One document matched: draft-deng-aplusp-experiment-results-00.txt
Network Working Group X.Deng
Internet Draft M. Boucadair
Intended status: Informational L.Wang
Expires: September 2011 France Telecom
March 8, 2011
Implementing A+P in the provider's IPv6-only network
draft-deng-aplusp-experiment-results-00.txt
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Abstract
This memo describes an implementation of A+P in the provider's IPv6-
only network. It provides an overview of the implementation
environment which consists of network elements and configurations,
and the results of the application compatibility test to verify the
feasibility of deploying A+P in the IPv6-only network and to assess
the impacts on services and also the viability of A+P proposed
approach.
This memo focuses on the IPv6 flavor of A+P.
Table of Contents
1. Introduction.................................................3
2. Terminology..................................................3
3. Implementation environment...................................4
3.1. Environment Overview....................................4
3.2. Implementation and Configuration........................5
3.2.1. IPv4-Embedded IPv6 Address Format For A+P..........5
3.2.2. DHCPv6 Configurations..............................6
3.2.3. Avoiding Fragmentation.............................6
4. Application Tests and Experiments in A+P Environment.........7
4.1. A+P Impacts on Applications.............................7
4.2. UPnP extension experiment...............................8
4.3. Port Usage of Applications.............................10
4.4. BitTorrent Behaviour in A+P............................11
5. Security Considerations.....................................12
6. IANA Considerations.........................................12
7. Conclusion..................................................12
8. References..................................................13
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8.1. Normative References...................................13
8.2. Informative References.................................13
9. Acknowledgments.............................................14
1. Introduction
A+P [draft-ymbk-aplusp-09] is a technique to share IPv4 addresses
during the IPv6 transition period without requiring a NAT function in
the provider's network. The main idea of A+P is treating some bits
from the port number in the TCP/UDP header as additional end point
identifiers to extend the address field, thereby leaving a range of
ports available to applications. This feature facilitates migration
of networks to IPv6-only while offering the IPv4 connectivity ervices
to customers, because the IPv4 address and the significant bits from
the port range can be encoded in an IPv6 address and therefore
transporting IPv4 traffic over IPv6 network by stateless IPv6
routing.
We have implemented A+P in a residential ADSL access network, where
IPv6-only access network is provided over PPPoE. In this document, we
describe the implementation environment including A+P IPv6 prefix
format and network elements configurations, and results of
application tests as well. The document focuses on the implementation
of the SMAP function specified in [draft-ymbk-aplusp-09]:
o Implement DHCPv6 options to retrieve an IPv4-embedded IPv6 address
and a port range.
o Support of those DHCPv6 options in both the DHCPv6 server side and
the DHCPv6 client side.
o Support of those DHCPv6 options in both the DHCPv6 server side and
the DHCPv6 client side.
For extensive application tests results in A+P environment, please
refer to [draft-boucadair-behave-bittorrent-portrange-02] and [draft-
boucadair-port-range-01].
2. Terminology
This document makes use of the following terms:
o PRR: Port Range Router
o A+P CPE: A+P aware Customer Premise Equipment
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3. Implementation environment
3.1. Environment Overview
public
addresses +----------+
realm | PRR |
| |
=== +----------+
IPv4 ^ ^ ^
| | |
| v v
| +--------------+
| | PPPoE/DHCPv6 |
over | | Server |
| +--------------+
| === ^ ^
| IPv6 ^ | |
| over | | |
IPv6 | PPPoE | | |
V v | |
=== === v v
^ +----------+
| | A+P |
| | CPE |
| +----------+
Private | ^ ^
RFC1918 | | |
realm | v v
| +----------+
| | Host |
| | |
V +----------+
Figure 1 : Implementation Environment
We had developed both A+P home gate way function and Port Range
Router (PRR) function on Linux platform and ported the home gate way
function to a Linksys wrt 54G CPE, on which an openwrt 2.6.32 (based
on Linux kernel) is running.
Figure 2 shows the Parameters of A+P CPE. IPv6 is provisioning over
PPPoE to CPE while DHCPv6 server offers IPv6 prefix and A+P
parameters by extended options defined in [draft-boucadair-dhcpv6-
shared-address-option].
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+--------+------------+-------+-----+------------+-----------+------+
| Model | CPU Speed | Flash | RAM | Wireless | Wireless | Wired|
| | (MHz) | (MB) | (MB)| NIC | Standard | Ports|
+--------+---------- -+-------+-----+------------+-----------+------+
| Linksys| 200 | 8 | 32 | Broadcom | 11g | 5 |
| WRT54GS| | | |(integrated)| | |
+--------+------------+-------+-----+------------+-----------+------+
Figure 2 :Parameters of A+P CPE
3.2. Implementation and Configuration
Aplusp CPE, using Netfilter framework, the IPv4 port restricted NAT
operation performed by CPE has been implemented by simply rules
through iptables tool on Linux. After the port restriceted NAT
operation, the IPv4 packets are sent to a TUN interface which is
described as a virtual network interface in Linux. Using the IPv4-
Embedded IPv6 address format defined in section 3.2.1, an IPv4-in-
IPv6 encapsulation/decapsulation is performed by the TUN interface
handler.
PRR, located in the interconnection point of the IPv6 network and
IPv4 network, has been implemented with two main functions: 1) IPv4-
in-IPv6 encapsulation/decapsulation; Like CPE, TUN driver is also
used in PRR to achieve function IPv4-in-IPv6
encapsulation/decapsulation. 2) destination port based routing
function, which is responsible for routing the IPv4 traffic
originated from the IPv4 Internet to the Port Range restricted A+P
CPE. Destination port based routing is implemented by generating IPv6
destination address, pre-assigned from IPv4 address and port range to
each CPE, according to IPv4-Embedded IPv6 address format defined in
section 3.2.1.
3.2.1. IPv4-Embedded IPv6 Address Format For A+P
|31bits|1bit| 32bits|8 bits|16bits|4bits|1bit|1bit|1bit|1bit|32 bits|
+------+----+-------+------+------+-----+----+----+----+----+-------+
|AplusP|flag|Public | EUI64| port |Port |flag|flag|flag|flag|Public |
|Prefix| 0 |IPv4 | | Range|Range| 1 | 2 | 3 | 4 |IPv4 |
| | |Address| | |Size | | | | |Address|
+------+----+-------+------+------+-----+----+----+----+----+-------+
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Figure 3 :IPv4-Embedded IPv6 address format
flag0: Is this address used by CPE or PRR?
flag1: Is address shared?
flag2: Is length of invariable present?
flag3: Is port range identifying sub network?
flag4: Reserved?
To facilitate test and experiment on AplusP solution, recently, we
are considering release this AplusP implementation under open source
license. For more implementation details, please refer to
[Implementing A+P]
3.2.2. DHCPv6 Configurations
DHCPv6 options defined in [draft-boucadair-dhcpv6-shared-address-
option] have been implemented. These options allow to configure a
shared address together with a port range using DHCPv6.
3.2.3. Avoiding Fragmentation
Normally the TCP protocol stack will employ Maximum Segment Size
(MSS) negotiation and/or Path Maximum Transmission Unit Discovery
(PMTUD) to determine
the maximum packet size, and then try to send as large as possible
datagram to achieve better throughput. However the IPv4-in-IPv6
encapsulation and the PPPoE header is very likly to cause a larger
packet that exceeds the maximum MTU of the wire, and result in
undesired fragmentation processing and decrease transmission
efficiency.
A simple solution is to enable iptables on A+P CPE to modify the MSS
value of TCP session, using the command like "iptables -t mangle -A
FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss
DESIRED_MSS_VALUE". Here the DESIRED_MSS_VALUE is taken into account
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of common size of IPv4 header without options, common size of TCP
header and size of basic IPv6 header and PPPoE header as well.
4. Application Tests and Experiments in A+P Environment
A set of well-known applications have been tested in this IPv6 flavor
of A+P environment to access A+P impacts on them. The test results
show that IPv6 flavor of A+P has the same impacts on applications as
IPv4 flavor A+P does [draft-boucadair-port-range-01]. Web browsing
(IE and Firefox), Email (Outlook),Instant message(MSN),Skype, Google
Earth work normally with A+P. For more details, please refer to
[draft-boucadair-port-range-01].
4.1. A+P Impacts on Applications
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+------------------+--------------------------------------+
| Application | A+P impacts |
+------------------+--------------------------------------+
| IE | None |
+------------------+--------------------------------------+
| Firefox | None |
+------------------+--------------------------------------+
| FTP(Passive mode)| None |
+------------------+--------------------------------------+
| FTP(Active mode) | require opening port forwarding |
| | |
+------------------+--------------------------------------+
| Skype | None |
+------------------+--------------------------------------+
| Outlook | None |
+------------------+--------------------------------------+
| Google Earth | None |
+------------------+--------------------------------------+
| BitComet | UPnP extensions may be required, when|
| | listening port is out of A+P range; |
| | other minor effects(see section 4.4) |
+------------------+--------------------------------------+
| uTorrent | UPnP extensions may be required, when|
| | listening port is out of A+P range; |
| | other minor effects(see section 4.4) |
+------------------+--------------------------------------+
| Live Messenger | None |
+------------------+--------------------------------------+
Figure 4 :Aplusp impacts on applications
For P2P (Peer-to-Peer) applications, when some of them listening on
specific port to expect inbounding connection, it is likely to fail
due to the listening port is out of A+P port range. Some UPnP
extensions may be required to make P2P applications work properly
with A+P. Other minor effects of A+P are discussed in section 4.4.
4.2. UPnP extension experiment
To make P2P application work properly with port restricted NAT , we
have designed extensions including new variables, new errorcodes as
well as new actions to UPnP 1.0, and have them implemented with
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[Emule], open source [UPnP SDK 1.0.4 for Linux] and [Linux UPnP IGD
0.92].
In figure 5, a new error code is proposed for the existing
"AddPortMapping" action to explicitly indicate the situation that the
requested external port is out of range.
+----------+-----------------------+-----------------------------+
| ErrorCode| errorDescription | Description |
+----------+-----------------------+-----------------------------+
| 728 |ExternalPortOutOfRange | The external port is out |
| | | of the port range assigned |
| | | to this external interface |
+----------+-----------------------+-----------------------------+
Figure 5 :New ErrorCode for "AddPortMapping" action
New state variables have been introduced to reflect the valid port
range. The definitions of these state variables are shown in figure
6.
+-------------+-------+------+----------+---------+-------+
|Variable |Req. or| Data | Allowed | Default | Eng. |
| Name | Opt.| Type | Value | Value | Units |
+-------------+-------+------+----------+---------+-------+
|PortRangeLow | O | ui2 | >=0 | 0 | N/A |
+-------------+-------+------+----------+---------+-------+
PortRangeHigh| O | ui2 | <=65535 | 65535 | N/A |
+-------------+-------+------+----------+---------+-------+
Figure 6 : New state variables
Correspondingly, new actions, GetPortRangeLow and GetPortRangeHigh ,
defined to retrieve port range information are illustrated in figure
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7. An IP address should be provided as argument to invoke the new
actions, for the port range is associated with a specific IP address.
+----------------+-----------------------+----+--------------------+
| Action Name | Argument |Dir.| Related |
| | | | StateVariable |
+----------------+-----------------------+----+--------------------+
|GetPortRangeLow | NewExternal IPAddress | IN | ExternalIPAddress |
| +-----------------------+----+--------------------+
| | NewPortRange Low | out| PortRangeLow |
+----------------+-----------------------+----+--------------------+
|GetPortRangeHigh| NewExternal IPAddress | IN | ExternalIPAddress |
| +-----------------------+----+--------------------+
| | NewPortRange High | out| PortRangeHigh |
+----------------+-----------------------+----+--------------------+
Figure 7 : New actions
Please refer to [UPnP Extension] for more details of UPnP extension
experiment in A+P.
4.3. Port Usage of Applications
Port consumptions of applications not only impact the deployment
factor (i.e., port range size) for AplusP solution but also play an
important role in determining the port limitation of per customer on
AFTR for Dual-Stack Lite.
Therefore we have also developed and deployed a Service Probe in our
IPv6 network, which use IPv6 TCP socket to ask AplusP CPE for NAT
session usage, and store AplusP NAT statistics in a Mysql database
for further analysis of application behaviors in terms of port and
session consumptions.
In figure 8, the maximum port usage of each application is the peak
number of port consumption per second during the whole communication
process. The duration time represents the total time from the first
NAT binding entry being established to the last one being destroyed.
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+-----------+--------------------------+--------------+----------+
|Application| Test case | Maximum | Duration |
| | | port usage | (seconds)|
+-----------+--------------------------+--------------+----------+
| | browsing a news website | 20-25 | 200 |
| IE +--------------------------+--------------+----------+
| | browsing a video website | 40-50 | 337 |
+-----------+--- ----------------------+--------------+----------+
| | browsing a news website | 25-30 | 240 |
| Firefox +--------------------------+--------------+----------+
| | browsing a video website | 80-90 | 230 |
+-----------+--------------------------+--------------+----------+
| | browsing a news website | 50-60 | 340 |
| Chrome +--------------------------+--------------+----------+
| | browsing a video website | 80-90 | 360 |
+-----------+--------------------------+--------------+----------+
| Andrio | browsing a news website | 40-50 | 300 |
| Chrome +--------------------------+--------------+----------+
| | browsing a video website | under 10 | 160 |
+-----------+--------------------------+--------------+----------+
| Google | locating a place | 30-35 | 240 |
| Earth | | | |
+-----------+--------------------------+--------------+----------+
| Andrio | | | |
| Google | locating a place | 10-15 | 240 |
| Earth | | | |
+-----------+--------------------------+--------------+----------+
| Skype | make a call | under 10 | N/A |
+-----------+--------------------------+--------------+----------+
| BitTorrent| downloading a file | 200 | N/A |
+-----------+--------------------------+--------------+----------+
Figure 8 : Port usage of applications
4.4. BitTorrent Behaviour in A+P
[draft-boucadair-behave-bittorrent-portrange] provides an exhaustive
testing report about the behaviour of BiTtorrent in an A+P
architecture. [draft-boucadair-behave-bittorrent-portrange] describes
the main behavior of BitTorrent service in an IP shared address
environment. Particularly, the tests have been carried out on a
testbed implementing [ID.boucadair-port-range] solution. The results
are, however, valid for all IP shared address based solutions.
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Two limitations were experienced. The first limitation occurs when
two clients sharing the same IP address want to simultaneously
retrieve the SAME file located in a SINGLE remote peer. This
limitation is due to the default BitTorrent configuration on the
remote peer which does not permit sending the same file to multiple
ports of the same IP address. This limitation is mitigated by the
fact that clients sharing the same IP address can exchange portions
with each other, provided the clients can find each other through a
common tracker, DHT, or Peer Exchange. Even if they can not, we
observed that the remote peer would begin serving portions of the
file automatically as soon as the other client (sharing the same IP
address) finished downloading. This limitation is eliminated if the
remote peer is configured with bt.allow_same_ip == TRUE.
The second limitation occurs when a client tries to download a file
located on several seeders, when those seeders share the same IP
address. This is because the clients are enforcing bt.allow_same_ip
parameter to FALSE. The client will only be able to connect to one
sender, among those having the same IP address, to download the file
(note that the client can retrieve the file from other seeders having
distinct IP addresses). This limitation is eliminated if the local
client is configured with bt.allow_same_ip == TRUE, which is somewhat
likely as those clients will directly experience better throughput by
changing their own configuration.
Mutual file sharing between hosts having the same IP address has been
checked. Indeed, machines having the same IP address can share
files with no alteration compared to current IP architectures.
5. Security Considerations
TBD
6. IANA Considerations
This document includes no request to IANA.
7. Conclusion
Despite A+P introduces some impacts on existence applications, issues
of P2P applications due to the port restricted NAT have been resolved
by UPnP extension experiment in our test bed, and other issues are
shared by other IP address sharing solutions. Therefore, from our
work, it has been proved that deploying A+P in the Service Provider's
IPv6 network during IPv6 transition period is feasible.
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8. References
8.1. Normative References
[Implementing A+P]
Xiaoyu ZHAO.,"Implementing Public IPv4 Sharing in IPv6
Environment", ICCGI 2010
[UPnP Extension]
Xiaoyu ZHAO., "UPnP Extensions for Public IPv4 Sharing in
IPv6 Environment", ICNS 2010
8.2. Informative References
[draft-ymbk-aplusp-09]
R. Bush., " The A+P Approach to the IPv4 Address Shortage",
draft-ymbk-aplusp-09 (work in progress), February 17, 2011.
[draft-boucadair-dhcpv6-shared-address-option]
M. Boucadair., "Dynamic Host Configuration Protocol (DHCPv6)
Options for Shared IP Addresses Solutions", draft-
boucadair-dhcpv6-shared-address-option-01 (work in
progress), December 21, 2009
[draft-boucadair-port-range-01]
"IPv4 Connectivity Access in the Context of IPv4 Address
Exhaustion", draft-boucadair-port-range-01(work in
progress), January 30, 2009
[Emule]
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http://www.emule-project.net/. [Accessed October 26, 2009]
[UPnP SDK 1.0.4 for Linux]
http://upnp.sourceforge.net/. [Accessed October 26, 2009].
[Linux UPnP IGD 0.92].
http://linuxigd.sourceforge.net/. [Accessed October 26,
2009].
[draft-boucadair-behave-bittorrent-portrange]
M. Boucadair.,"Behaviour of BitTorrent service in an IP
Shared Address Environment", draft-boucadair-behave-
bittorrent-portrange-02.txt
9. Acknowledgments
The experiments and tests described in this document have been
explored, developed and implemented with help from Zheng Tao, Zhao
Xiaoyu, Eric Burgey, Ma Yan and JACQUENET Christian.
Thanks to Jan Zorz for comments.
This document was prepared using 2-Word-v2.0.template.dot.
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Authors' Addresses
Xiaohong Deng
France Telecom
Hai dian district, 100190, Beijing, China
Email: xiaohong.deng@orange-ftgroup.com
Mohamed Boucadair
France Telecom
Rennes,35000 France
Email: mohamed.boucadair@orange-ftgroup.com
Lan Wang
France Telecom
Hai dian district, 100190, Beijing, China
Email: lan.wang@orange-ftgroup.com
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