Internet Engineering Task Force X.Deng Internet Draft M.Boucadair Intended status: Informational France Telecom Expires: September 2, 2012 Y.Lee Comcast X.Huang Q.Zhao BUPT March 1, 2012 Implementing A+P in the provider's IPv6-only network draft-deng-softwire-aplusp-experiment-results-02.txt Abstract 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. 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/. 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 September 2, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. Deng, et al. Expires May 1, 2012 [Page 1]
Internet-Draft A+P Implementation March 2012 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-continuous Port Sets allocation mechanism ...... 7 3.3.2. IPv4-Embedded IPv6 Address Format for Non-continuous Port Sets A+P CPE ....................................... 10 3.3.3. Customize a non-continuous Ports Set A+P NAT ...... 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. UPnP 1.0 friendliness attempts .................... 14 4.3. Port Usage of Applications ............................. 16 4.4. BitTorrent Behaviour in A+P ............................ 17 5. Security Considerations .................................... 18 6. IANA Considerations ........................................ 18 7. Conclusion ................................................. 18 8. References ................................................. 19 8.1. Normative References ................................... 19 8.2. Informative References ................................. 19 9. Additional Authors ......................................... 20 10. Acknowledgments ........................................... 20 Deng, et al. Expires May 1, 2012 [Page 2]
Internet-Draft A+P Implementation March 2012 1. Introduction A+P [RFC6346] is a technique to share IPv4 addresses over IPv6-only network without requiring a NAT function in the provider's network. The main idea of A+P is borrowing some bits from the port number in the TCP/UDP header to identify the end point. Those port numbers assigned to the end point will be used by IPv4 applications. A+P can facilitate network migration to IPv6-only while continue to offer IPv4 connectivity to customers by tunneling IPv4 packets over IPv6- only network. We implemented A+P in a residential ADSL access network, where IPv6- only access network is provided over PPPoE. In this memo, we first describe the implementation environment including A+P IPv6 prefix format and network elements configurations, then we describes the test results. In particular, this memo focuses on the SMAP function implementation specified in [RFC6346]. For more application test results in A+P environment, please refer to [draft-boucadair-behave-bittorrent-portrange-02] and [draft- boucadair-port-range-01]. 2. Terminology This memo uses the following terms: o PRR: Port Range Router o A+P CPE: A+P aware Customer Premise Equipment Deng, et al. Expires May 1, 2012 [Page 3]
Internet-Draft A+P Implementation March 2012 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 developed both A+P CPE function and Port Range Router (PRR) function on Linux. A+P CPE function was implemented on Linksys WRT54GS router running OpenWRT 2.6.32. PRR function was implemented on standard Intel based server. Figure 1 shows the high-level network diagram of the test environment. Figure 2 shows the configuration of A+P CPE. IPv6 prefix was provisioned over PPPoE to CPE by a DHCPv6 server. In addition, it also offered A+P parameters via DHCPv6 options defined in [draft- boucadair-dhcpv6-shared-address-option]. Deng, et al. Expires May 1, 2012 [Page 4]
Internet-Draft A+P Implementation March 2012 +--------+------------+-------+-----+------------+-----------+------+ | 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 uses Netfilter framework to implement the port-set restricted NAT. Port set restricted NAT operation was done by iptables rules. After the port restricted NAT operation, IPv4 packets were sent to a TUN interface which was a virtual network interface in Linux. The TUN interface is a virtual interface that performs the IPv4-in-IPv6 function. Using the IPv4-Embedded IPv6 address format defined in section 3.2.1, an IPv4-in-IPv6 function is performed by the TUN interface handler. PRR bridges the IPv6 access network to the IPv4 Internet. It contains two main functions: 1) IPv4-in-IPv6 encapsulation/decapsulation; Similar to A+P CPE, PRR implementation leveraged the virtual TUN driver handler for IPv4-in-IPv6 function. 2) Destination IPv4 address and layer 4 port based routing function is responsible for routing the IPv4 traffic originated from the IPv4 Internet to the Port Range restricted A+P CPE. The goal of PRR is to deliver the IPv4 packet to the A+P CPE that was assigned with the port number used in the destination port in the layer 4 header. Since PRR delivers the IPv4 packet over IPv4-in-IPv6 tunnel, PRR can embed the IPv4 address and port number in the IPv6 address. The IPv4-Embedded IPv6 address is used to uniquely identify the A+P CPE. Details of how to construct the IPv4-Embedded IPv6 address format is defined in Section 3.2.1. Deng, et al. Expires May 1, 2012 [Page 5]
Internet-Draft A+P Implementation March 2012 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 other parties who are also interested in testing A+P solution, we are considering to 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] were implemented. These options allow configuring a shared address and a port range using a DHCPv6 option. 3.2.3. Avoiding Fragmentation Normally the host TCP/IP protocol stack uses TCP protocol stack uses Maximum Segment Size (MSS) option and/or Path Maximum Transmission Unit Discovery (PMTUD) to determine the MTU. However adding the IPv6 Header and the PPPoE header to the IPv4 packet may exceed the maximum MTU of the wire and consequently results in IP fragmentation. Deng, et al. Expires May 1, 2012 [Page 6]
Internet-Draft A+P Implementation March 2012 One solution is to add a rule to iptables on A+P CPE to modify the MSS value in TCP SYN and SYN-ACK. This can be done using command "iptables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss DESIRED_MSS_VALUE". The DESIRED_MSS_VALUE is set to exclude IPv4 header, TCP header, IPv6 header and PPPoE header length. 3.3. Implementing non-continuous Port Sets for A+P 3.3.1. Non-continuous Port Sets allocation mechanism [I-D.ietf-intarea-shared-addressing-issues] states that a bulk of incoming ports can be reserved as a centralized resource shared by all subscribers using a given restricted IPv4 address. We could distribute a range of continuous ports to each subscriber. This may create security concerns such as blind attack. An alternative would be to assign a bulk of non-continuous random ports to each subscriber. The following session would describe the implementation of non-continuous port-set. Note that the non-continuous port-set allocation mechanism described here is just one possible solution to implement non-continuous port provisioning. The implementation itself is to achieve two goals: 1) Proving of feasibility of non-continuous port-set with A+P approach; 2) Evaluating UPnP 1.0 compatibility with non-continuous port-set. Experiment results are provided in Section 4.2.2. Given a port-set size N, log2(N) bits are randomly chosen as subscribers identification bits(S-bit). S-bit must be chosen between 1st and 16th bits. For example: if sharing ration is 1:32, each subscriber will have five S-bits. Figure 4 shows an example of 5 S-bits (2nd, 5th, 7th, 9th and 11th) for a subscriber. Subscriber ID pattern is formed by setting all the S-bits to 1 and other trivial bits to 0. Figure 5 illustrates an example of subscriber ID pattern based on S-bits example in Figure 4. Note that the subscriber ID pattern must be identical for each subscriber that shares the same IPv4 address. Subscribers ID value is assigned by setting subscriber ID pattern bits (s bits shown in figure 4) to a unique customer value to identify each customer 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. Deng, et al. Expires May 1, 2012 [Page 7]
Internet-Draft A+P Implementation March 2012 |1st |2nd |3rd |4th |5th |6th |7th | 8th| +----+----+----+----+----+----+----+----+ | 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). |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 March 2012 |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 define 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; if(five-tuple is unique) return restricted_next_ephemeral; } Deng, et al. Expires May 1, 2012 [Page 9]
Internet-Draft A+P Implementation March 2012 Figure 7 : Random ephemeral port selection within the restricted port set 3.3.2. IPv4-Embedded IPv6 Address Format for Non-continuous Port 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? To support non-continuous port-set, PRR maintains a mapping table which contains the pairs 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); Figure 9 :PRR calculates SID Value Deng, et al. Expires May 1, 2012 [Page 10]
Internet-Draft A+P Implementation March 2012 3.3.3. Customize a non-continuous Ports Set A+P NAT On a Linux kernel 2.6.32.36, only one line of linux kernel code was Changed to implement this feature. Figure 10 shows the change. Figure 11 show the IPtables commands required in the PRR. The beginning of port range changed to SID_Value and the ending of the port range changed to SID_Pattern. 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 March 2012 4. Application Tests and Experiments in A+P Environment A set of well-known applications was tested. The tests compared A+P over IPv6 and simple A+P without encapsulation on a pain IPv4 network. The test results showed that both share the same impacts [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 +------------------+--------------------------------------+ | 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 Deng, et al. Expires May 1, 2012 [Page 12]
Internet-Draft A+P Implementation March 2012 P2P (Peer-to-Peer) applications using specific port for inbounding connection are likely to fail, because the specific ports may not be available for that A+P subscriber. 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 [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. Deng, et al. Expires May 1, 2012 [Page 13]
Internet-Draft A+P Implementation March 2012 +-------------+-------+------+----------+---------+-------+ |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 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. UPnP 1.0 friendliness attempts Deng, et al. Expires May 1, 2012 [Page 14]
Internet-Draft A+P Implementation March 2012 +-------------------+----------------------------------------------+ | 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 | +-------------------+----------------------------------------------+ Figure 16 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 March 2012 The Behaviors test results in the previous figure shows that if a request of external port failed, some UPnP 1.0 applications, namely Microtorrent v2.2 and Azureus v4.6.0.2 attempt to issue (at most) 4 more times request until succeed. With each external port request attempts, the desired external port is incremented by 1 of the previous requested external port. Hence, allocating port sets in a way that each A+P subscriber has sub sets interval less than 5 would make some UPnP 1.0 applications succeed in 5 times retrying. For example, In case a Subscriber ID Pattern 0x02 that makes 2 customers sharing one IPv4 address, and customer 1 have the available ports { 0,1 | 4,5 | 8,9 |12,13|....} while customer 2 have the available ports: { 2,3 | 6,7 | 10,11|14,15|....} Microtorrent v2.2 and Azureus v4.6.0.2 would be compatible with port restriction feature of A+P. IGD:1 is known to be broken in shared address environment [RFC6269]; IGD:2 mitigates the issues encountered in IGD:1. The efforts, documented in section 4.2, were attempts before standardization of IGD:2. 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. 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 Deng, et al. Expires May 1, 2012 [Page 16]
Internet-Draft A+P Implementation March 2012 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 17: 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 Deng, et al. Expires May 1, 2012 [Page 17]
Internet-Draft A+P Implementation March 2012 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 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- Deng, et al. Expires May 1, 2012 [Page 18]
Internet-Draft A+P Implementation March 2012 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 [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]. Deng, et al. Expires May 1, 2012 [Page 19]
Internet-Draft A+P Implementation March 2012 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. Additional Authors 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 Yan MA Beijing University of Post and Telecommunication Email: mayan@bupt.edu.cn 10. 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 20]
Internet-Draft A+P Implementation March 2012 11. Authors' Addresses Xiaohong Deng France Telecom Hai dian district, 100190, Beijing, China Email: dxhbupt@gmail.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. Email: Yiu_Lee@Cable.Comcast.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 Deng, et al. Expires May 1, 2012 [Page 21]