Network Working Group K. Chittimaneni
Internet-Draft Google Inc.
Intended status: Informational T. Chown
Expires: July 16, 2014 University of Southampton
L. Howard
Time Warner Cable
V. Kuarsingh
Dyn Inc
Y. Pouffary
Hewlett Packard
E. Vyncke
Cisco Systems
January 12, 2014
Enterprise IPv6 Deployment Guidelines
draft-ietf-v6ops-enterprise-incremental-ipv6-05
Abstract
Enterprise network administrators worldwide are in various stages of
preparing for or deploying IPv6 into their networks. The
administrators face different challenges than operators of Internet
access providers, and have reasons for different priorities. The
overall problem for many administrators will be to offer Internet-
facing services over IPv6, while continuing to support IPv4, and
while introducing IPv6 access within the enterprise IT network. The
overall transition will take most networks from an IPv4-only
environment to a dual stack network environment and eventually an
IPv6-only operating mode. This document helps provide a framework
for enterprise network architects or administrators who may be faced
with many of these challenges as they consider their IPv6 support
strategies.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
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This Internet-Draft will expire on July 16, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Enterprise Assumptions . . . . . . . . . . . . . . . . . 4
1.2. IPv4-only Considerations . . . . . . . . . . . . . . . . 4
1.3. Reasons for a Phased Approach . . . . . . . . . . . . . . 5
2. Preparation and Assessment Phase . . . . . . . . . . . . . . 6
2.1. Program Planning . . . . . . . . . . . . . . . . . . . . 6
2.2. Inventory Phase . . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Network infrastructure readiness assessment . . . . . 8
2.2.2. Applications readiness assessment . . . . . . . . . . 8
2.2.3. Importance of readiness validation and testing . . . 9
2.3. Training . . . . . . . . . . . . . . . . . . . . . . . . 9
2.4. Security Policy . . . . . . . . . . . . . . . . . . . . . 10
2.4.1. IPv6 is no more secure than IPv4 . . . . . . . . . . 10
2.4.2. Similarities between IPv6 and IPv4 security . . . . . 11
2.4.3. Specific Security Issues for IPv6 . . . . . . . . . . 11
2.5. Routing . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.6. Address Plan . . . . . . . . . . . . . . . . . . . . . . 13
2.7. Tools Assessment . . . . . . . . . . . . . . . . . . . . 16
3. External Phase . . . . . . . . . . . . . . . . . . . . . . . 17
3.1. Connectivity . . . . . . . . . . . . . . . . . . . . . . 17
3.2. Security . . . . . . . . . . . . . . . . . . . . . . . . 18
3.3. Monitoring . . . . . . . . . . . . . . . . . . . . . . . 19
3.4. Servers and Applications . . . . . . . . . . . . . . . . 20
3.5. Network Prefix Translation for IPv6 . . . . . . . . . . . 20
4. Internal Phase . . . . . . . . . . . . . . . . . . . . . . . 20
4.1. Security . . . . . . . . . . . . . . . . . . . . . . . . 21
4.2. Network Infrastructure . . . . . . . . . . . . . . . . . 21
4.3. End user devices . . . . . . . . . . . . . . . . . . . . 23
4.4. Corporate Systems . . . . . . . . . . . . . . . . . . . . 24
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5. IPv6-only . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6. Considerations For Specific Enterprises . . . . . . . . . . . 26
6.1. Content Delivery Networks . . . . . . . . . . . . . . . . 26
6.2. Data Center Virtualization . . . . . . . . . . . . . . . 26
6.3. University Campus Networks . . . . . . . . . . . . . . . 26
7. Security Considerations . . . . . . . . . . . . . . . . . . . 27
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 27
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28
10. Informative References . . . . . . . . . . . . . . . . . . . 28
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction
An Enterprise Network is defined in [RFC4057] as 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 (the "administrator", whether a single person or department of
administrators). Administrators generally support an internal
network, consisting of users' workstations, personal computers, other
computing devices and related peripherals, a server network,
consisting of accounting and business application servers, and an
external network, consisting of Internet-accessible services such as
web servers, email servers, VPN systems, and customer applications.
This document is intended as guidance for network architects and
administrators in planning their IPv6 deployments.
The business reasons for spending time, effort, and money on IPv6
will be unique to each enterprise. The most common drivers are due
to the fact that when Internet service providers, including mobile
wireless carriers, run out of IPv4 addresses, they will provide
native IPv6 and non-native IPv4. The non-native IPv4 service may be
NAT64, NAT444, Dual-stack Lite, or other transition technologies.
Compared to tunneled or translated, native traffic typically performs
better and more reliably than non-native. For example, for client
networks trying to reach enterprise networks, the IPv6 experience
will be better than the transitional IPv4 if the enterprise deploys
IPv6 in its public-facing services. The native IPv6 network path
should also be simpler to manage and, if necessary, troubleshoot.
Further, enterprises doing business in growing parts of the world may
find IPv6 growing faster there, where again potential new customers,
employees and partners are using IPv6. It is thus in the
enterprise's interests to deploy native IPv6, at the very least in
its public-facing services, but ultimately across the majority or all
of its scope.
The text in this document provides specific guidance for enterprise
networks, and complements other related work in the IETF, including
[I-D.ietf-v6ops-design-choices] and [RFC5375].
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1.1. Enterprise Assumptions
For the purpose of this document, we assume:
o The administrator is considering deploying IPv6 (but see
Section 1.2 below).
o The administrator has existing IPv4 networks and devices which
will continue to operate and be supported.
o The administrator will want to minimize the level of disruption to
the users and services by minimizing number of technologies and
functions that are needed to mediate any given application. In
other words, provide native IP wherever possible.
Based on these assumptions, an administrator will want to use
technologies which minimize the number of flows being tunnelled,
translated or intercepted at any given time. The administrator will
choose transition technologies or strategies which allow most traffic
to be native, and will manage non-native traffic. This will allow
the administrator to minimize the cost of IPv6 transition
technologies, by containing the number and scale of transition
systems.
Tunnels used for IPv6/IPv4 transition are expected as near/mid- term
mechanisms, while IPv6 tunneling will be used for many long-term
operational purposes such as security, routing control, mobility,
multi-homing, traffic engineering, etc. We refer to the former class
of tunnels as "transition tunnels"
1.2. IPv4-only Considerations
As described in [RFC6302] administrators should take certain steps
even if they are not considering IPv6. Specifically, Internet-facing
servers should log the source port number, timestamp (from a reliable
source), and the transport protocol. This will allow investigation
of malefactors behind address-sharing technologies such as NAT444 or
Dual-stack Lite.
Other IPv6 considerations may impact ostensibly IPv4-only networks,
e.g. [RFC6104] describes the rogue IPv6 RA problem, which may cause
problems in IPv4-only networks where IPv6 is enabled in end systems
on that network. Further discussion of the security implications of
IPv6 in IPv4-only networks can be found in
[I-D.ietf-opsec-ipv6-implications-on-ipv4-nets]).
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1.3. Reasons for a Phased Approach
Given the challenges of transitioning user workstations, corporate
systems, and Internet-facing servers, a phased approach allows
incremental deployment of IPv6, based on the administrator's own
determination of priorities. The Preparation Phase is highly
recommended to all administrators, as it will save errors and
complexity in later phases. Each administrator must decide whether
to begin with the External Phase (as recommended in [RFC5211]) or the
Internal Phase. There is no "correct" answer here; the decision is
one for each enterprise to make.
Each scenario is likely to be different to some extent, but we can
highlight some considerations:
o In many cases, customers outside the network will have IPv6 before
the internal enterprise network. For these customers, IPv6 may
well perform better, especially for certain applications, than
translated or tunneled IPv4, so the administrator may want to
prioritize the External Phase such that those customers have the
simplest and most robust connectivity to the enterprise, or at
least its external-facing elements.
o Employees who access internal systems by VPN may find that their
ISPs provide translated IPv4, which does not support the required
VPN protocols. In these cases, the administrator may want to
prioritize the External Phase, and any other remotely-accessible
internal systems. It is worth noting that a number of emerging
VPN solutions provide dual-stack connectivity; thus a VPN service
may be useful for employees in IPv4-only access networks to access
IPv6 resources in the enterprise network (much like many public
tunnel broker services, but specifically for the enterprise).
o Internet-facing servers cannot be managed over IPv6 unless the
management systems are IPv6-capable. These might be Network
Management Systems (NMS), monitoring systems, or just remote
management desktops. Thus in some cases, the Internet-facing
systems are dependent on IPv6-capable internal networks. However,
dual-stack Internet-facing systems can still be managed over IPv4.
o Virtual machines may enable a faster rollout once initial system
deployment is complete. Management of VMs over IPv6 is still
dependent on the management software supporting IPv6.
o IPv6 is enabled by default on all modern operating systems, so it
may be more urgent to manage and have visibility on the internal
traffic. It is important to manage IPv6 for security purposes,
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even in an ostensibly IPv4-only network, as described in
[I-D.ietf-opsec-ipv6-implications-on-ipv4-nets].
o In many cases, the corporate accounting, payroll, human resource,
and other internal systems may only need to be reachable from the
internal network, so they may be a lower priority. As enterprises
require their vendors to support IPv6, more internal applications
will support IPv6 by default and it can be expected that
eventually new applications will only support IPv6. The
inventory, as described in Section 2.2, will help determine the
systems' readiness, as well as the readiness of the supporting
network elements and security, which will be a consideration in
prioritization of these corporate systems.
o Some large organizations (even when using private IPv4
addresses[RFC1918]) are facing IPv4 address exhaustion because of
the internal network growth (for example the vast number of
virtual machines) or because of the acquisition of other companies
that often raise private IPv4 address overlapping issues.
o IPv6 restores end to end transparency even for internal
applications (of course security policies must still be enforced).
When two organizations or networks merge [RFC6879], the unique
addressing of IPv6 can make the merger much easier and faster. A
merger may, therefore, prioritize IPv6 for the affected systems.
These considerations are in conflict; each administrator must
prioritize according to their company's conditions. It is worth
noting that the reasons given in one "Large Corporate User's View of
IPng", described in [RFC1687], for reluctance to deploy have largely
been satisfied or overcome in the intervening 18 years.
2. Preparation and Assessment Phase
2.1. Program Planning
As with any project, an IPv6 deployment project will have its own
phases. Generally, one person is identified as the project sponsor
or champion, who will make sure time, people and other resources are
committed appropriately for the project. Because enabling IPv6 can
be a project with many interrelated tasks, identifying a project
manager is also recommended. The project manager and sponsor can
initiate the project, determining the scope of work, the
corresponding milestones and deliverables, and identifying whose
input is required, and who will be affected by work. The scope will
generally include the Preparation Phase, and may include the Internal
Phase, the External Phase, or both, and may include any or all of the
Other Phases identified. It may be necessary to complete the
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Preparation Phase before determining which of the other phases will
be prioritized, since needs and readiness assessments are part of
that phase.
The project manager will need to spend some time on planning. It is
often useful for the sponsor to communicate with stakeholders at this
time, to explain why IPv6 is important to the enterprise. Then, as
the project manager is assessing what systems and elements will be
affected, the stakeholders will understand why it is important for
them to support the effort. Well-informed project participants can
help significantly by explaining the relationships between
components. For a large enterprise, it may take several iterations
to really understand the level of effort required; some systems will
require additional development, some might require software updates,
and others might need new versions or alternative products from other
vendors. Once the projects are understood, the project manager can
develop a schedule and a budget, and work with the project sponsor to
determine what constraints can be adjusted, if necessary.
It is tempting to roll IPv6 projects into other architectural
upgrades - this can be an excellent way to improve the network and
reduce costs. Project participants are advised that by increasing
the scope of projects, the schedule is often affected. For instance,
a major systems upgrade may take a year to complete, where just
patching existing systems may take only a few months. Understanding
and evaluating these trade-offs are why a project manager is
important.
The deployment of IPv6 will not generally stop all other technology
work. Once IPv6 has been identified as an important initiative, all
projects will need to evaluate their ability to support IPv6. If
expansions or new deployments fail to include IPv6, then additional
work will be required after all initial IPv6 has been completed.
Having a purchasing policy that no hardware or software will be
purchased that is not trivially upgradeable to IPv6 will help
minimizing such future work.It may not be possible to delay regular
projects for IPv6, if their IPv6 support is dependent on network
elements that have not yet been upgraded, but the projects need to
include a return to IPv6 support in their eventual timeline.
It is very common for assessments to continue in some areas even as
execution of the project begins in other areas. This is fine, as
long as recommendations in other parts of this document are
considered, especially regarding security (for instance, one should
not deploy IPv6 on a system before security has been evaluated). The
project manager will need to continue monitoring the progress of
discrete projects and tasks, to be aware of changes in schedule,
budget, or scope. "Feature creep" is common, where engineers or
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management wish to add other features while IPv6 development or
deployment is ongoing; each feature will need to be individually
evaluated for its effect on the schedule and budget, and whether
expanding the scope increases risk to any other part of the project.
As projects are completed, the project manager will confirm that work
has been completed, often by means of seeing a completed test plan,
and will report back to the project sponsor on completed parts of the
project. A good project manager will remember to thank the people
who executed the project.
2.2. Inventory Phase
To comprehend the scope of the inventory phase we recommend dividing
the problem space in two: network infrastructure readiness and
applications readiness.
2.2.1. Network infrastructure readiness assessment
The goal of this assessment is to identify the level of IPv6
readiness of network equipment. This is an important step as it will
help identify the effort required to move to an infrastructure that
supports IPv6 with the same functional service capabilities as the
existing IPv4 network. This may also require a feature comparison
and gap analysis between IPv4 and IPv6 functionality on the network
equipment and software.
Be able to understand which network devices are already capable,
which devices can be made IPv6 ready with a code/firmware upgrade,
and which devices will need to be replaced. The data collection
consists of a network discovery to gain an understanding of the
topology and inventory network infrastructure equipment and code
versions with information gathered from static files and IP address
management, DNS and DHCP tools.
Since IPv6 might already be present in the environment, through
default configurations or VPNs, an infrastructure assessment (at
minimum) is essential to evaluate potential security risks.
2.2.2. Applications readiness assessment
Just like network equipment, application software needs to support
IPv6. This includes OS, firmware, middleware and applications
(including internally developed applications). Vendors will
typically handle IPv6 enablement of off-the-shelf products, but often
enterprises need to request this support from vendors. For
internally developed applications it is the responsibility of the
enterprise to enable them for IPv6. Analyzing how a given
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application communicates over the network will dictate the steps
required to support IPv6. Applications should be made to use APIs
which hide the specifics of a given IP address family. Any
applications that use APIs, such as the C language, which exposes the
IP version specificity, need to be modified to also work with IPv6.
There are two ways to IPv6-enable applications. The first approach
is to have separate logic for IPv4 and IPv6, thus leaving the IPv4
code path mainly untouched. This approach causes the least
disruption to the existing IPv4 logic flow, but introduces more
complexity, since the application now has to deal with two logic
loops with complex race conditions and error recovery mechanisms
between these two logic loops. The second approach is to create a
combined IPv4/IPv6 logic, which ensures operation regardless of the
IP version used on the network. Knowing whether a given
implementation will use IPv4 or IPv6 in a given deployment is a
matter of some art; see Source Address Selection [RFC6724] and Happy
Eyeballs [RFC6555]. It is generally recommend that the application
developer use industry IPv6-porting tools to locate the code that
needs to be updated. Some discussion of IPv6 application porting
issues can be found in [RFC4038].
2.2.3. Importance of readiness validation and testing
Lastly IPv6 introduces a completely new way of addressing endpoints,
which can have ramifications at the network layer all the way up to
the applications. So to minimize disruption during the transition
phase we recommend complete functionality, scalability and security
testing to understand how IPv6 impacts the services and networking
infrastructure.
2.3. Training
IPv6 planning and deployment in the enterprise does not only affect
the network. IPv6 adoption will be a multifaceted undertaking that
will touch everyone in the organization unlike almost any other
project. While technology and process transformations are taking
place, it is critical that personnel training takes place as well.
Training will ensure that people and skill gaps are assessed
proactively and managed accordingly. We recommend that training
needs be analyzed and defined in order to successfully inform, train,
and prepare staff for the impacts of the system or process changes.
Better knowledge of the requirements to deploy IPv6 may also help
inform procurement processes.
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2.4. Security Policy
It is obvious that IPv6 networks should be deployed in a secure way.
The industry has learnt a lot about network security with IPv4, so,
network operators should leverage this knowledge and expertise when
deploying IPv6. IPv6 is not so different than IPv4: it is a
connectionless network protocol using the same lower layer service
and delivering the same service to the upper layer. Therefore, the
security issues and mitigation techniques are mostly identical with
same exceptions that are described further.
2.4.1. IPv6 is no more secure than IPv4
Some people believe that IPv6 is inherently more secure than IPv4
because it is new. Nothing can be more wrong. Indeed, being a new
protocol means that bugs in the implementations have yet to be
discovered and fixed and that few people have the operational
security expertise needed to operate securely an IPv6 network. This
lack of operational expertise is the biggest threat when deploying
IPv6: the importance of training is to be stressed again.
One security myth is that thanks to its huge address space, a network
cannot be scanned by enumerating all IPv6 address in a /64 LAN hence
a malevolent person cannot find a victim. [RFC5157] describes some
alternate techniques to find potential targets on a network, for
example enumerating all DNS names in a zone. Additional advice in
this area is also given in [I-D.ietf-opsec-ipv6-host-scanning].
Another security myth is that IPv6 is more secure because it mandates
the use of IPsec everywhere. While the original IPv6 specifications
may have implied this, [RFC6434] clearly states that IPsec support is
not mandatory. Moreover, if all the intra-enterprise traffic is
encrypted, then this renders a lot of the network security tools
(IPS, firewall, ACL, IPFIX, etc) blind and pretty much useless.
Therefore, IPsec should be used in IPv6 pretty much like in IPv4 (for
example to establish a VPN overlay over a non-trusted network or
reserved for some specific applications).
The last security myth is that amplification attacks (such as
[SMURF]) do not exist in IPv6 because there is no more broadcast.
Alas, this is not true as ICMP error (in some cases) or information
messages can be generated by routers and hosts when forwarding or
receiving a multicast message (see Section 2.4 of [RFC4443]).
Therefore, the generation and the forwarding rate of ICMPv6 messages
must be limited as in IPv4.
It should be noted that in a dual-stack network the security
implementation for both IPv4 and IPv6 needs to be considered, in
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addition to security considerations related to the interaction of
(and transition between) the two, while they coexist.
2.4.2. Similarities between IPv6 and IPv4 security
As mentioned earlier, IPv6 is quite similar to IPv4, therefore
several attacks apply for both protocol families:
o Application layer attacks: such as cross-site scripting or SQL
injection
o Rogue device: such as a rogue Wi-Fi Access Point
o Flooding and all traffic-based denial of services (including the
use of control plane policing for IPv6 traffic see [RFC6192])
o Etc.
A specific case of congruence is IPv6 Unique Local Addresses (ULAs)
[RFC4193] and IPv4 private addressing [RFC1918], which do not provide
any security by 'magic'. In both cases, the edge router must apply
strict filters to block those private addresses from entering and,
just as importantly, leaving the network. This filtering can be done
by the enterprise or by the ISP, but the cautious administrator will
prefer to do it in the enterprise.
IPv6 addresses can be spoofed as easily as IPv4 addresses and there
are packets with bogon IPv6 addresses (see [CYMRU]). Anti-bogon
filtering must be done in the data and routing planes. It can be
done by the enterprise or by the ISP, or both, but again the cautious
administrator will prefer to do it in the enterprise.
2.4.3. Specific Security Issues for IPv6
Even if IPv6 is similar to IPv4, there are some differences that
create some IPv6-only vulnerabilities or issues. We give examples of
such differences in this section.
Privacy extension addresses [RFC4941] are usually used to protect
individual privacy by periodically changing the interface identifier
part of the IPv6 address to avoid tracking a host by its otherwise
always identical and unique MAC-based EUI-64. While this presents a
real advantage on the Internet, moderated by the fact that the prefix
part remains the same, it complicates the task of following an audit
trail when a security officer or network operator wants to trace back
a log entry to a host in their network, because when the tracing is
done the searched IPv6 address could have disappeared from the
network. Therefore, the use of privacy extension addresses usually
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requires additional monitoring and logging of the binding of the IPv6
address to a data-link layer address (see also the monitoring section
of [I-D.ietf-opsec-v6]). Some early enterprise deployments have
taken the approach to use tools that harvest IP/MAC address mappings
from switch and router devices to provide address accountability;
this approach has been shown to work, though it can involve gathering
significantly more address data than in equivalent IPv4 networks. An
alternative is to try to prevent the use of privacy extension
addresses by enforcing the use of DHCPv6, such that hosts only get
addresses assigned by a DHCPv6 server. This can be done by
configuring routers to set the M-bit in Router Advertisements,
combined with all advertised prefixes being included without the
A-bit set (to prevent the use of stateless auto-configuration). This
technique of course requires that all hosts support stateful DHCPv6.
It is important to note that not all operating systems exhibit the
same behavior when processing RAs with the M-Bit set. The varying OS
behavior is related to the lack of prescriptive definition around the
A, M and O-bits within the ND protocol.
[I-D.liu-bonica-dhcpv6-slaac-problem] provides a much more detailed
analysis on the interaction of the M-Bit and DHCPv6.
Extension headers complicate the task of stateless packet filters
such as ACLs. If ACLs are used to enforce a security policy, then
the enterprise must verify whether its ACL (but also stateful
firewalls) are able to process extension headers (this means
understand them enough to parse them to find the upper layers
payloads) and to block unwanted extension headers (e.g., to implement
[RFC5095]). This topic is discussed further in [RFC7045].
Fragmentation is different in IPv6 because it is done only by source
host and never during a forwarding operation. This means that ICMPv6
packet-too-big messages must be allowed to pass through the network
and not be filtered [RFC4890]. Fragments can also be used to evade
some security mechanisms such as RA-guard [RFC6105]. See also
[RFC5722], and [I-D.ietf-v6ops-ra-guard-implementation].
One of the biggest differences between IPv4 and IPv6 is the
introduction of the Neighbor Discovery Protocol [RFC4861], which
includes a variety of important IPv6 protocol functions, including
those provided in IPv4 by ARP [RFC0826]. NDP runs over ICMPv6 (which
as stated above means that security policies must allow some ICMPv6
messages to pass, as described in RFC 4890), but has the same lack of
security as, for example, ARP, in that there is no inherent message
authentication. While Secure Neighbour Discovery (SeND) [RFC3971]
and CGA [RFC3972] have been defined, they are not widely
implemented). The threat model for Router Advertisements within the
NDP suite is similar to that of DHCPv4 (and DHCPv6), in that a rogue
host could be either a rogue router or a rogue DHCP server. An IPv4
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network can be made more secure with the help of DHCPv4 snooping in
edge switches, and likewise RA snooping can improve IPv6 network
security (in IPv4-only networks as well). Thus enterprises using
such techniques for IPv4 should use the equivalent techniques for
IPv6, including RA-guard (RFC 6105) and all work in progress from the
SAVI WG, e.g. [RFC6959], which is similar to the protection given by
dynamic ARP monitoring in IPv4. Other DoS vulnerabilities are
related to NDP cache exhaustion, and mitigation techniques can be
found in ([RFC6583]).
As stated previously, running a dual-stack network doubles the attack
exposure as a malevolent person has now two attack vectors: IPv4 and
IPv6. This simply means that all routers and hosts operating in a
dual-stack environment with both protocol families enabled (even if
by default) must have a congruent security policy for both protocol
versions. For example, permit TCP ports 80 and 443 to all web
servers and deny all other ports to the same servers must be
implemented both for IPv4 and IPv6. It is thus important that the
tools available to administrators readily support such behaviour.
2.5. Routing
An important design choice to be made is what IGP to use inside the
network. A variety of IGPs (IS-IS, OSPFv3 and RIPng) support IPv6
today and picking one over the other is a design choice that will be
dictated mostly by existing operational policies in an enterprise
network. As mentioned earlier, it would be beneficial to maintain
operational parity between IPv4 and IPv6 and therefore it might make
sense to continue using the same protocol family that is being used
for IPv4. For example, in a network using OSPFv2 for IPv4, it might
make sense to use OSPFv3 for IPv6. It is important to note that
although OSPFv3 is similar to OSPFv2, they are not the same. On the
other hand, some organizations may chose to run different routing
protocols for different IP versions. For example, one may chose to
run OSPFv2 for IPv4 and IS-IS for IPv6. An important design question
to consider here is whether to support one IGP or two different IGPs
in the longer term. [I-D.ietf-v6ops-design-choices] presents advice
on the design choices that arise when considering IGPs and discusses
the advantages and disadvantages to different approaches in detail.
2.6. Address Plan
The most common problem encountered in IPv6 networking is in applying
the same principles of conservation that are so important in IPv4.
IPv6 addresses do not need to be assigned conservatively. In fact, a
single larger allocation is considered more conservative than
multiple non-contiguous small blocks, because a single block occupies
only a single entry in a routing table. The advice in [RFC5375] is
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still sound, and is recommended to the reader. If considering ULAs,
give careful thought to how well it is supported, especially in
multiple address and multicast scenarios, and assess the strength of
the requirement for ULA. [I-D.ietf-v6ops-ula-usage-recommendations]
provides much more detailed analysis and recommendations on the usage
of ULAs.
The enterprise administrator will want to evaluate whether the
enterprise will request address space from a LIR (Local Internet
Registry, such as an ISP), a RIR (Regional Internet Registry, such as
AfriNIC, APNIC, ARIN, LACNIC, or RIPE-NCC) or a NIR (National
Internet Registry, operated in some countries). The normal
allocation is Provider Aggregatable (PA) address space from the
enterprise's ISP, but use of PA space implies renumbering when
changing provider. Instead, an enterprise may request Provider
Independent (PI) space; this may involve an additional fee, but the
enterprise may then be better able to be multihomed using that
prefix, and will avoid a renumbering process when changing ISPs
(though it should be noted that renumbering caused by outgrowing the
space, merger, or other internal reason would still not be avoided
with PI space).
The type of address selected (PI vs. PA) should be congruent with the
routing needs of the enterprise. The selection of address type will
determine if an operator will need to apply new routing techniques
and may limit future flexibility. There is no right answer, but the
needs of the external phase may affect what address type is selected.
Each network location or site will need a prefix assignment.
Depending on the type of site/location, various prefix sizes may be
used. In general, historical guidance suggests that each site should
get at least a /48, as documented in RFC 5375 and [RFC6177]. In
addition to allowing for simple planning, this can allow a site to
use its prefix for local connectivity, should the need arise, and if
the local ISP supports it.
When assigning addresses to end systems, the enterprise may use
manually-configured addresses (common on servers) or SLAAC or DHCPv6
for client systems. Early IPv6 enterprise deployments have used
SLAAC, both for its simplicity but also due to the time DHCPv6 has
taken to mature. However, DHCPv6 is now very mature, and thus
workstations managed by an enterprise may use stateful DHCPv6 for
addressing on corporate LAN segments. DHCPv6 allows for the
additional configuration options often employed by enterprise
administrators, and by using stateful DHCPv6, administrators
correlating system logs know which system had which address at any
given time. Such an accountability model is familiar from IPv4
management, though for DHCPv6 hosts are identified by DUID rather
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than MAC address. For equivalent accountability with SLAAC (and
potentially privacy addresses), a monitoring system that harvests IP/
MAC mappings from switch and router equipment could be used.
A common deployment consideration for any enterprise network is how
to get host DNS records updated. In a traditional IPv4 network, the
two commonly used methods are to either have the host send DNS
updates itself or have the DHCPv4 server update DNS records. The
former implies that there is sufficient trust between the hosts and
the DNS server while the latter implies a slightly more controlled
environment where only DHCP servers are trusted to make these
updates. If the enterprise uses the first model, then SLAAC is a
perfectly valid option to assign addresses to end systems. However,
an enterprise network with a more controlled environment will need to
disable SLAAC and force end hosts to use DHCPv6 only.
In the data center or server room, assume a /64 per VLAN. This
applies even if each individual system is on a separate VLAN. In a /
48 assignment, typical for a site, there are then still 65,535 /64
blocks. Addresses are either configured manually on the server, or
reserved on a DHCPv6 server, which may also synchronize forward and
reverse DNS. Because of the need to synchronize RA timers and DNS
TTLs, SLAAC is rarely, if ever, used for servers, and would require
tightly coupled dynamic DNS updates. [RFC6866]
All user access networks should be a /64. Point-to-point links where
Neighbor Discovery Protocol is not used may also utilize a /127 (see
[RFC6164]).
Plan to aggregate at every layer of network hierarchy. There is no
need for VLSM [RFC1817] in IPv6, and addressing plans based on
conservation of addresses are short-sighted. Use of prefixes longer
then /64 on network segments will break common IPv6 functions such as
SLAAC[RFC4862]. Where multiple VLANs or other layer two domains
converge, allow some room for expansion. Renumbering due to
outgrowing the network plan is a nuisance, so allow room within it.
Generally, plan to grow to about twice the current size that can be
accommodated; where rapid growth is planned, allow for twice that
growth. Also, if DNS (or reverse DNS) authority may be delegated to
others in the enterprise, assignments need to be on nibble boundaries
(that is, on a multiple of 4 bits, such as /64, /60, /56, ..., /48, /
44), to ensure that delegated zones align with assigned prefixes.
If using ULAs, it is important to note that AAAA and PTR records for
ULA are not recommended to be installed in the global DNS.
Similarly, reverse (address-to-name) queries for ULA MUST NOT be sent
to name servers outside of the organization, due to the load that
such queries would create for the authoritative name servers for the
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ip6.arpa zone. For more details please refer to section 4.4 of
[RFC4193].
Enterprise networks more and more include virtual networks where a
single physical node may host many virtualized addressable devices.
It is imperative that the addressing plans assigned to these virtual
networks and devices be consistent and non-overlapping with the
addresses assigned to real networks and nodes. For example, a
virtual network established within an isolated lab environment may at
a later time become attached to the production enterprise network.
2.7. Tools Assessment
Enterprises will often have a number of operational tools and support
systems which are used to provision, monitor, manage and diagnose the
network and systems within their environment. These tools and
systems will need to be assessed for compatibility with IPv6. The
compatibility may be related to the addressing and connectivity of
various devices as well as IPv6 awareness of the tools and processing
logic.
The tools within the organization fall into two general categories,
those which focus on managing the network, and those which are
focused on managing systems and applications on the network. In
either instance, the tools will run on platforms which may or may not
be capable of operating in an IPv6 network. This lack in
functionality may be related to Operating System version, or based on
some hardware constraint. Those systems which are found to be
incapable of utilizing an IPv6 connection, or which are dependent on
an IPv4 stack, may need to be replaced or upgraded.
In addition to devices working on an IPv6 network natively, or via a
transition tunnel, many tools and support systems may require
additional software updates to be IPv6 aware, or even a hardware
upgrade (usually for additional memory: IPv6 addresses are larger and
for a while, IPv4 and IPv6 addresses will coexist in the tool). This
awareness may include the ability to manage IPv6 elements and/or
applications in addition to the ability to store and utilize IPv6
addresses.
Considerations when assessing the tools and support systems may
include the fact that IPv6 addresses are significantly larger than
IPv4, requiring data stores to support the increased size. Such
issues are among those discussed in [RFC5952]. Many organizations
may also run dual-stack networks, therefore the tools need to not
only support IPv6 operation, but may also need to support the
monitoring, management and intersection with both IPv6 and IPv4
simultaneously. It is important to note that managing IPv6 is not
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just constrained to using large IPv6 addresses, but also that IPv6
interfaces and nodes are likely to use two or more addresses as part
of normal operation. Updating management systems to deal with these
additional nuances will likely consume time and considerable effort.
For networking systems, like node management systems, it is not
always necessary to support local IPv6 addressing and connectivity.
Operations such as SNMP MIB polling can occur over IPv4 transport
while seeking responses related to IPv6 information. Where this may
seem advantageous to some, it should be noted that without local IPv6
connectivity, the management system may not be able to perform all
expected functions - such as reachability and service checks.
Organizations should be aware that changes to older IPv4-only SNMP
MIB specifications have been made by the IETF related to legacy
operation in [RFC2096] and [RFC2011]. Updated specifications are now
available in [RFC4292] and [RFC4293] which modified the older MIB
framework to be IP protocol agnostic, supporting both IPv4 and IPv6.
Polling systems will need to be upgraded to support these updates as
well as the end stations which are polled.
3. External Phase
The external phase for enterprise IPv6 adoption covers topics which
deal with how an organization connects its infrastructure to the
external world. These external connections may be toward the
Internet at large, or to other networks. The external phase covers
connectivity, security and monitoring of various elements and outward
facing or accessible services.
How an organization connects to the outside worlds is very important
as it is often a critical part of how a business functions, therefore
it must be dealt accordingly.
3.1. Connectivity
The enterprise will need to work with one or more Service Providers
to gain connectivity to the Internet or transport service
infrastructure such as a BGP/MPLS IP VPN as described in [RFC4364]
and [RFC4659]. One significant factor that will guide how an
organization may need to communicate with the outside world will
involve the use of PI (Provider Independent) and/or PA (Provider
Aggregatable) IPv6 space.
Enterprises should be aware that depending on which address type they
selected (PI vs. PA) in their planning section, they may need to
implement new routing functions and/or behaviours to support their
connectivity to the ISP. In the case of PI, the upstream ISP may
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offer options to route the prefix (typically a /48) on the
enterprise's behalf and update the relevant routing databases. In
other cases, the enterprise may need to perform this task on their
own and use BGP to inject the prefix into the global BGP system. The
latter case however is not deployed by many enterprises today, which
is an important consideration.
Note that the rules set by the RIRs for an enterprise acquiring PI
address space have changed over time. For example, in the European
region the RIPE-NCC no longer requires an enterprise to be multihomed
to be eligible for an IPv6 PI allocation. Requests can be made
directly or via a LIR. It is possible that the rules may change
again, and may vary between RIRs.
When seeking IPv6 connectivity to a Service Provider, the Enterprise
will prefer to use native IPv6 connectivity. Native IPv6
connectivity is preferred since it provides the most robust and
efficient form of connectivity. If native IPv6 connectivity is not
possible due to technical or business limitations, the enterprise may
utilize readily available transition tunnel IPv6 connectivity. There
are IPv6 transit providers which provide robust tunnelled IPv6
connectivity which can operate over IPv4 networks. It is important
to understand the transition tunnel mechanism used, and to consider
that it will have higher latency than native IPv4 or IPv6, and may
have other problems, e.g. related to MTUs.
It is important to evaluate MTU considerations when adding in IPv6 to
an existing IPv4 network. It is generally desirable to have the IPv6
and IPv4 MTU congruent to simplify operations. If the enterprise
uses transition tunnels inside or externally for IPv6 connectivity,
then modification of the MTU on hosts/routers may be needed as mid-
stream fragmentation is no longer supported in IPv6. It is preferred
that pMTUD is used to optimize the MTU, so erroneous filtering of the
related ICMPv6 message types should be monitored. Adjusting the MTU
may be the only option if undesirable upstream ICMPv6 filtering
cannot be removed.
3.2. Security
The most important part of security for external IPv6 deployment is
filtering and monitoring. Filtering can be done by stateless ACLs or
a stateful firewall. The security policies must be consistent for
IPv4 and IPv6 (else the attacker will use the less protected protocol
stack), except that certain ICMPv6 messages must be allowed through
and to the filtering device (see [RFC4890]):
o Unreachable packet-too-big: it is very important to allow Path MTU
discovery to work
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o Unreachable parameter-problem
o Neighbor solicitation
o Neighbor advertisement
It could also be safer to block all fragments where the transport
layer header is not in the first fragment to avoid attacks as
described in [RFC5722]. Some filtering devices allow this filtering.
To be fully compliant with [RFC5095], all packets containing the
routing extension header type 0 must be dropped.
If an Intrusion Prevention System (IPS) is used for IPv4 traffic,
then an IPS should also be used for IPv6 traffic. In general, make
sure IPv6 security is at least as good as IPv4. This also includes
all email content protection (anti-spam, content filtering, data
leakage prevention, etc.).
The edge router must also implement anti-spoofing techniques based on
[RFC2827] (also known as BCP 38).
In order to protect the networking devices, it is advised to
implement control plane policing as per [RFC6192].
The potential NDP cache exhaustion attack (see [RFC6583]) can be
mitigated by two techniques:
o Good NDP implementation with memory utilization limits as well as
rate-limiters and prioritization of requests.
o Or, as the external deployment usually involves just a couple of
exposed statically configured IPv6 addresses (virtual addresses of
web, email, and DNS servers), then it is straightforward to build
an ingress ACL allowing traffic for those addresses and denying
traffic to any other addresses. This actually prevents the attack
as a packet for a random destination will be dropped and will
never trigger a neighbor resolution.
3.3. Monitoring
Monitoring the use of the Internet connectivity should be done for
IPv6 as it is done for IPv4. This includes the use of IP Flow
Information eXport (IPFIX) [RFC7012] to report abnormal traffic
patterns (such as port scanning, SYN-flooding, related IP source
addresses) from monitoring tools and evaluating data read from SNMP
MIBs [RFC4293] (some of which also enable the detection of abnormal
bandwidth utilization). Where Netflow is used, version 9 is required
for IPv6 support.
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3.4. Servers and Applications
The path to the servers accessed from the Internet usually involves
security devices (firewall, IPS), server load balancing (SLB) and
real physical servers. The latter stage is also multi-tiered for
scalability and security between presentation and data storage. The
ideal transition is to enable dual-stack on all devices but this may
seem too time-consuming and too risky.
Operators have used the following approaches with success:
o Use a network device to apply NAT64 and basically translate an
inbound TCP connection (or any other transport protocol) over IPv6
into a TCP connection over IPv4. This is the easiest to deploy as
the path is mostly unchanged but it hides all IPv6 remote users
behind a single IPv4 address which leads to several audit trail
and security issues (see [RFC6302]).
o Use the server load balancer which acts as an application proxy to
do this translation. Compared to the NAT64, it has the potential
benefit of going through the security devices as native IPv6 (so
more audit and trace abilities) and is also able to insert a HTTP
X-Forward-For header which contains the remote IPv6 address. The
latter feature allows for logging, and rate-limiting on the real
servers based on the IPV6 address even if those servers run only
IPv4.
3.5. Network Prefix Translation for IPv6
Network Prefix Translation for IPv6, or NPTv6 as described in
[RFC6296] provides a framework to utilize prefix ranges within the
internal network which are separate (address-independent) from the
assigned prefix from the upstream provider or registry. As mentioned
above, while NPTv6 has potential use-cases in IPv6 networks, the
implications of its deployment need to be fully understood,
particularly where any applications might embed IPv6 addresses in
their payloads.
Use of NPTv6 can be chosen independently from how addresses are
assigned and routed within the internal network and how prefixes are
routed towards the Internet (included both PA and PI address
assignment options).
4. Internal Phase
This phase deals with the delivery of IPv6 to the internal user-
facing side of the IT infrastructure, which comprises various
components such as network devices (routers, switches, etc.), end
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user devices and peripherals (workstations, printers, etc.), and
internal corporate systems.
An important design paradigm to consider during this phase is "dual-
stack when you can, tunnel when you must". Dual-stacking allows a
more robust, production-quality IPv6 network than is typically
facilitated by internal use of transition tunnels that are harder to
troubleshoot and support, and that may introduce scalability and
performance issues. Tunnels may of course still be used in
production networks, but their use needs to be carefully considered,
e.g. where the transition tunnel may be run through a security or
filtering device. Tunnels do also provide a means to experiment with
IPv6 and gain some operational experience with the protocol.
[RFC4213] describes various transition mechanisms in more detail.
[RFC6964] suggests operational guidance when using ISATAP tunnels
[RFC5214], though we would recommend use of dual-stack wherever
possible.
4.1. Security
IPv6 must be deployed in a secure way. This means that all existing
IPv4 security policies must be extended to support IPv6; IPv6
security policies will be the IPv6 equivalent of the existing IPv4
ones (taking into account the difference for ICMPv6 [RFC4890]). As
in IPv4, security policies for IPv6 will be enforced by firewalls,
ACL, IPS, VPN, and so on.
Privacy extension addresses [RFC4941] raise a challenge for an audit
trail as explained in section Section 2.4.3. The enterprise may
choose to attempt to enforce use of DHCPv6, or deploy monitoring
tools that harvest accountability data from switches and routers
(thus making the assumption that devices may use any addresses inside
the network).
But the major issue is probably linked to all threats against
Neighbor Discovery. This means, for example, that the internal
network at the access layer (where hosts connect to the network over
wired or wireless) should implement RA-guard [RFC6105] and the
techniques being specified by SAVI WG [RFC6959]; see also
Section 2.4.3 for more information.
4.2. Network Infrastructure
The typical enterprise network infrastructure comprises a combination
of the following network elements - wired access switches, wireless
access points, and routers (although it is fairly common to find
hardware that collapses switching and routing functionality into a
single device). Basic wired access switches and access points
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operate only at the physical and link layers, and don't really have
any special IPv6 considerations other than being able to support IPv6
addresses themselves for management purposes. In many instances,
these devices possess a lot more intelligence than simply switching
packets. For example, some of these devices help assist with link
layer security by incorporating features such as ARP inspection and
DHCP Snooping, or they may help limit where multicast floods by using
IGMP (or, in the case of IPv6, MLD) snooping.
Another important consideration in enterprise networks is first hop
router redundancy. This directly ties into network reachability from
an end host's point of view. IPv6 Neighbor Discovery (ND),
[RFC4861], provides a node with the capability to maintain a list of
available routers on the link, in order to be able to switch to a
backup path should the primary be unreachable. By default, ND will
detect a router failure in 38 seconds and cycle onto the next default
router listed in its cache. While this feature provides a basic
level of first hop router redundancy, most enterprise IPv4 networks
are designed to fail over much faster. Although this delay can be
improved by adjusting the default timers, care must be taken to
protect against transient failures and to account for increased
traffic on the link. Another option to provide robust first hop
redundancy is to use the Virtual Router Redundancy Protocol for IPv6
(VRRPv3), [RFC5798]. This protocol provides a much faster switchover
to an alternate default router than default ND parameters. Using
VRRPv3, a backup router can take over for a failed default router in
around three seconds (using VRRPv3 default parameters). This is done
without any interaction with the hosts and a minimum amount of VRRP
traffic.
Last but not the least, one of the most important design choices to
make while deploying IPv6 on the internal network is whether to use
Stateless Automatic Address Configuration (SLAAC), [RFC4862], or
Dynamic Host Configuration Protocol for IPv6 (DHCPv6), [RFC3315], or
a combination thereof. Each option has advantages and disadvantages,
and the choice will ultimately depend on the operational policies
that guide each enterprise's network design. For example, if an
enterprise is looking for ease of use, rapid deployment, and less
administrative overhead, then SLAAC makes more sense for
workstations. Manual or DHCPv6 assignments are still needed for
servers, as described in the External Phase and Address Plan sections
of this document. However, if the operational policies call for
precise control over IP address assignment for auditing then DHCPv6
may be preferred. DHCPv6 also allows you to tie into DNS systems for
host entry updates and gives you the ability to send other options
and information to clients. It is worth noting that in general
operation RAs are still needed in DHCPv6 networks, as there is no
DHCPv6 Default Gateway option. Similarly, DHCPv6 is needed in RA
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networks for other configuration information, e.g. NTP servers or, in
the absence of support for DNS resolvers in RAs [RFC6106], DNS
resolver information.
4.3. End user devices
Most operating systems (OSes) that are loaded on workstations and
laptops in a typical enterprise support IPv6 today. However, there
are various out-of-the-box nuances that one should be mindful about.
For example, the default behavior of OSes vary; some may have IPv6
turned off by default, some may only have certain features such as
privacy extensions to IPv6 addresses (RFC 4941) turned off while
others have IPv6 fully enabled. Further, even when IPv6 is enabled,
the choice of which address is used may be subject to Source Address
Selection (RFC 6724) and Happy Eyeballs (RFC 6555). Therefore, it is
advised that enterprises investigate the default behavior of their
installed OS base and account for it during the Inventory phases of
their IPv6 preparations. Furthermore, some OSes may have some
transition tunneling mechanisms turned on by default and in such
cases it is recommended to administratively shut down such interfaces
unless required.
It is important to note that it is recommended that IPv6 be deployed
at the network and system infrastructure level before it is rolled
out to end user devices; ensure IPv6 is running and routed on the
wire, and secure and correctly monitored, before exposing IPv6 to end
users.
Smartphones and tablets are poised to become one of the major
consumers of IP addresses and enterprises, and should be ready to
support IPv6 on various networks that serve such devices. In
general, support for IPv6 in these devices, albeit in its infancy,
has been steadily rising. Most of the leading smartphone OSes have
some level of support for IPv6. However, the level of configurable
options are mostly at a minimum and are not consistent across all
platforms. Also, it is fairly common to find IPv6 support on the Wi-
Fi connection alone and not on the radio interface in these devices.
This is sometimes due to the radio network not being IPv6 ready, or
it may be device-related. An IPv6-enabled enterprise Wi-Fi network
will allow the majority of these devices to connect via IPv6. Much
work is still being done to bring the full IPv6 feature set across
all interfaces (802.11, 3G, LTE, etc.) and platforms. For example,
mobility management functions will be needed to accommodate handovers
between diverse access technologies.
IPv6 support in peripheral equipment such as printers, IP cameras,
etc., has been steadily rising as well, although at a much slower
pace than traditional OSes and smartphones. Most newer devices are
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coming out with IPv6 support but there is still a large installed
base of legacy peripheral devices that might need IPv4 for some time
to come. The audit phase mentioned earlier will make it easier for
enterprises to plan for equipment upgrades, in line with their
corporate equipment refresh cycle.
4.4. Corporate Systems
No IPv6 deployment will be successful without ensuring that all the
corporate systems that an enterprise uses as part of its IT
infrastructure support IPv6. Examples of such systems include, but
are not limited to, email, video conferencing, telephony (VoIP), DNS,
RADIUS, etc. All these systems must have their own detailed IPv6
rollout plan in conjunction with the network IPv6 rollout. It is
important to note that DNS is one of the main anchors in an
enterprise deployment, since most end hosts decide whether or not to
use IPv6 depending on the presence of IPv6 AAAA records in a reply to
a DNS query. It is recommended that system administrators
selectively turn on AAAA records for various systems as and when they
are IPv6 enabled; care must be taken though to ensure all services
running on that host name are IPv6-enabled before adding the AAAA
record. Additionally, all monitoring and reporting tools across the
enterprise would need to be modified to support IPv6.
5. IPv6-only
Early IPv6 enterprise deployments have generally taken a dual-stack
approach to enabling IPv6, i.e. the existing IPv4 services have not
been turned off. Although IPv4 and IPv6 networks will coexist for a
long time, the long term enterprise network roadmap should include
steps on gradually deprecating IPv4 from the dual-stack network. In
some extreme cases, deploying dual-stack networks may not even be a
viable option for very large enterprises due to the RFC 1918 address
space not being large enough to support the network's growth. In
such cases, deploying IPv6-only networks might be the only choice
available to sustain network growth. In other cases, there may be
elements of an otherwise dual-stack network that may be run
IPv6-only.
If nodes in the network don't need to talk to an IPv4-only node, then
deploying IPv6-only networks should be fairly trivial. However, in
the current environment, given that IPv4 is the dominant protocol on
the Internet, an IPv6-only node most likely needs to talk to an
IPv4-only node on the Internet. It is therefore important to provide
such nodes with a translation mechanism to ensure communication
between nodes configured with different address families. As
[RFC6144] points out, it is important to look at address translation
as a transition strategy towards running an IPv6-only network.
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There are various stateless and stateful IPv4/IPv6 translation
methods available today that help IPv6 to IPv4 communication. RFC
6144 provides a framework for IPv4/IPv6 translation and describes in
detail various scenarios in which such translation mechanisms could
be used. [RFC6145] describes stateless address translation. In this
mode, a specific IPv6 address range will represent IPv4 systems
(IPv4-converted addresses), and the IPv6 systems have addresses
(IPv4-translatable addresses) that can be algorithmically mapped to a
subset of the service provider's IPv4 addresses. [RFC6146], NAT64,
describes stateful address translation. As the name suggests, the
translation state is maintained between IPv4 address/port pairs and
IPv6 address/port pairs, enabling IPv6 systems to open sessions with
IPv4 systems. [RFC6147], DNS64, describes a mechanism for
synthesizing AAAA resource records (RRs) from A RRs. Together, RFCs
6146 and RFC 6147 provide a viable method for an IPv6-only client to
initiate communications to an IPv4-only server. At the enterprise
level, operating NAT64 and DNS64 services for heavy usage may have
significant practical implications.
The address translation mechanisms for the stateless and stateful
translations are defined in [RFC6052]. It is important to note that
both of these mechanisms have limitations as to which protocols they
support. For example, RFC 6146 only defines how stateful NAT64
translates unicast packets carrying TCP, UDP, and ICMP traffic only.
The classic problems of IPv4 NAT also apply, e.g. handling IP
literals in application payloads. The ultimate choice of which
translation mechanism to chose will be dictated mostly by existing
operational policies pertaining to application support, logging
requirements, etc.
There is additional work being done in the area of address
translation to enhance and/or optimize current mechanisms. For
example, [I-D.xli-behave-divi] describes limitations with the current
stateless translation, such as IPv4 address sharing and application
layer gateway (ALG) problems, and presents the concept and
implementation of dual-stateless IPv4/IPv6 translation (dIVI) to
address those issues.
It is worth noting that for IPv6-only access networks that use
technologies such as NAT64, the more content providers (and
enterprises) that make their content available over IPv6, the less
the requirement to apply NAT64 to traffic leaving the access network.
This particular point is important for enterprises which may start
their IPv6 deployment well into the global IPv6 transition. As time
progresses, and given the current growth in availability of IPv6
content, IPv6-only operation using NAT64 to manage some flows will
become less expensive to run versus the traditional NAT44 deployments
since only IPv6 to IPv4 flows need translation. [RFC6883] provides
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guidance and suggestions for Internet Content Providers and
Application Service Providers in this context.
Enterprises should also be aware that networks may be subject to
future convergence with other networks (i.e. mergers, acquisitions,
etc). An enterprise considering IPv6-only operation may need to be
aware that additional transition technologies and/or connectivity
strategies may be required depending on the level of IPv6 readiness
and deployment in the merging networking.
6. Considerations For Specific Enterprises
6.1. Content Delivery Networks
Some guidance for Internet Content and Application Service Providers
can be found in [RFC6883], which includes a dedicated section on
CDNs. An enterprise that relies on CDN to deliver a 'better'
e-commerce experience needs to ensure that their CDN provider also
supports IPv4/IPv6 traffic selection so that they can ensure 'best'
access to the content.
6.2. Data Center Virtualization
IPv6 Data Center considerations are described in
[I-D.ietf-v6ops-dc-ipv6].
6.3. University Campus Networks
A number of campus networks around the world have made some initial
IPv6 deployment. This has been encouraged by their National Research
and Education Network (NREN) backbones having made IPv6 available
natively since the early 2000's. Universities are a natural place for
IPv6 deployment to be considered at an early stage, perhaps compared
to other enterprises, as they are involved by their very nature in
research and education.
Campus networks can deploy IPv6 at their own pace; there is no need
to deploy IPv6 across the entire enterprise from day one, rather
specific projects can be identified for an initial deployment, that
are both deep enough to give the university experience, but small
enough to be a realistic first step. There are generally three areas
in which such deployments are currently made.
In particular those initial areas commonly approached are:
o External-facing services. Typically the campus web presence and
commonly also external-facing DNS and MX services. This ensures
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early IPv6-only adopters elsewhere can access the campus services
as simply and as robustly as possible.
o Computer science department. This is where IPv6-related research
and/or teaching is most likely to occur, and where many of the
next generation of network engineers are studying, so enabling
some or all of the campus computer science department network is a
sensible first step.
o The eduroam wireless network. Eduroam [I-D.wierenga-ietf-eduroam]
is the de facto wireless roaming system for academic networks, and
uses 802.1X-based authentication, which is agnostic to the IP
version used (unlike web-redirection gateway systems). Making a
campus' eduroam network dual-stack is a very viable early step.
The general IPv6 deployment model in a campus enterprise will still
follow the general principles described in this document. While the
above early stage projects are commonly followed, these still require
the campus to acquire IPv6 connectivity and address space from their
NREN (or other provider in some parts of the world), and to enable
IPv6 on the wire on at least part of the core of the campus network.
This implies a requirement to have an initial address plan, and to
ensure appropriate monitoring and security measures are in place, as
described elsewhere in this document.
Campuses which have deployed to date do not use ULAs, nor do they use
NPTv6. In general, campuses have very stable PA-based address
allocations from their NRENs (or their equivalent). However, campus
enterprises may consider applying for IPv6 PI; some have already done
so. The discussions earlier in this text about PA vs. PI still
apply.
Finally, campuses may be more likely than many other enterprises to
run multicast applications, such as IP TV or live lecture or seminar
streaming, so may wish to consider support for specific IPv6
multicast functionality, e.g. Embedded-RP [RFC3956] in routers and
MLDv1 and MLDv2 snooping in switches.
7. Security Considerations
This document has multiple security sections detailing how to
securely deploy an IPv6 network within an enterprise network.
8. Acknowledgements
The authors would like to thank Chris Grundemann, Ray Hunter, Brian
Carpenter, Tina Tsou, Christian Jaquenet, and Fred Templin for their
substantial comments and contributions.
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9. IANA Considerations
There are no IANA considerations or implications that arise from this
document.
10. Informative References
[RFC0826] Plummer, D., "Ethernet Address Resolution Protocol: Or
converting network protocol addresses to 48.bit Ethernet
address for transmission on Ethernet hardware", STD 37,
RFC 826, November 1982.
[RFC1687] Fleischman, E., "A Large Corporate User's View of IPng",
RFC 1687, August 1994.
[RFC1817] Rekhter, Y., "CIDR and Classful Routing", RFC 1817, August
1995.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP
5, RFC 1918, February 1996.
[RFC2011] McCloghrie, K., "SNMPv2 Management Information Base for
the Internet Protocol using SMIv2", RFC 2011, November
1996.
[RFC2096] Baker, F., "IP Forwarding Table MIB", RFC 2096, January
1997.
[RFC2827] Ferguson, P. and D. Senie, "Network Ingress Filtering:
Defeating Denial of Service Attacks which employ IP Source
Address Spoofing", BCP 38, RFC 2827, May 2000.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous
Point (RP) Address in an IPv6 Multicast Address", RFC
3956, November 2004.
[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005.
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[RFC4038] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E.
Castro, "Application Aspects of IPv6 Transition", RFC
4038, March 2005.
[RFC4057] Bound, J., "IPv6 Enterprise Network Scenarios", RFC 4057,
June 2005.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213, October 2005.
[RFC4293] Routhier, S., "Management Information Base for the
Internet Protocol (IP)", RFC 4293, April 2006.
[RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, April
2006.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006.
[RFC4443] Conta, A., Deering, S., and M. Gupta, "Internet Control
Message Protocol (ICMPv6) for the Internet Protocol
Version 6 (IPv6) Specification", RFC 4443, March 2006.
[RFC4659] De Clercq, J., Ooms, D., Carugi, M., and F. Le Faucheur,
"BGP-MPLS IP Virtual Private Network (VPN) Extension for
IPv6 VPN", RFC 4659, September 2006.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering
ICMPv6 Messages in Firewalls", RFC 4890, May 2007.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, September 2007.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095, December
2007.
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[RFC7012] Claise, B. and B. Trammell, "Information Model for IP Flow
Information Export (IPFIX)", RFC 7012, September 2013.
[RFC5157] Chown, T., "IPv6 Implications for Network Scanning", RFC
5157, March 2008.
[RFC5211] Curran, J., "An Internet Transition Plan", RFC 5211, July
2008.
[RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
March 2008.
[RFC5375] Van de Velde, G., Popoviciu, C., Chown, T., Bonness, O.,
and C. Hahn, "IPv6 Unicast Address Assignment
Considerations", RFC 5375, December 2008.
[RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments",
RFC 5722, December 2009.
[RFC5798] Nadas, S., "Virtual Router Redundancy Protocol (VRRP)
Version 3 for IPv4 and IPv6", RFC 5798, March 2010.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952, August 2010.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
October 2010.
[RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement
Problem Statement", RFC 6104, February 2011.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
February 2011.
[RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 6106, November 2010.
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation", RFC 6144, April 2011.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011.
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[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
[RFC6147] Bagnulo, M., Sullivan, A., Matthews, P., and I. van
Beijnum, "DNS64: DNS Extensions for Network Address
Translation from IPv6 Clients to IPv4 Servers", RFC 6147,
April 2011.
[RFC6177] Narten, T., Huston, G., and L. Roberts, "IPv6 Address
Assignment to End Sites", BCP 157, RFC 6177, March 2011.
[RFC6164] Kohno, M., Nitzan, B., Bush, R., Matsuzaki, Y., Colitti,
L., and T. Narten, "Using 127-Bit IPv6 Prefixes on Inter-
Router Links", RFC 6164, April 2011.
[RFC6192] Dugal, D., Pignataro, C., and R. Dunn, "Protecting the
Router Control Plane", RFC 6192, March 2011.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
Translation", RFC 6296, June 2011.
[RFC6302] Durand, A., Gashinsky, I., Lee, D., and S. Sheppard,
"Logging Recommendations for Internet-Facing Servers", BCP
162, RFC 6302, June 2011.
[RFC6434] Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
Requirements", RFC 6434, December 2011.
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, April 2012.
[RFC6583] Gashinsky, I., Jaeggli, J., and W. Kumari, "Operational
Neighbor Discovery Problems", RFC 6583, March 2012.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012.
[RFC6866] Carpenter, B. and S. Jiang, "Problem Statement for
Renumbering IPv6 Hosts with Static Addresses in Enterprise
Networks", RFC 6866, February 2013.
[RFC6879] Jiang, S., Liu, B., and B. Carpenter, "IPv6 Enterprise
Network Renumbering Scenarios, Considerations, and
Methods", RFC 6879, February 2013.
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[RFC6883] Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet
Content Providers and Application Service Providers", RFC
6883, March 2013.
[RFC6959] McPherson, D., Baker, F., and J. Halpern, "Source Address
Validation Improvement (SAVI) Threat Scope", RFC 6959, May
2013.
[RFC6964] Templin, F., "Operational Guidance for IPv6 Deployment in
IPv4 Sites Using the Intra-Site Automatic Tunnel
Addressing Protocol (ISATAP)", RFC 6964, May 2013.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC7045 , December 2013,
<http://tools.ietf.org/html/rfc7045>.
[I-D.xli-behave-divi]
Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual-
Stateless IPv4/IPv6 Translation", draft-xli-behave-divi-06
(work in progress), January 2014.
[I-D.wierenga-ietf-eduroam]
Wierenga, K., Winter, S., and T. Wolniewicz, "The eduroam
architecture for network roaming", draft-wierenga-ietf-
eduroam-01 (work in progress), July 2013.
[I-D.ietf-v6ops-dc-ipv6]
Lopez, D., Chen, Z., Tsou, T., Zhou, C., and A. Servin,
"IPv6 Operational Guidelines for Datacenters", draft-ietf-
v6ops-dc-ipv6-00 (work in progress), August 2013.
[I-D.ietf-v6ops-design-choices]
Matthews, P., "Design Choices for IPv6 Networks", draft-
ietf-v6ops-design-choices-00 (work in progress), February
2013.
[I-D.ietf-opsec-v6]
Chittimaneni, K., Kaeo, M., and E. Vyncke, "Operational
Security Considerations for IPv6 Networks", draft-ietf-
opsec-v6-04 (work in progress), October 2013.
[I-D.ietf-opsec-ipv6-host-scanning]
Gont, F. and T. Chown, "Network Reconnaissance in IPv6
Networks", draft-ietf-opsec-ipv6-host-scanning-02 (work in
progress), July 2013.
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[I-D.ietf-opsec-ipv6-implications-on-ipv4-nets]
Gont, F. and W. Will, "Security Implications of IPv6 on
IPv4 Networks", draft-ietf-opsec-ipv6-implications-on-
ipv4-nets-07 (work in progress), December 2013.
[I-D.ietf-v6ops-ra-guard-implementation]
Gont, F., "Implementation Advice for IPv6 Router
Advertisement Guard (RA-Guard)", draft-ietf-v6ops-ra-
guard-implementation-07 (work in progress), November 2012.
[I-D.liu-bonica-dhcpv6-slaac-problem]
Liu, B. and R. Bonica, "DHCPv6/SLAAC Address Configuration
Interaction Problem Statement", draft-liu-bonica-dhcpv6
-slaac-problem-02 (work in progress), September 2013.
[I-D.ietf-v6ops-ula-usage-recommendations]
Liu, B., Jiang, S., and C. Byrne, "Recommendations of
Using Unique Local Addresses", draft-ietf-v6ops-ula-usage-
recommendations-01 (work in progress), October 2013.
[SMURF] "CERT Advisory CA-1998-01 Smurf IP Denial-of-Service
Attacks",
<http://www.cert.org/advisories/CA-1998-01.html>.
[CYMRU] "THE BOGON REFERENCE",
<http://www.team-cymru.org/Services/Bogons/>.
Authors' Addresses
Kiran K. Chittimaneni
Google Inc.
1600 Amphitheater Pkwy
Mountain View, California CA 94043
USA
Email: kk@google.com
Tim Chown
University of Southampton
Highfield
Southampton, Hampshire SO17 1BJ
United Kingdom
Email: tjc@ecs.soton.ac.uk
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Lee Howard
Time Warner Cable
13820 Sunrise Valley Drive
Herndon, VA 20171
US
Phone: +1 703 345 3513
Email: lee.howard@twcable.com
Victor Kuarsingh
Dyn Inc
150 Dow Street
Manchester, NH
US
Email: victor@jvknet.com
Yanick Pouffary
Hewlett Packard
950 Route Des Colles
Sophia-Antipolis 06901
France
Email: Yanick.Pouffary@hp.com
Eric Vyncke
Cisco Systems
De Kleetlaan 6a
Diegem 1831
Belgium
Phone: +32 2 778 4677
Email: evyncke@cisco.com
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