Internet DRAFT - draft-yang-v6ops-fast6
draft-yang-v6ops-fast6
Internet Engineering Task Force Y. Wu
Internet-Draft J. Tan
Intended status: Informational Y. Li
Expires: September 31, 2013 China Telecom
March 31, 2013
Fundamental Architecture of Services Provider's network Transitioning to
IPv6 (FAST6)
draft-yang-v6ops-fast6-02
Abstract
The IANA free pool of IPv4 addresses was depleted, IPv6 migration has
become the most imperative task. There are many transition
mechanisms designed for different scenarios, however, some problems
arosed in the practice. FAST6, specified in this draft, is based on
the ideas of native dual stack and address sharing. It can solves
the mixed route problem and simplify the planning of private IPv4
address space by using tunnel technology. FAST6 is an economical and
stable technology for smooth network transition.
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 September 31, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
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carefully, as they describe your rights and restrictions with respect
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Terminologies . . . . . . . . . . . . . . . . . . . . . . . . 4
3. FAST6 Architecture . . . . . . . . . . . . . . . . . . . . . . 4
3.1. FTS . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. FTN . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. FAST6 Tunnel South(FTS) . . . . . . . . . . . . . . . . . . . 6
4.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 6
4.3. Fragmentation and Reassembly . . . . . . . . . . . . . . . 6
4.4. Discovery . . . . . . . . . . . . . . . . . . . . . . . . 6
5. FAST6 Tunnel Nouth(FTN) . . . . . . . . . . . . . . . . . . . 6
5.1. Definition . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 7
5.3. Resource Pool Maintenance . . . . . . . . . . . . . . . . 7
5.4. FAST6 NAT . . . . . . . . . . . . . . . . . . . . . . . . 7
5.5. address mapping table maintenance . . . . . . . . . . . . 7
6. FAST6 Data Flow . . . . . . . . . . . . . . . . . . . . . . . 8
7. FAST6 Deployment . . . . . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
10. Security Considerations . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
11.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. Introduction
As we known, available transition mechanisms have their
own drawbacks in practice. Nowadays, most applications don't
support IPv6 and the protocol translation technologies, such as
NAT64 which cannot help in the application level.Therefore it is
necessary to provide the IPv4 and IPv6 service separately. However,
4over6 technology is a risky method for network migration since any
troubles happen in the IPv6 network will influence the IPv4 service,
especially in the period when IPv4 flows are dominant in the network.
Simultaneously, 4over6 technology doesn't help to stimulate
applications translation of ICPs who are unaware of the well prepared
IPv6 network. In the mean time, 6over4 technology is not proper
for the continuously expanding network. Native dual stack technology
can avoid those problems essentially for it can provide dual stack
service separately, making IPv4 decoupling from IPv6 and providing
network environment for IPv6 service migration. However, native dual
stack is not enough and IP address sharing has to be used when the
IPv4 addresses were exhausted.
NAT444 seems to be a good solution except some carrier grade problems
such as mixed routing (private address routing and public address
routing), additional unified arrangement of private IPv4 address
spaces among BNGs and so on. All these problems will cause overload
maintenance cost. This document specifies the FAST6 technology,
which is aimed at balancing the costs and benefits in service
provider networks better. FAST6 is based on native dual-stack. By
taking the advantages of tunnel technology and native dual-stack
technology, FAST6 overcomes carrier grade NAT problems. It
stimulates the IPv6 migration and also decouples the IPv4 from IPv6,
making network transition smoother and guaranteeing the user
experience effectively.
This document will first briefly introduce the overall architecture
of FAST6 and then describe the detailed behaviors of FAST6 elements.
It will then depict an intuitive example about FAST6 through data
flow. At last, we will present the FAST6 implementation in current
network and show some of its advantages.
1.1. 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].
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2. Terminologies
The technology described in this document is known as FAST6. The
abbreviation "FAST6" will be used throughout this text.
FAST6: Fundamental Architecture of Services Provider's network
Transitioning to IPv6
FTN: FAST6 tunnel North
FTS: FAST6 tunnel South.
Resource Pool: One of the element in FTN, including address pool,
Tunnel ID-address pool mapping table, port resource pool.
FAST6 NAT: A module use triple-tuple for NAT.
CR: Core Router (CR) in a metropolitan area network is the
egress router of the MAN and connecting to the ISP's
backbone in upstream and connecting to BRASs for
downstream.
BNG: Broadband Network Gateway, BRAS and SR
Dual stack: Defined in RFC 4213
Nat related terminology: Defined in RFC 1417
IP-in-IP tunnel: Defined in RFC 2003
3. FAST6 Architecture
FAST6 consists of two functional modules. One is FTS (FAST6 tunnel
south) , the other is FTN(FAST6 tunnel north). FTS is the tunnel
endpoint present at the user side. FTN is the tunnel endpoint
present at the network side.
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+-----+-----+ +-----+-----+
| IPv4 host| | IPv6 host|
+-----------+ +-----------+
| |
--------|--------------|------
/ | | \
| Internet | |
\ | | /
--------|--------------|------
|-------------------|--------------|--------------|
| +-------------------+ | FAST6 |
| | FTN | | |
| +---------|---------+ | |
| ||| | |
| ||| IP in IP Tunnel |
| +-------------------+ | |
| | FTS | | |
| +---------|---------+ | |
| | | |
|____________________|_____________|______________|
+-----+-----+ |
| CPE/ host|-------|
+-----------+
Figure 1: FAST6 architecture
3.1. FTS
As the tunnel endpoint at user side, FTS is responsible for
encapsulating private IPv4 packet within a public IPv4 packet to
establish an IP-in-IP tunnel, or decapsulating private IPv4 packet
from the tunnel.
3.2. FTN
FTN is the tunnel endpoint at network side. It has four functions:
encapsulation and decapsulation, address translation, address mapping
table maintenance, resource pool maintenance.
From south to north, FTN decapsulates the private IP address packet
from the tunnel, marking the public IPv4 address as the tunnel ID and
finding the corresponding IP address pool and port resource in the
resource pool based on the tunnel ID. Then FTN replaces the private
IPv4 address header with the public IPv4 address header and generates
an address mapping entry.
From the north to south, FTN searches the address mapping table for
the corresponding triple tuple ( tunnel ID, private address, port)
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according to the received public IPv4 address and port. Then FTN
forwards the packet to the corresponding tunnel.
4. FAST6 Tunnel South(FTS)
4.1. Definition
As defined above, FTS is a function module used to establish the
IPv4-in-IPv4 tunnel to FTN, encapsulating and decapsulating the
packet.
4.2. Encapsulation
FTS uses a public IPv4 address to encapsulate the private IPv4
packet. The packet encapsulation structure is as below.
+-----+-----+-----+-----+-----+-----+
|Public IPv4|private IPv4|payload |
+-----------+-----------+-----------+
Figure 2: The encapsulation module
For the encapsulation format and parameters, please refer to RFC2003
and other encapsulation mode will be considered in the future.
4.3. Fragmentation and Reassembly
The encapsulation of IPv4 packet over IPv4 packet will increase 20
extra bytes in IP headerGBP[not]it is necessary for the service
provider to manually increase the MTU size for all the links between
the FTS element and the FTN elements, by at least 20 bytes to
accommodate both the IPv4 encapsulation header and the IPv4 datagram
without fragmenting the IPv4 packet.
4.4. Discovery
The number of FTSs (the number of the tunnels) is very limited, so
the IPv4-in-IPv4 tunnel establishment between FTN and FTS can be
configured manually.
5. FAST6 Tunnel Nouth(FTN)
5.1. Definition
As defined above, FTN has four functions: encapsulation and
decapsulation, address translation, address mapping table
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maintenance, resource pool maintenance.
+----------------------------------------------------+
|resource pool |
| +-------------------+ +----------+ +-----------+ |
| |tunnel ID-address pool|address pool| port resource
| |mapping table | | | | | |
| +---------|---------+ +-----|----+ +-|---------+ |
+------------|------------------ /------/------------+
| / /
+------+ +-----------------+/ / +---------------+
| encap| |address traslation------/ | mapping table |
| decap| | | | |
+----- + +-----------------+ +---------------+
Figure 3: FTN architecture
5.2. Encapsulation
The encapsulation format of FTN is the same as FTS. The
fragmentation and reassembly mode are also the same as FTS.
5.3. Resource Pool Maintenance
The resource pool includes the !otunnel ID "C IP address pool!+/-
mapping table, address pool and port resource pool. The planning of
address pool depends on the specific network deployment. Usually,
each tunnel ID has its own IP address pool. In addition, the
resource pool has to maintain the available port resource and address
for each address pool.
5.4. FAST6 NAT
From south to north, FTN assign a public address and port after
checking the resource table according to the triple tuple (Tunnel ID,
private address, port). From north to south, FTN searches the
address mapping table after receiving the packet and finds the
corresponding tunnel ID, private address and port information, then
forwards the packet to corresponding tunnel.
5.5. address mapping table maintenance
From south to north, FTN will generate a network address mapping
table. The parameters listed in the entry is in the following order:
GBP"converted public IPv4 address, converted port, tunnel ID, private
IPv4 address, port).
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6. FAST6 Data Flow
The following picture describes the procedure of accessing internet
from user end through FAST6. Users visit the IPv4 internet resources
through IPv4 network and use IPv6 network to access the IPv6 internet
resources.
+-----+-----+ +-----+-----+
| IPv4 host| | IPv6 host|
+-----------+ +-----------+
| |
--------|--------------|-----
/ | | \
| Internet | |
\ | | /
--------|--------------|------
|--------120.0.0.1--|--------------|--------------|
| +-------------------+ | FAST6 |
| | FTN | | |
| +---------|---------+ | |
| ||| | |
| 59.43.0.1 ||| IPv4-in-IPv4 Tunnel |
| +-------------------+ | |
| | FTS | | |
| +---------|---------+ | |
| | | |
|___________10.0.1.1_|_____________|______________|
+-----+-----+ |
| CPE/ host|-------|
+-----------+
Figure 4: FAST6 Data Flow
Customer 1 sends a TCP packet with source address 10.0.1.1 and port
1000 to the ICP server whose address is 198.8.8.8. When the packet
arrives at the FTS, FTS encapsulates the private IPv4 packet in a
public IPv4 header (59.43.0.1) with the destination 59.43.0.2, the
other end of tunnel. When the packet arrives at the FTN, FTN
decapsulates it , checks the corresponding IP address pool based on
Tunnel ID and chooses 120.0.0.1 and port 2000 to replace the former
header. Then FTN generates a mapping
entryGBP"120.0.0.1,2000,59.43.0.2,10.0.1.1,1000GBP(C).
From north to south, when FTN receives the packet with the
destination address 120.0.0.1/2000, it checks the address mapping
table , finds the
entryGBP"120.0.0.1,2000,59.43.0.2,10.0.1.1,1000GBP(C)and forwards the
packet to tunnel established by FTS1 according to the last 3
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parameters.
+-----------------+--------------+-----------------+
| Datagram | Header field | Contents |
+-----------------+--------------+-----------------+
| IPv4 datagram 1 | IPv4 Dst | 198.8.8.8 |
| | IPv4 Src | 10.0.0.1 |
| | TCP Dst | 80 |
| | TCP Src | 1000 |
| --------------- | ------------ | ------------- |
| IPv4 datagram 2 |IPv4 Dst outer| 59.43.0.2 |
| |IPv4 Src outer| 59.43.0.1 |
| | IPv4 Dst | 198.8.8.8 |
| | IPv4 Src | 10.0.0.1 |
| | TCP Dst | 80 |
| | TCP Src | 1000 |
| --------------- | ------------ | ------------- |
| IPv4 datagram 3 | IPv4 Dst | 198.8.8..8 |
| | IPv4 Src | 120.0.0.1 |
| | TCP Dst | 80 |
| | TCP Src | 2000 |
+-----------------+--------------+-----------------+
Figure 5: packet header translation table
7. FAST6 Deployment
This chapter will briefly introduce the FAST6 deployment in real
network and some of its advantages. The following picture only
depicts IPv4 part of FAST6.The detailed deployment, cutover and
network transition will be stated in other document.
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+-----+-----+
| IPv4 host|
+-----------+
|
--------|------------
/ | \
| Internet |
\ | /
--------|-------------
|
+---------------------------+
| CR |
+---|---------|---------|---+
| | |
120.0.0.1 120.0.0.2 120.0.1.1
+----------------------------+
| FTN |
+----------------------------+
|| || \\
|| || \\
59.43.0.1 59.43.0.3 59.43.0.5
+------//----BNG1--//----+ + \\---BNG2-----+
| || || | | \\ |
| +--//----+ +--//----+ | | +-\\-----+ |
| | FTS | | FTS | | | | FTS | |
| +---|----+ +---|----+ | | +--|-----+ |
+-----|-----------|------+ +----|----------+
10.0.1.1 10.0.1.2 10.0.1.1
+-----+-----+ +-----+-----+ +-----+-----+
| host1 | | host2 | | host3 |
+-----------+ +-----------+ +-----------+
Figure 6: FAST6 Deployment
FAST6 is suitable for layer 2 and layer3 access modes. The FTS
component can be installed in BNG equipments tunnel interface. The
FTN unit is similar to CGN device and can be embedded in the CR as a
card or deployed as an independent device.
FAST6 can eliminate the mixed routing problem by establish a tunnel
from BNG to FTN. In the mean time, since it uses the public address
as the tunnel ID to separate different BNGs, the private address pool
can be overlapped among BNGs, saving the workload for arranging the
private IPv4 address pool in the whole network uniformly. Besides,
since FTS can be configured in the ingress direction of user
interface on BNG, the tunnel can also isolate the mixed route within
the device. This feature fits BNG for providing multiple services
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which are running behind different address distribution policies (for
example, private address for common users and public address for VIP
customers.).
The IPv4 address used for tunnel encapsulation is different for
different FTS. The address pool can be overlapped for each FTS. FTS
can be deployed flexibly in centralized and distributed form in the
network depending on private IPv4 traffic flow amount. When the FTN
is distributed, FTN and FTS may probably be in the same card in this
case, FAST6 is as same as NAT444.
In addition, FAST6 have some the following advantages:
(1) Retaining the current access method and customer behaviors,
modifications of CPE are not required.
(2) Providing dual stack services for users, no need for protocol
translation and consequently decreasing the influence on
applications.
(3) Easier for troubleshooting. IPv4 is decoupled from IPv6, so it
will not be influenced by IPv6.
(4) Suitable for the initial period of network transition, and it can
be seamlessly compatible with any other technologies used for later
stage of transition.
8. Acknowledgements
TBD...
9. IANA Considerations
This memo includes no request to IANA.
10. Security Considerations
This document has no impact on the security properties of specific
IPv6 transition tools. When introducing IPv6, it is important to
ensure that the necessary security capabilities exist on the network
components even when dealing with IPv6 traffic. The security issues
should be considered when deploying any transition technology. For
instance, firewall and logging system for illegal activity tracing is
still a challenge in IPv6 and NAT deployments.
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11. References
11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[min_ref] authSurName, authInitials., "Minimal Reference", 2012.
11.2. Informative References
[I-D.arkko-ipv6-transition-guidelines]
Arkko, J. and F. Baker, "Guidelines for Using IPv6
Transition Mechanisms during IPv6 Deployment",
draft-arkko-ipv6-transition-guidelines-14 (work in
progress), December 2010.
[I-D.ietf-behave-lsn-requirements]
Perreault, S., Yamagata, I., Miyakawa, S., Nakagawa, A.,
and H. Ashida, "Common requirements for Carrier Grade NATs
(CGNs)", draft-ietf-behave-lsn-requirements-05 (work in
progress), November 2011.
[I-D.ietf-softwire-dual-stack-lite]
Durand, A., Droms, R., Woodyatt, J., and Y. Lee, "Dual-
Stack Lite Broadband Deployments Following IPv4
Exhaustion", draft-ietf-softwire-dual-stack-lite-10 (work
in progress), May 2011.
[I-D.kuarsingh-lsn-deployment]
Kuarsingh, V. and J. Cianfarani, "NAT44/LSN Deployment
Options and Experiences",
draft-kuarsingh-lsn-deployment-01 (work in progress),
January 2011.
[I-D.shirasaki-nat444]
Yamagata, I., Shirasaki, Y., Nakagawa, A., Yamaguchi, J.,
and H. Ashida, "NAT444", draft-shirasaki-nat444-03 (work
in progress), January 2011.
[I-D.shirasaki-nat444-isp-shared-addr]
Shirasaki, Y., Miyakawa, S., Nakagawa, A., Yamaguchi, J.,
and H. Ashida, "NAT444 addressing models",
draft-shirasaki-nat444-isp-shared-addr-05 (work in
progress), January 2011.
[I-D.yang-v6ops-fast6-tools-selection]
Yang, G. and C. Huang, "The analysis of tools selection
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for broadband ISP",
draft-yang-v6ops-fast6-tools-selection-00 (work in
progress), May 2011.
[RFC1661] Simpson, W., "The Point-to-Point Protocol (PPP)", STD 51,
RFC 1661, July 1994.
[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC2516] Mamakos, L., Lidl, K., Evarts, J., Carrel, D., Simone, D.,
and R. Wheeler, "A Method for Transmitting PPP Over
Ethernet (PPPoE)", RFC 2516, February 1999.
[RFC2661] Townsley, W., Valencia, A., Rubens, A., Pall, G., Zorn,
G., and B. Palter, "Layer Two Tunneling Protocol "L2TP"",
RFC 2661, August 1999.
[RFC3022] Srisuresh, P. and K. Egevang, "Traditional IP Network
Address Translator (Traditional NAT)", RFC 3022,
January 2001.
[RFC4029] Lind, M., Ksinant, V., Park, S., Baudot, A., and P.
Savola, "Scenarios and Analysis for Introducing IPv6 into
ISP Networks", RFC 4029, March 2005.
[RFC4213] Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
for IPv6 Hosts and Routers", RFC 4213, October 2005.
[RFC4241] Shirasaki, Y., Miyakawa, S., Yamasaki, T., and A.
Takenouchi, "A Model of IPv6/IPv4 Dual Stack Internet
Access Service", RFC 4241, December 2005.
[RFC5569] Despres, R., "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd)", RFC 5569, January 2010.
[RFC5969] Townsley, W. and O. Troan, "IPv6 Rapid Deployment on IPv4
Infrastructures (6rd) -- Protocol Specification",
RFC 5969, August 2010.
[RFC6036] Carpenter, B. and S. Jiang, "Emerging Service Provider
Scenarios for IPv6 Deployment", RFC 6036, October 2010.
[RFC6146] Bagnulo, M., Matthews, P., and I. van Beijnum, "Stateful
NAT64: Network Address and Protocol Translation from IPv6
Clients to IPv4 Servers", RFC 6146, April 2011.
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Authors' Addresses
Youming Wu
China Telecom
109, Zhongshan Ave. West,
Guangzhou, Tianhe District 510630
P.R. China
Phone:
Email: 13316090389@189.cn
Jinhua Tan
China Telecom
109, Zhongshan Ave. West,
Guangzhou, Tianhe District 510630
P.R. China
Phone:
Email: 13316097209@189.cn
YangChun Li
China Telecom
109, Zhongshan Ave. West,
Guangzhou, Tianhe District 510630
P.R. China
Phone:
Email: liyc_gsta@189.cn
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