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Internet Engineering Task Force (IETF) K. Chittimaneni
Request for Comments: 7381 Dropbox, Inc.
Category: Informational T. Chown
ISSN: 2070-1721 University of Southampton
L. Howard
Time Warner Cable
V. Kuarsingh
Dyn, Inc.
Y. Pouffary
Hewlett Packard
E. Vyncke
Cisco Systems
October 2014
Enterprise IPv6 Deployment Guidelines
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 document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7381.
Chittimaneni, et al. Informational [Page 1]
RFC 7381 Enterprise IPv6 Deployment October 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
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Enterprise Assumptions . . . . . . . . . . . . . . . . . 5
1.2. IPv4-Only Considerations . . . . . . . . . . . . . . . . 5
1.3. Reasons for a Phased Approach . . . . . . . . . . . . . . 6
2. Preparation and Assessment Phase . . . . . . . . . . . . . . 7
2.1. Program Planning . . . . . . . . . . . . . . . . . . . . 7
2.2. Inventory Phase . . . . . . . . . . . . . . . . . . . . . 8
2.2.1. Network Infrastructure Readiness Assessment . . . . . 8
2.2.2. Application Readiness Assessment . . . . . . . . . . 9
2.2.3. Importance of Readiness Validation and Testing . . . 9
2.3. Training . . . . . . . . . . . . . . . . . . . . . . . . 10
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 . . . . . . . . . . . . . . . . . . . . . . 14
2.7. Tools Assessment . . . . . . . . . . . . . . . . . . . . 16
3. External Phase . . . . . . . . . . . . . . . . . . . . . . . 17
3.1. Connectivity . . . . . . . . . . . . . . . . . . . . . . 18
3.2. Security . . . . . . . . . . . . . . . . . . . . . . . . 19
3.3. Monitoring . . . . . . . . . . . . . . . . . . . . . . . 20
3.4. Servers and Applications . . . . . . . . . . . . . . . . 20
3.5. Network Prefix Translation for IPv6 . . . . . . . . . . . 21
4. Internal Phase . . . . . . . . . . . . . . . . . . . . . . . 21
4.1. Security . . . . . . . . . . . . . . . . . . . . . . . . 22
4.2. Network Infrastructure . . . . . . . . . . . . . . . . . 22
4.3. End-User Devices . . . . . . . . . . . . . . . . . . . . 23
4.4. Corporate Systems . . . . . . . . . . . . . . . . . . . . 24
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 . . . . . . . . . . . . . . . . . . . 28
8. Informative References . . . . . . . . . . . . . . . . . . . 28
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 35
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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 a department
of administrators). Administrators generally support an internal
network, consisting of users' workstations; personal computers;
mobile devices; 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
enterprise 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 (DS-Lite), Mapping of Address and Port
using Translation (MAP-T), Mapping of Address and Port using
Encapsulation (MAP-E), or other transition technologies. Compared to
tunneled or translated service, 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 interest 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
[IPv6-DESIGN] and [RFC5375].
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1.1. Enterprise Assumptions
For the purpose of this document, we assume the following:
o The administrator is considering deploying IPv6 (but see
Section 1.2 below).
o The administrator has existing IPv4 networks and devices that 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 the 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 that minimize the number of flows being tunneled,
translated, or intercepted at any given time. The administrator will
choose transition technologies or strategies that both allow most
traffic to be native and 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,
multihoming, 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,
MAP, or DS Lite. Such logs should be protected for integrity,
safeguarded for privacy, and periodically purged within applicable
regulations for log retention.
Other IPv6 considerations may impact ostensibly IPv4-only networks,
e.g., [RFC6104] describes the rogue IPv6 Router Advertisement (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
[RFC7123].
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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. This document outlines suggested
phases: a Preparation and Assessment Phase, an Internal Phase, and an
External Phase. 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 an
External Phase (enabling IPv6 for Internet-facing systems, as
recommended in [RFC5211]) or an Internal Phase (enabling IPv6 for
internal interconnections first).
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).
Some security considerations are described in [RFC7359].
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 (VMs) 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.
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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,
even in an ostensibly IPv4-only network, as described in
[RFC7123].
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 VMs) 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 "A Large Corporate User's View of
IPng", described in [RFC1687], for reluctance to deploy have largely
been satisfied or overcome in the intervening years.
2. Preparation and Assessment Phase
2.1. Program Planning
Since enabling IPv6 is a change to the most fundamental Internet
Protocol, and since there are so many interdependencies, having a
professional project manager organize the work is highly recommended.
In addition, an executive sponsor should be involved in determining
the goals of enabling IPv6 (which will establish the order of the
phases) and should receive regular updates.
It may be necessary to complete the Preparation Phase before
determining whether to prioritize the Internal or External Phase,
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since needs and readiness assessments are part of that phase. For a
large enterprise, it may take several iterations to really understand
the level of effort required. Depending on the required schedule, it
may be useful to roll IPv6 projects into other architectural upgrades
-- this can be an excellent way to improve the network and reduce
costs. However, 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.
The deployment of IPv6 will not generally stop all other technology
work. Once IPv6 has been identified as an important initiative, all
projects, both new and in progress, will need to be reviewed to
ensure IPv6 support.
It is normal for assessments to continue in some areas while
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).
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 will 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.
IPv6 support will require testing; features often work differently in
vendors' labs than production networks. Some devices and software
will require IPv4 support for IPv6 to work.
The inventory will show 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.
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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. Application 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
application communicates over the network will dictate the steps
required to support IPv6. Applications should avoid instructions
specific to a given IP address family. Any applications that use
APIs, such as the C language, that expose the IP version
specifically, 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 recommended 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.
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2.3. Training
Many organizations falter in IPv6 deployment because of a perceived
training gap. Training is important for those who work with
addresses regularly, as with anyone whose work is changing. Better
knowledge of the reasons IPv6 is being deployed will help inform the
assessment of who needs training and what training they need.
2.4. Security Policy
It is obvious that IPv6 networks should be deployed in a secure way.
The industry has learned 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
the 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 addresses 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 [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, both malefactors and security tools that rely on payload
inspection (Intrusion Prevention System (IPS), firewall, Access
Control List (ACL), IP Flow Information Export (IPFIX) ([RFC7011] and
[RFC7012]), etc.) will be affected. Therefore, IPsec is as useful in
IPv6 as in IPv4 (for example, to establish a VPN overlay over a non-
trusted network or to reserve for some specific applications).
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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
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, including:
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])
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
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part of the IPv6 address to avoid tracking a host by its otherwise
always identical and unique 64-bit Extended Unique Identifier
(EUI-64) based on Media Access Control (MAC). 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
requires additional monitoring and logging of the binding of the IPv6
address to a data-link layer address (see also the monitoring section
in [IPv6-SECURITY], Section 2.5). Some early enterprise deployments
have taken the approach of using 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 RAs, combined with
all advertised prefixes being included without the A bit set (to
prevent the use of stateless autoconfiguration). Of course, this
technique 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 Neighbor Discovery Protocol (NDP).
[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 ACLs (but also stateful
firewalls) are able to process extension headers (this means
understand them enough to parse them to find the upper-layer
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 the
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 [RFC7113].
One of the biggest differences between IPv4 and IPv6 is the
introduction of NDP [RFC4861], which includes a variety of important
IPv6 protocol functions, including those provided in IPv4 by the
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Address Resolution Protocol (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 Neighbor Discovery (SEND)
[RFC3971] and Cryptographically Generated Addresses (CGAs) [RFC3972]
have been defined, they are not widely implemented). The threat
model for RAs 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 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 [RFC6105] and all
work in progress from the Source Address Validation Improvement
(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 behavior.
2.5. Routing
An important design choice to be made is what IGP is to use inside
the network. A variety of IGPs (IS-IS, OSPFv3, and Routing
Information Protocol Next Generation (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; 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. [IPv6-DESIGN] presents advice on the design choices
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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
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. [ULA-USAGE] 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 Local Internet Registry
(LIR) such as an ISP; a Regional Internet Registry (RIR) such as
AfriNIC, APNIC, ARIN, LACNIC, or RIPE-NCC; or a National Internet
Registry (NIR) operated in some countries. The normal allocation is
Provider-Aggregated (PA) address space from the enterprise's ISP, but
use of PA space implies renumbering when changing providers.
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 Stateless
Address Autoconfiguration (SLAAC) or DHCPv6 for client systems.
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Early IPv6 enterprise deployments have used SLAAC both for its
simplicity and the time DHCPv6 has taken to mature. However, DHCPv6
is now very mature; 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 DHCPv6 hosts are identified by a DHCP
Unique Identifier (DUID) rather than a 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. Commonly, either the host will send
DNS updates or the DHCP server will update records. If there is
sufficient trust between the hosts and the DNS server, the hosts may
update (and the enterprise may use SLAAC for addressing). Otherwise,
the DHCPv6 server can be configured to update the DNS server. Note
that an enterprise network with this more controlled environment will
need to disable SLAAC on network segments 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. Some administrators reserve a /64 but configure a small
subnet, such as /112, /126, or /127, to prevent rogue devices from
attaching and getting numbers; an alternative is to monitor traffic
for surprising addresses or Neighbor Discovery (ND) tables for new
entries. Addresses are either configured manually on the server or
reserved on a DHCPv6 server, which may also synchronize forward and
reverse DNS (though see [RFC6866] for considerations on static
addressing). SLAAC is not recommended for servers because of the
need to synchronize RA timers with DNS Times to Live (TTLs) so that
the DNS entry expires at the same time as the address.
All user access networks should be a /64. Point-to-point links where
NDP is not used may also utilize a /127 (see [RFC6164]).
Plan to aggregate at every layer of network hierarchy. There is no
need for variable length subnet mask (VLSM) [RFC1817] in IPv6, and
addressing plans based on conservation of addresses are shortsighted.
Use of prefixes longer then /64 on network segments will break common
IPv6 functions such as SLAAC [RFC4862]. Where multiple VLANs or
other Layer 2 domains converge, allow some room for expansion.
Renumbering due to outgrowing the network plan is a nuisance, so
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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
ULAs 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
ip6.arpa zone. For more details, please refer to Section 4.4 of
[RFC4193].
Enterprise networks are increasingly including 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 that 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 that focus on managing the network and those that are focused
on managing systems and applications on the network. In either
instance, the tools will run on platforms that 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 that 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
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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
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 and are related to
legacy operation in [RFC2096] and [RFC2011]. Updated specifications
are now available in [RFC4292] and [RFC4293] that 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 that
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.
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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 and/or PA IPv6 space.
Enterprises should be aware that, depending on which address type
they selected (PI vs. PA) in their planning phase, they may need to
implement new routing functions and/or behaviors to support their
connectivity to the ISP. In the case of PI, the upstream ISP may
offer options to route the prefix (typically a /48) on the
enterprise's behalf and update the relevant routing databases.
Otherwise, the enterprise may need to perform this task on their own
and use BGP to inject the prefix into the global BGP system.
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, 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 that provide robust tunneled IPv6
connectivity that 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 IPv6 to an
existing IPv4 network. It is generally desirable to have the IPv6
and IPv4 MTU congruent to simplify operations (so the two address
families behave similarly, that is, as expected). 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 Path MTU Discovery (pMTUD) be 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.
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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 (or 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 Packet Too Big: essential to allow Path MTU discovery to work
o Parameter Problem
o Time Exceeded
In addition, NDP messages (including Neighbor Solicitation, RAs,
etc.) are required for local hosts.
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.
Ingress filters and firewalls should follow [RFC5095] in handling
routing extension header type 0, dropping the packet and sending
ICMPv6 Parameter Problem, unless Segments Left = 0 (in which case,
ignore the header).
If an 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
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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 IPFIX
[RFC7012] to report abnormal traffic patterns (such as port scanning,
SYN flooding, and 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) and syslogs
(finding server and system errors). Where NetFlow is used, Version 9
is required for IPv6 support. Monitoring systems should be able to
examine IPv6 traffic, use IPv6 for connectivity, and record IPv6
addresses, and any log parsing tools and reporting need to support
IPv6. Some of this data can be sensitive (including personally
identifiable information) and care in securing it should be taken,
with periodic purges. Integrity protection on logs and sources of
log data is also important to detect unusual behavior
(misconfigurations or attacks). Logs may be used in investigations,
which depend on trustworthy data sources (tamper resistant).
In addition, monitoring of external services (such as web sites)
should be made address specific, so that people are notified when
either the IPv4 or IPv6 version of a site fails.
3.4. Servers and Applications
The path to the servers accessed from the Internet usually involves
security devices (firewall and 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 native dual stack on all devices; but
as part of the phased approach, operators have used the following
techniques 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 an HTTP X-Forward-For header that contains the remote IPv6
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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.
In either of these cases, care should be taken to secure logs for
privacy reasons and to periodically purge them.
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 that 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, how prefixes are
routed towards the Internet, or whether PA or PI addresses are used.
4. Internal Phase
This phase deals with the delivery of IPv6 to the internal user-
facing side of the Information Technology (IT) infrastructure, which
comprises various components such as network devices (routers,
switches, etc.), end-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. Of course, tunnels may 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 Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP) tunnels [RFC5214],
though we would recommend use of dual stack wherever possible.
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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 2.4.3 of this document. 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).
One major issue is threats against ND. 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 the SAVI WG [RFC6959]; see also
Section 2.4.3 of this document 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
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, Multicast Listener Discovery (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 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
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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 in which to provide robust first-hop redundancy is to use the
Virtual Router Redundancy Protocol Version 3 (VRRPv3) for IPv6
[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 least, one of the most important design choices to make
while deploying IPv6 on the internal network is whether to use SLAAC
[RFC4862], the 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 Address Plan and External
Phase sections of this document; see Sections 2.6 and 3,
respectively. 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
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
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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 significant IPv6-capable platforms,
depending on the support of the carrier's data network.
IPv6 support for peripherals varies. Much like servers, printers are
generally configured with a static address (or DHCP reservation) so
clients can discover them reliably.
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. Care with web proxies is advised; a mismatch in the level of
IPv6 support between the client, proxy, and server can cause
communication problems. All monitoring and reporting tools across
the enterprise will 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 to simplify engineering and operations by 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 address space described in RFC 1918 not being large enough
to support the network's growth. In such cases, deploying IPv6-only
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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 in IPv6 only.
If nodes in the network don't need to talk to an IPv4-only node, then
deploying IPv6-only networks should be straightforward. However,
most nodes will need to communicate with some IPv4-only nodes; an
IPv6-only node may, therefore, require a translation mechanism. As
[RFC6144] points out, it is important to look at address translation
as a transition strategy towards running an IPv6-only network.
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. NAT64 [RFC6146]
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. DNS64 [RFC6147] 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. As described in Enterprise
Assumptions, Section 1.1, the administrator will usually want most
traffic or flows to be native and only translate as needed.
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, [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.
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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 that 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
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
Content Delivery Networks (CDNs). An enterprise that relies on a 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. A CDN could enable
external IPv6 content delivery even if the enterprise provides that
content over IPv4.
6.2. Data Center Virtualization
IPv6 Data Center considerations are described in [IPv6-DC].
6.3. University Campus Networks
A number of campus networks around the world have made some initial
IPv6 deployments. 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.
Chittimaneni, et al. Informational [Page 26]
RFC 7381 Enterprise IPv6 Deployment October 2014
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 mail exchange (MX) services.
This ensures 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 [EDUROAM] is the de facto
wireless roaming system for academic networks and uses
authentication based on 802.1X, 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 that 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 they may wish to consider support for specific IPv6
multicast functionality, e.g., the Embedded Rendezvous Point
Chittimaneni, et al. Informational [Page 27]
RFC 7381 Enterprise IPv6 Deployment October 2014
(Embedded-RP) [RFC3956] in routers and MLDv1 and MLDv2 snooping in
switches.
7. Security Considerations
This document has multiple security sections detailing with how to
securely deploy an IPv6 network within an enterprise network.
8. Informative References
[CYMRU] Team CYMRU Community Services, "THE BOGON REFERENCE",
Version 7, April 2012,
<http://www.team-cymru.org/Services/Bogons/>.
[DHCPv6-SLAAC-PROBLEM]
Liu, B. and R. Bonica, "DHCPv6/SLAAC Address Configuration
Interaction Problem Statement", Work in Progress, draft-
liu-bonica-dhcpv6-slaac-problem-02, September 2013.
[DIVI] Bao, C., Li, X., Zhai, Y., and W. Shang, "dIVI: Dual-
Stateless IPv4/IPv6 Translation", Work in Progress, draft-
xli-behave-divi-06, January 2014.
[EDUROAM] Wierenga, K., Winter, S., and T. Wolniewicz, "The eduroam
architecture for network roaming", Work in Progress,
draft-wierenga-ietf-eduroam-04, August 2014.
[HOST-SCANNING]
Gont, F. and T. Chown, "Network Reconnaissance in IPv6
Networks", Work in Progress, draft-ietf-opsec-ipv6-host-
scanning-04, June 2014.
[IPv6-DC] Lopez, D., Chen, Z., Tsou, T., Zhou, C., and A. Servin,
"IPv6 Operational Guidelines for Datacenters", Work in
Progress, draft-ietf-v6ops-dc-ipv6-01, February 2014.
[IPv6-DESIGN]
Matthews, P. and V. Kuarsingh, "Design Choices for IPv6
Networks", Work in Progress, draft-ietf-v6ops-design-
choices-02, September 2014.
[IPv6-SECURITY]
Chittimaneni, K., Kaeo, M., and E. Vyncke, "Operational
Security Considerations for IPv6 Networks", Work in
Progress, draft-ietf-opsec-v6-04, October 2013.
Chittimaneni, et al. Informational [Page 28]
RFC 7381 Enterprise IPv6 Deployment October 2014
[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,
<http://www.rfc-editor.org/info/rfc826>.
[RFC1687] Fleischman, E., "A Large Corporate User's View of IPng",
RFC 1687, August 1994,
<http://www.rfc-editor.org/info/rfc1687>.
[RFC1817] Rekhter, Y., "CIDR and Classful Routing", RFC 1817, August
1995, <http://www.rfc-editor.org/info/rfc1817>.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP
5, RFC 1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>.
[RFC2011] McCloghrie, K., "SNMPv2 Management Information Base for
the Internet Protocol using SMIv2", RFC 2011, November
1996, <http://www.rfc-editor.org/info/rfc2011>.
[RFC2096] Baker, F., "IP Forwarding Table MIB", RFC 2096, January
1997, <http://www.rfc-editor.org/info/rfc2096>.
[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,
<http://www.rfc-editor.org/info/rfc2827>.
[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,
<http://www.rfc-editor.org/info/rfc3315>.
[RFC3956] Savola, P. and B. Haberman, "Embedding the Rendezvous
Point (RP) Address in an IPv6 Multicast Address", RFC
3956, November 2004,
<http://www.rfc-editor.org/info/rfc3956>.
[RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005,
<http://www.rfc-editor.org/info/rfc3971>.
[RFC3972] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005,
<http://www.rfc-editor.org/info/rfc3972>.
Chittimaneni, et al. Informational [Page 29]
RFC 7381 Enterprise IPv6 Deployment October 2014
[RFC4038] Shin, M-K., Hong, Y-G., Hagino, J., Savola, P., and E.
Castro, "Application Aspects of IPv6 Transition", RFC
4038, March 2005,
<http://www.rfc-editor.org/info/rfc4038>.
[RFC4057] Bound, J., "IPv6 Enterprise Network Scenarios", RFC 4057,
June 2005, <http://www.rfc-editor.org/info/rfc4057>.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005,
<http://www.rfc-editor.org/info/rfc4193>.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213, October 2005,
<http://www.rfc-editor.org/info/rfc4213>.
[RFC4292] Haberman, B., "IP Forwarding Table MIB", RFC 4292, April
2006, <http://www.rfc-editor.org/info/rfc4292>.
[RFC4293] Routhier, S., "Management Information Base for the
Internet Protocol (IP)", RFC 4293, April 2006,
<http://www.rfc-editor.org/info/rfc4293>.
[RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private
Networks (VPNs)", RFC 4364, February 2006,
<http://www.rfc-editor.org/info/rfc4364>.
[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,
<http://www.rfc-editor.org/info/rfc4443>.
[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,
<http://www.rfc-editor.org/info/rfc4659>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007, <http://www.rfc-editor.org/info/rfc4861>.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC4890] Davies, E. and J. Mohacsi, "Recommendations for Filtering
ICMPv6 Messages in Firewalls", RFC 4890, May 2007,
<http://www.rfc-editor.org/info/rfc4890>.
Chittimaneni, et al. Informational [Page 30]
RFC 7381 Enterprise IPv6 Deployment October 2014
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
[RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
of Type 0 Routing Headers in IPv6", RFC 5095, December
2007, <http://www.rfc-editor.org/info/rfc5095>.
[RFC5157] Chown, T., "IPv6 Implications for Network Scanning", RFC
5157, March 2008,
<http://www.rfc-editor.org/info/rfc5157>.
[RFC5211] Curran, J., "An Internet Transition Plan", RFC 5211, July
2008, <http://www.rfc-editor.org/info/rfc5211>.
[RFC5214] Templin, F., Gleeson, T., and D. Thaler, "Intra-Site
Automatic Tunnel Addressing Protocol (ISATAP)", RFC 5214,
March 2008, <http://www.rfc-editor.org/info/rfc5214>.
[RFC5375] Van de Velde, G., Popoviciu, C., Chown, T., Bonness, O.,
and C. Hahn, "IPv6 Unicast Address Assignment
Considerations", RFC 5375, December 2008,
<http://www.rfc-editor.org/info/rfc5375>.
[RFC5722] Krishnan, S., "Handling of Overlapping IPv6 Fragments",
RFC 5722, December 2009,
<http://www.rfc-editor.org/info/rfc5722>.
[RFC5798] Nadas, S., "Virtual Router Redundancy Protocol (VRRP)
Version 3 for IPv4 and IPv6", RFC 5798, March 2010,
<http://www.rfc-editor.org/info/rfc5798>.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952, August 2010,
<http://www.rfc-editor.org/info/rfc5952>.
[RFC6052] Bao, C., Huitema, C., Bagnulo, M., Boucadair, M., and X.
Li, "IPv6 Addressing of IPv4/IPv6 Translators", RFC 6052,
October 2010, <http://www.rfc-editor.org/info/rfc6052>.
[RFC6104] Chown, T. and S. Venaas, "Rogue IPv6 Router Advertisement
Problem Statement", RFC 6104, February 2011,
<http://www.rfc-editor.org/info/rfc6104>.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
February 2011, <http://www.rfc-editor.org/info/rfc6105>.
Chittimaneni, et al. Informational [Page 31]
RFC 7381 Enterprise IPv6 Deployment October 2014
[RFC6106] Jeong, J., Park, S., Beloeil, L., and S. Madanapalli,
"IPv6 Router Advertisement Options for DNS Configuration",
RFC 6106, November 2010,
<http://www.rfc-editor.org/info/rfc6106>.
[RFC6144] Baker, F., Li, X., Bao, C., and K. Yin, "Framework for
IPv4/IPv6 Translation", RFC 6144, April 2011,
<http://www.rfc-editor.org/info/rfc6144>.
[RFC6145] Li, X., Bao, C., and F. Baker, "IP/ICMP Translation
Algorithm", RFC 6145, April 2011,
<http://www.rfc-editor.org/info/rfc6145>.
[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,
<http://www.rfc-editor.org/info/rfc6146>.
[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, <http://www.rfc-editor.org/info/rfc6147>.
[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,
<http://www.rfc-editor.org/info/rfc6164>.
[RFC6177] Narten, T., Huston, G., and L. Roberts, "IPv6 Address
Assignment to End Sites", BCP 157, RFC 6177, March 2011,
<http://www.rfc-editor.org/info/rfc6177>.
[RFC6192] Dugal, D., Pignataro, C., and R. Dunn, "Protecting the
Router Control Plane", RFC 6192, March 2011,
<http://www.rfc-editor.org/info/rfc6192>.
[RFC6296] Wasserman, M. and F. Baker, "IPv6-to-IPv6 Network Prefix
Translation", RFC 6296, June 2011,
<http://www.rfc-editor.org/info/rfc6296>.
[RFC6302] Durand, A., Gashinsky, I., Lee, D., and S. Sheppard,
"Logging Recommendations for Internet-Facing Servers", BCP
162, RFC 6302, June 2011,
<http://www.rfc-editor.org/info/rfc6302>.
[RFC6434] Jankiewicz, E., Loughney, J., and T. Narten, "IPv6 Node
Requirements", RFC 6434, December 2011,
<http://www.rfc-editor.org/info/rfc6434>.
Chittimaneni, et al. Informational [Page 32]
RFC 7381 Enterprise IPv6 Deployment October 2014
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, April 2012,
<http://www.rfc-editor.org/info/rfc6555>.
[RFC6583] Gashinsky, I., Jaeggli, J., and W. Kumari, "Operational
Neighbor Discovery Problems", RFC 6583, March 2012,
<http://www.rfc-editor.org/info/rfc6583>.
[RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, September 2012,
<http://www.rfc-editor.org/info/rfc6724>.
[RFC6866] Carpenter, B. and S. Jiang, "Problem Statement for
Renumbering IPv6 Hosts with Static Addresses in Enterprise
Networks", RFC 6866, February 2013,
<http://www.rfc-editor.org/info/rfc6866>.
[RFC6879] Jiang, S., Liu, B., and B. Carpenter, "IPv6 Enterprise
Network Renumbering Scenarios, Considerations, and
Methods", RFC 6879, February 2013,
<http://www.rfc-editor.org/info/rfc6879>.
[RFC6883] Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet
Content Providers and Application Service Providers", RFC
6883, March 2013,
<http://www.rfc-editor.org/info/rfc6883>.
[RFC6959] McPherson, D., Baker, F., and J. Halpern, "Source Address
Validation Improvement (SAVI) Threat Scope", RFC 6959, May
2013, <http://www.rfc-editor.org/info/rfc6959>.
[RFC6964] Templin, F., "Operational Guidance for IPv6 Deployment in
IPv4 Sites Using the Intra-Site Automatic Tunnel
Addressing Protocol (ISATAP)", RFC 6964, May 2013,
<http://www.rfc-editor.org/rfc/rfc6964.txt>.
[RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of
the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information", STD 77, RFC 7011, September
2013, <http://www.rfc-editor.org/info/rfc7011>.
[RFC7012] Claise, B. and B. Trammell, "Information Model for IP Flow
Information Export (IPFIX)", RFC 7012, September 2013,
<http://www.rfc-editor.org/info/rfc7012>.
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RFC 7381 Enterprise IPv6 Deployment October 2014
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045, December 2013,
<http://www.rfc-editor.org/info/rfc7045>.
[RFC7113] Gont, F., "Implementation Advice for IPv6 Router
Advertisement Guard (RA-Guard)", RFC 7113, February 2014,
<http://www.rfc-editor.org/info/rfc7113>.
[RFC7123] Gont, F. and W. Liu, "Security Implications of IPv6 on
IPv4 Networks", RFC 7123, February 2014,
<http://www.rfc-editor.org/info/rfc7123>.
[RFC7359] Gont, F., "Layer 3 Virtual Private Network (VPN) Tunnel
Traffic Leakages in Dual-Stack Hosts/Networks", RFC 7359,
August 2014, <http://www.rfc-editor.org/info/rfc7359>.
[SMURF] The Cert Division of the Software Engineering Institute,
"Smurf IP Denial-of-Service Attacks", CERT Advisory CA-
1998-01, March 2000,
<http://www.cert.org/advisories/CA-1998-01.html>.
[ULA-USAGE]
Liu, B. and S. Jiang, "Considerations of Using Unique
Local Addresses", Work in Progress, draft-ietf-v6ops-ula-
usage-recommendations-03, July 2014.
Acknowledgements
The authors would like to thank Robert Sparks, Steve Hanna, Tom
Taylor, Brian Haberman, Stephen Farrell, Chris Grundemann, Ray
Hunter, Kathleen Moriarty, Benoit Claise, Brian Carpenter, Tina Tsou,
Christian Jacquenet, and Fred Templin for their substantial comments
and contributions.
Chittimaneni, et al. Informational [Page 34]
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Authors' Addresses
Kiran K. Chittimaneni
Dropbox, Inc.
185 Berry Street, Suite 400
San Francisco, CA 94107
United States
EMail: kk@dropbox.com
Tim Chown
University of Southampton
Highfield
Southampton, Hampshire SO17 1BJ
United Kingdom
EMail: tjc@ecs.soton.ac.uk
Lee Howard
Time Warner Cable
13820 Sunrise Valley Drive
Herndon, VA 20171
United States
Phone: +1 703 345 3513
EMail: lee.howard@twcable.com
Victor Kuarsingh
Dyn, Inc.
150 Dow Street
Manchester, NH
United States
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
Chittimaneni, et al. Informational [Page 35]