One document matched: draft-carpenter-v6ops-icp-guidance-03.xml
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<rfc ipr="trust200902" docName="draft-carpenter-v6ops-icp-guidance-03" category="info" >
<front>
<title abbrev="IPv6 ICP and ASP Guidance">IPv6 Guidance for Internet Content and Application Service Providers</title>
<author initials="B. E." surname="Carpenter" fullname="Brian Carpenter">
<organization abbrev="Univ. of Auckland"></organization>
<address>
<postal>
<street>Department of Computer Science</street>
<street>University of Auckland</street>
<street>PB 92019</street>
<city>Auckland</city>
<region></region>
<code>1142</code>
<country>New Zealand</country>
</postal>
<email>brian.e.carpenter@gmail.com</email>
</address>
</author>
<author fullname="Sheng Jiang" initials="S." surname="Jiang">
<organization>Huawei Technologies Co., Ltd</organization>
<address>
<postal>
<street>Q14, Huawei Campus</street>
<street>No.156 Beiqing Road</street>
<city>Hai-Dian District, Beijing</city>
<code>100095</code>
<country>P.R. China</country>
</postal>
<email>jiangsheng@huawei.com</email>
</address>
</author>
<date day="23" month="February" year="2012" />
<area>Operations and Management</area>
<workgroup>V6OPS</workgroup>
<abstract>
<t>This document provides guidance and suggestions for Internet Content Providers and Application Service Providers
who wish to offer their service to both IPv6 and IPv4 customers. Many of the points will also apply to any enterprise
network preparing for IPv6 users.
</t>
</abstract>
</front>
<middle>
<section anchor="intro" title="Introduction">
<t>The deployment of IPv6 <xref target="RFC2460"/> is now in progress, and users
with no IPv4 access are likely to appear in increasing
numbers in the coming years. Any provider of content or application services over the Internet will need to arrange for
IPv6 access or else risk losing large numbers of potential customers. The time for action is now, while
the number of such customers is small, so that appropriate skills, software and equipment can be acquired
in good time to scale up the IPv6 service as demand increases. An additional advantage of early support for
IPv6 customers is that it will reduce the number of customers connecting later via IPv4 "extension" solutions
such as double NAT, which will otherwise degrade the user experience. </t>
<t>Nevertheless, it is important that the introduction of IPv6 service should not make service for IPv4
customers worse. In some circumstances, technologies intended to assist in the transition from IPv4 to IPv6
are known to have negative effects on the user experience. A deployment strategy for IPv6 must avoid these
effects as much as possible. </t>
<t>The purpose of this document is to provide guidance and suggestions for Internet Content Providers (ICPs)
and Application Service Providers (ASPs) who wish to offer their services to both IPv6 and IPv4 customers.
For simplicity, the term ICP is mainly used in the body of this document, but the guidance
also applies to ASPs. Many of the points in this document will also apply to enterprise networks that do not
classify themselves as ICPs. Any enterprise or department that runs at least one externally accessible
server, such as an HTTP server, may also be concerned. Although specific managerial and technical
approaches are described, this is not a rule book; each operator will need to make its own plan, tailored
to its own services and customers. </t>
</section> <!-- intro -->
<section anchor="strat" title="General Strategy">
<t>The most importance advice here is to actually have a general strategy. Adding support for
a second network layer protocol is a new departure for most modern organisations, and it cannot
be done casually on a day-by-day basis. Even if it is impossible to write a precisely dated
plan, the intended steps in the process need to be defined well in advance. There is no single
blueprint for this. The rest of this document is meant to provide a set of topics to be taken
into account in defining the strategy. </t>
<t>In determining the urgency of this strategy, it should be noted that the central IPv4 registry
(IANA) ran out of spare blocks of IPv4 addresses in February 2011 and the various regional
registries are expected to exhaust their reserves over the next one to two years. After this, Internet
Service Providers (ISPs) will run out at dates determined by their own customer base. No precise
date can be given for when IPv6-only customers will appear in commercially significant numbers,
but - particularly in the case of mobile users - it may be quite soon. Complacency about this
is therefore not an option for any ICP that wishes to grow its customer base over the coming
years. </t>
<t>The most common strategy for an ICP is to provide dual stack services - both IPv4 and IPv6
on an equal basis - to cover both existing and future customers. This is the recommended
strategy in <xref target="RFC6180"/> for straightforward situations. Some ICPs who already have
satisfactory operational experience with IPv6 might consider an IPv6-only strategy, with IPv4
clients being supported by translation or proxy at their ISP border. However, the present document
is addressed to ICPs without IPv6 experience, who are likely to prefer the dual stack model to build
on their existing IPv4 service. </t>
<t>Within the dual stack model,
two approaches could be adopted, sometimes referred to as "outside in" and "inside out":</t>
<t><list style = "symbols">
<t>Outside in: start by providing external users with an IPv6 public access to your services,
for example by running a reverse proxy that handles IPv6 customers (see <xref target="proxy"/> for details).
Progressively enable IPv6 internally. </t>
<t>Inside out: start by enabling internal networking infrastructure, hosts, and applications
to support IPv6. Progressively reveal IPv6 access to external customers. </t>
</list></t>
<t>Which of these approaches to adopt depends on the precise circumstances of the ICP concerned.
"Outside in" has the benefit of giving interested customers IPv6 access at an early stage, and thereby
gaining precious operational experience, before meticulously updating every piece of equipment
and software. For example, if some back-office system, that is never exposed to users, only supports
IPv4, it will not cause delay. "Inside out" has the benefit of completing the implementation of
IPv6 as a single project. Any ICP could choose this approach, but it might be most appropriate
for a small ICP without complex back-end systems. </t>
<t>A point that must be considered in the strategy is that some customers will remain IPv4-only for
many years, others will have both IPv4 and IPv6 access, and yet others will have only IPv6. Additionally,
mobile customers may find themselves switching between IPv4 and IPv6 access as they travel, even within
a single session. Services and applications must be able to deal with this, just as easily as they
deal today with a user whose IPv4 address changes (see the discussion of cookies in <xref target="appl"/>). </t>
<t>Neverthless, the end goal is to have a network that does not need major changes when at some point
in the future it becomes possible to transition to IPv6-only, even if only for some parts of the network.
That is, the IPv6 deployment should be designed in such a way as to more or less assume that IPv4 is
absent, so the network will function seamlessly when it is indeed no longer there. </t>
<t>An important first step in every strategy is to determine from every hardware and software
supplier details of their planned dates for providing full IPv6 support, with performance
equivalent to IPv4, in their products and services. </t>
</section> <!-- strat -->
<section anchor="edu" title="Education and Skills">
<t>Some older staff may have experience of running multiprotocol networks, which were common
twenty years ago before the dominance of IPv4. However, IPv6 will be new to them, and also
to younger staff brought up on TCP/IP. It is not enough to have one "IPv6 expert" in a team.
On the contrary, everybody who knows about IPv4 needs to know about IPv6, from network architect
to help desk responder. Therefore, an early and essential part of the strategy must be
education, including practical training, so that all staff acquire a general understanding
of IPv6, how it affects basic features such as the DNS, and the relevant practical skills.
To take a trivial example, any staff used to dotted-decimal IPv4 addresses need to become
familiar with the colon-hexadecimal format used for IPv6. </t>
<t>There is an anecdote of one IPv6 deployment in which prefixes including the letters A to F
were avoided by design, to avoid confusing sysadmins unfamiliar with hexadecimal notation.
This is not a desirable result. There is another anecdote of a help desk responder telling a customer
to "disable one-Pv6" in order to solve a problem. It should be a goal to avoid having untrained staff who
don't understand hexadecimal or who can't even spell "IPv6". </t>
<t>It is very useful to have a small laboratory network available for training and self-training
in IPv6, where staff may experiment and make mistakes without disturbing the operational IPv4
service. This lab should run both IPv4 and IPv6, to gain experience with a dual-stack environment
and new features such as having multiple addresses per interface. </t>
<t>A final remark about training is that it should not be given too soon, or it will be forgotten.
Training has a definite need to be done "just in time" in order to properly "stick."
Training, lab experience, and actual deployment should therefore follow each other immediately.
If possible, training should even be combined with actual operational experience. </t>
</section> <!-- edu -->
<section anchor="isp" title="Arranging IPv6 Connectivity">
<t>There are, in theory, two ways to obtain IPv6 connectivity to the Internet. </t>
<t><list style="symbols">
<t>Native. In this case the ISP simply provides IPv6 on exactly the same basis
as IPv4 - it will appear at the ICP's border router(s), which must then be
configured in dual-stack mode to forward IPv6 packets in both directions.
This is by far the better method. An ICP should contact all its ISPs to
verify when they will provide native IPv6 support, whether this has any
financial implications, and whether the same service level agreement will
apply as for IPv4. Any ISP that has no definite plan to offer native IPv6 service
should be avoided. </t>
<t>Tunnel. It is possible to configure an IPv6-in-IPv4 tunnel to a remote ISP
that offers such a service. A dual-stack router in the ICP's network will act
as a tunnel end-point, or this function could be included in the ICP's border router.
<vspace blankLines="1" />
A tunnel is a reasonable way to obtain IPv6 connectivity for initial testing and
skills acquisition. However, it introduces an inevitable extra latency compared
to native IPv6, giving users a noticeably worse response time for complex web pages.
It is also likely to limit the IPv6 MTU size. In normal circumstances, native IPv6
will provide an MTU size of at least 1500 bytes, but it will almost inevitably be less
for a tunnel, possibly as low as 1280 bytes (the minimum MTU allowed for IPv6).
Apart from the resulting loss of efficiency, there are cases in which Path MTU
Discovery fails, therefore IPv6 fragmentation fails, and in this case the lower
tunnel MTU will actually cause connectivity failures for customers.
<vspace blankLines="1" />
For these reasons,
ICPs are strongly recommended to obtain native IPv6 service before attempting
to offer a production-quality service to their users. </t>
</list></t>
</section> <!-- isp -->
<section anchor="site" title="IPv6 Infrastructure">
<section anchor="addr" title="Address and subnet assignment">
<t>An ICP must first decide whether to apply for its own Provider Independent (PI) address prefix for
IPv6. The default is to obtain a Provider Aggregated (PA) prefix from each of its ISPs, and operate
them in parallel. Both solutions are viable in IPv6. However, scaling properties of the wide area
routing system (BGP4) limit the routing of PI prefixes, so only large content providers can
justify the bother and expense of obtaining a PI prefix and convincing their ISPs to route it.
Millions of enterprise networks, including smaller content providers, will use PA prefixes.
In this case, a change of ISP would necessitate a change of the corresponding PA prefix, using
the procedure outlined in <xref target="RFC4192"/>.
<vspace blankLines="1" />
An ICP that has multiple connections via multiple ISPs will have multiple PA prefixes. This results in
multiple PA-based addresses for the servers, or for load balancers if they are in use.
</t>
<t>An ICP may also choose to operate a Unique Local Address prefix <xref target="RFC4193"/> for internal
traffic only, as described in <xref target="RFC4864"/>. </t>
<t>Depending on its projected future size, an ICP might choose to obtain /48 PI or PA prefixes (allowing
16 bits of subnet address) or longer PA prefixes, e.g. /56 (allowing 8 bits of subnet address).
Clearly the choice of /48 is more future-proof. Advice
on the numbering of subnets may be found in <xref target="RFC5375"/>. </t>
<t>Since IPv6 provides for operating multiple prefixes simultaneously, it is important to check that
all relevant tools, such as address management packages, can deal with this. In particular, the need to
allow for multiple PA prefixes with IPv6, and the possible need to renumber, means that using
manually assigned static addresses for servers is problematic <xref target="I-D.carpenter-6renum-static-problem"/>.</t>
<t>Theoretically, it would be possible to operate an ICP's IPv6 network using only Stateless Address
Autoconfiguration <xref target="RFC4862"/>. In practice, an ICP of reasonable size will probably choose to operate
DHCPv6 <xref target="RFC3315"/> and use it to support stateful and/or on-demand address assignment. </t>
</section>
<section anchor="rout" title="Routing">
<t>In a dual stack network, IPv4 and IPv6 routing protocols operate quite independently and in parallel.
The common routing protocols all exist in IPv6 versions, such as OSPFv3 <xref target="RFC5340"/>,
IS-IS <xref target="RFC5308"/>, and even RIPng <xref target="RFC2080"/> <xref target="RFC2081"/>.
For trained staff, there should be no particular difficulty in deploying IPv6 routing without
disturbance to IPv4 services. </t>
<t>The performance impact of dual stack routing needs to be evaluated. In particular, what
performance does the router vendor claim for IPv6? If the performance is significantly inferior
compared to IPv4, will this be an operational problem? To answer this question, the ICP will
need a projected model for the amount of IPv6 traffic expected initially, and its likely
rate of increase. [[Note: further input from the WG is needed on this point.]] </t>
<t>If a site operates multiple PA prefixes as mentioned in <xref target="addr"/>, complexities may appear in
routing configuration. In particular, source-based routing rules may be needed
to ensure that outgoing packets are routed to the appropriate border router and ISP link.
Normally, a packet sourced from an address assigned by ISP X should not be sent via ISP Y,
to avoid ingress filtering by Y <xref target="RFC2827"/> <xref target="RFC3704"/>.
Additional considerations may be found in <xref target="I-D.ietf-v6ops-ipv6-multihoming-without-ipv6nat"/>. </t>
<t>Each IPv6 subnet normally has a /64 prefix, leaving another 64 bits for the interface identifiers
of individual hosts. In contrast, a typical IPv4 subnet will have no more than 8 bits for the host
identifier, thus limiting the subnet to 256 or fewer hosts. A dual stack design will typically
use the same subnet topology for IPv4 and IPv6, and therefore the same router topology. This means
that the limited subnet size of IPv4 will be imposed on IPv6. It would be theoretically possible to
avoid this limitation by implementing a different subnet and router topology for IPv6, for example
by ingenious use of VLANs. This is not advisable, as it would result in extremely complex
fault diagnosis when something went wrong. </t>
</section>
<section title="DNS">
<t>This is largely a case of "just do it." Each externally visible host
(or virtual host) that has an A record for its IPv4 address needs an AAAA
record <xref target="RFC3596"/> for its IPv6 address, and a reverse entry if applicable. One important
detail is that some clients (especially Windows XP) can only resolve DNS names
via IPv4, even if they can use IPv6 for application traffic. It is therefore
advisable for all DNS servers to respond to queries via both IPv4 and IPv6. </t>
</section>
</section> <!-- site -->
<section anchor="load" title="Load Balancers">
<t>It is to be expected that IPv6 traffic will initially be low, i.e. a small percentage of IPv4 traffic. For this reason,
updating load balancers to fully support IPv6 can perhaps be delayed; however, such an update needs to be planned
in anticipation of significant growth over a period of several years. The same would apply to TLS or HTTP
proxies used for load balancing purposes. It is important to obtain appropriate assurances from
vendors about their IPv6 support, including performance aspects (as discussed for routers in <xref target="rout"/>). </t>
</section> <!-- load -->
<section anchor="proxy" title="Proxies">
<t>An HTTP proxy <xref target="RFC2616"/> can readily be configured to handle incoming connections over IPv6 and to proxy them
to a server over IPv4. Therefore, a single proxy can be used as the first step in an outside-in strategy, as
shown in the following diagram: </t>
<figure><artwork>
___________________________________________
( )
( IPv6 Clients in the Internet )
(___________________________________________)
|
-------------
| Ingress |
| router |
-------------
____________|_____________
|
-------------
| IPv6 stack|
|-----------|
| HTTP proxy|
|-----------|
| IPv4 stack|
-------------
____________|_____________
|
-------------
| IPv4 stack|
|-----------|
| HTTP |
| server |
-------------
</artwork> </figure>
<t>In this case, the AAAA record for the service would provide the IPv6 address of the proxy.
This approach will work for any HTTP or HTTPS applications that operate successfully
via a proxy, as long as IPv6 load remains low. </t>
</section> <!-- proxy -->
<section anchor="serv" title="Servers">
<section title="Network Stack">
<t>The TCP/IP network stacks in popular operating systems have supported IPv6 for many years. In most
cases, it is sufficient to enable IPv6 and possibly DHCPv6; the rest will follow. Servers inside an ICP network will
not need to support any transition technologies beyond a simple dual stack, with a possible exception
for 6to4 mitigation noted below in <xref target="xition"/>. </t>
</section>
<section anchor="appl" title="Application Layer">
<t>Basic HTTP servers have been able to handle an IPv6-enabled network stack for some years, so at the most
it will be necessary to update to a more recent software version. The same is true of generic applications
such as email protocols. No general statement can be made about other applications, especially proprietary
ones, so each ASP will need to make its own determination. </t>
<t>One important recommendation here is that all applications should use domain names, which are IP-version-independent,
rather than IP addresses. Applications based on middlware platforms which have uniform support for IPv4 and IPv6,
for example Java, may be able to support both IPv4 and IPv6 naturally without additional work. </t>
<t>A specific issue for HTTP-based services is that IP address-based cookie authentication schemes
will need to deal with dual-stack clients. Servers might create a cookie for an
IPv4 connection or an IPv6 connection, depending on the setup at the client site and
on the whims of the client operating system. There is no guarentee that a given client
will consistently use the same address family, especially when accessing a collection
of sites rather than a single site. If the client is using privacy addresses <xref target="RFC4941"/>,
the IPv6 address (but not its /64 prefix) might change quite frequently. Any cookie mechanism
based on 32-bit IPv4 addresses will need significant remodelling. </t>
<t>Generic considerations on application transition are discussed in <xref target="RFC4038"/>, but
many of them will not apply to the dual-stack ICP scenario. An ICP that creates and maintains its
own applications will need to review them for any dependency on IPv4. </t>
</section>
<section title="Geolocation">
<t>As time goes on, it is to be assumed that geolocation methods and databases will be updated to
fully support IPv6 prefixes. There is no reason they will be more or less accurate in the long term
than those available for IPv4. However, we can expect many more clients to be mobile
as time goes on, so geolocation based on IP addresses alone may become problematic. Initially, at least,
ICPs may observe some weakness in geolocation for IPv6 clients. </t>
</section>
</section> <!-- serv -->
<section anchor="xition" title="Coping with Transition Technologies">
<t>As mentioned above, an ICP should obtain native IPv6 connectivity from
its ISPs. In this way, the ICP can avoid most of the complexities of the numerous
IPv4-to-IPv6 transition technologies that have been developed; they are all second-best solutions.
However, some clients are sure to be using such technologies. An ICP needs to be aware of
the operational issues this may cause and how to deal with them. </t>
<t>In some cases outside the ICP's control, clients might reach a content server via a network-layer
translator from IPv6 to IPv4. ICPs who are offering a dual stack service and providing both A
and AAAA records, as recommended in this document, should not normally receive traffic from NAT64
translators <xref target="RFC6146"/>. Exceptionally, however, such traffic could arrive via IPv4
from an IPv6-only client whose DNS resolver failed to receive the ICP's AAAA record for some reason.
Such traffic would be indistinguishable from regular IPv4-via-NAT traffic. </t>
<t>Alternatively, ICPs who are offering a dual stack service might exceptionally receive
IPv6 traffic translated from an IPv4-only client that somehow failed to receive the ICP's
A record. An ICP could also receive IPv6 traffic with translated prefixes <xref target="RFC6296"/>.
These two cases would only be an issue if the ICP was offering any service that depends
on the assumption of end-to-end IPv6 address transparency. </t>
<t>In other cases, also outside the ICP's control, IPv6 clients may reach the IPv6 Internet via
some form of IPv6-in-IPv4 tunnel. In this case a variety of problems can arise, the most acute
of which affect clients connected using the Anycast 6to4 solution <xref target="RFC3068"/>.
Advice on how ICPs may mitigate these 6to4 problems is given in Section 4.5. of <xref target="RFC6343"/>.
For the benefit of all tunnelled clients, it is essential to verify
that Path MTU Discovery works correctly (i.e., the relevant ICMPv6 packets are not blocked)
and that the server-side TCP implementation correctly supports the Maximum Segment Size (MSS)
negotiation mechanism <xref target="RFC2923"/> for IPv6 traffic. </t>
<t>Some ICPs have implemented an interim solution to mitigate transition problems
by limiting the visibility of their AAAA records to users with validated IPv6
connectivity <xref target="I-D.ietf-v6ops-v6-aaaa-whitelisting-implications"/>. </t>
<t>Another approach taken by some ICPs is to offer IPv6-only support via a specific DNS
name, e.g., ipv6.example.com, if the primary service is www.example.com. In this case
ipv6.example.com would have an AAAA record only. This has some
value for testing purposes, but is otherwise only of interest to hobbyist users
willing to type in special URLs. </t>
<t>There is little an ICP can do to deal with client-side or remote ISP deficiencies in IPv6 support,
but it is hoped that the "happy eyeballs" <xref target="I-D.ietf-v6ops-happy-eyeballs"/> approach
will improve the ability for clients to deal with such problems. </t>
</section> <!-- xition -->
<section anchor="cdn" title="Content Delivery Networks">
<t>DNS-based techniques for diverting users to Content Delivery Network (CDN) points of presence (POPs)
will work for IPv6, if AAAA records are provided as well as A records. In general the CDN should follow
the recommendations of this document, especially by operating a full dual stack service
at each POP. Additionally, each POP will need to handle IPv6 routing exactly like IPv4,
for example running BGP4+ <xref target="RFC4760"/> if appropriate. </t>
<t>Note that if an ICP supports IPv6 but its CDN does not, its clients will continue to use
IPv4 and any IPv6-only clients will have to use a transition solution of some kind. This is
not a desirable situation, since the ICP's work to support IPv6 will be wasted. The converse is not
true: if the CDN supports IPv6 but the ICP does not, dual-stack and IPv6-only clients will
obtain IPv6 access. </t>
<t>An ICP might face a complex situation, if its CDN provider
supports IPv6 at some POPs but not at others. IPv6-only clients could only be diverted
to a POP supporting IPv6. There are also scenarios where a dual-stack client would be diverted
to a mixture of IPv4 and IPv6 POPs for different URLs, according to the A and AAAA records provided
and the availability of optimisations such as "happy eyeballs." These complications do not affect
the viability of relying on a dual-stack CDN, however. </t>
<t>The CDN itself faces related complexity: "As IPv6 rolls out, it's going to roll
out in pockets, and that's going to make the routing around congestion points that much more
important but also that much harder," stated John Summers of Akamai in 2010.
</t>
</section> <!-- cdn -->
<section anchor="partner" title="Business Partners">
<t>As noted earlier, it is in an ICP's or ASP's best interests that their users have direct
IPv6 connectivity, rather than indirect IPv4 connectivity via double NAT. If the ICP or ASP
has a direct business relationship with some of their clients, or with the networks that connect them to their
clients, they are advised to coordinate with those partners to ensure that they have a plan to enable IPv6.
They should also verify and test that there is first-class IPv6 connectivity end-to-end between the networks concerned.
This is especially true for implementations that require IPv6 support in specialized programs or systems
in order for the IPv6 support on the ICP/ASP side to be useful. </t>
</section> <!-- partner -->
<section anchor="oam" title="Operations and Management">
<t>There is no doubt that, initially, IPv6 deployment will have operational impact, as well as
requiring education and training as mentioned in <xref target="edu"/>. Staff will have to update
network elements such as routers, update configurations, provide information to end users,
and diagnose new problems. However, for an enterprise network, there is plenty of experience,
e.g. on numerous university campuses, showing that dual stack operation is no harder than IPv4-only
in the steady state. </t>
<t>Whatever management, monitoring and logging is performed for IPv4 is also needed for IPv6. Therefore,
all products and tools used for these purposes must be updated to fully support IPv6. Note that
since an IPv6 network may operate with more than one IPv6 prefix and therefore more than
one address per host, the tools must deal with this as a normal situation. This includes
any address management tool in use (see <xref target="addr"/>) as well as tools used
for creating DHCP and DNS configurations. There is significant overlap here with the
tools involved in site renumbering <xref target="I-D.jiang-6renum-enterprise"/>. </t>
<t>As far as possible, however, mutual dependency between IPv4 and IPv6 operations should be avoided.
A failure of one should not cause a failure of the other. One precaution to avoid this would be for
back-end systems such as network management databases to be dual stacked as soon as convenient.
It should also be possible to use IPv4 connectivity to repair IPv6 configurations, and
vice versa. </t>
<t>Dual stack, while necessary, does have management scaling and overhead considerations. As
noted earlier, the long term goal is to move to single-stack IPv6, when the network and
its customers can support this. This is an additional reason why mutual dependency between the
address families should be avoided in the management system in particular; a hidden dependency
on IPv4 that had been forgotten for many years would be highly inconvenient. </t>
</section> <!-- oam -->
<section anchor="security" title="Security Considerations">
<t>Essentially every threat that exists for IPv4 exists or will
exist for IPv6. Therefore, it is essential to update firewalls, intrusion detection
systems, denial of service precautions, and security auditing technology to fully support IPv6.
Otherwise, IPv6 will become an attractive target for attackers. </t>
<t>When multiple PA prefixes are in use as mentioned in <xref target="addr"/>, firewall rules
must allow for all valid prefixes, and must be set up to work as intended even if
packets are sent via one ISP but return packets arrive via another. </t>
<t>Performance aspects of dual stack firewalls must be considered (as discussed for routers in <xref target="rout"/>). </t>
<t>In a dual stack operation, there may be a risk of cross-contamination between the two
protocols. For example, a successful IPv4-based denial of service attack might also
deplete resources needed by the IPv6 service, or vice versa. This risk strengthens the
argument that IPv6 security must be up to the same level as IPv4. </t>
<t>A general overview of techniques to protect an IPv6 network against external attack is given in
<xref target="RFC4864"/>. Assuming an ICP has native IPv6 connectivity, it is advisable to block incoming IPv6-in-IPv4
tunnel traffic using IPv4 protocol type 41. Outgoing traffic of this kind should be blocked except
for the case noted in Section 4.5 of <xref target="RFC6343"/>. ICMPv6 traffic should only be blocked
in accordance with <xref target="RFC4890"/>; in particular, Packet Too Big messages, which are
essential for PMTU discovery, must not be blocked. </t>
<t>Scanning attacks to discover the existence of hosts are much less
likely to succeed for IPv6 than for IPv4 <xref target="RFC5157"/>. However,
this is only true if IPv6 hosts are configured with interface identifiers
that are hard to guess; for example, it is not advisable to manually configure servers
with static interface identifiers starting from "1". </t>
<t>Transport Layer Security version 1.2 <xref target="RFC5246"/> and its predecessors work
correctly with TCP over IPv6, meaning that HTTPS-based security solutions are immediately
applicable. The same should apply to any other transport-layer or application-layer security
techniques. </t>
<t>If an ASP uses IPsec <xref target="RFC4301"/> and IKE <xref target="RFC5996"/>
in any way to secure connections with clients, these too are fully
applicable to IPv6, but only if the software stack at each end has been appropriately updated. </t>
</section> <!-- security -->
<section anchor="iana" title="IANA Considerations">
<t>This document requests no action by IANA. </t>
</section> <!-- iana -->
<section anchor="ack" title="Acknowledgements">
<t>
Valuable contributions were made by Erik Kline. Useful comments were
received from
Tassos Chatzithomaoglou,
Wesley George,
Victor Kuarsingh,
Bing Liu,
John Mann,
and other participants in the V6OPS working group.
</t>
<t>This document was produced using the xml2rfc tool
<xref target="RFC2629"/>.</t>
</section> <!-- ack -->
<section anchor ="changes" title="Change log [RFC Editor: Please remove]">
<t>draft-carpenter-v6ops-icp-guidance-03: additional WG comments, 2012-02-23.</t>
<t>draft-carpenter-v6ops-icp-guidance-02: additional WG comments, 2012-01-07.</t>
<t>draft-carpenter-v6ops-icp-guidance-01: multiple clarifications after WG comments, 2011-12-06.</t>
<t>draft-carpenter-v6ops-icp-guidance-00: original version, 2011-10-22.</t>
</section> <!-- changes -->
</middle>
<back>
<references title="Normative References">
&RFC2460;
&RFC5246;
&RFC4301;
&RFC5996;
&RFC2616;
&RFC4193;
&RFC4862;
&RFC3315;
&RFC5340;
&RFC3596;
&RFC4760;
&RFC5308;
&RFC2080;
&RFC2827;
&RFC3704;
</references>
<references title="Informative References">
&RFC2629;
&RFC6146;
&RFC6343;
&RFC2923;
&RFC5157;
&RFC3068;
&RFC4941;
&RFC4038;
&RFC4864;
&RFC4890;
&RFC5375;
&RFC6180;
&RFC4192;
&RFC6296;
&RFC2081;
&DRAFT-dnswl;
&DRAFT-happy;
&DRAFT-static;
&DRAFT-renum;
&DRAFT-multi;
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 05:57:55 |