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draft-ietf-cdi-scenarios-01



Please publish the attached as as Internet-Draft.

Thanks.



Network Working Group                                        P. Rzewski 
Internet-Draft                                                  Inktomi 
Expires: October 24, 2002                                        M. Day 
                                                                  Cisco 
                                                            D. Gilletti 
                                                              CacheFlow 
                                                         April 24, 2002 
    
                  Content Internetworking (CDI) Scenarios 
                      draft-ietf-cdi-scenarios-01.txt 
    
Status of this Memo 
    
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026. 
    
   Internet-Drafts are working documents of the Internet Engineering 
   Task Force (IETF), its areas, and its working groups. Note that 
   other groups may also distribute working documents as Internet-
   Drafts. 
    
   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." 
    
   The list of current Internet-Drafts can be accessed at 
   http://www.ietf.org/ietf/1id-abstracts.txt. 
    
   The list of Internet-Draft Shadow Directories can be accessed at 
   http://www.ietf.org/shadow.html. 
    
   This Internet-Draft will expire on October 24, 2002. 
    
Copyright Notice 
    
   Copyright (C) The Internet Society (2002). All Rights Reserved. 
    
Abstract 
    
   In describing content internetworking as a technology targeted for 
   use in production networks, it's useful to provide examples of the 
   sequence of events that may occur when two content networks decide 
   to interconnect. The scenarios presented here seek to provide some 
   concrete examples of what content internetworking is, and also to 
   provide a basis for evaluating content internetworking proposals. 






 
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Table of Contents 
    
   1.  Introduction...................................................3 
   1.1 Terminology....................................................3 
   2.  Special Cases of Content Networks..............................3 
   2.1 Publishing Content Network.....................................4 
   2.2 Brokering Content Network......................................4 
   2.3 Local Request-Routing Content Network..........................4 
   3.  Content Internetworking Arrangements...........................5 
   4.  Content Internetworking Scenarios..............................6 
   4.1 General Content Internetworking................................6 
   4.2 BCN providing ACCOUNTING INTERNETWORKING and REQUEST-ROUTING 
       INTERNETWORKING................................................9 
   4.3 BCN providing ACCOUNTING INTERNETWORKING......................11 
   4.4 PCN ENLISTS multiple CNs......................................12 
   4.5 Multiple CNs ENLIST LCN.......................................13 
   5.  Security Considerations.......................................15 
   6.  Acknowledgements..............................................15 
       References....................................................15 
       Authors' Addresses............................................16 
       Full Copyright Statement......................................16 































 
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1. Introduction 
    
   In [1], the concept of a "content network" is introduced and 
   described. In addition to describing some general types of content 
   networks, it also describes motivations for allowing content 
   networks to interconnect (defined as "content internetworking"). 
    
   In describing content internetworking as a technology targeted for 
   use in production networks, it's useful to provide examples of the 
   sequence of events that may occur when two content networks decide 
   to interconnect. Naturally, different types of content networks may 
   be created due to different business motivations, and so many 
   combinations are likely. 
    
   This document first provides detailed examples of special cases of 
   content networks that are specifically designed to participate in 
   content internetworking (Section 2). We then discuss the steps that 
   would be taken in order to "bring up" or "tear down" a content 
   internetworking arrangement (Section 3). Next we provide some 
   detailed examples of how content networks (such as those from 
   Section 2) could interconnect (Section 4). Finally, we describe any 
   security considerations that arise specifically from the examples 
   presented here (Section 5). 
    
   The scenarios presented here answer two distinct needs: 
    
   1.  To provide some concrete examples of what content 
       internetworking is, and 
        
   2.  To provide a basis for evaluating content internetworking 
       proposals. 
    
   For details on the architectural framework used in the development 
   of actual content internetworking protocols and interfaces, refer to 
   [2]. For specific examples of systems where content internetworking 
   has been implemented, refer to [5]. 
    
1.1 Terminology 
    
   Terms in ALL CAPS are defined in [1]. 
    
2. Special Cases of Content Networks 
    
   A CN is defined in [2] as having REQUEST-ROUTING, DISTRIBUTION, and 
   ACCOUNTING interfaces. However, some participating networks may 
   gravitate toward particular subsets of the CONTENT INTERNETWORKING 
   interfaces. Others may be seen differently in terms of how they 
   relate to their CLIENT bases. This section describes these refined 
   cases of the general CN case so they may be available for easier 
   reference in the further development of CONTENT INTERNETWORKING 
   scenarios. The special cases described are the Publishing Content 
 
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   Network, the Brokering Content Network, and the Local Request-
   Routing Content Network. 
    
2.1 Publishing Content Network 
    
   A Publishing Content Network (PCN), maintained by a PUBLISHER, 
   contains an ORIGIN and has a NEGOTIATED RELATIONSHIP with two or 
   more CNs. A PCN may contain SURROGATES for the benefit of serving 
   some CONTENT REQUESTS locally, but does not intend to allow its 
   SURROGATES to serve CONTENT on behalf of other PUBLISHERS. 
    
   Several implications follow from knowing that a particular CN is a 
   PCN. First, the PCN contains the AUTHORITATIVE REQUEST-ROUTING 
   SYSTEM for the PUBLISHER's CONTENT. This arrangement allows the 
   PUBLISHER to determine the distribution of CONTENT REQUESTS among 
   ENLISTED CNs. Second, it implies that the PCN need only participate 
   in a subset of CONTENT INTERNETWORKING. For example, a PCN's 
   DISTRIBUTION INTERNETWORKING SYSTEM need only be able to receive 
   DISTRIBUTION ADVERTISEMENTS, it need not send them. Similarly, a 
   PCN's REQUEST-ROUTING INTERNETWORKING SYSTEM has no reason to send 
   AREA ADVERTISEMENTS. Finally, a PCN's ACCOUNTING INTERNETWORKING 
   SYSTEM need only be able to receive ACCOUNTING data, it need not 
   send it. 
    
2.2 Brokering Content Network 
    
   A Brokering Content Network (BCN) is a network that does not operate 
   its own SURROGATES. Instead, a BCN operates only CIGs as a service 
   on behalf other CNs. A BCN may therefore be regarded as a 
   "clearinghouse" for CONTENT INTERNETWORKING information. 
    
   For example, a BCN may choose to participate in DISTRIBUTION 
   INTERNETWORKING and/or REQUEST-ROUTING INTERNETWORKING in order to 
   aggregate ADVERTISEMENTS from one set of CNs into a single update 
   stream for the benefit of other CNs. To name a single specific 
   example, a BCN could aggregate CONTENT SIGNALS from CNs that 
   represent PUBLISHERS into a single update stream for the benefit of 
   CNs that contain SURROGATES. A BCN may also choose to participate in 
   ACCOUNTING INTERNETWORKING in order to aggregate utilization data 
   from several CNs into combined reports for CNs that represent 
   PUBLISHERS. 
    
   This definition of a BCN implies that a BCN's CIGs would implement 
   the sending and/or receiving of any combination of ADVERTISEMENTS 
   and ACCOUNTING data as is necessary to provide desired services to 
   other CONTENT NETWORKS. For example, if a BCN is only interested in 
   aggregating ACCOUNTING data on behalf of other CNs, it would only 
   need to have an ACCOUNTING INTERNETWORKING interface on its CIGs. 
    
2.3 Local Request-Routing Content Network 
    

 
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   Another type of CN is the Local Request-Routing CONTENT NETWORK 
   (LCN). An LCN is defined as a type of network where CLIENTS' CONTENT 
   REQUESTS are always handled by some local SERVER (such as a caching 
   proxy [1]). In this context, "local" is taken to mean that both the 
   CLIENT and SERVER are within the same administrative domain, and 
   there is an administrative motivation for forcing the local mapping. 
   This type of arrangement is common in enterprises where all CONTENT 
   REQUESTS must be directed through a local SERVER for access control 
   purposes. 
    
   As implied by the name, the LCN creates an exception to the rule 
   that there is a single AUTHORITATIVE REQUEST-ROUTING SYSTEM for a 
   particular item of CONTENT. By directing CONTENT REQUESTS through 
   the local SERVER, CONTENT RESPONSES may be given to CLIENTS without 
   first referring to the AUTHORITATIVE REQUEST-ROUTING SYSTEM. Knowing 
   this to be true, other CNs may seek a NEGOTIATED RELATIONSHIP with 
   an LCN in order to perform DISTRIBUTION into the LCN and receive 
   ACCOUNTING data from it. Note that once SERVERS participate in 
   DISTRIBUTION INTERNETWORKING and ACCOUNTING INTERNETWORKING, they 
   effectively take on the role of SURROGATES. However, an LCN would 
   not intend to allow its SURROGATES to be accessed by non-local 
   CLIENTS. 
    
   This set of assumptions implies multiple things about the LCN's 
   CONTENT INTERNETWORKING relationships. First, it is implied that the 
   LCN's DISTRIBUTION INTERNETWORKING SYSTEM need only be able to send 
   DISTRIBUTION ADVERTISEMENTS, it need not receive them. Second, it is 
   implied that an LCN's ACCOUNTING INTERNETWORKING SYSTEM need only be 
   able to send ACCOUNTING data, it need not receive it. Finally, due 
   to the locally defined REQUEST-ROUTING, the LCN would not 
   participate in REQUEST-ROUTING INTERNETWORKING. 
    
3. Content Internetworking Arrangements 
    
   When the controlling interests of two CNs decide to interconnect 
   their respective networks (such as for business reasons), it is 
   expected that multiple steps would need to occur. 
    
   The first step would be the creation of a NEGOTIATED RELATIONSHIP. 
   This relationship would most likely take the form of a legal 
   document that describes the services to be provided, cost of 
   services, SLAs, and other stipulations. For example, if an 
   ORIGINATING CN wished to leverage another CN's reach into a 
   particular country, this would be laid out in the NEGOTIATED 
   RELATIONSHIP. 
    
   The next step would be to configure CONTENT INTERNETWORKING 
   protocols on the CIGs of the respective CNs in order to technically 
   support the terms of the NEGOTIATED RELATIONSHIP. To follow our 
   previous example, this could include the configuration of the 
   ENLISTED CN's CIGs in a particular country to send DISTRIBUTION 
   ADVERTISEMENTS to the CIGs of the ORIGINATING CN. In order to 
 
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   configure these protocols, technical details (such as CIG 
   addresses/hostnames and authentication information) would be 
   exchanged by administrators of the respective CNs. 
    
   Note also that some terms of the NEGOTIATED RELATIONSHIP would be 
   upheld through means outside the scope of CDI protocols. These could 
   include non-technical terms (such as financial settlement) or other 
   technical terms (such as SLAs). 
    
   In the event that the controlling interests of two CNs no longer 
   wish to have their networks interconnected, it is expected that 
   these tasks would be undone. That is, the protocol configurations 
   would be changed to cease the movement of ADVERTISEMENTS and/or 
   ACCOUNTING data between the networks, and the NEGOTIATED 
   RELATIONSHIP would be legally terminated. 
    
4. Content Internetworking Scenarios 
    
   This section provides several scenarios that may arise in CONTENT 
   INTERNETWORKING implementations. 
    
   Note that we obviously cannot examine every single permutation. 
   Specifically, it should be noted that: 
    
   o  Any one of the interconnected CNs may have other CONTENT 
      INTERNETWORKING arrangements that may or may not be transitive to 
      the relationships being described in the diagram. 
       
   o  The graphical figures do not illustrate the CONTENT REQUEST 
      paths. It is assumed that the direction of CONTENT REQUESTS 
      follow the methodology given in [2] and that the end result is 
      that a REQUEST-ROUTING SYSTEM eventually returns to the CLIENT 
      the IP address of the SURROGATE deemed appropriate to honor the 
      CLIENT's CONTENT REQUEST. 
    
   The scenarios described include a general case, two cases in which 
   BCNs provide limited interfaces, a case in which a PCN enlists the 
   services of multiple CNs, and a case in which multiple CNs enlist 
   the services of an LCN. 
    
4.1 General Content Internetworking 
    
   This scenario considers the general case where two or more existing 
   CNs wish to establish a CONTENT INTERNETWORKING relationship in 
   order to provide increased scale and reach for their existing 
   customers. It assumes that all of these CNs already provide REQUEST-
   ROUTING, DISTRIBUTION, and ACCOUNTING services and that they will 
   continue to provide these services to existing customers as well as 
   offering them to other CNs. 
    
   In this scenario, these CIs would interconnect with others via a CIG 
   that provides a REQUEST-ROUTING INTERNETWORKING SYSTEM, a 
 
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   DISTRIBUTION INTERNETWORKING SYSTEM, and an ACCOUNTING 
   INTERNETWORKING SYSTEM. The net result of this interconnection would 
   be that a larger set of SURROGATES will now be available to the 
   CLIENTS. 
    
   FIGURE 1 shows three CNs which have interconnected to provide 
   greater scale and reach to their existing customers. They are all 
   participating in DISTRIBUTION INTERNETWORKING, REQUEST-ROUTING 
   INTERNETWORKING, and ACCOUNTING INTERNETWORKING. 
    
   As a result of the NEGOTIATED RELATIONSHIPS it is assumed that: 
    
   1.  CONTENT that has been INJECTED into any one of these ORIGINATING 
       CNs may be distributed into any other ENLISTED CN. 
        
   2.  Commands affecting the DISTRIBUTION of CONTENT may be issued 
       within the ORIGINATING CN, or may also be issued within the 
       ENLISTED CN. The latter case allows local decisions to be made 
       about DISTRIBUTION within the ENLISTED CN, but such commands 
       would not control DISTRIBUTION within the ORIGINATING CN. 
        
   3.  ACCOUNTING information regarding CLIENT access and/or 
       DISTRIBUTION actions will be made available to the ORIGINATING 
       CN by the ENLISTED CN. 
        
   4.  The ORIGINATING CN would provide this ACCOUNTING information to 
       the PUBLISHER based on existing Service Level Agreements (SLAs). 
        
   5.  CONTENT REQUESTS by CLIENTS may be directed to SURROGATES within 
       any of the ENLISTED CNs. 
    
   The decision of where to direct an individual CONTENT REQUEST may be 
   dependent upon the DISTRIBUTION and REQUEST-ROUTING policies 
   associated with the CONTENT being requested as well as the specific 
   algorithms and methods used for directing these requests. For 
   example, a REQUEST-ROUTING policy for a piece of CONTENT may 
   indicate multiple versions exist based on the spoken language of a 
   CLIENT. Therefore, the REQUEST-ROUTING SYSTEM of an ENLISTED CN 
   would likely direct a CONTENT REQUEST to a SURROGATE known to be 
   holding a version of CONTENT of a language that matches that of a 
   CLIENT. 











 
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              FIGURE 1 - General CONTENT INTERNETWORKING 
    
   +--------------+                               +--------------+ 
   |     CN A     |                               |     CN B     | 
   |..............|   +---------+   +---------+   |..............+ 
   | REQ-ROUTING  |<=>|         |<=>|         |<=>| REQ-ROUTING  | 
   |..............|   | CONTENT |   | CONTENT |   |..............| 
   | DISTRIBUTION |<=>|INTWRKING|<=>|INTWRKING|<=>| DISTRIBUTION | 
   |..............|   | GATEWAY |   | GATEWAY |   |..............| 
   |  ACCOUNTING  |<=>|         |<=>|         |<=>|  ACCOUNTING  | 
   +--------------+   +---------+   +---------+   +--------------+ 
         | ^           \^ \^ \^       ^/ ^/ ^/           | ^ 
         v |            \\ \\ \\     // // //            v | 
   +--------------+      \\ \\ \\   // // //      +--------------+ 
   |  SURROGATES  |       \\ v\ v\ /v /v //       |  SURROGATES  | 
   +--------------+        \\+---------+//        +--------------+ 
          ^ |               v|         |v                ^ | 
          | |                | CONTENT |                 | | 
          | |                |INTWRKING|                 | | 
          | |                | GATEWAY |                 | | 
          | |                |         |                 | | 
          | |                +---------+                 | | 
          | |                  ^| ^| ^|                  | | 
          | |                  || || ||                  | | 
          | |                  |v |v |v                  | | 
          | |              +--------------+              | | 
          | |              |     CN C     |              | | 
          | |              |..............|              | | 
          | |              | REQ-ROUTING  |              | | 
          | |              |..............|              | | 
          \ \              | DISTRIBUTION |             / / 
           \ \             |..............|            / / 
            \ \            |  ACCOUNTING  |           / / 
             \ \           |--------------|          / / 
              \ \                | ^                / / 
               \ \               v |               / / 
                \ \        +--------------+       / / 
                 \ \       |  SURROGATES  |      / / 
                  \ \      +--------------+     / / 
                   \ \           | ^           / / 
                    \ \          | |          / / 
                     \ \         v |         / / 
                      \ \    +---------+    / / 
                       \ \-->| CLIENTS |---/ / 
                        \----|         |<---/ 
                             +---------+ 






 
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4.2 BCN providing ACCOUNTING INTERNETWORKING and REQUEST-ROUTING 
    INTERNETWORKING 
    
   This scenario describes the case where a single entity (BCN A) 
   performs ACCOUNTING INTERNETWORKING and REQUEST-ROUTING 
   INTERNETWORKING functions, but has no inherent DISTRIBUTION or 
   DELIVERY capabilities. A potential configuration which illustrates 
   this concept is given in FIGURE 2. 
    
   In the scenario shown in FIGURE 2, BCN A is responsible for 
   collecting ACCOUNTING information from multiple CONTENT NETWORKS (CN 
   A and CN B) to provide a clearinghouse/settlement function, as well 
   as providing a REQUEST-ROUTING service for CN A and CN B. 
     
   In this scenario, CONTENT is injected into either CN A or CN B and 
   its DISTRIBUTION between these CNs is controlled via the 
   DISTRIBUTION INTERNETWORKING SYSTEMS within the CIGs. The REQUEST-
   ROUTING SYSTEM provided by BCN A is informed of the ability to serve 
   a piece of CONTENT from a particular CONTENT NETWORK by the REQUEST-
   ROUTING SYSTEMS within the interconnected CIGs. 
    
   BCN A collects statistics and usage information via the ACCOUNTING 
   INTERNETWORKING SYSTEM and disseminates that information to CN A and 
   CN B as appropriate.  
    
   As illustrated in FIGURE 2, there are separate REQUEST-ROUTING 
   SYSTEMS employed within CN A and CN B. If the REQUEST-ROUTING SYSTEM 
   provided by BCN A is the AUTHORITATIVE REQUEST-ROUTING SYSTEM for a 
   given piece of CONTENT this is not a problem. However, each 
   individual CN may also provide the AUTHORITATIVE REQUEST-ROUTING 
   SYSTEM for some portion of its PUBLISHER customers. In this case 
   care must be taken to ensure that the there is one and only one 
   AUTHORITATIVE REQUEST-ROUTING SYSTEM identified for each given 
   CONTENT object. 


















 
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          FIGURE 2 - BCN providing ACCOUNTING INTERNETWORKING and 
                      REQUEST-ROUTING INTERNETWORKING 
    
    
       +--------------+ 
       |    BCN A     | 
       |..............|     +-----------+ 
       | REQ-ROUTING  |<===>|           | 
       |..............|     |  CONTENT  | 
       |  ACCOUNTING  |<===>| INTWRKING | 
       +--------------+     |  GATEWAY  | 
                            |           | 
                            +-----------+ 
                             ^| ^| ^| ^| 
   +--------------+         // //   \\ \\         +--------------+ 
   |     CN A     |        |v |v     |v |v        |     CN B     | 
   |..............|   +---------+   +---------+   |..............| 
   | REQ-ROUTING  |<=>|         |   |         |<=>| REQ-ROUTING  | 
   |..............|   | CONTENT |   | CONTENT |   |..............| 
   | DISTRIBUTION |<=>|INTWRKING|<=>|INTWRKING|<=>| DISTRIBUTION | 
   |..............|   | GATEWAY |   | GATEWAY |   |..............| 
   |  ACCOUNTING  |<=>|         |   |         |<=>|  ACCOUNTING  | 
   +--------------+   +---------+   +---------+   +--------------+ 
         | ^                                             | ^ 
         v |                                             v | 
   +--------------+                               +--------------+ 
   |  SURROGATES  |                               |  SURROGATES  | 
   +--------------+                               +--------------+ 
                ^ \                               ^ / 
                 \ \                             / / 
                  \ \                           / / 
                   \ \                         / / 
                    \ \      +---------+      / / 
                     \ \---->| CLIENTS |-----/ / 
                      \------|         |<-----/ 
                             +---------+ 















 
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4.3 BCN providing ACCOUNTING INTERNETWORKING 
    
   This scenario describes the case where a single entity (BCN A) 
   performs ACCOUNTING INTERNETWORKING to provide a clearinghouse/ 
   settlement function only. In this scenario, BCN A would enter into 
   NEGOTIATED RELATIONSHIPS with multiple CNs that each perform their 
   own DISTRIBUTION INTERNETOWRKING and REQUEST-ROUTING INTERNETWORKING 
   as shown in FIGURE 3. 
    
    
       FIGURE 3 - BCN providing ACCOUNTING INTERNETWORKING  
    
    
       +--------------+ 
       |    BCN A     | 
       |..............|     +-----------+ 
       |  ACCOUNTING  |<===>|           | 
       +--------------+     |  CONTENT  | 
                            | INTWRKING | 
                            |  GATEWAY  | 
                            |           | 
                            +-----------+ 
                                ^| ^| 
   +--------------+            //   \\            +--------------+ 
   |     CN A     |           |v     |v           |     CN B     | 
   |..............|   +---------+   +---------+   |..............| 
   | REQ-ROUTING  |<=>|         |<=>|         |<=>| REQ-ROUTING  | 
   |..............|   | CONTENT |   | CONTENT |   |..............| 
   | DISTRIBUTION |<=>|INTWRKING|<=>|INTWRKING|<=>| DISTRIBUTION | 
   |..............|   | GATEWAY |   | GATEWAY |   |..............| 
   |  ACCOUNTING  |<=>|         |   |         |<=>|  ACCOUNTING  | 
   +--------------+   +---------+   +---------+   +--------------+ 
         | ^                                             | ^ 
         v |                                             v | 
   +--------------+                               +--------------+ 
   |  SURROGATES  |                               |  SURROGATES  | 
   +--------------+                               +--------------+ 
                ^ \                               ^ / 
                 \ \                             / / 
                  \ \                           / / 
                   \ \                         / / 
                    \ \      +---------+      / / 
                     \ \---->| CLIENTS |-----/ / 
                      \------|         |<-----/ 
                             +---------+ 






 
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4.4 PCN ENLISTS multiple CNs 
    
   In the previously enumerated scenarios, PUBLISHERS have not been 
   discussed. Much of the time, it is assumed that the PUBLISHERS will 
   allow CNs to act on their behalf. For example, a PUBLISHER may 
   designate a particular CN to be the AUTHORITATIVE REQUEST-ROUTING 
   SYSTEM for its CONTENT. Similarly, a PUBLISHER may rely on a 
   particular CN to aggregate all its ACCOUNTING data, even though that 
   data may originate at SURROGATES in multiple distant CNs. Finally, a 
   PUBLISHER may INJECT content only into a single CN and rely on that 
   CN to ENLIST other CNs to obtain scale and reach. 
    
   However, a PUBLISHER may wish to maintain more control and take on 
   the task of ENLISTING CNs itself, therefore acting as a PCN (Section 
   2.1). This scenario, shown in FIGURE 4, describes the case where a 
   PCN wishes to directly enter into NEGOTIATED RELATIONSHIPS with 
   multiple CNs. In this scenario, the PCN would operate its own CIG 
   and enter into DISTRIBUTION INTERNETWORKING, ACCOUNTING 
   INTERNETWORKING, and REQUEST-ROUTING INTERNETWORKING relationships 
   with two or more CNs. 































 
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                    FIGURE 4 - PCN ENLISTS multiple CNs 
    
    
   +--------------+ 
   |     PCN      | 
   |..............|   +-----------+ 
   | REQ-ROUTING  |<=>|           |<---\ 
   |..............|   |  CONTENT  |----\\ 
   | DISTRIBUTION |<=>| INTWRKING |     \\ 
   |..............|   |  GATEWAY  |--\   \\ 
   |  ACCOUNTING  |<=>|           |<-\\   \\ 
   +--------------+   +-----------+   \\   \\ 
                        ^| ^| ^|  ^|   \\   || 
   +--------------+     || || ||   \\   ||  ||    +--------------+ 
   |     CN A     |     |v |v |v    \v  |v  |v    |     CN B     | 
   |..............|   +---------+   +---------+   |..............| 
   | REQ-ROUTING  |<=>|         |   |         |<=>| REQ-ROUTING  | 
   |..............|   | CONTENT |   | CONTENT |   |..............| 
   | DISTRIBUTION |<=>|INTWRKING|   |INTWRKING|<=>| DISTRIBUTION | 
   |..............|   | GATEWAY |   | GATEWAY |   |..............| 
   |  ACCOUNTING  |<=>|         |   |         |<=>|  ACCOUNTING  | 
   +--------------+   +---------+   +---------+   +--------------+ 
         | ^                                             | ^ 
         v |                                             v | 
   +--------------+                               +--------------+ 
   |  SURROGATES  |                               |  SURROGATES  | 
   +--------------+                               +--------------+ 
                ^ \                               ^ / 
                 \ \                             / / 
                  \ \                           / / 
                   \ \                         / / 
                    \ \      +---------+      / / 
                     \ \---->| CLIENTS |-----/ / 
                      \------|         |<-----/ 
                             +---------+ 
 
 
4.5 Multiple CNs ENLIST LCN 
    
   A type of CN described in Section 2.3 is the LCN. In this scenario, 
   we imagine a tightly administered CN (such as within an enterprise) 
   has determined that all CONTENT REQUESTS from CLIENTS must be 
   serviced locally. Likely due to a large CLIENT base in the LCN, 
   multiple CNs determine they would like to engage in DISTRIBUTION 
   INTERNETWORKING with the LCN in order to extend control over CONTENT 
   objects held in the LCN's SURROGATES. Similarly, the CNs would like 
   to engage in ACCOUNTING INTERNETWORKING with the LCN in order to 
   receive ACCOUTING data regarding the usage of the content in the 
   local SURROGATES. This scenario is shown in FIGURE 5. 



 
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                    FIGURE 5 - Multiple CNs ENLIST LCN 
    
    
   +--------------+                               +--------------+ 
   |     CN A     |                               |     CN B     | 
   |..............|   +---------+   +---------+   |..............+ 
   | REQ-ROUTING  |<=>|         |<=>|         |<=>| REQ-ROUTING  | 
   |..............|   | CONTENT |   | CONTENT |   |..............| 
   | DISTRIBUTION |<=>|INTWRKING|<=>|INTWRKING|<=>| DISTRIBUTION | 
   |..............|   | GATEWAY |   | GATEWAY |   |..............| 
   |  ACCOUNTING  |<=>|         |<=>|         |<=>|  ACCOUNTING  | 
   +--------------+   +---------+   +---------+   +--------------+ 
         | ^              \^ \^       ^/ ^/              | ^ 
         v |               \\ \\     // //               v | 
   +--------------+         \\ \\   // //         +--------------+ 
   |  SURROGATES  |          v\ v\ /v /v          |  SURROGATES  | 
   +--------------+          +---------+          +--------------+ 
                             |         |  
                             | CONTENT | 
                             |INTWRKING| 
                             | GATEWAY | 
                             |         | 
                             +---------+ 
                                  ^| ^| 
                                  || || 
                                  |v |v 
                           +--------------+ 
                           |    LCN A     | 
                           |..............| 
                           | DISTRIBUTION | 
                           |..............| 
                           |  ACCOUNTING  | 
                           |--------------| 
                                 | ^ 
                                 v | 
                           +--------------+ 
                           |  SURROGATES  | 
                           +--------------+ 
                                 | ^ 
                                 | | 
                                 v | 
                             +---------+ 
                             | CLIENTS | 
                             |         | 
                             +---------+ 






 
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5. Security Considerations 
    
   This section contains security considerations that arise 
   specifically from the examples presented here. For a more general 
   discussion of security in the CDI protocols, see [2]. 
    
   Due to the likely reliance on ACCOUNTING data as the basis of 
   payment for services, the likelihood of fraud may be a concern of 
   parties that participate in CONTENT INTERNETWORKING. Indeed, it's 
   easy to imagine fabricating log entries or increasing throughput 
   numbers to increase revenue. While this is a difficult problem to 
   solve, there are some approaches to be explored. A useful tool would 
   be a "fraud detection" analysis tool that is capable of modeling 
   human usage patterns and detecting anomalies. It may be logical for 
   such a tool to be run by a BCN that is acting as an "impartial third 
   party", ENLISTED only to ensure fairness among participants. 
   Additionally, a BCN may be ENLISTED to perform random audits of 
   ACCOUNTING data. 
    
6. Acknowledgements 
    
   The authors acknowledge the contributions and comments of Fred 
   Douglis (AT&T), Raj Nair (Cisco), Gary Tomlinson (CacheFlow), John 
   Scharber (CacheFlow), Nalin Mistry (Nortel), Steve Rudkin (BT), 
   Christian Hoertnagl (IBM), Christian Langkamp (Oxford University), 
   and Don Estberg (Activate). 
    
References 
    
   [1]  Day, M., Cain, B., Tomlinson, G., and P. Rzewski, "A Model for 
        Content Internetworking (CDI)", draft-ietf-cdi-model-01.txt 
        (work in progress), February 2002, 
        <URL:http://www.ietf.org/internet-drafts/draft-ietf-cdi-model-
        01.txt>. 
         
   [2]  Green, M., Cain, B., Tomlinson, G., Thomas, S., and P. Rzewski, 
        "Content Internetworking Architectural Overview", draft-ietf-
        cdi-architecture-00.txt (work in progress), February 2002, 
        <URL:http://www.ietf.org/internet-drafts/draft-ietf-cdi-
        architecture-00.txt>. 
         
   [3]  Gilletti, D., Nair, R., Scharber, J., and J. Guha, "CDN-I 
        Internetworking Authentication, Authorization, and Accounting 
        Requirements", draft-ietf-cdi-aaa-reqs-00.txt (work in 
        progress), February 2002, 
        <URL:http://www.ietf.org/internet-drafts/draft-ietf-cdi-aaa-
        reqs-00.txt>. 
         
   [4]  Aboba, B., Arkko, J. and D. Harrington, "Introduction to 
        Accounting Management", RFC 2975, October 2000, 

 
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        <URL:ftp://ftp.isi.edu/in-notes/rfc2975.txt>. 
         
   [5]  Douglis, F., Chaudhri, I. and P. Rzewski, "Known Mechanisms for 
        Content Internetworking", draft-douglis-cdi-known-mech-00.txt, 
        November 2001, 
        <URL:http://www.ietf.org/internet-drafts/draft-douglis-cdi-
        known-mech-00.txt>. 
         
Authors' Addresses 
    
   Mark S. Day 
   Cisco Systems 
   135 Beaver Street 
   Waltham, MA  02452 
   US 
    
   Phone: +1 781 663 8310 
   EMail: markday@cisco.com 
    
    
   Don Gilletti 
   CacheFlow, Inc. 
   441 Moffett Park Drive 
   Sunnyvale, CA 94089 USA 
   US 
    
   Phone: +1 408 543 0437 
   EMail: don@cacheflow.com 
    
    
   Phil Rzewski 
   Inktomi 
   4100 East Third Avenue 
   MS FC2-4 
   Foster City, CA 94404 
   US 
    
   Phone +1 650 653 2487 
   Email: philr@inktomi.com 
    
Full Copyright Statement 
    
   Copyright (C) The Internet Society (2002). All Rights Reserved. 
    
   This document and translations of it may be copied and furnished to 
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   or assist in its implementation may be prepared, copied, published 
   and distributed, in whole or in part, without restriction of any 
   kind, provided that the above copyright notice and this paragraph 
   are included on all such copies and derivative works. However, this 
   document itself may not be modified in any way, such as by removing 
   the copyright notice or references to the Internet Society or other 
 
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   Internet organizations, except as needed for the purpose of 
   developing Internet standards in which case the procedures for 
   copyrights defined in the Internet Standards process must be 
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   English. 
    
   The limited permissions granted above are perpetual and will not be 
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Acknowledgement 
    
   Funding for the RFC editor function is currently provided by the 
   Internet Society. 
    






























 
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--
Phil Rzewski - Senior Architect - Inktomi Corporation                  
650-653-2487 (office) - 650-303-3790 (cell) - 650-653-1848 (fax)