ipsecme M. Boucadair
Internet-Draft Orange
Updates: 7296 (if approved) October 21, 2019
Intended status: Standards Track
Expires: April 23, 2020
IKEv2 Notification Status Types for IPv4/IPv6 Coexistence
draft-ietf-ipsecme-ipv6-ipv4-codes-04
Abstract
This document specifies new IKEv2 notification status types to better
manage IPv4 and IPv6 co-existence.
This document updates RFC7296.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 23, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Why Not INTERNAL_ADDRESS_FAILURE? . . . . . . . . . . . . . . 3
4. IP6_ALLOWED and IP4_ALLOWED Status Types . . . . . . . . . . 4
5. An Update to RFC7296 . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
9.1. Normative References . . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
As described in [RFC7849], if the subscription data or network
configuration allows only one IP address family (IPv4 or IPv6), the
cellular host must not request a second PDP-Context to the same
Access Point Name (APN) for the other IP address family (AF). The
Third Generation Partnership Project (3GPP) network informs the
cellular host about allowed Packet Data Protocol (PDP) types by means
of Session Management (SM) cause codes. In particular, the following
cause codes can be returned:
o cause #50 "PDP type IPv4 only allowed": This cause code is used by
the network to indicate that only PDP type IPv4 is allowed for the
requested Public Data Network (PDN) connectivity.
o cause #51 "PDP type IPv6 only allowed": This cause code is used by
the network to indicate that only PDP type IPv6 is allowed for the
requested PDN connectivity.
o cause #52 "single address bearers only allowed": This cause code
is used by the network to indicate that the requested PDN
connectivity is accepted with the restriction that only single IP
version bearers are allowed.
If the requested IPv4v6 PDP-Context is not supported by the network
but IPv4 and IPv6 PDP types are allowed, then the cellular host will
be configured with an IPv4 address or an IPv6 prefix by the network.
It must initiate another PDP-Context activation of the other address
family in addition to the one already activated for a given APN. The
purpose of initiating a second PDP-Context is to achieve dual-stack
connectivity by means of two PDP-Contexts.
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When the User Equipment (UE) attaches the network using a Wireless
Local Area Network (WLAN) access by means of Internet Key Exchange
Protocol Version 2 (IKEv2) capabilities [RFC7296], there are no
equivalent notification codes to inform the UE why an IP address
family is not assigned or whether that UE should retry with another
address family.
This document fills that void by introducing new IKEv2 notification
status types for the sake of deterministic UE behaviors (Section 4).
These notification status types are not specific to 3GPP
architectures, but can be used in other deployment contexts.
Cellular networks are provided as an illustration example.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document makes use of the terms defined in [RFC7296]. In
particular, readers should be familiar with "initiator" and
"responder" terms used in that document.
3. Why Not INTERNAL_ADDRESS_FAILURE?
The following address assignment failures may be encountered when an
initiator requests assignment of IP addresses/prefixes:
o An initiator asks for IPvx, but IPvx address assignment is not
supported by the responder.
o An initiator requests both IPv4 and IPv6 addresses, but only IPv4
address assignment is supported by the responder.
o An initiator requests both IPv4 and IPv6 addresses, but only IPv6
prefix assignment is supported by the responder.
o An initiator asks for both IPv4 and IPv6 addresses, but only one
address family can be assigned by the responder for policy
reasons.
Section 3.15.4 of [RFC7296] defines a generic notification error type
that is related to a failure to handle an address assignment request.
That error type does not explicitly allow an initiator to determine
why a given address family is not assigned, nor whether it should try
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using another address family. INTERNAL_ADDRESS_FAILURE is a catch-
all error type when an address-related issue is encountered by an
IKEv2 responder.
INTERNAL_ADDRESS_FAILURE does not provide sufficient hints to the
IKEv2 initiator to adjust its behavior.
4. IP6_ALLOWED and IP4_ALLOWED Status Types
IP6_ALLOWED and IP4_ALLOWED status types (see Section 7) are defined
to inform the initiator about the responser's address family
assignment support capabilities, and to report to the initiator the
reason why an address assignment failed. These notification status
types are used by the initiator to adjust its behavior accordingly
(Section 5).
No data is associated with these notifications.
5. An Update to RFC7296
If the initiator is dual-stack, it MUST include both address families
in its request (absent explicit policy/configuration otherwise).
The responder MUST include IP6_ALLOWED and/or IP4_ALLOWED status type
in a response to an address assignment request as indicated in
Table 1.
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+----------------+----------------+---------------+-----------------+
| | | | Returned |
| Requested | Supported | Assigned | Notification |
| AF(s) | AF(s) | AF(s) | Status Type(s) |
| (Initiator) | (Responder) | (Responder) | (Responder) |
+----------------+----------------+---------------+-----------------+
| IPv4 | IPv6 | None | IP6_ALLOWED |
| IPv4 | IPv4 | IPv4 | IP4_ALLOWED |
| IPv4 | IPv4 and IPv6 | IPv4 | IP4_ALLOWED, |
| | | | IP6_ALLOWED |
| IPv6 | IPv6 | IPv6 | IP6_ALLOWED |
| IPv6 | IPv4 | None | IP4_ALLOWED |
| IPv6 | IPv4 and IPv6 | IPv6 | IP4_ALLOWED, |
| | | | IP6_ALLOWED |
| IPv4 and IPv6 | IPv4 | IPv4 | IP4_ALLOWED |
| IPv4 and IPv6 | IPv6 | IPv6 | IP6_ALLOWED |
| IPv4 and IPv6 | IPv4 and IPv6 | IPv4 and IPv6 | IP4_ALLOWED, |
| | | | IP6_ALLOWED |
| IPv4 and IPv6 | IPv4 or IPv6 | IPv4 or IPv6 | IP4_ALLOWED, |
| | (Policy-based) | | IP6_ALLOWED |
+----------------+----------------+---------------+-----------------+
Table 1: Returned Notification Status Types
If the initiator only receives one single notification IP4_ALLOWED or
IP6_ALLOWED from the responder, the initiator MUST NOT send a request
for an alternate address family not supported by the responder.
If a dual-stack initiator requests only an IPv6 prefix (or an IPv4
address) but only receives IP4_ALLOWED (or IP6_ALLOWED) notification
status type from the responder, the initiator MUST send a request for
IPv4 address(es) (or IPv6 prefix(es)).
If a dual-stack initiator requests both an IPv6 prefix and an IPv4
address but receives an IPv6 prefix (or an IPv4 address) only with
both IP4_ALLOWED and IP6_ALLOWED notification status types from the
responder, the initiator MAY send a request for the other AF (i.e.,
IPv4 address (or IPv6 prefix)). In such case, the initiator MUST
create a new IKE Security Association (SA) and request that another
address family using the new IKE SA.
For other address-related error cases that have not been covered by
the aforementioned notification status types, the repsonder/initiator
MUST follow the procedure defined in Section 3.15.4 of [RFC7296].
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6. Security Considerations
This document adheres to the security considerations defined in
[RFC7296].
7. IANA Considerations
This document requests IANA to update the "IKEv2 Notify Message Types
- Status Types" registry available at:
https://www.iana.org/assignments/ikev2-parameters/
ikev2-parameters.xhtml with the following status types:
Value NOTIFY MESSAGES - STATUS TYPES Reference
TBD IP4_ALLOWED [This-Document]
TBD IP6_ALLOWED [This-Document]
8. Acknowledgements
Many thanks to Christian Jacquenet for the review.
Thanks to Paul Wouters, Yaov Nir, Valery Smyslov, Daniel Migault,
Tero Kivinen, and Michael Richardson for the comments and review.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[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, <https://www.rfc-editor.org/info/rfc7296>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
9.2. Informative References
[RFC7849] Binet, D., Boucadair, M., Vizdal, A., Chen, G., Heatley,
N., Chandler, R., Michaud, D., Lopez, D., and W. Haeffner,
"An IPv6 Profile for 3GPP Mobile Devices", RFC 7849,
DOI 10.17487/RFC7849, May 2016,
<https://www.rfc-editor.org/info/rfc7849>.
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Author's Address
Mohamed Boucadair
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
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