Internet DRAFT - draft-li-softwire-dslite-intra-domain
draft-li-softwire-dslite-intra-domain
softwire Z. Li
Internet-Draft China Mobile
Intended status: Standards Track Q. Zhao
Expires: April 26, 2012 X. Huang
Y. Ma
Beijing University of Posts and
Telecommunications
October 24, 2011
DS-Lite Intra-Domain Automatic Tunnel
draft-li-softwire-dslite-intra-domain-00
Abstract
This document specifies an automatic tunneling mechanism for
providing IPv4 connectivity service to IPv6 end users in the same DS-
Lite domain. Key aspects include stateless operation and algorithmic
mapping between IPv4 addresses and IPv6 tunnel endpoints.
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 26, 2012.
Copyright Notice
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document authors. All rights reserved.
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. CPE Configuration . . . . . . . . . . . . . . . . . . . . . 4
4.2. CGN Configuration . . . . . . . . . . . . . . . . . . . . . 4
5. Algorithmic Mapping Rules . . . . . . . . . . . . . . . . . . . 4
5.1. From a CPE tunnel address to a Domain IPv6 prefix . . . . . 5
5.2. From a CPE tunnel address to a Domain IPv4 prefix . . . . . 5
5.3. From a CPE tunnel address to a CPE IPv4 prefix . . . . . . 5
5.4. From an IPv4 address to a CPE tunnel address . . . . . . . 5
6. CPE and CGN behaviors . . . . . . . . . . . . . . . . . . . . . 6
6.1. CPE reception of an IPv4 packet . . . . . . . . . . . . . . 6
6.2. CPE reception of an IPv6 packet . . . . . . . . . . . . . . 6
6.3. CGN reception of an IPv4 packet . . . . . . . . . . . . . . 7
6.4. CGN reception of an IPv6 packet . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
9.1. Normative References . . . . . . . . . . . . . . . . . . . 7
9.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
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1. Introduction
DS-Lite [RFC6333] technology is used to deploy IPv6 following IPv4
exhaustion in service provider networks. It enables a broadband
service provider to share IPv4 addresses among customers by combining
IPv4-in-IPv6 tunnel and NAT44 translation.
From the view of network topology, DS-Lite is a good solution to
"Hubs and Spokes" problem [RFC4925] since all the IPv4 traffic from
B4 will be concentrated at AFTR even if all the IPv4 traffic are
between two adjacent B4 devices. But, there are huge IPv4 traffic
demands among end users. Many applications such as Instant Messenger
are providing directly end-to-end highspeed transport when they find
corresponding users are adjacent, instead of relaying the traffic by
remote server.
Current DS-Lite technology concentrates all end users' IPv4 traffic
in IPv4-in-IPv6 tunnels at AFTR and AFTR relays IPv4 traffic among
different tunnels. It delays packet delivery among adjacent users,
aggravates additional workload on AFTR or CGN and involves redundant
forwarding path.
This document introduces the concept of domain to DS-Lite technology.
A DS-Lite domain consists of many home gateways or CPEs with B4
function and one CGN with AFTR function. IPv4 packets encapsulated
by DS-Lite follow the IPv6 routing topology within the SP network
between CPEs or between CPE and CGN. From the view of network
topology, CPE-to-CPE IPv4 traffic in an IPv6 domain is a "Mesh"
problem [RFC4925]. This document introduces intra-domain automatic
tunnel technology to solve it.
2. 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 [RFC2119].
3. Terminology
DS-Lite domain (Domain): A set of DS-Lite CPEs and CGN connected to
the same virtual DS-Lite link. An SP may deploy DS-Lite within a
single DS-Lite domain or across multiple DS-Lite domains.
DS-Lite CPE (CPE): The home gateway with B4 function.
DS-Lite CGN (CGN): The tunnel concentrate points with AFTR funtion.
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CPE IPv4 prefix: The IPv4 prefix of the CPE. It is derived from the
CPE tunnel address. CPE IPv4 prefix is the subset of Domain IPv4
prefix and can be assigned to LAN side.
CPE tunnel address: The IPv6 address on the B4 interface of CPE. It
is combined by Domain IPv6 prefix and CPE IPv4 prefix.
CGN tunnel address: The IPv6 address on the AFTR interface of CGN.
It may be any global IPv6 address.
Domain IPv4 prefix: A part of or all of IPv4 private address space
shared among different service providers. It is non-overlapping in a
DS-Lite Domain.
Domain IPv6 prefix: A part of global IPv6 address space. It differs
among different DS-Lite Domains and keeps the same within a DS-Lite
Domain.
4. Configuration
For a given DS-Lite domain, the CPE and CGN MUST be configured with a
set of mapping rules and tunnel addresses. The configuration MUST be
consistent for all CPEs and CGN within a given DS-Lite domain.
A mapping rules consists of the following elements: a CPE tunnel
address, a Domain IPv6 prefix length, a Domain IPv4 prefix length, a
CPE IPv4 prefix length. See section 5 for detailed description of
mapping rules.
4.1. CPE Configuration
The CPE can obtain necessary parameters via DHCPv6 [RFC3315]
protocols with new options. Generally, CPE needs an independent IPv6
address via DHCPv6 to access native IPv6 Internet. Besides, CPE
needs mapping rules and CGN tunnel address from DHCPv6 options to
access IPv4 Internet. Also, these parameters can be manually
configured on CPE.
4.2. CGN Configuration
The CGN should be configured with CGN tunnel address at least.
5. Algorithmic Mapping Rules
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5.1. From a CPE tunnel address to a Domain IPv6 prefix
When a mapping rule is received, CPE will extract necessary
parameters from it. Domain IPv6 prefix is calculated by CPE tunnel
address and Domain IPv6 prefix length.
<---------------- CPE tunnel address (128) ---------------->
+------------------------------+--------------------+--------+-----+
| Domain IPv6 Prefix | Domain IPv4 Prefix | CPE ID | 0 |
+------------------------------+--------------------+--------+-----+
<- Domain IPv6 Prefix length ->
Figure 1: From a CPE tunnel address to a Domain IPv6 prefix
5.2. From a CPE tunnel address to a Domain IPv4 prefix
When a mapping rule is received, CPE will extract necessary
parameters from it. Domain IPv4 prefix is calculated by CPE tunnel
address and Domain IPv4 prefix length.
<---------------- CPE tunnel address (128) ---------------->
+--------------------+------------------------------+--------+-----+
| Domain IPv6 Prefix | Domain IPv4 Prefix | CPE ID | 0 |
+--------------------+------------------------------+--------+-----+
<- Domain IPv4 Prefix length ->
Figure 2: From a CPE tunnel address to a Domain IPv6 prefix
5.3. From a CPE tunnel address to a CPE IPv4 prefix
When a mapping rule is received, CPE will extract necessary
parameters from it. CPE IPv4 prefix is calculated by CPE tunnel
address and CPE IPv4 prefix length.
<---------------- CPE tunnel address (128) ---------------->
+------------------------+------------------------+----------+-----+
| Domain IPv6 Prefix | Domain IPv4 Prefix | CPE ID | 0 |
+------------------------+------------------------+----------+-----+
<- CPE IPv4 Prefix length ->
Figure 3: From a CPE tunnel address to a Domain IPv6 prefix
5.4. From an IPv4 address to a CPE tunnel address
When a packet destined for hosts intra-domain is received, the
destination IPv4 address will be mapped to the CPE tunnel address of
destination host. The Domain IPv6 Prefix has been calculated out
from mapping rule during initialization. The CPE IPv4 Prefix length
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keeps the same in a DS-Lite domain. The CPE IPv4 Prefix can be
calculated by destination IPv4 address and CPE IPv4 Prefix length.
<- CPE IPv4 Prefix length ->
+------------------------+-----------------------------------+-----+
| Domain IPv6 Prefix | CPE IPv4 Prefix | 0 |
+------------------------+-----------------------------------+-----+
<---------------- CPE tunnel address (128) ---------------->
Figure 4: From a CPE tunnel address to a Domain IPv6 prefix
6. CPE and CGN behaviors
6.1. CPE reception of an IPv4 packet
Step 1:
CPE calculates destination CPE IPv4 prefix by CPE IPv4 Prefix length
and the IPv4 destination address in the received IPv4 packet. Then
CPE compares it with the Domain IPv4 prefix.
If the destination CPE IPv4 prefix is a part of Domain IPv4 prefix,
the IPv4 packet will be encapsulated in intra-domain automatic IPv4-
in-IPv6 tunnel. The source IPv6 address is source CPE tunnel address
and the destination IPv6 address is calculated as descibed in section
5.4. An automatic tunnel will be established between source CPE and
destination CPE bypassing CGN.
If the destination CPE IPv4 prefix is out of Domain IPv4 prefix, CPE
proceeds to step2.
Step 2:
The IPv4 packet will be encapsulated in primitive DS-Lite IPv4-in-
IPv6 tunnel. The source IPv6 address is source CPE tunnel address
and the destination IPv6 address is the CGN tunnel address.
6.2. CPE reception of an IPv6 packet
Step 1:
CPE decapsulates the IPv6 packet and forwards the IPv4 packets to
destination host.
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6.3. CGN reception of an IPv4 packet
The same with existing AFTR mechanisms.
6.4. CGN reception of an IPv6 packet
The same with existing AFTR mechanisms.
7. Security Considerations
TBD.
8. IANA Considerations
This document makes no request of IANA.
Note to RFC Editor: this section may be removed on publication as an
RFC.
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[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.
[RFC4925] Li, X., Dawkins, S., Ward, D., and A. Durand, "Softwire
Problem Statement", RFC 4925, July 2007.
[RFC6333] Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", RFC 6333, August 2011.
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Authors' Addresses
Zhenqiang Li
China Mobile
Unit2, Dacheng Plaza, No. 28 Xuanwumenxi Ave, Xicheng District
Beijing 100053
P.R. China
Email: lizhenqiang@chinamobile.com
Qin Zhao
Beijing University of Posts and Telecommunications
Information Network Center, No. 10 Xitucheng Road, Haidian District
Beijing 100876
P.R. China
Email: zhaoqin@bupt.edu.cn
Xiaohong Huang
Beijing University of Posts and Telecommunications
Information Network Center, No. 10 Xitucheng Road, Haidian District
Beijing 100876
P.R. China
Email: huangxh@bupt.edu.cn
Yan Ma
Beijing University of Posts and Telecommunications
Information Network Center, No. 10 Xitucheng Road, Haidian District
Beijing 100876
P.R. China
Email: mayan@bupt.edu.cn
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