draft-ietf-tsvwg-behave-requirements-update-06.txt   draft-ietf-tsvwg-behave-requirements-update-07.txt 
TSVWG R. Penno TSVWG R. Penno
Internet-Draft Cisco Internet-Draft Cisco
Updates: 4787, 5382, 5508 (if approved) S. Perreault Updates: 4787, 5382, 5508 (if approved) S. Perreault
Intended status: Best Current Practice Jive Communications Intended status: Best Current Practice Jive Communications
Expires: July 21, 2016 M. Boucadair, Ed. Expires: August 19, 2016 M. Boucadair, Ed.
Orange Orange
S. Sivakumar S. Sivakumar
Cisco Cisco
K. Naito K. Naito
NTT NTT
January 18, 2016 February 16, 2016
Network Address Translation (NAT) Behavioral Requirements Updates Network Address Translation (NAT) Behavioral Requirements Updates
draft-ietf-tsvwg-behave-requirements-update-06 draft-ietf-tsvwg-behave-requirements-update-07
Abstract Abstract
This document clarifies and updates several requirements of RFC4787, This document clarifies and updates several requirements of RFC4787,
RFC5382 and RFC5508 based on operational and development experience. RFC5382, and RFC5508 based on operational and development experience.
The focus of this document is NAT44. The focus of this document is NAT44.
This document updates RFC4787, RFC5382 and RFC5508. This document updates RFCs 4787, 5382, and 5508.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 July 21, 2016. This Internet-Draft will expire on August 19, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 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
skipping to change at page 2, line 34 skipping to change at page 2, line 34
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. TCP Session Tracking . . . . . . . . . . . . . . . . . . . . 3 2. TCP Session Tracking . . . . . . . . . . . . . . . . . . . . 3
2.1. TCP Transitory Connection Idle-Timeout . . . . . . . . . 5 2.1. TCP Transitory Connection Idle-Timeout . . . . . . . . . 5
2.2. TCP RST . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2. TCP RST . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Port Overlapping Behavior . . . . . . . . . . . . . . . . . . 5 3. Port Overlapping Behavior . . . . . . . . . . . . . . . . . . 5
4. Address Pooling Paired (APP) . . . . . . . . . . . . . . . . 6 4. Address Pooling Paired (APP) . . . . . . . . . . . . . . . . 6
5. EIM Protocol Independence . . . . . . . . . . . . . . . . . . 6 5. Endpoint-Independent Mapping (EIM) Protocol Independence . . 7
6. EIF Protocol Independence . . . . . . . . . . . . . . . . . . 7 6. Endpoint-Independent Filtering (EIF) Protocol Independence . 7
7. EIF Mapping Refresh . . . . . . . . . . . . . . . . . . . . . 7 7. Endpoint-Independent Filtering (EIF) Mapping Refresh . . . . 7
7.1. Outbound Mapping Refresh and Error Packets . . . . . . . 8 7.1. Outbound Mapping Refresh and Error Packets . . . . . . . 8
8. Port Parity . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Port Parity . . . . . . . . . . . . . . . . . . . . . . . . . 8
9. Port Randomization . . . . . . . . . . . . . . . . . . . . . 8 9. Port Randomization . . . . . . . . . . . . . . . . . . . . . 8
10. IP Identification (IP ID) . . . . . . . . . . . . . . . . . . 9 10. IP Identification (IP ID) . . . . . . . . . . . . . . . . . . 9
11. ICMP Query Mappings Timeout . . . . . . . . . . . . . . . . . 9 11. ICMP Query Mappings Timeout . . . . . . . . . . . . . . . . . 9
12. Hairpinning Support for ICMP Packets . . . . . . . . . . . . 9 12. Hairpinning Support for ICMP Packets . . . . . . . . . . . . 9
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
14. Security Considerations . . . . . . . . . . . . . . . . . . . 9 14. Security Considerations . . . . . . . . . . . . . . . . . . . 10
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
15.1. Normative References . . . . . . . . . . . . . . . . . . 10 15.1. Normative References . . . . . . . . . . . . . . . . . . 11
15.2. Informative References . . . . . . . . . . . . . . . . . 11 15.2. Informative References . . . . . . . . . . . . . . . . . 11
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
[RFC4787], [RFC5382] and [RFC5508] greatly advanced Network Address [RFC4787], [RFC5382], and [RFC5508] greatly advanced Network Address
Translation (NAT) interoperability and conformance. Operational Translation (NAT) interoperability and conformance. Operational
experience gained through widespread deployment and evolution of NAT experience gained through widespread deployment and evolution of NAT
indicates that some areas of the original documents need further indicates that some areas of the original documents need further
clarification or updates. This document provides such clarifications clarification or updates. This document provides such clarifications
and updates. and updates.
1.1. Scope 1.1. Scope
The goal of this document is to clarify and update the set of The goal of this document is to clarify and update the set of
requirements listed in [RFC4787], [RFC5382] and [RFC5508]. The requirements listed in [RFC4787], [RFC5382], and [RFC5508]. The
document focuses exclusively on NAT44. document focuses exclusively on NAT44.
The scope of this document has been set so that it does not create The scope of this document has been set so that it does not create
new requirements beyond those specified in the documents cited above. new requirements beyond those specified in the documents cited above.
Carrier-Grade NAT (CGN) related requirements are defined in Carrier-Grade NAT (CGN) related requirements are defined in
[RFC6888]. [RFC6888].
1.2. Terminology 1.2. Terminology
skipping to change at page 5, line 29 skipping to change at page 5, line 29
MAY allow the configured timeout to be less than 4 minutes. MAY allow the configured timeout to be less than 4 minutes.
However, a minimum default transitory connection idle-timeout of 4 However, a minimum default transitory connection idle-timeout of 4
minutes is RECOMMENDED. minutes is RECOMMENDED.
2.2. TCP RST 2.2. TCP RST
[RFC5382] leaves the handling of TCP RST packets unspecified. [RFC5382] leaves the handling of TCP RST packets unspecified.
Update: This document adopts a similar default behavior as in Update: This document adopts a similar default behavior as in
[RFC6146]. Concretely, when the NAT receives a TCP RST matching [RFC6146]. Concretely, when the NAT receives a TCP RST matching
an existing mapping, it MUST translate the packet according the an existing mapping, it MUST translate the packet according to the
NAT mapping entry. Moreover, the NAT SHOULD wait for 4 minutes NAT mapping entry. Moreover, the NAT SHOULD wait for 4 minutes
before deleting the session and removing any state associated with before deleting the session and removing any state associated with
it if no packets are received during that 4 minutes timeout. it if no packets are received during that 4 minutes timeout.
Admittedly, the NAT has to verify whether received TCP RST packets Notes:
belong to a connection. This verification check is required to
avoid off-path attacks.
If the NAT removes immediately the NAT mapping upon receipt of a * Admittedly, the NAT has to verify whether received TCP RST
TCP RST message, stale connections may be maintained by endpoints packets belong to a connection. This verification check is
if the first RST message is lost between the NAT and the required to avoid off-path attacks.
recipient.
* If the NAT removes immediately the NAT mapping upon receipt of
a TCP RST message, stale connections may be maintained by
endpoints if the first RST message is lost between the NAT and
the recipient.
3. Port Overlapping Behavior 3. Port Overlapping Behavior
REQ-1 from [RFC4787] and REQ-1 from [RFC5382] specify a specific port REQ-1 from [RFC4787] and REQ-1 from [RFC5382] specify a specific port
overlapping behavior; that is the external IP address and port can be overlapping behavior; that is the external IP address and port can be
reused for connections originating from the same internal source IP reused for connections originating from the same internal source IP
address and port irrespective of the destination. This is known as address and port irrespective of the destination. This is known as
endpoint-independent mapping (EIM). endpoint-independent mapping (EIM).
Update: This document clarifies that this port overlapping behavior Update: This document clarifies that this port overlapping behavior
skipping to change at page 6, line 25 skipping to change at page 6, line 28
address, destination port). address, destination port).
This enables concurrent use of a single NAT external port for This enables concurrent use of a single NAT external port for
multiple transport sessions, which allows a NAT to successfully multiple transport sessions, which allows a NAT to successfully
process packets in an IP address resource limited network (e.g., process packets in an IP address resource limited network (e.g.,
deployment with high address space multiplicative factor (refer to deployment with high address space multiplicative factor (refer to
Appendix B. of [RFC6269])). Appendix B. of [RFC6269])).
4. Address Pooling Paired (APP) 4. Address Pooling Paired (APP)
The Address Pooling Paired (APP) behavior for a NAT was recommended The "IP address pooling" behavior of "Paired" (APP) was recommended
in REQ-2 from [RFC4787], but the behavior when an external IPv4 runs in REQ-2 from [RFC4787], but the behavior when an external IPv4 runs
out of ports was left undefined. out of ports was left undefined.
Clarification: This document clarifies that if APP is enabled, new Clarification: This document clarifies that if APP is enabled, new
sessions from a host that already has a mapping associated with an sessions from a host that already has a mapping associated with an
external IP that ran out of ports SHOULD be dropped. A external IP that ran out of ports SHOULD be dropped. A
configuration parameter MAY be provided to allow a NAT to starting configuration parameter MAY be provided to allow a NAT to starting
using ports from another external IP address when the one that using ports from another external IP address when the one that
anchored the APP mapping ran out of ports. Tweaking this anchored the APP mapping ran out of ports. Tweaking this
configuration parameter is a trade-off between service continuity configuration parameter is a trade-off between service continuity
skipping to change at page 6, line 47 skipping to change at page 7, line 5
referred as 'soft-APP'. referred as 'soft-APP'.
As a reminder, the recommendation for the particular case of a CGN As a reminder, the recommendation for the particular case of a CGN
is that an implementation must use the same external IP address is that an implementation must use the same external IP address
mapping for all sessions associated with the same internal IP mapping for all sessions associated with the same internal IP
address, be they TCP, UDP, ICMP, something else, or a mix of address, be they TCP, UDP, ICMP, something else, or a mix of
different protocols [RFC6888]. different protocols [RFC6888].
Update: This behavior SHOULD apply also for TCP. Update: This behavior SHOULD apply also for TCP.
5. EIM Protocol Independence 5. Endpoint-Independent Mapping (EIM) Protocol Independence
REQ-1 from [RFC4787] and REQ-1 from [RFC5382] do not specify whether REQ-1 from [RFC4787] and REQ-1 from [RFC5382] do not specify whether
EIM are protocol-dependent or protocol-independent. For example, if EIM are protocol-dependent or protocol-independent. For example, if
an outbound TCP SYN creates a mapping, it is left undefined whether an outbound TCP SYN creates a mapping, it is left undefined whether
outbound UDP packets can reuse such mapping. outbound UDP packets can reuse such mapping.
Update: EIM mappings SHOULD be protocol-dependent. A configuration Update: EIM mappings SHOULD be protocol-dependent. A configuration
parameter MAY be provided to allow protocols that multiplex TCP parameter MAY be provided to allow protocols that multiplex TCP
and UDP over the same source IP address and port number to use a and UDP over the same source IP address and port number to use a
single mapping. The default value of this configuration parameter single mapping. The default value of this configuration parameter
MUST be protocol-dependent EIM. MUST be protocol-dependent EIM.
This update is compliant with the stateful NAT64 [RFC6146] that This update is consistent with the stateful NAT64 [RFC6146] that
clearly specifies three binding information bases (TCP, UDP, clearly specifies three binding information bases (TCP, UDP,
ICMP). ICMP).
6. EIF Protocol Independence 6. Endpoint-Independent Filtering (EIF) Protocol Independence
REQ-8 from [RFC4787] and REQ-3 from [RFC5382] do not specify whether REQ-8 from [RFC4787] and REQ-3 from [RFC5382] do not specify whether
EIF mappings are protocol-independent or protocol-dependent . For mappings with endpoint-independent filtering (EIF) are protocol-
example, if an outbound TCP SYN creates a mapping, it is left independent or protocol-dependent. For example, if an outbound TCP
undefined whether inbound UDP packets matching that mapping should be SYN creates a mapping, it is left undefined whether inbound UDP
accepted or rejected. packets matching that mapping should be accepted or rejected.
Update: EIF filtering SHOULD be protocol-dependent. A configuration Update: EIF filtering SHOULD be protocol-dependent. A configuration
parameter MAY be provided to make it protocol-independent. The parameter MAY be provided to make it protocol-independent. The
default value of this configuration parameter MUST be protocol- default value of this configuration parameter MUST be protocol-
dependent EIF. dependent EIF.
This behavior is aligned with the update in Section 5. This behavior is aligned with the update in Section 5.
Applications that can be transported over a variety of transport Applications that can be transported over a variety of transport
protocols and/or support transport fall back schemes won't protocols and/or support transport fall back schemes won't
experience connectivity failures if the NAT is configured with experience connectivity failures if the NAT is configured with
protocol-independent EIM and protocol-independent EIF. protocol-independent EIM and protocol-independent EIF.
7. EIF Mapping Refresh 7. Endpoint-Independent Filtering (EIF) Mapping Refresh
The NAT mapping Refresh direction may have a "NAT Inbound refresh The NAT mapping Refresh direction may have a "NAT Inbound refresh
behavior" of "True" according to REQ-6 from [RFC4787], but [RFC4787] behavior" of "True" according to REQ-6 from [RFC4787], but [RFC4787]
does not clarify how this behavior applies to EIF mappings. The does not clarify how this behavior applies to EIF mappings. The
issue in question is whether inbound packets that match an EIF issue in question is whether inbound packets that match an EIF
mapping but do not create a new session due to a security policy mapping but do not create a new session due to a security policy
should refresh the mapping timer. should refresh the mapping timer.
Clarification: This document clarifies that even when a NAT has an Clarification: This document clarifies that even when a NAT has an
inbound refresh behavior set to 'TRUE', such packets SHOULD NOT inbound refresh behavior set to 'TRUE', such packets SHOULD NOT
refresh the mapping. Otherwise a simple attack of a packet every refresh the mapping. Otherwise a simple attack of a packet every
2 minutes can keep the mapping indefinitely. 2 minutes can keep the mapping indefinitely.
Update: This behavior SHOULD apply also for TCP. Update: This behavior SHOULD apply also for TCP.
7.1. Outbound Mapping Refresh and Error Packets 7.1. Outbound Mapping Refresh and Error Packets
Update: In the case of NAT outbound refresh behavior, ICMP Errors or Update: In the case of NAT outbound refresh behavior, ICMP Errors or
TCP RST outbound packets, sent as response to inbound packets, TCP RST outbound packets, sent as response to inbound packets,
SHOULD NOT refresh the mapping. SHOULD NOT refresh the mapping. Other packets which indicate the
host is not interested in receiving packets MAY be configurable to
also not refresh state, such as STUN error response [RFC5389] or
IKE INVALID_SYNTAX [RFC7296].
8. Port Parity 8. Port Parity
Update: A NAT MAY disable port parity preservation for all dynamic Update: A NAT MAY disable port parity preservation for all dynamic
mappings. Nevertheless, A NAT SHOULD support means to explicitly mappings. Nevertheless, A NAT SHOULD support means to explicitly
request to preserve port parity (e.g., [I-D.ietf-pcp-port-set]). request to preserve port parity (e.g., [RFC7753]).
Note: According to [RFC6887], dynamic mappings are said to be Note: According to [RFC6887], dynamic mappings are said to be
dynamic in the sense that they are created on demand, either dynamic in the sense that they are created on demand, either
implicitly or explicitly: implicitly or explicitly:
1. Implicit dynamic mappings refer to mappings that are created 1. Implicit dynamic mappings refer to mappings that are created
as a side effect of traffic such as an outgoing TCP SYN or as a side effect of traffic such as an outgoing TCP SYN or
outgoing UDP packet. Implicit dynamic mappings usually have a outgoing UDP packet. Implicit dynamic mappings usually have a
finite lifetime, though this lifetime is generally not known finite lifetime, though this lifetime is generally not known
to the client using them. to the client using them.
skipping to change at page 10, line 7 skipping to change at page 10, line 16
NAT behavioral considerations are discussed in [RFC4787], [RFC5382], NAT behavioral considerations are discussed in [RFC4787], [RFC5382],
and [RFC5508]. and [RFC5508].
Because some of the clarifications and updates (e.g., Section 2) are Because some of the clarifications and updates (e.g., Section 2) are
inspired from NAT64, the security considerations discussed in inspired from NAT64, the security considerations discussed in
Section 5 of [RFC6146] apply also for this specification. Section 5 of [RFC6146] apply also for this specification.
The update in Section 3 allows for an optimized NAT resource usage. The update in Section 3 allows for an optimized NAT resource usage.
In order to avoid service disruption, the NAT MUST invoke this In order to avoid service disruption, the NAT MUST invoke this
functionality only if packets are to be sen to distinct destination functionality only if packets are to be sent to distinct destination
addresses. addresses.
Some of the updates (e.g., Section 7, Section 9, and Section 11) Some of the updates (e.g., Section 7, Section 9, and Section 11)
allow for an increased security compared to [RFC4787], [RFC5382], and allow for an increased security compared to [RFC4787], [RFC5382], and
[RFC5508]. Particularly: [RFC5508]. Particularly:
o The updates in Section 7 and Section 11 prevent an illegitimate o The updates in Section 7 and Section 11 prevent an illegitimate
node to maintain mappings activated in the NAT while these node to maintain mappings activated in the NAT while these
mappings should be cleared. mappings should be cleared.
o Port randomization (Section 9) complicates tracking hosts located o Port randomization (Section 9) complicates tracking hosts located
behind a NAT. behind a NAT.
Section 4 and Section 12 propose updates that increase the Section 4 and Section 12 propose updates that increase the
serviceability of a host located behind a NAT. These updates do not serviceability of a host located behind a NAT. These updates do not
introduce any additional security concerns to [RFC4787], [RFC5382], introduce any additional security concerns to [RFC4787], [RFC5382],
and [RFC5508]. and [RFC5508].
The updates in Section 5 and Section 6 allow for a better NAT The updates in Section 5 and Section 6 allow for a better NAT
transparency from an application standpoint. Hosts which require a transparency from an application standpoint. Hosts which require a
restricted filtering behavior should enable security-dedicated restricted filtering behavior should enable specific policies (e.g.,
features (e.g., access control list (ACL)) either locally or by access control list (ACL)) either locally or by soliciting a
soliciting a dedicated security device (e.g., firewall). dedicated security device (e.g., firewall). How a host updates its
filtering policies is out of scope of this document.
The update in Section 8 induces security concerns that are specific The update in Section 8 induces security concerns that are specific
to the protocol used to interact with the NAT. For example, if PCP to the protocol used to interact with the NAT. For example, if PCP
is used to explicitly request parity preservation for a given is used to explicitly request parity preservation for a given
mapping, the security considerations discussed in [RFC6887] should be mapping, the security considerations discussed in [RFC6887] should be
taken into account. taken into account.
The update in Section 10 may have undesired effects on the The update in Section 10 may have undesired effects on the
performance of the NAT in environments in which fragmentation is performance of the NAT in environments in which fragmentation is
massively experienced. Such issue may be used as an attack vector massively experienced. Such issue may be used as an attack vector
skipping to change at page 11, line 36 skipping to change at page 11, line 45
NAT64: Network Address and Protocol Translation from IPv6 NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146, Clients to IPv4 Servers", RFC 6146, DOI 10.17487/RFC6146,
April 2011, <http://www.rfc-editor.org/info/rfc6146>. April 2011, <http://www.rfc-editor.org/info/rfc6146>.
[RFC6864] Touch, J., "Updated Specification of the IPv4 ID Field", [RFC6864] Touch, J., "Updated Specification of the IPv4 ID Field",
RFC 6864, DOI 10.17487/RFC6864, February 2013, RFC 6864, DOI 10.17487/RFC6864, February 2013,
<http://www.rfc-editor.org/info/rfc6864>. <http://www.rfc-editor.org/info/rfc6864>.
15.2. Informative References 15.2. Informative References
[I-D.ietf-pcp-port-set]
Qiong, Q., Boucadair, M., Sivakumar, S., Zhou, C., Tsou,
T., and S. Perreault, "Port Control Protocol (PCP)
Extension for Port Set Allocation", draft-ietf-pcp-port-
set-13 (work in progress), October 2015.
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address [RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations", Translator (NAT) Terminology and Considerations",
RFC 2663, DOI 10.17487/RFC2663, August 1999, RFC 2663, DOI 10.17487/RFC2663, August 1999,
<http://www.rfc-editor.org/info/rfc2663>. <http://www.rfc-editor.org/info/rfc2663>.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network [RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022, Address Translator (Traditional NAT)", RFC 3022,
DOI 10.17487/RFC3022, January 2001, DOI 10.17487/RFC3022, January 2001,
<http://www.rfc-editor.org/info/rfc3022>. <http://www.rfc-editor.org/info/rfc3022>.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389,
DOI 10.17487/RFC5389, October 2008,
<http://www.rfc-editor.org/info/rfc5389>.
[RFC6269] Ford, M., Ed., Boucadair, M., Durand, A., Levis, P., and [RFC6269] Ford, M., Ed., Boucadair, M., Durand, A., Levis, P., and
P. Roberts, "Issues with IP Address Sharing", RFC 6269, P. Roberts, "Issues with IP Address Sharing", RFC 6269,
DOI 10.17487/RFC6269, June 2011, DOI 10.17487/RFC6269, June 2011,
<http://www.rfc-editor.org/info/rfc6269>. <http://www.rfc-editor.org/info/rfc6269>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and [RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013, DOI 10.17487/RFC6887, April 2013,
<http://www.rfc-editor.org/info/rfc6887>. <http://www.rfc-editor.org/info/rfc6887>.
[RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa, [RFC6888] Perreault, S., Ed., Yamagata, I., Miyakawa, S., Nakagawa,
A., and H. Ashida, "Common Requirements for Carrier-Grade A., and H. Ashida, "Common Requirements for Carrier-Grade
NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888, NATs (CGNs)", BCP 127, RFC 6888, DOI 10.17487/RFC6888,
April 2013, <http://www.rfc-editor.org/info/rfc6888>. April 2013, <http://www.rfc-editor.org/info/rfc6888>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <http://www.rfc-editor.org/info/rfc7296>.
[RFC7753] Sun, Q., Boucadair, M., Sivakumar, S., Zhou, C., Tsou, T.,
and S. Perreault, "Port Control Protocol (PCP) Extension
for Port-Set Allocation", RFC 7753, DOI 10.17487/RFC7753,
February 2016, <http://www.rfc-editor.org/info/rfc7753>.
Acknowledgements Acknowledgements
Thanks to Dan Wing, Suresh Kumar, Mayuresh Bakshi, Rajesh Mohan, Lars Thanks to Dan Wing, Suresh Kumar, Mayuresh Bakshi, Rajesh Mohan, Lars
Eggert, Gorry Fairhurst, Brandon Williams, and David Black for their Eggert, Gorry Fairhurst, Brandon Williams, and David Black for their
review and discussion. review and discussion.
Many thanks to Ben Laurie for the secdir review, and Dan Romascanu
for the Gen-ART review.
Dan Wing proposed some text for the configurable errors in
Section 7.1.
Contributors Contributors
The following individual contributed text to the document: The following individual contributed text to the document:
Sarat Kamiset, Insieme Networks, United States Sarat Kamiset, Insieme Networks, United States
Authors' Addresses Authors' Addresses
Reinaldo Penno Reinaldo Penno
Cisco Systems, Inc. Cisco Systems, Inc.
 End of changes. 28 change blocks. 
45 lines changed or deleted 66 lines changed or added

This html diff was produced by rfcdiff 1.42. The latest version is available from http://tools.ietf.org/tools/rfcdiff/