[Docs] [txt|pdf] [Tracker] [Email] [Diff1] [Diff2] [Nits]

Versions: 00 01 02 03 04

ALTO                                                             Kai Lee
Internet-Draft                                             China Telecom
Intended status: Informational                             GuangYao.Jian
Expires: Sep 11, 2012                                     Xunlei network
                                                          March 11, 2012

           ALTO and DECADE service trial within China Telecom
                draft-lee-alto-chinatelecom-trial-04.txt


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 Sep 11, 2012.

























<Kai.Lee>                 Expires Sep 11, 2012                  [Page 1]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


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
   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.








Abstract

      This document reports the experience of China Telecom in a recent
   experiment with the ALTO service and P2P caches deployment. It is
   found that the deployment of the ALTO service significantly improves
   the capability of a Service Provider to affect the distribution of
   P2P traffic. It is also found that a traffic localized ALTO policy
   may decrease the download speed of a P2P user. However, the
   deployment of some P2P caches can compensate such influence.




















<Kai.Lee>                 Expires Sep 11, 2012                  [Page 2]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2. High level description of the trial . . . . . . . . . . . . . .  4
     2.1. Difference between standard ALTO protocol . . . . . . . . .  4
     2.2. Difference between Comcast's trial  . . . . . . . . . . . .  5
   3. Trial results . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1. Trial configuration . . . . . . . . . . . . . . . . . . . .  6
     3.2. Xunlei traffic distribution before the trial  . . . . . . .  7
     3.3. ALTO policy test  . . . . . . . . . . . . . . . . . . . . .  8
     3.4. P2P cache test  . . . . . . . . . . . . . . . . . . . . . .  9
   4. Methods of data collection  . . . . . . . . . . . . . . . . . .  9
   5. Configurations and algorithms in trial  . . . . . . . . . . . . 10
     5.1. Configuration of PID MAP  . . . . . . . . . . . . . . . . . 10
     5.2. Algorithms of Xunlei using ALTO information . . . . . . . . 10
     5.3. Configuration of cache system . . . . . . . . . . . . . . . 12
   6. Next steps  . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   7. Security Considerations . . . . . . . . . . . . . . . . . . . . 13
   8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 13
   9. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 13
   Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13






























<Kai.Lee>                 Expires Sep 11, 2012                  [Page 3]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


1. Introduction
      Although another trial on P4P, the predecessor of the ALTO, is
   available by Comcast, the impact of ALTO on a large scale real
   network has never publicly reported. Such real network should post no
   limitation on either the number of contents or the number of users.
   This draft reports the experience of China Telecom in a recent
   experiment with the deployment of the ALTO service and P2P caches.

      With over 60 million fixed-line broadband subscribers, China
   Telecom is the largest broadband service provider in China. It has
   one IP backbone network that cover all of the 31 provinces in China
   and about 200 MAN networks are managed by the provinces respectively.
   This trial was taken place in one province with 7 million broadband
   subscribers and   about 11 MAN networks.

      Xunlei, the cooperator of this trial, is a leading P2P service
   provider in China. Xunlei supports both file downloads and real time
   media streaming. In 2009, when was this trail occurring, it serves
   over 20 million users each day.

      This trial is a joint effort of China Telecom and Xunlei. During
   this trial, China Telecom provided the following devices: an alto
   server to distribute ALTO information, some P2P caches to improve
   Xunlei service experience, and network management systems based on
   SNMP and DPI technology to monitor the traffic load within its
   backbone. Xunlei provided the P2P client and users. To support this
   trial, Xunlei modified its platform to support ALTO, and recorded
   operational information on its platform according to the requirement
   of China Telecom. Note that the client of Xunlei was not changed.


2. High level description of the trial

2.1. Difference between standard ALTO protocol

      Note that ALTO protocol is still on progressing, in this trail,
   some modifications were made to the ALTO.

      Firstly a server notification mechanism for the ALTO server is
   introduced. With this mechanism, the ALTO server notifies its clients
   the changes of network maps and cost maps. Thus, ALTO clients can
   make timely respond to the change of traffic optimizing
   policy(Note:different traffic optimizing policies mean different
   network maps and cost maps). This mechanism is mainly used to solve
   the problem related to alto effect evaluation. As we know the traffic
   within the IP backbone is highly periodical. For example, the traffic
   on each weekend is higher than which on the workday.As such, the
   evaluation traffic data to compare should be both collected in the



<Kai.Lee>                 Expires Sep 11, 2012                  [Page 4]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


   workday or in the weekend. We need to change the traffic optimizing
   policy constantly to collect the traffic data with and without effect
   of alto service to evaluate the effect of ALTO service. That's why we
   need the server notification in this trial.

      In this trail, ALTO clients were embedded in the trackers of
   Xunlei, not in the Xunlei clients. The reason for this is mainly for
   deployment consideration. There are hundreds of millions of Xunlei
   clients in use, To update these clients as the ALTO client in a short
   time is not feasible. However, according to the analysis of Xunlei,
   although both tracker based and tracker-less technology are adopted,
   the traffic does not controlled by the trackers is less than 15% of
   its total traffic. Based on this analysis, in this trial, Xunlei
   clients are not involved in the ALTO service which has negligible
   influence on the final evaluation of this trial. Such design can also
   reduce the load on the ALTO server.

      Secondly, only map service is provided in this trial. Endpoint
   property service and Endpoint cost service were not supplied, as they
   are not essential for this trial.

2.2. Difference between Comcast's trial

      Comcast has a trial with limited swarms, with the cooperation of
   Pando. According to the RFC5632 "Comcast's ISP Experiences in a
   Proactive Network Provider Participation for P2P (P4P) Technical
   Trial", there are five swarms, and overall 57,000 peers are involved
   in that trial.

      There are several differences between CT's trial and Comcast's
   trial:

   1. The scope of trail: CT's trial covers the whole province with over
      700 million broadband users. It lasted for over 4 months. There
      are countless swarms with all kinds of contents. from this point
      of view, our trial is more realistic than the previous trial from
      Comcast.

   2. The usage of P2P cache: CT's trail differs from the Comcast's
      trail by the utilization of P2P cache. In this trail, the average
      download speed of a Xunlei client decreases a little with the
      degree of traffic localization increased. Thus P2P cache was
      introduced to compensate the decrease of download speed.

   3. The evaluation method: In contrast to that all test data was
      collected by Pando client in Comcast's trial, we collect test data
      from two ways. Besides the data from Xunlei P2P client, we
      simultaneously collect the data from network operator's NMS



<Kai.Lee>                 Expires Sep 11, 2012                  [Page 5]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


      system.(such as data from SNMP reports and DPI(deep package
      inspection) device deployed on backbone). We can do this because
      Xunlei's p2p traffic occupy about 20% of whole backbone traffic
      flow in that province. This traffic flow will almost all be
      affected by alto service and it is big enough to be observed by
      CT's NMS system.

   4. The implementation of ALTO: In this trial, only the P2P trackers
      are ALTO clients, but not those Xunlei clients. There are some
      reasons to do this:

      a) To avoid the update all Xunlei clients and simplify the
         deployment of trial.

      b) To lessen the alto server load.

      c) Above 85% of Xunlei traffic flow is controlled by Xunlei
         tracker, the traffic flow affected by DHT mechanism is less
         than 15%. An alto server dedicated for Xunlei tracker can
         affect majority of Xunlei traffic flow.

3. Trial results
3.1. Trial configuration
      All Xunlei p2p client in the province and all contents that are
   requested or served by Xunlei P2P client in the province are involved
   in this trial. The trial environment is more realistic than
   Comcast's. A primary objective of this trial is to measure the
   effects of traffic localization and change of users download speed in
   comparison to those without alto service.

      The test process is divided into two parts: first part is just
   applied the ALTO server to measure the effects of traffic
   localization and change of P2P user experience. The second part is to
   introduce the P2P cache to the trial, to measure the improvement of
   user download speed, the bandwidth consumption and relationship with
   the scale of p2p cache and average download speed.

      Our trial starts at 2009.6.12 and ends at 2009.10.18, lasting
   nearly four months. We do this trial by applying different traffic
   control policy to Xunlei tracker through ALTO service. There are two
   kinds of traffic control policy: One is optimized policy and the
   other is un-optimized policy. corresponding to the different traffic
   control policy there are two kinds of network map and cost map the
   ALTO server need to create.The optimized policy tries to localize the
   traffic by utilizing the information from ALTO server. Here is the
   network map and cost map corresponding to the optimized policy below.





<Kai.Lee>                 Expires Sep 11, 2012                  [Page 6]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


                                 ----------
                        --------          --------
                     //-           PID12          -\\
                  ///                                \\\
                //               ---------              \\
             ///           --+---         ------          \\\
            /           ///  |                  \\\          \
          //         ///     |2                    \\\        \\
         /         //        |                        \\        \
        /         /       ---+-                         \        \
       |         /     ///     \\\                       \        |
      |        //    ||           |             -----     \\       |
      |       |      |    PID1     | ---1-    //     \\     |      |
     |        |      ||           |       ---+         |    |       |
     |       |         \\\     ///          |    PID2   |----+      |
    |       |             --\--             |           | 2   |      |
    |       |                \               |         |      |      |
    |       |                 \               \\-   -//       |      |
    |       |                  1              // ---          |      |
    |       |                   \           1/                |      |
    |       |                    \        //                  |      |
     |       |                  /-\-----\/                   |      |
     |        |             ////         \\\\               |       |
      |       |            |      PID..      |              |      |
      |        \\          |                 |            //       |
       |         \          \\\\         ////            /        |
        \         \             \----+--/               /        /
         \         \\                |                //        /
          \\         \\\             |2            ///        //
            \           \\\          |          ///          /
             \\\           ------    |    ------          ///
                \\               ----+----              //
                  \\\                                ///
                     \\-                          -//
                        --------          --------
                                ----------

      The normal policy will just use the original Xunlei peer selection
   and traffic control rules though . The corresponding network map just
   has one PID with all IPs.

      We usually change the alto policy in midnight of a day and send a
   notification to Xunlei tracker with notification
   mechanism.(http://tools.ietf.org/id/draft-sun-alto-notification-
   02.txt)

3.2. Xunlei traffic distribution before the trial
      Before we do the trial , we collect the information about Xunlei'S



<Kai.Lee>                 Expires Sep 11, 2012                  [Page 7]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


   peer and traffic distribution

       +------------------------------------------+--------------------+
       | No |Data Item   |Description             |The way of          |
       |    |            |                        |collection          |
       +----+---------- -+------------------------+--------------------+
       | 1  |Peer        |24.6% is within         |Random sampling by  |
       |    |distribution|the province,75.4%      |Xunlei tracker 24   |
       |    |            |is out of the           |times one day       |
       |    |            |province                |                    |
       +----+------------+------------------------+--------------------+
       |    |Traffic     |76.9% is                |Random selecting    |
       | 2  |distribution|inter-province traffic  |peers to report     |
       |    |            |23.1% is                |their traffic flow  |
       |    |            |intra-province traffic  |                    |
       +----+------------+------------------------+--------------------+

3.3. ALTO policy test

   After we applied the alto optimized policy about 60% inter-province
   traffic has became The intra-province traffic. Below is the result
   that we observed on china telecom's network NMS system:

   +------------------------------------------+-----------------------+
   | No |Data Item   |Description             |The way of             |
   |    |            |                        |collection             |
   +----+---------- -+------------------------+-----------------------+
   | 1  |Outbound    |Decreased 42.77Gbps,     Collecting max average |
   |    |bandwidth   |about 50.61% of total    outbound traffic of    |
   |    |            |Xunlei outbound         |a day from the DPI     |
   |    |            |traffic                 |system                 |
   +----+------------+------------------------+-----------------------+
   |    |Inbound/    |outbound bandwidth      |Collecting max average |
   | 2  |outbound    |decreased 31.58Gbps     |inbound/outbound       |
   |    |bandwidth   |inbound bandwidth        traffic of a day from  |
   |    |            |decreased 10.46Gbps     |the snmp system        |
   +----+------------+------------------------+-----------------------+














<Kai.Lee>                 Expires Sep 11, 2012                  [Page 8]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


3.4. P2P cache test
      In this trial we deployed 16 cache devices, each with 1.8TB SAS
   hard disks. The P2P cache system has 15Gbps links connected to the
   Internet.  We cached the content according to its popularity.
    +------------------------------------------+-----------------------+
    | No |Data Item   |Description             |The way of             |
    |    |            |                        |collection             |
    +----+---------- -+------------------------+-----------------------+
    | 1  |Outbound    |Decreased 40Gbps,        Collecting max average |
    |    |bandwidth   |about 54.47% of total    outbound traffic of    |
    |    |            |Xunlei outbound traffic |a day from the DPI     |
    |    |            |                        |system                 |
    +----+------------+------------------------+-----------------------+
    |    |Inbound/    |outbound bandwidth      |Collecting max average |
    | 2  |outbound    |decreased 39.18Gbps     |inbound/outbound       |
    |    |bandwidth   |inbound bandwidth        traffic of a day from  |
    |    |            |decreased 28.3 Gbps     |the snmp system        |
    +----+------------+------------------------+-----------------------+
    | 3  |Average     |From 279KBps up to      |Collection from Xunlei |
    |    |download    |294.5KBps               |OAM system             |
    |    |speed       |                        |                       |
    +----+------------+------------------------+-----------------------+



      The P2P cache system occupancy ratio is about 80%. Bandwidth
   consumed is about 4-5Gbps.After deployed the P2P cache system, the
   traffic flow in the the province has decreased a lot. Meanwhile the
   average download speed of Xunlei client has been increased.

4. Methods of data collection

      In this trial we have two ways for information collection; one is
   to collect from p2p service provider such as Pando and Xunlei just
   like Comcast's trial. The other is to collect from ISP's network OAM
   system. Because the Xunlei's inter-province traffic flow is about
   80Gbps that is large enough to be observed by ISP's network OAM
   system

   1. Information from ISP's network OAM system and DPI system

      a) Inbound/outbound traffic flow statistic

      b) Xunlei traffic flow detected by DPI system. The DPI system just
         monitored the uplink of the province to China telecom's
         backbone.

   2. Information from Xunlei



<Kai.Lee>                 Expires Sep 11, 2012                  [Page 9]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


      a) Inter-province/intra-province traffic flow.

      b) User average download speed.

5. Configurations and algorithms in trial

5.1. Configuration of PID MAP

      a) PID Map: We define 11 PIDs PID1-PID11 represent the 11 MANs of
                  the trial network PID12 represents rest of the
                  Internet

      b) Cost Map: Bidirectional cost between any PIDs from PID1 to
                   PID11 has the same value 1 Bidirectional cost between
                   PID12 and PIDi (1<=i<=11) has the same value 2

5.2. Algorithms of Xunlei using ALTO information

      Xunlei is a hybrid application utilizing both trackers and DHT,
   About 85% of Xunlei traffic controlled by Xunlei trackers. In this
   trail ALTO clients just include the Xunlei trackers not include the
   Xunlei client. Just the traffic controlled by Xunlei tracker has been
   affected.

      Before the trial Xunlei tracker peer selection algorithm is:Xunlei
   Peer selection algorithm depends on two properties: ISP ID and UC
   (upload capability), the peer selection priority is :

      Same ISP ID > different ISP ID

      Higher UC > lower UC

      The peers with same ISP ID with the requesting peer have higher
   priority than those with different ISP ID. If peers have same ISP ID
   then the peers with higher UC have higher priority than those with
   lower UC.

      After applying the ALTO information into the Xunlei peer selection
   algorithm. Xunlei changed his Peers select mechanism. All Xunlei
   peers are organized in a tree structure which is indexed by
   CID(content ID), in the second level ALTO_ISP and normal_ISP
   represent the network of ISP with and without alto information. In
   this trial 11 MANs in trial province became 11 ALTO_ISPs.The third
   level is defined by different upload capability(UC) of peers. The
   fourth level of normal_ISP branch is the different
   provinces(PRO1,PRO2) of ISP, the fifth level of the normal_ISP is
   different city of ISP.




<Kai.Lee>                 Expires Sep 11, 2012                 [Page 10]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


                               +-------------------+
                               |        CID        |
                               +-------------------+
                                /                     \
                   +----------+                    +----------+
                   |NORMAL_ISP|                    | ALTO_ISP |
                   +----------+                    +----------+
                   /     |     \                   /     |     \
                UC_BIG UC_MID  UC_SMALL         UC_BIG UC_MID  UC_SMALL
              /   |                              |   \
            PRO1 PRO2                            PEER1  PEER2
          /   |
      CITY1 CITY2
      |   \
   PEER1  PEER2

      The algorithms of cost between origination peer(peer_o) and
   destination peer(peer_d) is :

   If (peer_o and peer_d both from ALTO_ISP)

     If (peer_o and peer_d in the same ALTO_ISP) then cost = 0;

     Else cost = 100000;

   Else if (peer_o from ALTO_ISP and peer_d from normal_ISP) cost =
   100000;

   Else if (peer_o from normal_ISP and peer_d from ALTO_ISP) cost =
   1000;

   Else if (peer_o and peer_d both from normal_ISP){

     If (peer_o and peer_d from different normal_ISP) cost =1000;

     Else if (peer_o and peer_d from different province) cost = 100;

     Else if (peer_o and peer_d from different city) cost = 10;

     Else cost =0;

     }
      The peer select mechanism is lower cost peers will have higher
   priority

      The updated peer selection mechanism is not the best mechanism.
   For example a peer in MAN2 is supposed to be better choice than the
   peers which not located in china telecom's network when a peer in



<Kai.Lee>                 Expires Sep 11, 2012                 [Page 11]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


   MAN1 send a content request to tracker. But this mechanism will
   select the peer out of china telecom's network first then select the
   peer in the MAN2. Before we defined the network map with 12 PIDs. We
   first defined a network map with just 2 PIDs. PID1 represent the
   trial province and PID2 represent the other network to test the
   backbone traffic saving effect of ALTO service. The test result show
   that the network map with 12PIDs has almost same backbone traffic
   saving effect compared to the network map with 2 PIDs. So in the
   trial we deployed this mechanism.

      The other change is the number of returned peers from Xunlei
   tracker . If a listing request is from the trial province, the
   maximum # of returned peers from Xunlei tracker is set to 120, not
   the normal case of 500.

5.3. Configuration of cache system

      Before we deploy the cache system we have made some statistics
   about relationship of content popularity and network traffic caused
   by content with different popularity in trial province.

             +-----------+---------+----------+-------------+
             |content    | total   |total     | proportion  |
             | popularity| size(GB)|traffic   |  of total   |
             |           |         |(Gbps)    |traffic(%)   |
             +-----------+---------+----------+-------------+
             | top 10    |  18.9   |   1.34   |    9.3      |
             | top 20    |  29.3   |   1.68   |    11.7     |
             | top 50    |  51.8   |   2.28   |    15.9     |
             | top 100   |  93.6   |   2.89   |    20.1     |
             | top 500   |  418.7  |   4.74   |    33       |
             | top 1000  |  812.4  |   5.88   |    40.9     |
             | top 2000  |  1518.6 |   7.16   |    49.8     |
             | top 5000  |  3551   |   8.89   |    61.9     |
             +-----------+---------+----------+-------------+

      Our cache system has limited storage and access bandwidth so we
   need to know which content is most "valuable" to be cached. According
   the statistics from Xunlei if a downloading task is fed over 100
   peers , this task always can get the maximum download speed(this
   speed depends on the peer's access network, in the trial the average
   access speed of user is about 2Mbps). The top 2000 popular content
   almost all have over 100 seeds in trial province. That means the top
   2000 popular contents don't need be cached. Our cache policy is just
   cache the content which's popularity rank behind 2000.






<Kai.Lee>                 Expires Sep 11, 2012                 [Page 12]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012


6. Next steps

      The alto mechanism is very effective to optimize the traffic
   flow.If alto can cooperate with p2p cache or other service
   performance enhancement mechanism, it will be more practical. The
   ALTO service's effect depends on the SP such as Xunlei,pando how to
   use it. The mechanism such as peer selection mechanism and content
   cache mechanism need to be studied.

7. Security Considerations

   High-level security considerations can be found in the [draft-ietf-
   alto-problem-statement].

8. IANA Considerations

   This document requests the registration of a new media type:
   "application/alto"

9. References


   [RFC5693]  Seedorf, J. and E. Burger, "Application-Layer Traffic
              Optimization (ALTO) Problem Statement", RFC 5693, October
              2009.

   [RFC5632]  Griffiths, C., Livingood, J., Popkin, L., Woundy, R., and
              Y. Yang, "Comcast's ISP Experiences in a Proactive Network
              Provider Participation for P2P (P4P) Technical Trial",
              RFC 5632, September 2009.


   [I-D.ietf-alto-reqs] Kiesel, S., Popkin, L., Previdi, S., Woundy, R.,
   and Y.Yang,"Application-Layer Traffic Optimization (ALTO)
   Requirements",draft-ietf-alto-reqs-01 (work in progress),July 2009.

   [I-D.penno-alto-protocol] Penno, R. and Y. Yang, "ALTO
   Protocol",draft-ietf-alto-protocol-01 (work in progress),July 2009.

Author's Addresses

   Kai Lee
   China Telecom Beijing Research Institute
   Email: leekai@ctbri.com.cn

   GuangYao Jian
   Xunlei Network
   Email: jianguangyao@xunlei.com



<Kai.Lee>                 Expires Sep 11, 2012                 [Page 13]


Internet-Draft  <ALTO&DECADE trial within China Telecom>   March 11 2012





















































<Kai.Lee>                 Expires Sep 11, 2012                 [Page 14]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/