Network Working Group C. Xie
Internet-Draft China Telecom
Intended status: Standards Track S. Perreault
Expires: December 05, 2013 Viagenie
C. Zhou
Huawei Technologies
June 03, 2013
Provisioning Lightweight 4over6 (lw4o6) with the Port Control Protocol
(PCP)
draft-perreault-softwire-lw4over6-pcp-00
Abstract
This memo defines the procedures that a Lightweight B4 uses for
provisioning its parameters with the Port Control Protocol.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 05, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
Xie, et al. Expires December 05, 2013 [Page 1]
Internet-Draft Provisioning lw4o6 with PCP June 2013
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Lightweight B4 Provisioning with PCP . . . . . . . . . . . . 3
3.1. Setting Up the Tunnel . . . . . . . . . . . . . . . . . . 3
3.2. Configuration of the NAT44 . . . . . . . . . . . . . . . 4
3.3. PCP Proxy . . . . . . . . . . . . . . . . . . . . . . . . 4
3.4. Failover Mechanism . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Lightweight 4over6 (lw4o6) [I-D.ietf-softwire-lw4over6] defines a
model for providing IPv4 access over an IPv6 network in which the
Network Address Translation (NAT) function is performed by the
Customer-Premises Equipment (CPE) instead of being centralized on a
Carrier-Grade NAT (CGN).
Separately, the Port Control Protocol [RFC6887] is used to manipulate
port mappings in a NAT, firewall, port range router, or similar
equipment. It is extended in [I-D.ietf-pcp-port-set] with the
ability to manipulate sets of ports instead of individual ports.
This document describes how PCP is used to provision a Lightweight B4
(lwB4) with its port set and how to establish a tunnel to the
Lightweight AFTR (lwAFTR).
2. Terminology
Xie, et al. Expires December 05, 2013 [Page 2]
Internet-Draft Provisioning lw4o6 with PCP June 2013
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 [RFC2119].
Terminology defined in [I-D.ietf-softwire-lw4over6] is used
extensively in this document.
3. Lightweight B4 Provisioning with PCP
The elements that are needed for lwB4 provisioning are listed in
Section 5.1 of [I-D.ietf-softwire-lw4over6].
Note (to be removed before publication): These elements can be
provisioned with plain mode or encapsulation mode.
In the plain mode, PCP port-set request is sent using native IPv6
packet, while in the encapsulation mode, PCP Port-set request is
sent using ip-in-ip tunnel. In this draft, encapsulation mode is
recommended to guarantee that the same lwAFTR/PCP server would be
selected for PCP requests and subsequent ip-in-ip traffic.
3.1. Setting Up the Tunnel
The lwB4 initiates the provisioning procedure by requesting the
OPTION_AFTR_NAME DHCPv6 option as indicated in [RFC6334]. This
option provides the IPv6 address for the lwAFTR.
Once this address is known, the lwB4 sets up an IPv4-in-IPv6 tunnel
with the following characteristics:
IPv6 destination: value of OPTION_AFTR_NAME, after resolution of the
name
IPv6 source: derived from the IPv6 destination by applying Default
Address Selection [RFC3484]
IPv4 source: 192.0.0.2
IPv4 destination: 192.0.0.1
The IPv4 addresses correspond to the well-known B4 and AFTR addresses
defined in Section 5.7 of [RFC6333].
Xie, et al. Expires December 05, 2013 [Page 3]
Internet-Draft Provisioning lw4o6 with PCP June 2013
3.2. Configuration of the NAT44
Once the tunnel is up, the lwB4 sends a PCP MAP request with a
PORT_SET option. The request is sent inside the tunnel to 192.0.0.1.
The source is accordingly set to 192.0.0.2.
The MAP request's Internal Port is set to 1 and the PORT_SET option's
Port Set Size field is set to 65535, indicating that the lwB4 is
prepared to accept a maximal size port set. Practically, the server
will reply with a port set size corresponding to its configuration.
Note: Since there is no NAT in the lwAFTR, the internal port is
always equal to the external port. The PCP server cannot change
the internal port that the client sends. How can we overcome
this? Add an offset parameter in the PORT_SET option?
The PORT_SET option's P bit is set to 0.
When a success response is received from the PCP server, the lwB4
extracts the external IPv4 address and port set from the response and
uses them to configure its NAT44 function as described in
[I-D.ietf-softwire-lw4over6]. The lwB4 is now provisioned.
The lwB4 needs to periodically refresh the port set it obtained with
PCP as described in [RFC6887] section 15 for as long as the lw4over6
tunnel is to be operational.
3.3. PCP Proxy
The lwB4 SHOULD implement a back-to-back PCP server-client. The PCP
port-set client in lwB4 would get a public address and port-set from
the PCP port-set server, and then the PCP server in the lwB4 will
setup the mapping for the host behind the lwB4 and response with PCP
client.
The lwB4 MAY also implement a PCP proxy in case the host initiates a
port-set request directly. It would forward the port-set request to
PCP server to get a new port-set mapping or refresh an existing
mapping.
3.4. Failover Mechanism
This document considers two failover mechanisms: ICMP and PCP
ANNOUNCE. In the ICMP case, when the lwB4 receives an ICMP error
message from the lwAFTR, the lwB4 MAY re-initiate the dynamic port-
restricted provisioning process. The detailed ICMP processing is
introduced in [I-D.ietf-softwire-lw4over6].
Xie, et al. Expires December 05, 2013 [Page 4]
Internet-Draft Provisioning lw4o6 with PCP June 2013
In the PCP case, when the lwAFTR receives traffic it doesn't have
before, lwAFTR MAY send back a PCP unicast ANNOUNCE message. The
lwB4 then will re-initiate the PCP Port-set request after receiving
the ANNOUNCE message. In the case when there are large amount of
lwB4s, an optimization of this mechanism MAY be needed to achieve
fast failure recovery. Since it is layer 2 network between lwB4 and
BNG, A BNG device MAY act a PCP proxy to receive unicast ANNOUNCE
message from lwAFTR. It will then replace the unicast address of
itself with the lwb4's multicast address and sends multicast ANNOUNCE
message to the lwB4s.
4. Security Considerations
TO BE COMPLETED
5. IANA Considerations
This document has no IANA actions.
6. Acknowledgements
Special thanks to Qiong Sun for her many contributions to this
document.
The authors would like to thank the following individuals who have
participated in the drafting, review, and discussion of this memo:
Jean-Philippe Dionne, Marc Blanchet, and Tina Tsou.
7. References
7.1. Normative References
[I-D.ietf-pcp-port-set]
Sun, 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-00 (work
in progress), March 2013.
[I-D.ietf-softwire-lw4over6]
Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I.
Farrer, "Lightweight 4over6: An Extension to the DS-Lite
Architecture", draft-ietf-softwire-lw4over6-00 (work in
progress), April 2013.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Xie, et al. Expires December 05, 2013 [Page 5]
Internet-Draft Provisioning lw4o6 with PCP June 2013
[RFC3484] Draves, R., "Default Address Selection for Internet
Protocol version 6 (IPv6)", RFC 3484, February 2003.
[RFC6334] Hankins, D. and T. Mrugalski, "Dynamic Host Configuration
Protocol for IPv6 (DHCPv6) Option for Dual-Stack Lite",
RFC 6334, August 2011.
[RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P.
Selkirk, "Port Control Protocol (PCP)", RFC 6887, April
2013.
7.2. Informative References
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
Authors' Addresses
Chongfeng Xie
China Telecom
Room 708 No.118, Xizhimenneidajie
Beijing 100035
P.R.China
Email: xiechf@ctbri.com.cn
Simon Perreault
Viagenie
246 Aberdeen
Quebec, QC G1R 2E1
Canada
Phone: +1 418 656 9254
Email: simon.perreault@viagenie.ca
URI: http://viagenie.ca
Cathy Zhou
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: cathy.zhou@huawei.com
Xie, et al. Expires December 05, 2013 [Page 6]