Internet Engineering Task Force X.Deng Internet Draft M.Boucadair Intended status: Informational France Telecom Expires: May 1, 2012 Y.Lee Comcast T.Zheng L.Wang France Telecom X.Huang Q.Zhao Y.Ma BUPT Oct 31, 2011 Implementing A+P in the provider's IPv6-only network draft-deng-softwire-aplusp-experiment-results-01.txt Abstract This memo focuses on the IPv6 flavor of A+P. This memo describes an implementation of A+P in a provider's IPv6- only network. It provides details of the implementation, network elements, configurations and test results as well. Besides traditional port range A+P, a scattered port sets flavor of A+P is also implemented to verify feasibility of offering non-continuous port sets with A+P approach, and to investigate possibility and efforts of making UPnP 1.0 work with A+P. The test results consist of the application compatibility test, UPnP 1.0 extensions and UPnP 1.0 friendly port allocation for A+P, port usage and BitTorrent behaviors with A+P. This memo focuses on the IPv6 flavor of A+P. 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/. Deng, et al. Expires May 1, 2012 [Page 1] Internet-Draft A+P implementation October 2011 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 May 1, 2012. Copyright Notice Copyright (c) 2011 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 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....................................................3 2. Terminology.....................................................3 3. Implementation environment......................................4 3.1. Environment Overview.......................................4 3.2. Implementation and Configuration of A+P....................5 3.2.1. IPv4-Embedded IPv6 Address Format For A+P CPE.........6 3.2.2. DHCPv6 Configurations.................................6 3.2.3. Avoiding Fragmentation................................6 3.3. Implementing non-continuous Port Sets for A+P..............7 3.3.1. Non-continuousPort Sets allocation mechanism..........7 3.3.2. IPv4-Embedded IPv6 Address Format for Non- continuousPort Sets A+P CPE.................................10 3.3.3. Customize a non-continuousPorts Set A+P NAT on Linux.11 4. Application Tests and Experiments in A+P Environment...........12 4.1. A+P Impacts on Applications...............................12 4.2. UPnP extension experiment.................................13 4.2.1. UPnP 1.0 extension...................................13 4.2.2. Evaluation of non-continuous port allocation taking UPnP 1.0 friendliness into account..........................15 4.3. Port Usage of Applications................................17 Deng, et al. Expires May 1, 2012 [Page 2] Internet-Draft A+P implementation October 2011 4.4. BitTorrent Behaviour in A+P...............................19 5. Security Considerations........................................19 6. IANA Considerations............................................20 7. Conclusion.....................................................20 8. References.....................................................20 8.1. Normative References......................................20 8.2. Informative References....................................20 9. Acknowledgments................................................21 1. Introduction A+P [RFC6346] 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 services 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 [RFC6346]: 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 Deng, et al. Expires May 1, 2012 [Page 3] Internet-Draft A+P implementation October 2011 o A+P CPE: A+P aware Customer Premise Equipment 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. Deng, et al. Expires May 1, 2012 [Page 4] Internet-Draft A+P implementation October 2011 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]. +--------+------------+-------+-----+------------+-----------+------+ | 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 of A+P A+P 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 restricted 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. Deng, et al. Expires May 1, 2012 [Page 5] Internet-Draft A+P implementation October 2011 3.2.1. IPv4-Embedded IPv6 Address Format For A+P CPE |31bits|1bit| 32bits|8 bits|16bits|4bits|1bit|1bit|1bit|1bit|32 bits| +------+----+-------+------+------+-----+----+----+----+----+-------+ |A+P |flag|Public | EUI64| port |Port |flag|flag|flag|flag|Public | |Prefix| 0 |IPv4 | | Range|Range| 1 | 2 | 3 | 4 |IPv4 | | | |Address| | |Size | | | | |Address| +------+----+-------+------+------+-----+----+----+----+----+-------+ 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 A+P solution, recently, we are considering release this A+P 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 Deng, et al. Expires May 1, 2012 [Page 6] Internet-Draft A+P implementation October 2011 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 likely 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 of common size of IPv4 header without options, common size of TCP header and size of basic IPv6 header and PPPoE header as well. 3.3. Implementing non-continuous Port Sets for A+P 3.3.1. Non-continuousPort Sets allocation mechanism As described in [I-D.ietf-intarea-shared-addressing-issues], a bulk of incoming ports can be reserved as a centralized resource shared by all subscribers using a given restricted IPv4 address. In order to distribute incoming ports as non-continuous as possible among subscribers sharing the same restricted IPv4 address, other than allocating a continuous range of ports to per subscriber, a solution to distribute bulks of non-continuous ports among subscribers, which also takes port randomization of CPE NAT into account, because port randomization is one protection among others against blind attacks, is elaborated thereby. Note that the non-continuous port sets allocation mechanism implemented here is just one possible solution among others to offer non-continuous port provisioning. The implementation itself is to address two targets: 1) proving feasibility of non-continuous ports with A+P approach; 2) Evaluate efforts and investigate possibility of making UPnP 1.0 applications still work with this approach, with which experiments results will be described in Section 4.2.2. On every restricted IPv4 address, according to port set size N, log2(N)bits are randomly chose as subscribers identification bits(s bit) among 1st and 16th bits. Take a sharing ration 1:32 for example, Figure 4 shows an example of 5bits (2nd, 5th, 7th, 9th, 11th) being chose as s bit. |1st |2nd |3rd |4th |5th |6th |7th | 8th| Deng, et al. Expires May 1, 2012 [Page 7] Internet-Draft A+P implementation October 2011 +----+----+----+----+----+----+----+----+ | 0 | s | 0 | 0 | s | 0 | s | 0 | +----+----+----+----+----+----+----+----+ |9th |10th|11th|12th|13th|14th|15th|16th| +----+----+----+----+----+----+----+----+ | s | 0 | s | 0 | 0 | 0 | 0 | 0 | +----+----+----+----+----+----+----+----+ Figure 4 : An s bit selection example (on a sharing ration 1:32 address). Subscriber ID pattern is then formed by setting all the s bits to 1 and other trivial bits to 0. Figure 5 illustrates an example of subscriber ID pattern which follows the s bit selection of figure 4. Note that the subscriber ID pattern can be different, ensured by the random s bit selection, per restricted IP address no matter whether the sharing ratio varies. |1st |2nd |3rd |4th |5th |6th |7th | 8th| +----+----+----+----+----+----+----+----+ | 0 | 1 | 0 | 0 | 1 | 0 | 1 | 0 | +----+----+----+----+----+----+----+----+ |9th |10th|11th|12th|13th|14th|15th|16th| +----+----+----+----+----+----+----+----+ | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | +----+----+----+----+----+----+----+----+ Figure 5 : A subscriber ID pattern example (on a sharing ration 1:32 address). Deng, et al. Expires May 1, 2012 [Page 8] Internet-Draft A+P implementation October 2011 Subscribers ID value is then assigned by setting subscriber ID pattern bits (s bits shown in figure 4) to a unique customer value and setting other trivial bits to 1. An example of subscriber ID value, having a subscriber ID pattern shown in the figure 5 and a customer value 0, is shown in the figure 6. |1st |2nd |3rd |4th |5th |6th |7th | 8th| +----+----+----+----+----+----+----+----+ | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | +----+----+----+----+----+----+----+----+ |9th |10th|11th|12th|13th|14th|15th|16th| +----+----+----+----+----+----+----+----+ | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | +----+----+----+----+----+----+----+----+ Figure 6 : A subscriber ID value example (customer value: 0) Subscriber ID pattern and subscriber ID value together uniquely defines a restricted port set (Non-contiguous port sets or a contiguous port range, depends on Subscriber ID pattern and subscriber ID value) on a restricted IP address. Pseudo-code shown in the figure 7 describes how to use subscriber ID pattern and subscriber ID value to implement a random ephemeral port selection function within the defined restricted port sets on a customer NAT. do{ restricted_next_ephemeral = (random()|subscriber_ID_pattern) & subscriber_ID_value; Deng, et al. Expires May 1, 2012 [Page 9] Internet-Draft A+P implementation October 2011 if(five-tuple is unique) return restricted_next_ephemeral; } Figure 7 : Random ephemeral port selection within the restricted port set 3.3.2. IPv4-Embedded IPv6 Address Format for Non-continuousPort Sets A+P CPE |31bits|1bit| 32bits|8bits|16bits |4bits|1bit|1bit|1bit|1bit|32bits| +------+----+-------+------+------+-----+----+----+----+----+-------+ |A+P |flag|Public | EUI64|SID_ |Reser|flag|flag|flag|flag|Public | |Prefix| 0 |IPv4 | |Value |-ved | 1 | 2 | 3 | 4 | IPv4 | | | |Address| | | | | | | |Address| +------+----+-------+------+------+-----+----+----+----+----+-------+ Figure 8 :IPv4-Embedded IPv6 address format SID Value: Subscriber_ID_Value, which is unique for per subscriber sharing a given restricted IPv4 address. and has been allocated to each subscriber. 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? PRR maintains a mapping table, which consists of restricted IPv4 address and it's Subscriber ID Pattern. To form an IPv6 destination address for incoming packet, PRR could find the right SID Pattern according to a destination IPv4 address, and then apply a simple operation shown in the figure 9. SID_Value = Destination_Port | (~SID_Pattern); Deng, et al. Expires May 1, 2012 [Page 10] Internet-Draft A+P implementation October 2011 Figure 9 :PRR calculates SID Value 3.3.3. Customize a non-continuousPorts Set A+P NAT on Linux With a linux kernel 2.6.32.36, only one line of linux kernel code is changed, as shown in the figure 10, and the same IPtables command line interface is used with the only one change of semantic that the original staring of port range becomes SID_Value and the ending port of a port range becomes SID_Pattern. The command line with iptables to configure a non-continuousPorts Set A+P is illustrated in the figure 11. bool nf_nat_proto_unique_tuple(...) ... //The Original code: //*portptr = htons(min + off % range_size); // was changed to: *portptr = htons((ntohs(off) | min ) & max ); ... Figure 10:Function of finding a unique 5-tuple for a non- continuousport sets A+P NAT iptables -t nat -A POSTROUTING -o eth0 -p tcp -j SNAT --to-source a.b.c.d: SID_Value-SID_Pattern --random iptables -t nat -A POSTROUTING -o eth0 -p udp -j SNAT --to-source a.b.c.d: SID_Value-SID_Pattern --random Figure 11: IPtables commands for a non-continuousports set A+P NAT Deng, et al. Expires May 1, 2012 [Page 11] Internet-Draft A+P implementation October 2011 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 Deng, et al. Expires May 1, 2012 [Page 12] Internet-Draft A+P implementation October 2011 +------------------+--------------------------------------+ | 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 12: A+P 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 4.2.1. UPnP 1.0 extension To make P2P application work properly with port restricted NAT , we have designed extensions including new variables, new error codes as well as new actions to UPnP 1.0, and have them implemented with Deng, et al. Expires May 1, 2012 [Page 13] Internet-Draft A+P implementation October 2011 [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 13: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 14: New state variables for port range Correspondingly, new actions, GetPortRangeLow and GetPortRangeHigh, defined to retrieve port range information are illustrated in figure Deng, et al. Expires May 1, 2012 [Page 14] Internet-Draft A+P implementation October 2011 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 15: New actions for port range Please refer to [UPnP Extension] for more details of UPnP extension experiment in A+P. 4.2.2. Evaluation of non-continuous port allocation taking UPnP 1.0 friendliness into account UPnP 1.0 applications behaviors of asking for an external port Deng, et al. Expires May 1, 2012 [Page 15] Internet-Draft A+P implementation October 2011 +-------------------+----------------------------------------------+ | Application | Behaviors | | | | +-------------------+----------------------------------------------+ | Microtorrent v2.2 | call GetSpecificPortMapping by incremental by| | | 1 each time, | | (also known as | until find an external port available, and | | uTorrent) | then call AddPortMapping,or return error | | | after five failures | +-------------------+----------------------------------------------+ | Emule v0.50a | call AddPortMapping, after finding the | | | external port not available return error | | | | +-------------------+----------------------------------------------+ | Azureus v4.6.0.2 | call AddPortMapping, after finding the | | | external port not available, try the same | | | port 5 more times by call AddPortMapping, | | | then return error | |-------------------+----------------------------------------------+ | Shareazav2.2.5.7 | call GetSpecificPortMapping, after finding | | | the external port not available, return error| | | without issuing AddPortMapping | +-------------------+----------------------------------------------+ As per above typical behaviours of UPnP 1.0 applications' asking for external port, to instance a port allocation making port sets interval less than 5 so that some UPnP applications would probably succeed in 5 times retrying, A non-continuous port allocation example would be: Subscriber ID Pattern 0x02 and 2 customers share the same IP address, where 4 times retrying would succeed. Deng, et al. Expires May 1, 2012 [Page 16] Internet-Draft A+P implementation October 2011 +-------------------+----------------------------------------------+ | Application | Does it work with UPnP 1.0 friendly port | | | provisioning method? | | | | | | | +-------------------+----------------------------------------------+ | Microtorrent v2.2 | Yes | | | | | (also known as | | | uTorrent) | | | | | +-------------------+----------------------------------------------+ | Emule v0.50a | 1/5 chance of working | | | | | | | +-------------------+----------------------------------------------+ | Azureus v4.6.0.2 | 1/5 chance of working | | | | | | | | | | |-------------------+----------------------------------------------+ | Shareazav2.2.5.7 | 1/5 chance of working | | | | | | | +-------------------+----------------------------------------------+ The test results show that even with restricted UPnP 1.0 friendly port allocation, where however the sharing ratio 2 may not be applicable to most of use cases ,only one application among others would be granted working, while with others only the chances of success have been increased. IGD:1 is known to be broken in shared address environment [RFC6269]; IGD:2 mitigates the issues encountered in IGD:1. The efforts, documented above, to solve the encountered issues in IGD:1 thereby aiming only at evaluate the amount of requirement modifications and assess the validity of the approach. 4.3. Port Usage of Applications Port consumptions of applications not only impact the deployment factor (i.e., port range size) for A+P solution but also play an important role in determining the port limitation of per customer on AFTR for Dual-Stack Lite. Deng, et al. Expires May 1, 2012 [Page 17] Internet-Draft A+P implementation October 2011 Therefore we have also developed and deployed a Service Probe in our IPv6 network, which use IPv6 TCP socket to ask A+P CPE for NAT session usage, and store A+P NAT statistics in a Mysql database for further analysis of application behaviours 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. +-----------+--------------------------+--------------+----------+ |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 | +-----------+--------------------------+--------------+----------+ | Android | browsing a news website | 40-50 | 300 | | Chrome +--------------------------+--------------+----------+ | | browsing a video website | under 10 | 160 | +-----------+--------------------------+--------------+----------+ | Google | locating a place | 30-35 | 240 | | Earth | | | | +-----------+--------------------------+--------------+----------+ | Android | | | | | Google | locating a place | 10-15 | 240 | | Earth | | | | +-----------+--------------------------+--------------+----------+ | Skype | make a call | under 10 | N/A | +-----------+--------------------------+--------------+----------+ | BitTorrent| downloading a file | 200 | N/A | +-----------+--------------------------+--------------+----------+ Figure 16: Port usage of applications Deng, et al. Expires May 1, 2012 [Page 18] Internet-Draft A+P implementation October 2011 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. 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 Deng, et al. Expires May 1, 2012 [Page 19] Internet-Draft A+P implementation October 2011 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 both port range and non- continuous port sets A+P in the Service Provider's IPv6 network during IPv6 transition period is feasible. 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 [RFC6346] R. Bush., " The Address plus Port (A+P) Approach to the IPv4 Address Shortage", August,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 Deng, et al. Expires May 1, 2012 [Page 20] Internet-Draft A+P implementation October 2011 [Emule] 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 Zhao Xiaoyu, Eric Burgey and JACQUENET Christian. Appreciation to Randy Bush's intitial idea of documenting these experience results, for share the knowledge of what we have learnt with the community. Thanks to Jan Zorz for comments. Deng, et al. Expires May 1, 2012 [Page 21] Internet-Draft A+P implementation October 2011 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 Yiu L. Lee Comcast One Comcast Center Philadelphia, PA 19103 U.S.A. Lan Wang France Telecom Hai dian district, 100190, Beijing, China Email: lan.wang@orange-ftgroup.com Tao Zheng France Telecom Hai dian district, 100190, Beijing, China Email: tao.zheng@orange-ftgroup.com Xiaohong Huang Beijing University of Post and Telecommunication Email: huangxh@bupt.edu.cn Qin Zhao Beijing University of Post and Telecommunication Email: zhaoqin.bupt@gmail.com Yan MA Beijing University of Post and Telecommunication Email: mayan@bupt.edu.cn Deng, et al. Expires May 1, 2012 [Page 22] Internet-Draft A+P implementation October 2011 Deng, et al. Expires May 1, 2012 [Page 23]