draft-ietf-v6ops-6to4-to-historic-09.txt   draft-ietf-v6ops-6to4-to-historic-10.txt 
v6ops WG O. Troan v6ops WG O. Troan
Internet-Draft Cisco Internet-Draft Cisco
Obsoletes: 3068, 6732 (if approved) B. Carpenter, Ed. Obsoletes: 3068, 6732 (if approved) B. Carpenter, Ed.
Intended status: Best Current Practice Univ. of Auckland Intended status: Best Current Practice Univ. of Auckland
Expires: June 13, 2015 December 10, 2014 Expires: July 8, 2015 January 4, 2015
Deprecating Anycast Prefix for 6to4 Relay Routers Deprecating Anycast Prefix for 6to4 Relay Routers
draft-ietf-v6ops-6to4-to-historic-09.txt draft-ietf-v6ops-6to4-to-historic-10.txt
Abstract Abstract
Experience with the "Connection of IPv6 Domains via IPv4 Clouds Experience with the "Connection of IPv6 Domains via IPv4 Clouds
(6to4)" IPv6 transition mechanism defined in RFC 3056 has shown that (6to4)" IPv6 transition mechanism defined in RFC 3056 has shown that
when used in its anycast mode, the mechanism is unsuitable for when used in its anycast mode, the mechanism is unsuitable for
widespread deployment and use in the Internet. This document widespread deployment and use in the Internet. This document
therefore requests that RFC 3068, "An Anycast Prefix for 6to4 Relay therefore requests that RFC 3068, "An Anycast Prefix for 6to4 Relay
Routers", be made obsolete and moved to historic status. It also Routers", be made obsolete and moved to historic status. It also
obsoletes RFC 6732 "6to4 Provider Managed Tunnels". It recommends obsoletes RFC 6732 "6to4 Provider Managed Tunnels". It recommends
skipping to change at page 1, line 40 skipping to change at page 1, line 40
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 13, 2015. This Internet-Draft will expire on July 8, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
There would appear to be little evidence of substantial active use of The original form of the 6to4 transition mechanism [RFC3056] relies
the original form of 6to4 described in [RFC3056]. However, its on unicast addressing. However, its extension specified in "An
extension specified in "An Anycast Prefix for 6to4 Relay Routers" Anycast Prefix for 6to4 Relay Routers" [RFC3068] has been shown to
[RFC3068] has been shown to have severe practical problems when used have severe practical problems when used in the Internet. This
in the Internet. This document requests that RFC 3068 and RFC 6732 document requests that RFC 3068 and RFC 6732 be moved to Historic
be moved to Historic status as defined in section 4.2.4 of [RFC2026]. status as defined in section 4.2.4 of [RFC2026]. It complements the
It complements the deployment guidelines in [RFC6343]. deployment guidelines in [RFC6343].
6to4 was designed to help transition the Internet from IPv4 to IPv6. 6to4 was designed to help transition the Internet from IPv4 to IPv6.
It has been a good mechanism for experimenting with IPv6, but because It has been a good mechanism for experimenting with IPv6, but because
of the high failure rates seen with anycast 6to4 [HUSTON], end users of the high failure rates seen with anycast 6to4 [HUSTON], end users
may end up disabling IPv6 on hosts as a result, and some content may end up disabling IPv6 on hosts as a result, and some content
providers have been reluctant to make content available over IPv6. providers have been reluctant to make content available over IPv6.
[RFC6343] analyses the known operational issues in detail and [RFC6343] analyses the known operational issues in detail and
describes a set of suggestions to improve 6to4 reliability, given the describes a set of suggestions to improve 6to4 reliability, given the
widespread presence of hosts and customer premises equipment that widespread presence of hosts and customer premises equipment that
support it. However, experience shows that operational failures have support it. The advice to disable 6to4 by default has been widely
continued despite this advice being available. Fortunately the adopted in recent operating systems, and the failure modes have been
advice to disable 6to4 by default has been widely adopted in recent widely hidden from users by many browsers adopting the "Happy
operating systems, and the failure modes have been largely hidden Eyeballs" approach [RFC6555].
from users by many browsers adopting the "Happy Eyeballs" approach
[RFC6555]. Nevertheless, a substantial amount of 6to4 traffic is
still observed and the operational problems caused by 6to4 still
occur.
Although facts are hard to obtain, the remaining successful users of Nevertheless, a substantial amount of 6to4 traffic is still observed
anycast 6to4 are likely to be on hosts using the obsolete policy by IPv6 content providers. The remaining successful users of anycast
table [RFC3484] (which prefers 6to4 above IPv4), without Happy 6to4 are likely to be on hosts using the obsolete policy table
Eyeballs, with a route to an operational anycast relay, and accessing [RFC3484], which prefers 6to4 above IPv4, and running without Happy
sites that have a route to an operational return relay. Eyeballs. Furthermore, they must have a route to an operational
anycast relay and they must be accessing an IPv6 host that has a
route to an operational return relay.
However, experience shows that operational failures caused by anycast
6to4 have continued, despite the advice in RFC 6343 being available.
1.1. Related Work
IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) [RFC5969] IPv6 Rapid Deployment on IPv4 Infrastructures (6rd) [RFC5969]
explicitly builds on the 6to4 mechanism, and could be viewed as a explicitly builds on the 6to4 mechanism, using a service provider
superset of 6to4, using a service provider prefix instead of prefix instead of 2002::/16. However, the deployment model is based
2002::/16. However, the deployment model is based on service povider on service provider support, such that 6rd avoids the problems
support, such that 6rd can avoid the problems described here. In observed with anycast 6to4.
this sense, 6rd can be viewed as superseding 6to4 as described in
section 4.2.4 of [RFC2026].
Given that native IPv6 support and various reliable transition The framework for 6to4 Provider Managed Tunnels [RFC6732] is intended
mechanisms are now becoming common, the IETF sees no evolutionary to help a service provider manage 6to4 anycast tunnels. This
future for the 6to4 mechanism. framework only exists because of the problems observed with anycast
6to4.
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC "OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119]. 2119 [RFC2119].
The word "deprecate" and its derivatives are used only in their The word "deprecate" and its derivatives are used only in their
generic sense of "criticize or express disapproval" and do not have generic sense of "criticize or express disapproval" and do not have
any specific normative meaning. A deprecated function might exist in any specific normative meaning. A deprecated function might exist in
the Internet for many years to allow backwards compatibility. the Internet for many years to allow backwards compatibility.
3. 6to4 operational problems 3. 6to4 operational problems
6to4 is a mechanism designed to allow isolated IPv6 islands to reach 6to4 is a mechanism designed to allow isolated IPv6 islands to reach
each other using IPv6 over IPv4 automatic tunneling. To reach the each other using IPv6 over IPv4 automatic tunneling. To reach the
native IPv6 Internet the mechanism uses relay routers both in the native IPv6 Internet the mechanism uses relay routers both in the
forward and reverse direction. The mechanism is supported in many forward and reverse direction. The mechanism is supported in many
IPv6 implementations. With the increased deployment of IPv6, the IPv6 implementations. With the increased deployment of IPv6, the
mechanism has been shown to have a number of fundamental mechanism has been shown to have a number of shortcomings.
shortcomings.
6to4 depends on relays both in the forward and reverse direction to 6to4 depends on relays both in the forward and reverse direction to
enable connectivity with the native IPv6 Internet. A 6to4 node will enable connectivity with the native IPv6 Internet. A 6to4 node will
send IPv4 encapsulated IPv6 traffic to a 6to4 relay, that is send IPv4 encapsulated IPv6 traffic to a 6to4 relay, that is
connected both to the 6to4 cloud and to native IPv6. In the reverse connected both to the 6to4 cloud and to native IPv6. In the reverse
direction a 2002::/16 route is injected into the native IPv6 routing direction a 2002::/16 route is injected into the native IPv6 routing
domain to attract traffic from native IPv6 nodes to a 6to4 relay domain to attract traffic from native IPv6 nodes to a 6to4 relay
router. It is expected that traffic will use different relays in the router. It is expected that traffic will use different relays in the
forward and reverse direction. RFC 3068 adds an extension that forward and reverse direction.
allows the use of a well known IPv4 anycast address to reach the
nearest 6to4 relay in the forward direction.
One model of 6to4 deployment, described in section 5.2 of RFC 3056, One model of 6to4 deployment, described in section 5.2 of RFC 3056,
suggests that a 6to4 router should have a set of managed connections suggests that a 6to4 router should have a set of managed connections
(via BGP connections) to a set of 6to4 relay routers. While this (via BGP connections) to a set of 6to4 relay routers. While this
makes the forward path more controlled, it does not guarantee a makes the forward path more controlled, it does not guarantee a
functional reverse path. In any case this model has the same functional reverse path. In any case this model has the same
operational burden as manually configured tunnels and has seen no operational burden as manually configured tunnels and has seen no
deployment in the public Internet. deployment in the public Internet.
List of some of the known issues with 6to4: RFC 3068 adds an extension that allows the use of a well known IPv4
anycast address to reach the nearest 6to4 relay in the forward
o Use of relays. 6to4 depends on an unknown third party to operate direction. However, this anycast mechanism has a number of
the relays between the 6to4 cloud and the native IPv6 Internet. operational issues and problems, which are described in detail in
o The placement of the relay can lead to increased latency, and in Section 3 of [RFC6343]. This document is intended to deprecate the
the case the relay is overloaded, packet loss. anycast mechanism.
o There is generally no customer relationship between the end-user
and the relay operator, or even a way for the end-user to know who
the relay operator is, so no support is possible.
o A 6to4 relay for the reverse path and an anycast 6to4 relay used
for the forward path, are openly accessible, limited only by the
scope of routing. 6to4 relays can be used to anonymize traffic and
inject attacks into IPv6 that are very difficult to trace.
o 6to4 may silently discard traffic in the case where protocol (41)
is blocked in intermediate firewalls. Even if a firewall sent an
ICMP message unreachable back, an IPv4 ICMP message rarely
contains enough of the original IPv6 packet so that it can be
relayed back to the IPv6 sender. That makes this problem hard to
detect and react upon by the sender of the packet.
o As 6to4 tunnels across the Internet, the IPv4 addresses used must
be globally reachable. RFC 3056 states that a private address
[RFC1918] MUST NOT be used. 6to4 will not work in networks that
employ other addresses with limited topological span. In
particular it will predictably fail in the case of double network
address translation (NAT444).
For further analysis, see [RFC6343].
Peer-to-peer usage of the 6to4 mechanism, not depending on the Peer-to-peer usage of the 6to4 mechanism, not depending on the
anycast mechanism, might exist in the Internet, largely unknown to anycast mechanism, might exist in the Internet, largely unknown to
operators. This is harmless to third parties and the current operators. This is harmless to third parties and the current
document is not intended to prevent such traffic continuing. document is not intended to prevent such traffic continuing.
4. Deprecation 4. Deprecation
This document formally deprecates the anycast 6to4 transition This document formally deprecates the anycast 6to4 transition
mechanism defined in [RFC3068] and the associated anycast IPv4 mechanism defined in [RFC3068] and the associated anycast IPv4
skipping to change at page 5, line 44 skipping to change at page 5, line 24
2002::/16 to their own customers if and only if it leads to a 2002::/16 to their own customers if and only if it leads to a
correctly operating return relay as described in RFC 6343. IPv6-only correctly operating return relay as described in RFC 6343. IPv6-only
service providers, including those operating a NAT64 service service providers, including those operating a NAT64 service
[RFC6146], are advised that their own customers need a route to such [RFC6146], are advised that their own customers need a route to such
a relay in case a residual 6to4 user served by a different service a relay in case a residual 6to4 user served by a different service
provider attempts to communicate with them. provider attempts to communicate with them.
The guidelines in Section 4 of [RFC6343] remain valid for those who The guidelines in Section 4 of [RFC6343] remain valid for those who
choose to continue operating Anycast 6to4 despite its deprecation. choose to continue operating Anycast 6to4 despite its deprecation.
However, 6to4 Provider Managed Tunnels [RFC6732] will no longer be However, 6to4 Provider Managed Tunnels [RFC6732] will no longer be
necessary. necessary, so they are also deprecated by this document.
Incidental references to 6to4 should be reviewed and possibly removed Incidental references to 6to4 should be reviewed and possibly removed
from other IETF documents if and when they are updated. These from other IETF documents if and when they are updated. These
documents include RFC3162, RFC3178, RFC3790, RFC4191, RFC4213, documents include RFC3162, RFC3178, RFC3790, RFC4191, RFC4213,
RFC4389, RFC4779, RFC4852, RFC4891, RFC4903, RFC5157, RFC5245, RFC4389, RFC4779, RFC4852, RFC4891, RFC4903, RFC5157, RFC5245,
RFC5375, RFC5971, RFC6071 and RFC6890. RFC5375, RFC5971, RFC6071 and RFC6890.
5. IANA Considerations 5. IANA Considerations
The document creating the IANA IPv4 Special-Purpose Address Registry The document creating the IANA IPv4 Special-Purpose Address Registry
skipping to change at page 7, line 26 skipping to change at page 7, line 5
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., and B. Haberman, [RFC6890] Cotton, M., Vegoda, L., Bonica, R., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153, RFC "Special-Purpose IP Address Registries", BCP 153, RFC
6890, April 2013. 6890, April 2013.
8.2. Informative References 8.2. Informative References
[HUSTON] Huston, , "Flailing IPv6", December 2010, [HUSTON] Huston, , "Flailing IPv6", December 2010,
<http://www.potaroo.net/ispcol/2010-12/6to4fail.html>. <http://www.potaroo.net/ispcol/2010-12/6to4fail.html>.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets", BCP
5, RFC 1918, February 1996.
[RFC3484] Draves, R., "Default Address Selection for Internet [RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003. Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC3964] Savola, P. and C. Patel, "Security Considerations for [RFC3964] Savola, P. and C. Patel, "Security Considerations for
6to4", RFC 3964, December 2004. 6to4", RFC 3964, December 2004.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4 [RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification", RFC Infrastructures (6rd) -- Protocol Specification", RFC
5969, August 2010. 5969, August 2010.
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