versus External Tunnel End Point..................16
5.2 Manual versus Autoconfigured...............................17
6. IPv6 Dominant Network Deployment Analysis..................18
7. General Issues from Analysis...............................20
7.1 Staged Plan for IPv6 Deployment............................20
7.2 Network Infrastructure Requirements........................20
7.3 Stage 1: Initial connectivity steps........................20
7.3.1 Obtaining external connectivity..........................20
7.3.2 Obtaining global IPv6 address space......................21
7.4 Stage 2: Deploying generic basic service components........21
7.4.1 Developing an IPv6 addressing plan.......................21
7.4.2 IPv6 DNS.................................................22
7.4.3 IPv6 Routing.............................................22
7.4.4 Configuration of Hosts...................................23
7.4.5 Security.................................................23
7.5 Stage 3: Widespread Dual-Stack deployment on-site..........24
8. Applicable Transition Mechanisms...........................26
8.1 Recognizing Incompatible Network touchpoints...............26
8.2 Recognizing Application incompatibilities..................27
8.3 Using Multiple Mechanisms to Support IPv6 Transition.......28
9. Security Considerations....................................29
10. IANA Considerations........................................29
11. References.................................................29
11.1 Normative References......................................29
11.2 Non-Normative References..................................31
Change Log.....................................................32
Acknowledgments................................................34
Author's Addresses.............................................35
Intellectual Property and Copyright Statements.................36
Appendix A - Crisis Management Network Scenarios...............37
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1. Introduction
This document analyzes the transition to IPv6 in enterprise
networks focusing on IP Layer 3. These networks are characterized
as a network that has multiple internal links, one or more router
connections, to one or more Providers, and is managed by a network
operations entity. The analysis will focus on a base set of
transition notational networks and requirements expanded from a
previous Enterprise Scenarios document. Discussion is provided on a
focused set of transition analysis required for the enterprise to
transition to IPv6, assuming a Dual-IP layer (IPv4 and IPv6)
network and node environment, within the enterprise. Then a set of
transition mechanisms are recommended for each notational network.
The audience for this document is the enterprise network team
considering deployment of IPv6. The document will be useful for
enterprise teams that will have to determine the IPv6 transition
strategy for their enterprise. It is expected those teams include
members from management, network operations, and engineering. The
analysis and notational networks presented provide an example set
of cases the enterprise can use to build an IPv6 transition
strategy.
The enterprise analysis will begin by describing a matrix as a tool
to be used to portray the different IPv4 and IPv6 possibilities for
deployment. The document will then provide analysis to support a
wide Dual-IP layer deployment strategy across the enterprise, to
provide the reader a view of how that can be planned and what are
the options available. The document will then discuss the
deployment of sparse IPv6 nodes within the enterprise and what
requirements need to be considered and implemented, when the
enterprise will remain with IPv4-only routing infrastructure for
some time. The next discussion focuses on the use of IPv6 when it
is determined to be dominant across or within parts of the
enterprise network.
The document then begins to discuss the general issues and
applicability from the previous analysis. The document concludes
providing a set of current transition mechanism recommendations for
the notational network scenarios to support an enterprise planning
to deploy IPv6.
This document, as stated in the introduction, focuses only on the
deployment cases where a Dual-IP Layer 3 is supported across the
network and on the nodes in the enterprise. Additional deployment
transition analysis will be required from the effects of IPv6-only
node or Provider deployments, and beyond the scope of this
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document. In addition this document does not attempt to define or
discuss any use with network address translation [NATPT] or the use
of Provider Independent address space.
The following specific topics are currently out of scope for this
document:
- Multihoming
- Application transition/porting (see [APPS]).
- IPv6 VPN, firewall or intrusion detection deployment
- IPv6 network management and QoS deployment
- Detailed IT Department requirements
- Deployment of novel IPv6 services, e.g. Mobile IPv6
- Requirements or Transition at the Providers network
- Transport protocol selection for applications with IPv6
- Application layer and configuration issues.
- IPv6 only future deployment scenarios.
We are focusing in this document on IP Layer 3 deployment, in the
same way as the other IPv6 deployment analysis works have done
[UMAN] [ISPA] [3GPA]. This document covers deployment of IPv6 "on
the wire", including address management and DNS services.
We are also assuming that the enterprise deployment is being
undertaken by the network administration team, i.e. this document
is not discussing the case of an individual user gaining IPv6
connectivity (to some external IPv6 provider) from within an
enterprise network. Much of the analysis is applicable to wireless
networks, but there are additional considerations for wireless
networks not contained within this document.
In Section 2 we introduce the terminology used in this document. In
Section 3 we introduce and define a tools matrix and define the IP
layer 3 connectivity requirements. In Section 4 we discuss wide
scale Dual-IP layer use within an enterprise. In section 5 we
discuss sparse Dual-IP layer deployment within an enterprise. In
section 6 we discuss IPv6-dominant network deployment within the
enterprise. In section 7 we discuss general issues and
applicability. In section 8 a set of transition mechanisms are
recommended that can support the deployment of IPv6 with an
enterprise.
This document then provides Appendix A for readers depicting a
Crisis Management enterprise network to demonstrate an enterprise
network example that requires all the properties as analyzed in
Sections 3, 4, 5, 6, and 7. In addition we recommend readers of
this document also read another use case document to support an
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IPv6 Transition for a Campus Network [CAMP].
Readers should also be aware a parallel effort for an enterprise to
transition to IPv6 is training, but out of scope for this document.
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2. Terminology
Enterprise Network - A network that has multiple internal links,
one or more router connections, to one or
more Providers and is actively managed by a
network operations entity.
Provider - An entity that provides services and
connectivity to the Internet or
other private external networks for the
enterprise network.
IPv6-capable - A node or network capable of supporting both
IPv6 and IPv4.
IPv4-only - A node or network capable of supporting only
IPv4.
IPv6-only - A node or network capable of supporting only
IPv6. This does not imply an IPv6 only
stack, in this document.
Dual-IP - References a network or node that supports
both IPv4 and IPv6.
IP-capability - The ability to support IPv6 only, IPv4 only,
or Dual IP Layer
IPv6-dominant - A network running IPv6 routing and control plane
services that provides transport for both IPv4 and
IPv6 protocol services
Transition - The network strategy the enterprise uses to
Implementation transition to IPv6.
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3. Enterprise Matrix Analysis for Transition
In order to identify the best suited transition mechanisms for an
enterprise, it is recommended that the enterprise have an in-depth
up-to-date understanding of its current IT environment. This
understanding will help choose the best suited transition
mechanisms. It is important to note that one size does not fit all.
While selecting a mechanism it is suggested to select mechanisms
which reduce the impact on the existing environment. When selecting
a transition mechanism one must consider the functionality
required, its scalability characteristic, and the security
implications of each mechanism.
To provide context for an analysis of the transitioning enterprise
at layer 3 we have provided a matrix which describes various
scenarios which might be encountered during an IPv6 transition.
The notional enterprise network is comprised of hosts attached to
an enterprise-owned intranet(s) at two different global locations
separated by the Internet. The enterprise owns, operates and
maintains its own intranetworks, but relies on an external provider
organization that offers Internet Service. Both local and
destination intranetworks are operated by different organizations
within the same enterprise and consequently could have different
IP-capability, than other intranetworks, at certain times in the
transition period.
Addressing every possible combination of network IP-capability in
this notional enterprise network is impractical, therefore trivial
(i.e. pure IPv4, pure IPv6, and ubiquitous Dual-IP) are not
considered. In addition, the authors could not conceive of any
scenarios involving IPv6-only ISPs or IPv6-only nodes in the near
term and consequently have not addressed scenarios with IPv6-only
ISPs or IPv6-only nodes. We assume all nodes that host IPv6
applications are Dual IP. The matrix does not assume or suggest
that network address translation is used. The authors recommend
that network address translation not be used in these notional
cases.
Future enterprise transitions that support IPv6-only nodes and
IPv6-only ISPs will require separate analysis, that is beyond the
scope of this document.
Table 1 scenarios below is a matrix of ten possible Transition
Implementations that, being encountered in an enterprise, may
require analysis and the selection of an IPv6 transition mechanism
for that notional network. Each possible implementation is
represented by the rows of the matrix. The matrix describes a set
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of notional networks as follows:
- The first column represents the protocol used by the
application and below, the IP-capability of the node
originating the IP packets.
(Application/Host 1 OS).
- The second column represents the IP-capability of the
host network wherein the node originated the packet.
(Host 1 Network)
- The third column represents the IP-capability of the
service provider network.
(Service Provider)
- The fourth column represents the IP-capability of the
destination network wherein the originating IP packets
are received.
(Host 2 Network)
- The fifth column represents the protocol used by the
application and, below, the IP-capability of the
destination node receiving the originating IP packets.
(Application/Host 2 OS).
As an example, notional network 1 is an IPv6 application residing
on a Dual-IP layer host trying to establish a communications
exchange with a destination IPv6 application. To complete the
information exchange the packets must first traverse the host's
originating IPv4 network (intranet), then the service provider's,
and destination hosts Dual-IP network.
Obviously Table 1 does not describe every possible scenario.
Trivial notional networks (such as pure IPv4, pure IPv6, and
ubiquitous Dual-IP) are not addressed. However, the authors feel
these ten represent the vast majority of transitional situations
likely to be encountered in today's enterprise. Therefore, we will
use these ten to address the analysis for enterprise deployment.
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Table 1 - Enterprise Scenario Deployment Matrix
======================================================
|Application |Host 1 |Service |Host 2 |Application |
|----------- |Network|Provider|Network|---------- |
| Host 1 OS | | | | Host 2 OS |
=====================================+================
| IPv6 | |Dual IP | | IPv6 |
A | ---- | IPv4 | or |Dual IP| ---- |
| Dual IP | | IPv4 | | Dual IP |
======================================================
| IPv6 | | | | IPv6 |
B | ---- | IPv6 | IPv4 | IPv4 | ---- |
| Dual IP | | | | Dual IP |
======================================================
| IPv4 | | | | IPv4 |
C | ---- | IPv4 |Dual IP | IPv6 | ---- |
| Dual IP | | | | Dual IP |
======================================================
| IPv4 |Dual IP| | | IPv4 |
D | ---- | or | IPv4 | IPv6 | ---- |
| Dual IP | IPv6 | | | Dual IP |
======================================================
| IPv6 |Dual IP| |Dual IP| IPv4 |
E | ---- | or |Dual IP | or | ---- |
| Dual IP | IPv6 | | IPv6 | Dual IP |
======================================================
| IPv6 | | | | IPv4 |
F | ---- | IPv6 | IPv4 | IPv4 | ---- |
| Dual IP | | | | Dual IP |
======================================================
| IPv4 | | | | IPv6 |
G | ---- | IPv6 | Dual IP| IPv6 | ---- |
| Dual IP | | | | Dual IP |
======================================================
| IPv4 | | | | IPv6 |
H | ---- | IPv6 |Dual IP | IPv4 | ---- |
| IPv4 | | | | Dual IP |
======================================================
| IPv4 | | | | IPv6 |
I | ---- | IPv6 | IPv4 | IPv6 | ---- |
| IPv4 | | | | Dual IP |
======================================================
| IPv6 | | | | IPv4 |
J | ---- | IPv4 | IPv4 | IPv6 | ---- |
| Dual IP | | | | Dual IP |
======================================================
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The reader should note that scenarios A-C in Table 1 are variations
of compatible hosts communicating across largely (but not entirely)
homogenous networks. In each of the first three scenarios, the
packet must traverse at least one incompatible network component.
For example, scenario B represents an enterprise which wishes to
use IPv6 applications, but has yet to transition its internal
networks and its Service Provider also lags, offering only a v4
IP-service. Conversely, Scenario C represents an enterprise which
has completed transition to IPv6 in its core networks (as has its
Service Provider), but continues to require a legacy IPv4-based
application.
Scenario D represents the unusual situation where the enterprise
has transitioned its core intranetworks to IPv6, but (like scenario
B) it's ISP provider has yet to transition. In addition, this
Enterprise continues to retain critical legacy IPv4-based
applications which must communicate over this heterogeneous network
environment.
Scenarios E-J represent transitional situations wherein the
Enterprise has both IPv4 and IPv6 based instantiations of the same
application that must continue to interoperate. In addition, these
scenarios show that the Enterprise has not completed transition to
IPv6 in all its organic and/or Service Provider networks. Instead,
it maintains a variety of heterogeneous network segments between
the communicating applications. Scenarios E and J represent
distinctly different extremes on either end of the spectrum. In
scenario E, the enterprise has largely transitioned to IPv6 in both
its applications and networks. However, scenario E shows that a few
legacy IPv4-based applications may still be found in the
enterprise. On the other hand, scenario J shows an Enterprise that
has begun its transition in a very disjointed manner and, in which
IPv6-based applications and network segments are relatively rare.
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4. Wide-Scale Dual-Stack Deployment Analysis
In this section we address Scenario 1 as described in Section 3.1
of [BSCN]. The scenario, assumptions and requirements are driven
from the [BSCN] text. This analysis further corresponds to
Scenario A in Section 3 above (although Scenario A shows a
transitional situation wherein the enterprise has one network
segment still lagging on transition to Dual-IP).
Within these IPv6 deployment scenarios the enterprise network
administrator would introduce IPv6 by enabling IPv6 on the wire
(i.e. within the network infrastructure) in a structured fashion
with the existing IPv4 infrastructure. In such scenarios, a number
of the existing IPv4 routers (and thus subnets) will be made dual-
IP, such that communications can run over either protocol.
Nodes on the dual-IP links may themselves be IPv4-only or IPv6-
capable. The driver for deploying IPv6 on the wire may not be for
immediate wide-scale usage of IPv6, but rather to prepare an
existing IPv4 infrastructure to support IPv6-capable nodes. Thus,
while IPv6 is not used, dual-IP nodes exist, and the enterprise can
be transitioned to IPv6 on demand.
Analyzing this scenario against existing transition mechanisms for
their applicability, suggests a staged approach for IPv6 deployment
in the enterprise.
4.1 Staged Dual-Stack Deployment
Under these scenarios (as well as most others), the site
administrator should formulate a staged plan for the introduction
of a dual-IP IPv6 network. We suggest that the generic plan of
Section 7 of this document provides a good basis for such a plan.
In an enterprise network, the administrator will generally seek to
deploy IPv6 in a structured, controlled manner, such that IPv6 can
be enabled on specific links at various stages of deployment. There
may be a requirement that some links remain IPv4 only, or some that
specifically should not have IPv6 connectivity (e.g. Scenario A of
Table 1). There may also be a requirement that aggregatable global
IPv6 addresses, assigned by the enterprise's upstream provider from
the address space allocated to them by the Regional Internet
Registries (RIRs), be assigned.
In this document we do not discuss the deployment of Unique Local
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IPv6 Unicast Addresses [ULA] because the address type and scope
selected is orthogonal to the layer 3 analysis of this document.
A typical deployment would initially involve the establishment of a
single "testbed" Dual-IP subnet at the enterprise site prior to
wider deployment. Such a testbed not only allows the IPv6
capability of specific platforms and applications to be evaluated
and verified, but also permits the steps in Sections 7.3 and 7.4 of
this document to be undertaken without (potential) adverse impact
on the production elements of the enterprise.
Section 7.5 describes the stages for the widespread deployment in
the enterprise, which could be undertaken after the basic building
blocks for IPv6 deployment are in place.
4.2 Routing Capability Analysis for Dual-IP Deployment
A critical part of Dual-IP deployment is the selection of the
IPv6-capable routing infrastructure to be implemented. The path
taken will depend on whether the enterprise has existing Layer 2/3
switch/router equipment that has an IPv6 (routing) capability, or
that can be upgraded to have such capability.
In Section 4, we are not considering sparse IPv6 deployment; the
goal of Dual-IP deployment is widespread use in the enterprise.
4.2.1 IPv6 Routing Capability
Where IPv6 routing capability exists within the infrastructure, the
network administrator can enable IPv6 on the same physical hardware
as the existing IPv4 service. This is the end goal of any
enterprise to support Dual-IP deployment, when the capability,
performance, and robustness of the Dual-IP operational deployment
has been verified.
Ideally, the IPv6 capability will span the entire enterprise,
allowing deployment on any link or subnet. If not, techniques from
Section 4.4 below may be required.
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4.2.2 IPv6 Routing Non-Capability
If the enterprise cannot provide IPv6 routing initially there are
alternative methods for transition. In this case the enterprise
administrator faces two basic choices, either to tunnel IPv6 over
some or all of the existing IPv4 infrastructure, or to deploy a
parallel IPv6 routing infrastructure providing IPv6 connectivity
into existing IPv4 subnets.
It may thus be the case that a nodes IPv4 and IPv6 default routes
to reach other links (subnets) are through different routing
platforms.
4.2.2.1 Tunnel IPv6 over the IPv4 infrastructure
Consider the situation where there exists IPv6 edge routers which
are IPv6-capable, while others,and perhaps the enterprise backbone
itself, are not IPv6-capable (Scenario B of Table 1). Tunneling,
as described in [BCNF] would be established between the Dual-IP
capable routers on the enterprise, thus "bypassing" existing non
IPv6-capable routers and platforms.
In the widespread dual-IP scenario, a more structured, manageable
method is required, where the administrator has control of the
deployment per-link and (ideally) long-term, aggregatable global
IPv6 addressing is obtained, planned and used from the outset.
4.2.2.2 Deploy a parallel IPv6 infrastructure
Alternatively,the administrator may deploy a new, separate IPv6-
capable router (or set of routers). It is quite possible that such
a parallel infrastructure would be IPv6-dominant.
Such an approach would likely require additional hardware, but it
has the advantage that the existing IPv4 routing platforms are not
disturbed by the introduction of IPv6.
To distribute IPv6 to existing IPv4 enterprise subnets, either
dedicated physical infrastructure can be employed or, if available,
IEEE 802.1q VLANs could be used, as described in [VLAN]. The
latter has the significant advantage of not requiring any
additional physical cabling/wiring and also offers all the
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advantages of VLANs for the new dual-IP environment. Many router
platforms can tag multiple VLAN IDs on a single physical interface
based on the subnet/link the packet is destined for; thus multiple
IPv6 links can be collapsed for delivery on a single (or small
number of) physical IPv6 router interfaces in the early stages of
deployment.
The parallel infrastructure should only be seen as an interim step
towards full Dual-IP deployment on a unified infrastructure. The
parallel infrastructure however allows all other aspects of the
IPv6 enterprise services to be deployed, including IPv6 addressing,
thus making the enterprise ready for that unifying step at a later
date.
4.3 Remote IPv6 access to the enterprise
When the enterprise's users are off-site, and using an ISP that
does not support any native IPv6 service or IPv6 transition aids,
the enterprise may consider deploying it's own remote IPv6 access
support. Such remote support might for example be offered by
deployment of an IPv6 Tunnel Broker [TBRK].
4.4 Other considerations
There are some issues associated with turning IPv6 on by default,
including application connection delays, poor connectivity, and
network insecurity, as discussed in [V6DEF]. The issues can be
worked around or mitigated by following the advice in [V6DEF]
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5. Sparse Dual-Stack Deployment Analysis
This section covers the Scenario 2 as described in Section 3.1 of
[BSCN]. This scenario assumes the requirements defined within the
[BSCN] text.
IPv6 deployment within the enterprise network, with an existing
IPv4 infrastructure, could be motivated by mission critical or
business applications or services that require IPv6. In this case
the prerequisite is that only the nodes using those IPv6
applications need to be upgraded to be IPv6-capable. The routing
infrastructure will not be upgraded to support IPv6, nor does the
enterprise wish to deploy a parallel IPv6 routing infrastructure at
this point, since this is an option in section 4.
There is a need for end-to-end communication with IPv6, but the
infrastructure only supports IPv4 routing. Thus, the only viable
method for end-to-end communication with IPv6 is to tunnel the
traffic over the existing IPv4 infrastructure, within this analysis
documents boundaries defined.
The network team needs to decide which are the most efficient the
available transition tunneling mechanisms to deploy, so they can be
used without disrupting the existing IPv4 infrastructure. Several
conditions require analysis, as introduced in the following sub
sections.
5.1 Internal versus External Tunnel End Point
Let's assume the upstream provider has deployed some IPv6 services,
either native IPv6 in its backbone or in the access network, or
some combination of both (Scenario B of Table 1). In this case, the
provider will likely also deploy one or more transition mechanisms
to support their IPv6 subscribers. Obviously, the enterprise could
decide to take advantage of those transition services offered from
the Provider. However, this will usually mean that individual nodes
in the network will require their own IPv6-in-IPv4 tunnel. The end
result is somewhat inefficient IPv6 intranetworks communication,
because all IPv6 traffic must be forwarded by the Enterprise's IPv4
infrastructure to the Tunnel End-Point offered by the Provider.
Nevertheless, this may be acceptable paticularly if the IPv6
applications do not require intranetworks communication at all. For
example when an application's server is located outside of the
enterprise network, or on other intranetworks of the same
enterprise.
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Alternatively, the enterprise could decide to deploy its own
transition mechanism node, possibly collocating it adjacent to the
border router that connects to the upstream Provider. In this case,
intranetnetworks communication using this tunnel end point is also
possible.
5.2 Manual versus Autoconfigured
If the number of nodes to be using IPv6 is low, the first option is
to use statically configured tunnels. However, automatically
configured tunnels may be preferable, especially if the number is
higher.
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6. IPv6 Dominant Network Deployment Analysis
In this section we are covering Scenario 3 as described in Section
3.1 of [BSCN]. The scenario, assumptions and requirements are
driven from the [BSCN] text. Within this document, this situation
is captured in Scenario C of Table 1.
Some enterprise networks may wish to employ an IPv6-dominant
network deployment strategy. What this means essentially is that
the network or specific sites within the enterprise network will
transition to IPv6 using only IPv6 routing to transfer both IPv4
and IPv6 packets over the network, even though the network may be
Dual-IP capable. IPv4 routing would not be turned on within an
IPv6-dominant network, except if required to support edge IPv4
networks.
Under this scenario, communications between IPv6 nodes will use
IPv6. When IPv6-capable nodes in the IPv6-dominant network need to
communicate with IPv4 nodes, the IPv6 nodes will use their Dual-IP
implementation to tunnel IPv4 packets in IPv6 [V6TUN]. An edge
router within the IPv6-dominant network will decapsulate the IPv4
packet and route to the path of the IPv4 node on the network. This
permits Dual-IP layer nodes to communicate with legacy IPv4 nodes
within an IPv6-dominant network.
From Table 1 scenarios E and F depict additional cases where an
IPv6- dominant deployment strategy could be in place. In scenario
E the entire network could be IPv6-dominant, but the Host OS 2
system is running an IPv4 application. In scenario F the Host OS 1
system network could be IPv6-dominant, but the rest of the networks
are all IPv4.
In each case, communicating with an IPv4 end host or over an IPv4
network requires a transition point exist within the network to
support that operation. Furthermore, the node in the IPv6-dominant
network must acquire an IPv4 address (to interoperate with the IPv4
end host), and locate a tunnel endpoint on their network which
permits the IPv4 packet to be tunneled to the next hop IPv6 router
and eventually to a destination Dual IP router.
While retaining interoperability with IPv4 is a noble goal for
Enterprise architects, it is an unfortunate fact that maintaining
IPv4 services in an IPv6-dominant network slows and may even impede
your ability to reap the maximum benefits of IPv6.
The decision whether or not to use an IPv6-dominant network
deployment strategy is completely driven by the Enterprise's
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business and operational objectives and guided by the Enterprise's
transition plan.
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7. General Issues from Analysis
In this section we describe generic enterprise IPv6 deployment
issues, applicable to the analysis sections 4-6 in this document.
7.1 Staged Plan for IPv6 Deployment
The enterprise network administrator will need to follow a staged
plan for IPv6 deployment. What this means is that a strategic
identification of the enterprise network must be performed for all
points and components of the transition.
7.2 Network Infrastructure Requirements
The considerations for the enterprise components are detailed in
Section 3.2 of [BSCN]. We do not go into detail of all aspects of
such components in this document. In this document we focus on
Layer 3 issues.
7.3 Stage 1: Initial connectivity steps
The first steps for IPv6 deployment do not involve technical
aspects per se; the enterprise needs to select an external IPv6
provider, and obtain globally routable IPv6 address space from that
provider.
7.3.1 Obtaining external connectivity
The enterprise service provider would typically be a
topographically close IPv6 provider that is able to provide an IPv6
upstream link. It would be expected that the enterprise would use
either native IPv6 upstream connectivity or, in its absence, a
manually configured tunnel [BCNF] to the upstream provider.
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7.3.2 Obtaining global IPv6 address space
The enterprise will obtain global IPv6 address space from its
selected upstream provider, as provider assigned (PA) address
space.
The enterprise should receive at least a /48 allocation from its
provider, as described in [ALLOC].
Should an enterprise change their provider, a procedure for
enterprise renumbering between providers is described in [RENUM].
7.4 Stage 2: Deploying generic basic service components
Most of these are discussed in Section 4 of [BSCN]. Here we comment
on those aspects that we believe are in scope for this analysis
document. Thus we have not included network management,
multihoming, multicast or application transition analysis here, but
these aspects should be addressed in Stage 2.
7.4.1 Developing an IPv6 addressing plan
A site will need to formulate an IPv6 addressing plan, utilizing
the globally aggregatable public IPv6 prefix allocated to it by its
upstream connectivity provider.
In a Dual-IP deployment, the site will need to decide whether it
wishes to deploy IPv6 links to be congruent with existing IPv4
subnets. In this case, nodes will fall into the same links or
subnets for both protocols. Such a scheme could be followed, with
IPv6 prefix allocations being made such that room for topological
growth is provisioned (reducing the potential requirement for
future renumbering due to restructuring).
A beneficial property of IPv6 is that an administrator will not
need to invest as much effort in address conservation. With IPv4,
a site will likely allocate IPv4 subnets to be as small as possible
for the number of hosts currently in the subnet (e.g. a /26 for 50
nodes), because IPv4 address conservation is required. This creates
problems when the number of nodes on a subnet grows, larger IPv4
prefixes are then required, and potentially time-consuming and
disruptive renumbering events will follow.
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With IPv6, a link can in effect have any number of nodes, allowing
link growth without the need to adjust prefix allocations with the
associated renumbering requirement. The size of the initial site
allocation (currently recommended to be a /48) also is likely to
allow room for site growth without a need to return to the
connectivity provider to obtain more, potentially non-sequential,
address space (as is the case for IPv4 today, with the associated
paperwork and probable delays).
At the time of writing, best practice in IPv6 site address planning
is restricted due to limited wide-scale deployments. Administrators
should allocate /64 size prefixes for subnets, and do so in a way
that has scope for growth within a site. The site should utilize a
plan that reserves space for topological growth in the site, given
that its initial IPv6 prefix allocation (currently recommended to
be a /48) is likely to include such room for growth. Also see IPv6
unicast address assignments document in process [UNAD].
7.4.2 IPv6 DNS
The enterprise site should deploy a DNS service that is capable of
both serving IPv6 DNS records using the AAAA format [DNSV6R] and of
communicating over IPv6 transport.
Specific IPv6 DNS issues are reported in [DNSOP6].
7.4.3 IPv6 Routing
The enterprise network will need to support methods for internal
and external routing.
For a single-homed single-site network, a static route to a single
upstream provider may be sufficient, although the site may choose
to use an exterior routing protocol, especially where it has
multiple upstream providers.
For internal routing, an appropriate interior routing protocol may
be deployed. IPv6 routing protocols that can be used are as
follows: BGP4+ [BGP4], IS-IS [ISIS], OSPFv3 [OSPF] and RIPng
[RIPng].
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7.4.4 Configuration of Hosts
An enterprise network will have a number of tools available for
IPv4 address and other configuration information delegation and
management, including manual configuration, NIS [NIS] or DHCP
[DHCPv4].
In an IPv6 enterprise, Stateless Address Autoconfiguration [CONF]
may be used to configure a host with a global IPv6 address, a
default router, and an on-link prefix information.
Where support for secure autoconfiguration is required, SEND [SEND]
can be used. Readers should see the applicability statements to
IPsec [IPSEC] within the SEND document.
A stateless configured node wishing to gain other configuration
information (e.g. DNS, NTP servers) will likely need a Stateful
DHCPv6 [DHCPv6] service available.
For nodes configuring using DHCPv6, where DHCPv6 servers are
offlink, a DHCPv6 Relay Agent function will be required. Where
DHCPv4 and DHCPv6 service are deployed together, dual-stack
considerations need to be made, as discussed within current work on
DHCP dual stack issues [DHDS].
Hosts may also generate or request IPv6 Privacy Addresses [PRIVv6];
there is support for DHCPv6 to assign privacy addresses to nodes in
managed environments.
7.4.5 Security
When deploying IPv6 within a Dual-IP network, a site will need to
implement its site security policy for IPv6-capable nodes as it
does for IPv4-capable nodes. For example, a border firewall
should be capable of filtering and controlling IPv6 traffic by
enforcing the same policy as it already does for IPv4.
However, a site will also need to review its security policy in
light of IPv6 specific functionality that will be deployed in the
site, e.g. Mobile IPv6, stateless autoconfiguration (and SEND),
IPv6 Privacy Extensions, end-to-end IPsec, and, not least, the use
of globally aggregatable public address space where for IPv4
private addressing and NAT may have been used.
An overview of how Network Architecture Protection (NAP) using IPv6
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can provide the same or more benefits without the need for NAT can
be found in [NAP]. This describes how the perceived security with
IPv4 NAT can be achieved and surpassed with IPv6, i.e. how IPv6
technology can be used to provide the market-perceived benefits of
IPv4 NAT.
Where deployed, intrusion detection systems will need to be
enhanced to both check IPv6 transport for known application layer
attack patterns and also to check for new potential IPv6 threats,
e.g. excessive hop-by-hop headers, or errant IPv6 header options.
The deployment of specific transition mechanisms may also introduce
threats, e.g. carrying IPv6 data tunnelled in IPv4. The site
security policy should embrace the transition mechanisms that are
deployed.
An overview of IPv6 security issues can be found in [V6SEC]. This
includes discussion of issues specific to the IPv6 protocol, to
transition mechanisms, and to IPv6 deployment itself.
In addition an enterprise should review all current Host Based
security requirements for their networks and verify support for
IPv6.
7.5 Stage 3: Widespread Dual-Stack deployment on-site
With the basic building blocks of external connectivity, interior
IPv6 routing, an IPv6 DNS service and address allocation management
in place, the IPv6 capability can be rolled out to the wider
enterprise. This involves putting IPv6 on the wire in the desired
links, and enabling applications and other services to begin using
an IPv6 transport.
In the Dual-IP deployment case, this means enabling IPv6 on
existing IPv4 subnets. As described in Section 7.4.4 above, it is
likely that IPv6 links will be congruent with IPv4 subnets, because
IPv4 subnets tend to be created for geographic, policy or
administrative reasons that would be IP version-independent.
While the use of IPv6 by some applications can be administratively
controlled (e.g. in the case of open source software by compiling
the application without IPv6 support enabled), the use of IPv6
transport, and preference over IPv4 transport, will vary per
application based on the developer/author's implementation.
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A Dual-IP deployment will often be made by sites wishing to support
use of IPv6 within a site, even if IPv6 transport is not preferred
by all applications. Putting support for IPv6 in all site
infrastructure (DNS, email transport, etc) allows IPv6 usage to be
phased in over time. As nodes become IPv6 capable, and
applications and services IPv6 enabled, the IPv6 capable
infrastructure can be leveraged. For most networks, Dual-IP will
be at the very least a medium-term transition towards an IPv6-
dominant future. However, the introduction of IPv6 support, with
the potential benefits of globally aggregatable public address
usage (with [NAP]), and other new IPv6 capabilities, can bring more
immediate benefits for the site.
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8. Applicable Transition Mechanisms
This section will provide general guidance for the use of specific
transition mechanisms which in turn can be used by the enterprise
to support the enterprise matrix notional networks (rows) in
Section 3, and within the context of the analysis discussed in
Sections 4, 5, and 6.
Table 1 provides a number of common scenarios that an enterprise
architect might encounter as they consider how and where they
should consider deploying transition mechanisms to support the
network transition to IPv6. Selecting the most appropriate
mechanism for each scenario is more of an art than a science and
consequently making recommendations against each of the ten
scenarios would be simply fodder for sharpshooters touting their
favored product. However we can provide some high-level guidance
that should benefit the architect's decision making process.
8.1 Recognizing Incompatible Network touchpoints
Mapping your specific situation into one of the ten scenarios of
Table 1 is far less important than recognizing the critical
touchpoints within the enterprise networks where incompatible
networks interface. Unless a transition mechanism is being offered
by the enterprise as a service, it is at these touchpoints that a
mechanism must be considered.
A quick review of Table 1 reveals that the ten scenarios can be
boiled down to variations of four major themes. The simplest, but
also most favored (due to its flexibility), is wide spread Dual IP
with compatible hosts at either end. This situation is illustrated
in Scenario A and transition mechanism considerations have already
been described in some detail in Section 4.
In the second common theme (depicted in Scenarios B-D of Table 1),
the enterprise is comprised of compatible hosts, with one or more
incompatible network touchpoints in between. As described in
Section 4.2.2.1, tunneling can be used to "bypass" the incompatible
network segments. One tunneling option, Manual Configured Tunnels
[BCNF] could be used by the enterprise, but as the name implies,
this mechanism provides no automated tunnel configuration.
6TO4 [6TO4] can be used to support enterprises that do not have an
assigned IPv6 prefix address.
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Identifying the responsible device to perform the tunneling is
driven by the position of the incompatible touchpoint. If a local
network is incompatible then host tunneling is appropriate. If the
backbone (provider) network is incompatible then gateway-to-gateway
tunneling might be a better choice. By working to ensure tunnel
endpoints are always configured at dual-IP devices, end-to-end
communication or services (IPv4 or IPv6) can be preserved.
Readers should review the current work regarding tunnels within the
IETF Softwire working group and problem statement [SOFTW].
Having IPv6 applications on a Dual-IP host on a v4-only network
requires some form of tunneling. Where configured tunnels are not
sufficient a more automatic solution may be appropriate. Available
solutions include ISATAP [ISTP] or Teredo [TRDO] to tunnel to a v6
end service. ISATAP [ISTP] can be used to provide end node IPv6
connectivity from nodes on an isolated IPv4 network, through the
use of automatic tunneling of IPv6 in IPv4. Teredo [TRDO] can be
used when the enterprise network is behind a NAT.
Enterprise architects should consider providing a Tunnel Broker
[TBRK] [TSPB] as a cost effective service to local users or
applications. Tunnel Brokers can be used to provide tunnel setup
for an enterprise using manual configured tunnels and 6TO4 [6TO4].
Tunnel Brokers can automate the use of tunnels across an enterprise
deploying IPv6.
Later in the transition process, after the enterprise has
transitioned to a predominately IPv6 infrastructure, the architect
will need to determine a network transition strategy to tunnel IPv4
within IPv6 [V6TUN] across IPv6-dominant links, or the enterprise
Intranet. Or in the case of early deployment of IPv6-dominant
networks the architect will need to address this from the beginning
of the required transition planning.
8.2 Recognizing Application incompatibilities
Having recognized incompatible network touchpoints, it is also
incumbent on the architect to identify application
incompatibilities. During the transition period, particularly for
large enterprises, it is to be expected that applications hosted at
one location may lead (or lag) the IPv6-compability of its peer (or
server) at some other location.
This leads us to the third theme represented by Scenario E and G,
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i.e. incompatible applications communicating across a homogenous
network. Translation is an obvious solution, but not recommended
except for legacy devices at the network edge which cannot or never
will be upgraded to IPv6. A more scaleable solution would be to
use an Application Layer Gateways (ALG) between the incompatible
hosts.
8.3 Using Multiple Mechanisms to Support IPv6 Transition
Inevitably, during the course of transitioning a large enterprise
to IPv6, the architect will be faced with both incompatible hosts
and simultaneously (at different parts of the enterprise)
incompatible networks. These highly complex situations represent
the fourth common theme in Table 1 and are specifically depicted by
Scenarios F, H, I and J. Maintaining IP interoperability in these
situations requires additional planning and may require multiple or
even nested use of diverse transition mechanisms. For example, an
ALG co-located with the application server may be required to
service both IPv4 and IPv6 data streams that are simultaneously
tunneled through incompatible network segment(s).
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9. Security Considerations
Security considerations for IPv6 deployment in a Dual-IP
environment are discussed above in section 7.4.5, where external
references to overview documents [V6SEC] [NAP] are also included.
10. IANA Considerations
This document has no actions for IANA.
11. References
11.1 Normative References
[CONF] Thomson, S., Narten, T., "IPv6 Stateless
Autoconfiguration" RFC 2462 December 1998.
[DHCPv6] Droms, R., Bound, J., Volz, B., Lemon, T.,
et al. "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)" RFC 3315 July 2003.
[6TO4] Carpenter, B., Moore, K., "Connection of IPv6
Domains via IPv4 Clouds" RFC 3056 February 2001.
[BSCN] Bound, J., (Ed) et al. "IPv6 Enterprise Network
Scenarios" RFC 4057 June 2005.
[TRDO] Huitema, C., "Teredo: Tunneling IPv6 over UDP
through NATs" RFC 4380.
[ISTP] Templin, F., et al "Intra-Site Automatic Tunnel
Addressing Protocol (ISATAP)".
RFC 4214 October 2005.
[V6TUN] Conta, A., Deering, S., "Generic Packet Tunneling
in IPv6" RFC 2473 December 1998.
[TBRK] Durand, A., et al "IPv6 Tunnel Broker"
RFC 3053 January 2001.
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[ALLOC] IAB, IESG, "IAB/IESG Recommendations on IPv6
Address Allocations to Sites"
RFC 3177 September 2001.
[NATPT] Tsirtsis, G., Srisuresh, P., "Network Address
`Translation - Protocol Translation (NAT-PT)"
RFC 2766 February 2000
[UMAN] Huitema, C.,. et al "Evaluation of IPv6
Transition Mechanisms for Unmanaged Networks".
RFC 3904 September 2004.
[ISPA] Lind, M., et al "Scenarios and Analysis for
Introducing IPv6 into ISP Networks".
RFC 4029 March 2005.
[3GPA] Wiljakka, J., "Analysis on IPv6 Transition in
3GPP Networks" RFC 4215 October 2005.
[OSPF] Coltun, R., Ferguson, D., Moy, J. "OSPF for
IPv6" RFC2740 December 1999.
[BGP4] Bates, T., Rekhter, Y. et. al. "Multiprotocol
Extensions for BGP-4", RFC2858 June 2000.
[ISIS] Oran, D. EDITOR, "OSI IS-IS Intra-domain
Routing Protocol", RFC1142 February 1990.
[RIPng] Malkin, G., Minnear, R. "RIPng for IPv6"
RFC2080 January 1997
[APPS] Shin, M-K., Hong, Y-G., Haigino, J., Savola, P.,
Castro, E., "Application Aspects of IPv6
Transition" RFC 4038 March 2005.
[RENUM] Baker, F., Lear, E., Droms, R., "Procedures for
Renumbering an IPv6 Network without a Flag Day".
RFC 4192 September 2005.
[BCNF] Nordmark, E., Gilligan, R., "Basic Transition
Mechanisms for IPv6 Hosts and Routers"
RFC 4213 October 2005
[ULA] Hinden, B., Haberman, B., "Unique Local IPv6
Addresses". RFC 4193 October 2005.
[DNSOP6] Durand, A., Ihren, J. and P. Savola,
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"Operational Considerations and Issues with
IPv6 DNS". RFC 4472 April 2006.
[DNSV6R] Thomson, S., Huitema, C., et al "DNS
Extensions to Support IP Version 6".
RFC 3596 October 2003.
[NIS] Kalusivalingam. V, "Network Information
Service (NIS) Configuration Options for D
HCPv6. RFC 3898 October 2004.
[DHCPv4] Droms, R., "Dynamic Host Configuration
Protocol" RFC 2131 March 1997.
[IPSEC] Eastlake. D., "Cryptographic Algorithm
Implementation Requirements for Encapsulating
Security Payload (ESP) and Authentication
Header (AH)". RFC 4305 December 2005.
[SEND] Arkko, J. et al. "Secure Neighbor Discovery
(SEND)". RFC 3971 March 2005.
[PRIVv6] Narten, T., Draves, R., "Privacy Extensions
for Stateless Address Autoconfiguration in
IPv6. RFC 3041 January 2001.
11.2 Non-Normative References
[TSPB] Blanchet, M., Parent, F. "IPv6 Tunnel Broker
with the Tunnel Setup Protocol".
Work in Progress.
[V6SEC] Davies, E. et al "IPv6 Transition/Co-existence
Security Considerations". Work in Progress.
[NAP] Van de Velde, G. et al "IPv6 Network
Architecture Protection". Work in Progress.
[CAMP] Chown, T., "IPv6 Campus Transition Scenario
Description and Analysis". Work in Progress.
[DHDS] Chown, T., "DHCP: IPv4 and IPv6 Dual-Stack
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Issues", Work in Progress.
[UNAD] Van de Velde, G., Popoviciu, C., Chown, T.,
"IPv6 Unicast Address Assignment".
Work in Progress.
[VLAN] Chown, T. "Use of VLANs for IPv4-IPv6
Coexistence in Enterprise Networks".
Work in Progress.
[V6DEF] Roy, S., Durand, A., Paugh, J., "IPv6 Neighbor
Discovery On-Link Assumption Considered
Harmful". Work in Progress.
[SOFTW] Dawkins, S. (Ed) "Softwire Problem Statement"
Work in Progress
Change Log
June 2006 - Oct 2006
ID 06-07
- Add IP Layer 3 Focus to the title
- Remove IPsec use SEND for Autoconfiguration
- Remove all mentions of DSTM
- Add Softwire Tunnel Reference
- Add Host Based Security check to security section
May 2006 - June 2006
ID 05 - 06
- Fix ID Nits for IESG
February - May 2006
ID 04 to 05
- Edits: Intro, Sections 4 and 7, References
- Update definition IPv6-Dominant
- Add Campus Deployment Reference
- Fix ID-Nits
July 2005 - February 2006
ID 03 to 04
- Edits to document (minor).
- Removed any reference to DSTM as IETF supported mechanism.
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- Remove 8.4 Transition Mechanisms Recommendations.
- Updated references move to RFC.
- Added Normative references.
June 2005 - to July 2005
ID 02 to 03
- Fixed more IETF id-nits.
- Added Section 8.4 Transition Mechanism Summary
analysis.
March 2005 to June 2005
ID 01 to 02
- Fixed IETF id-nits.
- Updated Section 3 Table 1 and added discussion of intent and
scenario analysis per WG input.
- Completed sections 6, 7, and 8.
- Completed required Security Section.
- Fixed normative vs. non-normative references.
- Changed abstract and context of document to only deal with dual
IP layer networks and nodes.
- Removed Table of Content Campus VLAN appendix place holder.
November 2004 to March 2005
ID 00 to 01
- Changed introduction, Section 1-3 to reflect authors and IETF WG
discussions to attempt consensus on these initial sections.
- Added explanation of why Appendix A is in the document to
introduction.
- Expanded what topics are out of scope for this document.
- Updated terminology section.
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- Updated section 3 matrix and description to simplify and focus
on dual IP layer.
- Edited base text of Sections 4-7 but all three require extensive
additional test for descriptions.
- Edited section 8 and removed table and will reference table in
section 3. This section still needs to be written.
Acknowledgments
The Author's would like to acknowledge contributions from the
following: IETF v6ops Working Group members, Fred Baker, Pekka
Savola, and Jordi Palet
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Author's Addresses
Jim Bound
HP
110 Spitbrook Road
Nashua, NH 03062
USA
Phone: 603.465.3130
Email: jim.bound@hp.com
Yanick Pouffary
HP Competency Center
950, Route des Colles, BP027,
06901 Sophia Antipolis CEDEX
FRANCE
Phone: + 33492956285
Email: Yanick.pouffary@hp.com
Tim Chown
School of Electronics and Computer Science
University of Southampton
Southampton SO17 1BJ
United Kingdom
Email: tjc@ecs.soton.ac.uk
David Green
Command Information
13655 Dulles Technology Drive
Suite 500
Herndon, VA 20171
USA
Phone: 703.561.5937
Email: green@commandinformation.com
Steve Klynsma
The MITRE Corporation
7515 Colshire Drive
McLean, VA 22102-5708
USA
703-883-6469
Email: sklynsma@mitre.org
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Intellectual Property and Copyright Statements
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Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
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on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
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attempt made to obtain a general license or permission for the use of
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specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
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rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf.org.
Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
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Appendix A - Crisis Management Network Scenarios
Introduction:
This appendix first describes different scenarios for the
introduction of IPv6 into a crisis management network for emergency
services, defense, or security forces that are currently running
IPv4 service. Then, the scenarios for introducing IPv6 are analyzed
and the relevance of already defined transition mechanisms are
evaluated. Known challenges are also identified.
When a crisis management enterprise deploys IPv6, its goal is to
provide IPv6 connectivity on it's institutional fixed networks and
on the mobile wireless services that are deployed to a crisis area.
The new IPv6 service must be added to an already existing IPv4
service, the introduction of IPv6 must not interrupt this IPv4
service, and the IPv6 services must be interoperable with existing
IPv4 services.
Crisis management enterprises accessing IPv4 service across mobile
ground networks, airborne networks, and satellites will find
different ways to add IPv6 to this service based on their network
architecture, funding, and institutional goals. This document
discusses a small set of scenarios representing the architectures
for IPv6 expected to be dominant in crisis management networks
during the next decade. It evaluates the relevance of the existing
transition mechanisms in the context of these deployment scenarios,
and points out the lack of essential functionality in these methods
to the ISP's operation of an IPv6 service.
The document is focused on services that include both IPv6 and IPv4
and does cover issues surrounding accessing IPv4 services across
IPv6-only networks. It is outside the scope of this document to
describe detailed implementation plans for IPv6 in defense networks
Scenarios for IPv6 Deployment in Crisis Management Networks:
Scenario 1: Limited IPv6 Deployment Network.....................
Sparse IPv6 dual-stack deployment in an existing IPv4 network
infrastructure. Enterprise with an existing IPv4 network wants to
deploy a set of particular IPv6 "applications" and have some
ability to interoperate with other institutions that are using IPv6
services. The IPv6 deployment is limited to the minimum required to
operate this set of applications.
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Assumptions: IPv6 software/hardware components for the application
are available, and platforms for the application are IPv6 capable.
Requirements: Do not disrupt IPv4 infrastructure.
Scenario 2: Dual Stack Network
Wide-scale/total dual-stack deployment of IPv4 and IPv6 capable
hosts and network infrastructure. Enterprise with an existing IPv4
network wants to deploy IPv6 in conjunction with their IPv4 network
in order to take advantage of emerging IPv6 network-centric
capabilities and to be interoperable with other agencies,
international partners, and commercial enterprises that are
deploying an IPv6 architecture.
Assumptions: The IPv4 network infrastructure used has an
equivalent capability in IPv6.
Requirements: Do not disrupt existing IPv4 network infrastructure
with IPv6. IPv6 should be equivalent or "better" than the network
infrastructure in IPv4. It may not be feasible to deploy IPv6 on
all parts of the network immediately. Dual stacked defense
enterprise network must be interoperable with both IPv4 and IPv6
networks and applications.
Scenario 3: IPv6 Dominant Network
Enterprise has some limited IPv4-capable/only nodes/applications
needing to communicate over the IPv6 infrastructure. Crisis
management enterprise re-structuring an existing network, decides
to pursue aggressive IPv6 transition as an enabler for network-
centric services and wants to run some native IPv6-only networks to
eliminate cost/complexity of supporting a dual stack. Some legacy
IPv4 capable nodes/applications within the enterprise will have
slow technical refresh/replacement path and will need to
communicate over the IPv6 dominant infrastructure for years until
they are replaced. The IPv6 dominant enterprise network will need
to be interoperable with it's own legacy networks, commercial
networks, and the legacy networks of similar organizations that
will remain IPv4 dominant during a long transition period. Reserve
units, contractors, other agencies, and international partners may
need IPv4 service across this enterprise's IPv6 dominant backbone.
Assumptions: Required IPv6 network infrastructure is available, or
available over some defined timeline, supporting the aggressive
transition plan.
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Requirements: Reduce operation and maintenance requirements and
increase net-centricity through aggressive IPv6 transition.
Interoperation and coexistence with legacy IPv4 networks and
applications is required. Legacy IPv4 nodes/applications/networks
will need to be able to operate across the IPv6 backbone and need
to be able to interoperate with the IPv6-dominant network's
nodes/applications.
Description of a Generic Crisis Management Network
A generic network topology for a crisis management reflects the
various ways a crisis management network can connect customers
through their network infrastructure. Because the institution's
existing wired and fixed site wireless infrastructure can be
destroyed or unavailable in a crisis, the crisis management network
must be able to deploy it's own mobile wireless network or connect
through external wired and wireless networks provided by ISPs or
partner organizations. This infrastructure lets us divide the
basic areas for IPv4/IPv6 interoperability into three main areas:
the customer applications, the local network, and the network
backbone.
The basic components in a crisis management network are depicted in
Figure 1.
------------ ---------- ---- Wired Connection
| Network and| | | .... Wireless Connection
| Service |--| Backbone |
| Operation | | |
------------ ----------
/ | ---------------------
/ : _|Connection to |
/ : |Commercial Internet |
/ : ---------------------
Network Backbone
-------------- /------|-------------|--------------------
---------- / ---------- ----------
| Home |/ | Wireless | External |.............
| Base | | Mobile | |Untrusted |+--------- :
| Network | | Network | |Network | | :
---------- ---------- ---------- | :
| : : | :
Local Network
-----:------------:-----------------------------------
Custome Applications
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| : : | :
+--------+ +--------+ +--------+ | :
| | | | | | | :
|Customer| |Customer| |Customer|+----------- :
| | | | | |..............
+--------+ +--------+ +--------+
Figure 1: Crisis Management Network Topology.
Stages of IPv6 Deployment:
The stages are derived from the generic description of scenarios
for crisis management networks in Section 2. Combinations of
different building blocks that constitute an crisis network
environment lead to a number of scenarios from which the network
engineers can choose. The scenarios most relevant to this document
are those that maximize the network's ability to offer IPv6 to its
customers in the most efficient and feasible way. The assumption in
the first three stages the goal is to offer both IPv4 and IPv6 to
the customer, and that in the distant future all IPv4 services will
be eventually switched to IPv6. This document will cover
engineering the first four stages.
The four most probable stages are:
o Stage 1 Limited Launch
o Stage 2 Dual Stack Dominance
o Stage 3 IPv6 Dominance
o Stage 4 IPv6 Transition Complete
Generally, a crisis management network is able to entirely upgrade
a current IPv4 network to provide IPv6 services via a dual-stack
network in Stage 2 and then slowly progress to stages 3 and 4 as
indicted in Figure 2. During stage 2, When most applications are
IPv6 dominant, operational and maintenance costs can be reduced on
some networks by moving to stage 3 and running backbone networks
entirely on IPv6 while adding IPv4 backwards compatibility via v4
in v6 tunneling or translation mechanisms to the existing
configuration from stage 2. When designing a new network, if a new
IPv6-only service is required, it can be implemented at a lower
cost jumping directly to stage 3/4 if there are only limited/no
legacy concerns.
Stage 1 Scenario: Limited Launch
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The first stage begins with an IPv4-only network and IPv4
customers. This is the most common case today and the natural
starting point for the introduction of IPv6. During this stage the
enterprise begins to connect individual IPv6 applications run on
dual stacked hosts through host based tunneling using Tunnel
Broker, ISATAP, Teredo. Some early adopter networks are created for
pilot studies and networked together through configured tunnels and
6to4.
The immediate first step consists of obtaining a prefix allocation
typically a /32) from the appropriate RIR (e.g. AfriNIC, APNIC,
ARIN, LACNIC, RIPE) according to allocation procedures.
The crisis management enterprise will also need to establish IPv6
connectivity between its home base networks and mobile wireless
networks over it's backbone and negotiate IPv6 service with its
service providers and with peer organizations; it is of utmost
importance to require IPv6 capability or an upgrade plan when
negotiating purchases of network applications and infrastructure.
In the short term, network connections, especially legacy wireless
networks, that cannot provide IPv6 services can provide IPv6
services through the use of tunnels. However, the longer-term goal
must be requiring and obtaining IPv6 native connectivity from the
transit networks, because otherwise the quality of IPv6
connectivity will likely be poor and the transition to stage 2 will
be delayed.
Stage 2 Scenario: Dual Stack Dominance
Stage 2 occurs when most applications, local networks, and network
backbones become dual-stacked so that native IPv6 connections are
enabled. At this point there is a mix of IPv4 and IPv6 applications
and services in use across the enterprise. The enterprise may be
made IPv6-capable through either software upgrades, hardware
upgrades, or a combination of both. Generally IPv6 is added during
normal technical refresh as the enterprise buys new equipment that
is IPv6 ready.
Specialty legacy applications and wireless/satellite networks may
be especially slow to transition to IPv6 capability due to upgrade
costs so plans must be made for backwards compatibility for these
systems. Since some new IPv6 services cannot be provided through
IPv4, and some legacy network connections may not yet be upgraded,
tunneling mechanisms have to be provided on the backbone to provide
IPv6 connectivity through to customer IPv6 applications still
relying on legacy IPv4-only networks. The tunnels may provide
host-based tunneling for individual customers or site-to-site
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tunnels to connect small IPv6 domains through IPv4 only networks.
If any new applications are IPv6-only rather than dual-stacked, and
need to interact with IPv4-only legacy applications, translators
will be used as a transition mechanism of last resort during this
stage.
Stage 3 Scenario: IPv6 Dominance
Applications are deployed specifically to use IPv6 as benefit, thus
network backbone and nodes use IPv6 and not IPv4, except where IPv4
is legacy.
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