Internet DRAFT - draft-chen-softwire-ce-non-pd
draft-chen-softwire-ce-non-pd
Network Working Group G. Chen
Internet-Draft China Mobile
Intended status: Standards Track July 9, 2012
Expires: January 10, 2013
Parameter Provisioning with non-DHCP-PD in Carrier-side Stateless
Solution
draft-chen-softwire-ce-non-pd-00
Abstract
The deployment of carrier-side stateless solution requires some
particular considerations in mobile network contexts. The widely
existed legacy network restricts the development of IP address
provisioning based on DHCP-PD. The memo provided several potential
approaches to facilitate the issues and provide the possibilities
leveraging 3GPP mechanism. The stateless algorithm is required to be
updated depending to the preferred solution accordingly.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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 January 10, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Possible Solutions . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Design Principles . . . . . . . . . . . . . . . . . . . . . 3
2.2. Using IID to carry EA-bits . . . . . . . . . . . . . . . . 4
2.3. Changing ND behaviour to deliver IPv6 prefix . . . . . . . 4
2.4. Combination of DHCPv4v6 Approach . . . . . . . . . . . . . 5
3. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
The work item of carrier-side stateless has been chartered and
motivation has been described in
[I-D.ietf-softwire-stateless-4v6-motivation]. Several candidates
solutions have been designed to meet the demands, such as
4rd[I-D.ietf-softwire-4rd] and MAP-E, MAP-T[I-D.ietf-softwire-map].
Regarding the configuration rule provisioning, a particular DHCPv6
option have been proposed to assign mapping rules to CE nodes.
Mapping rules may serve to derive IPv4 address depending on delegated
CE IPv6 prefix. Since the potential dependency between IPv4 and IPv6
is existing, CE IPv6 prefix inserted with EA-bits is presumably
delegated using DHCP-PD[RFC3633].
IPv6 prefix delegation is a feature of 3GPP Release-10 and is not
covered by any earlier releases[RFC6459]. In another words, when the
case is coming down to a mobile network contexts, those provisioning
should require 3GPP Release 10 or beyond network, which is not
deployed anywhere today. Some implementations may consider the lack
of the functionalities to use static configuration on mobile
terminals, but such solution is not scale well, especially facing
several million of customers. Therefore, the absence of DHCP-PD may
become a push-back during the deployment in 3GPP network.
This document proposed a number of alternative solutions to the
problem, such that the softwires wg can discuss both of them. It is
expected that once the softwires wg converges on a preferred
solution, the other ones will be removed from the document.
2. Possible Solutions
2.1. Design Principles
In earlier Release 3GPP network, only the /64 prefix could be
allocated for each user via SLAAC[RFC4862]. Statelss DHCPv6[RFC3736]
is available in those network, but stateful DHCPv6[RFC3315] is not
supported. The following solutions is trying to leverage current
mobile network. Considering operational approaches to resolve the
problems, the document avoid introduce additional protocol changes to
existing devices in network sides. The potential changes on UE sides
could be easily implemented using user-land codes. A address block
could be reserved from addressing plan corresponding to Rule IPv6
prefix. Such CE-specific IPv6 prefix can't be delivered through
DHCP-PD, but could be achieved through following approaches.
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2.2. Using IID to carry EA-bits
Without IPv6 prefix delegation, network could not assign a prefix
shorter than /64. Therefore, a IPv6 prefix with EA-bits might be
nowhere to get. One possible approach is to change current port
algorithm a bit to get EA-bits from interface identifier (IID),
because 3GPP network would assign a IID to user before a global IPv6
address is delivered. Referring to Section 9.2.1.1 in 3GPP
[TS23.060], IPv6 address allocation is experiencing two phases.
Mobile Gateway shall provide an interface identifier to the user in
advance to ensure that the link-local address generated by the user
does not collide with the link-local address of the mobile gateway.
Mobile gateway could deliver such IID so as to carry EA-bits. When
mapping rule has delivered to CE at second phase, CE nodes could
derive the EA-bits by shifting with length of u-bits and digging the
bits with EA length.
CE could synthesize a CE IPv6 prefix and address according the
algorithm respectively. The translation could be performed
afterwards with such CE-generated IPv6 address. Since the system
already reserve an address block, there is no address collision risks
when transmitting the packages.
The pros of the approach is this mechanism doesn't require any
changes to 3GPP network. The cons is that requires updates on
current algorithm. Distinguishing DHCP-PD and non-PD case is needed
to perform EA-bits generation.
2.3. Changing ND behaviour to deliver IPv6 prefix
IPv6 Stateless Address Autoconfiguration (SLAAC), as specified in
[RFC4861] and [RFC4862], is widely available in earlier 3GPP network.
Since a IPv6 block have been reserved for CE prefix, this block can
be treated as on-line for specific user. Referring to Section
9.2.1.1 in 3GPP [TS23.060], UE may send router solicitation message
to the mobile gateway on point-to-point link at second phase. Normal
process of gateway is to assign a router advertisement message
containing /64 prefix heading to UE with A bit set in Prefix
Information option. In order to delivery the CE prefix through ND,
the gateway should response RA with prefix information option
including reserved CE prefix, length of which is usually shorter than
/64. The configuration of this prefix option should set O bit and
unset A bit.
CE receiving the option could set the prefix as CE IPv6 prefix. The
process of algorithm can be remained as-is.
The pros of the approach is to keep current algorithm with no
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changes. The cons for that is to increase the provisioning
complexity on mobile gateway.
2.4. Combination of DHCPv4v6 Approach
3GPP network can't support the stateful DHCPv6[RFC3315] process. Any
process related to stateful would be failed in 3GPP network.
Therefore, the provisioning of mapping rules through DHCPv6 would be
restricted to stateless parameters provisioning, like rule IPv4
prefix and rule IPv6 prefix. Dynamic information should be retrieved
through another way. 3GPP network could support DHCPv4[RFC2131] by
indicating to the network within PDP(Packet Data Protocol) activation
protocol negotiations. That provides a possibility to carry port-
restricted information from DHCPv4 options. In such consideration,
port delegation with port mask allocation in
[I-D.bajko-pripaddrassign]can be combined with stateless
DHCPv6[RFC3736] to populate CE with complete mapping rules.
CE could synthesize a CE IPv6 prefix and address according the
algorithm respectively, because CE already received sufficient
information to generate IPv6 prefix automatically. The translation
could be performed afterwards with such CE-generated IPv6 address.
Since the system already reserve the address block, there is no
duplicated risks when transmitting the packages.
The combination of DHCPv4v6 would leverage 3GPP process and doesn't
require any change to existing 3GPP system. The cons for this
approach would potentially cause doubling PDP counts for earlier
release terminals before Release 8. The algorithm should also be
needed to update accordingly.
3. Conclusions
Three aforementioned solutions have been proposed to address issues
of non-DHCP-PD provisioning in mobile contexts. It required WG to
evaluate the solutions and determine the workaround for the issues.
The minimal impacts to 3GPP system are desirable for the preferable
solution.
4. IANA Considerations
This document makes no request of IANA.
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5. Security Considerations
TBD
6. References
6.1. Normative References
[I-D.bajko-pripaddrassign]
Bajko, G., Savolainen, T., Boucadair, M., and P. Levis,
"Port Restricted IP Address Assignment",
draft-bajko-pripaddrassign-04 (work in progress),
April 2012.
[I-D.ietf-softwire-4rd]
Despres, R., Penno, R., Lee, Y., Chen, G., and S. Jiang,
"IPv4 Residual Deployment via IPv6 - a unified Stateless
Solution (4rd)", draft-ietf-softwire-4rd-02 (work in
progress), June 2012.
[I-D.ietf-softwire-map]
Troan, O., Dec, W., Li, X., Bao, C., Zhai, Y., Matsushima,
S., and T. Murakami, "Mapping of Address and Port (MAP)",
draft-ietf-softwire-map-01 (work in progress), June 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, March 1997.
[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.
[RFC3736] Droms, R., "Stateless Dynamic Host Configuration Protocol
(DHCP) Service for IPv6", RFC 3736, April 2004.
[TS23.060]
"General Packet Radio Service (GPRS); Service description;
Stage 2", June 2012.
6.2. Informative References
[I-D.ietf-softwire-stateless-4v6-motivation]
Boucadair, M., Matsushima, S., Lee, Y., Bonness, O.,
Borges, I., and G. Chen, "Motivations for Carrier-side
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Stateless IPv4 over IPv6 Migration Solutions",
draft-ietf-softwire-stateless-4v6-motivation-03 (work in
progress), June 2012.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862, September 2007.
[RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T.,
Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
Partnership Project (3GPP) Evolved Packet System (EPS)",
RFC 6459, January 2012.
Author's Address
Gang Chen
China Mobile
No.32 Xuanwumen West Street
Xicheng District
Beijing 100053
China
Email: phdgang@gmail.com
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