One document matched: draft-ietf-speermint-architecture-08.txt

Differences from draft-ietf-speermint-architecture-07.txt


Speermint Working Group                                   A.Uzelac(Ed.) 
Internet Draft                                          Global Crossing 
Intended status: Informational                                    
Expires: September 2009                                                    
                                                      March 2, 2009 
                                     
                       SPEERMINT Peering Architecture 
                     draft-ietf-speermint-architecture-08 


Status of this Memo 
 
   This Internet-Draft is submitted to IETF in full conformance with the 
   provisions of BCP 78 and BCP 79. 
 
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   This Internet-Draft will expire on September 2, 2009. 
 
Copyright Notice 
 
   Copyright (c) 2009 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 
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   carefully, as they describe your rights and restrictions with respect 
   to this document. 
 
 
Abstract 

   This document defines the SPEERMINT peering architecture, its functional 
   components and peering interface functions. It also describes the steps taken 
   to establish a session between two peering domains in the context of the 
   functions defined.    
 
 
 
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Table of Contents 

    
   1. Introduction...................................................3 
   2. Network Context................................................3 
   3. Reference SPEERMINT Architecture...............................4 
   4. Procedures of Interdomain SSP Session Establishment............6 
   5. Recommended SSP Procedures.....................................7 
      5.1. Originating SSP Procedures................................7 
         5.1.1. The Look-Up Function (LUF)...........................7 
            5.1.1.1. Target address analysis.........................7 
            5.1.1.2. End User ENUM Lookup............................8 
            5.1.1.3. Infrastructure ENUM lookup......................8 
         5.1.2. Location Routing Function (LRF)......................8 
            5.1.2.1. SIP DNS Resolution..............................8 
            5.1.2.2. Routing Table...................................9 
            5.1.2.3. SIP Redirect Server.............................9 
         5.1.3. The Signaling Function (SF)..........................9 
            5.1.3.1. Establishing a Trusted Relationship.............9 
            5.1.3.2. Sending the SIP request........................10 
      5.2. Terminating SSP Procedures...............................10 
         5.2.1. The Location Function (LF)..........................10 
            5.2.1.1. Publish ENUM records...........................10 
            5.2.1.2. Publish SIP DNS records........................11 
            5.2.1.3. Subscribe Notify...............................11 
         5.2.2. Signaling Function (SF).............................11 
            5.2.2.1. TLS............................................11 
            5.2.2.2. Receive SIP requests...........................11 
      5.3. Target SSP Procedures....................................12 
         5.3.1. Signaling Function (SF).............................12 
            5.3.1.1. TLS............................................12 
            5.3.1.2. Receive SIP requests...........................12 
      5.4. Media Function (MF)......................................12 
      5.5. Policy Considerations....................................12 
   6. Call Control and Media Control Deployment Options.............13 
   7. Address space considerations..................................14 
   8. Security Considerations.......................................15 
   9. IANA Considerations...........................................15 
   10. Acknowledgments..............................................15 
   11. References...................................................16 
      11.1. Normative References....................................16 
      11.2. Informative References..................................17 
   Author's Addresses...............................................18          
    


 
 
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1. Introduction    

   The objective of this document is to define a reference peering architecture in 
   the context of Session PEERing for Multimedia INTerconnect (SPEERMINT). In this 
   process, we define the peering reference architecture, its functional 
   components, and peering interface functions from the perspective of a SIP 
   Service provider's (SSP) network.   

   This architecture allows the interconnection of two SSPs in layer 5 peering as 
   defined in the SPEERMINT Requirements [14] and Terminology [13] documents. 

   Layer 3 peering is outside the scope of this document. Hence, the figures in 
   this document do not show routers so that the focus is on Layer 5 protocol 
   aspects.   

   This document uses terminology defined in the SPEERMINT Terminology document 
   [13], so the reader should be familiar with all the terms defined there. 

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",   "SHALL", 
   "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are 
   to be interpreted as described in [RFC2119]. 

2. Network Context  

   Figure 1 allows for the following potential SPEERMINT peering scenarios:  

     o Enterprise to Enterprise across the public Internet  

     o Enterprise to SSP across the public Internet  

     o SSP to SSP across the public Internet  

     o Enterprise to enterprise across a private Layer 3 network  

     o Enterprise to SSP across a private Layer 3 network  

     o SSP to SSP across a private Layer 3 network  

                           +-------------------+  
                           |                   |               
                           |     Public        |  
                           |       SIP         |  
                           |     Peering       |  
                           |                   |                            
                           +-------------------+                              
                                    |  
                                  -----  
 
 
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      +-----------+              /     \              +-----------+  
      |Enterprise |            --       --            |Enterprise |  
      |Provider A |-----------/           \-----------|Provider B |  
      +-----------+         --             --         +-----------+  
                           /      Public     \  
                           |     Internet    |  
                           \     (Layer 3)   /  
      +-----------+         --             --         +-----------+  
      |  SSP C    |-----------\           /-----------|  SSP D    |  
      |           |            --       --            |           |  
      +-----------+              \_____/              +-----------+  
                                    | Layer 3 Peering  
                                    | Point (out of scope)  
                                  -----  
      +-----------+              /     \              +-----------+  
      |Enterprise |            --       --            |Enterprise |  
      |Provider E |-----------/           \-----------|Provider F |  
      +-----------+         --   Private   --         +-----------+  
                           /     Network    \          
                           |    (Layer 3)    |          
                           \                /           
      +-----------+         --            --          +-----------+  
      |  SSP G    |-----------\           /-----------|   SSP H   |  
      |           |            --       --            |           |  
      +-----------+               \____/              +-----------+  
                                     |  
                           +-------------------+  
                           |     Private       |               
                           |       SIP         |  
                           |     Peering       |  
                           |                   |                              
                           +-------------------+       
                      Figure 1: SPEERMINT Network Context  
 
 
3. Reference SPEERMINT Architecture  

   Figure 2 depicts the SPEERMINT architecture and logical functions that form the 
   peering between two SSPs.  








 
 
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                                +------+ 
                                | DNS, | 
                    +---------->| Db,  |<---------+ 
                    |           | etc  |          | 
                    |           +------+          | 
                    |                             | 
              ------|--------              -------|------- 
             /      v        \            /       v       \ 
            |    +--LUF-+     |          |     +--LUF-+    | 
            |    |      |     |          |     |      |    | 
            |    |      |     |          |     |      |    | 
            |    |      |     |          |     |      |    | 
            |    +------+     |          |     +------+    | 
            |                 |          |                 | 
            |    +--LRF-+     |          |     +--LRF-+    | 
            |    |      |     |          |     |      |    | 
            |    |      |     |          |     |      |    | 
            |    |      |     |          |     |      |    | 
            |    +------+     |          |     +------+    | 
            |                 |          |                 | 
            |                 |          |                 | 
            |             +---SF--+  +---SF--+             | 
            |             |       |  |       |             | 
            |             |  SBE  |  |  SBE  |             | 
            | Originating |       |  |       |  Target     | 
            |             +---SF--+  +---SF--+             | 
            |    SSP          |          |       SSP       | 
            |             +---MF--+  +---MF--+             | 
            |             |       |  |       |             | 
            |             |  DBE  |  |  DBE  |             | 
            |             |       |  |       |             | 
            |             +---MF--+  +---MF--+             | 
             \               /            \               / 
              ---------------              --------------- 
                  Figure 2: Reference SPEERMINT Architecture 
 
   The following procedures are implemented by a set of peering functions:  

   The Look-Up Function (LUF) provides a mechanism for determining for a given 
   request the target domain to which the request should be routed.   

   The Location Routing Function (LRF) determines for the target domain of a given 
   request the location of the SF in that domain and optionally develops other 
   Session Establishment Data (SED) required to route the request to that domain.  


 
 
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   The Signaling Function (SF) provides SIP call routing, to optionally perform 
   termination and re-initiation of call, to optionally implement security and 
   policies on SIP messages, and to assist in discovery/exchange of parameters to 
   be used by the Media Function (MF).  

   The Media Function (MF) provides media related functions such as media 
   transcoding, topology hiding and media security implementation between two 
   SSPs.  

   The intention of defining these functions is to provide a framework for design 
   segmentation and allow each one to evolve independently.  

 
4. Procedures of Interdomain SSP Session Establishment 

   This document assumes that in order for a session to be established from a UA 
   in the originating SSP's network to an UA in the Target SSP's network the 
   following steps are taken:   

     1. analyze the target address.   

          a. If the target address represents an intra-SSP resource, the 
             behavior is out-of-scope with respect to this draft.  

     2. determine the target SSP (LUF) 

     3. determine the SF next-hop in the target SSP (LRF)  

     4. enforce authentication and potentially other policies  

     5. determine of the UA  

     6. establish the session,   

     7. transfer of media which could include voice, video, text and others,  

     8. terminate the session (BYE) 

   The originating SSP would likely perform steps 1-4, and the target SSP would 
   likely perform steps 4-5.  

   In the case the target SSP changes, then steps 1-4 would be repeated. This is 
   reflected in Figure 2 that shows the target SSP with its own peering functions.  




 
 
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5. Recommended SSP Procedures  

   This section describes the functions in more detail and provides some 
   recommendations on the role they would play in a SIP call in a Layer 5 peering 
   scenario.  

   Some of the information in the section is taken from [14] and is put here for 
   continuity purposes. 

5.1. Originating SSP Procedures 

5.1.1. The Look-Up Function (LUF) 

 
   Purpose is to determine the SF of the target domain of a given request and 
   optionally develop Session Establishment Data.  

5.1.1.1. Target address analysis  

 
   When the originating SSP receives a request to communicate, it analyzes the 
   target URI to determine whether the call needs to be routed internal or 
   external to its network. The analysis method is internal to the SSP; thus, 
   outside the scope of SPEERMINT. Note that the SSP may also consult any manner 
   of private data sources to make this determination.  

   If the target address does not represent a resource inside the originating 
   SSP's administrative domain or federation of domains, the originating SSP 
   resolves the call routing data by using the Location Routing Function (LRF).  

   For example, if the request to communicate is for an im: or pres: URI type, the 
   originating SSP follows the procedures in [8].  If the highest priority 
   supported URI scheme is sip: or sips: the originating SSP skips to SIP DNS 
   resolution in Section 5.1.3. Likewise, if the target address is already a sip: 
   or sips: URI in an external domain, the originating SSP skips to SIP DNS 
   resolution in Section 5.1.2.1.   

   If the target address corresponds to a specific E.164 address, the SSP may need 
   to perform some form of number plan mapping according to local policy.  For 
   example, in the United States, a dial string beginning "011 44" could be 
   converted to "+44", or in the United Kingdom "00 1" could be converted to "+1".  
   Once the SSP has an E.164 address, it can use ENUM.  

 



 
 
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5.1.1.2. End User ENUM Lookup  

   If an external E.164 address is the target, the originating SSP consults the 
   public "User ENUM" rooted at e164.arpa, according to the procedures described 
   in RFC 3761.  The SSP must query for the "E2U+sip" enumservice as described in 
   RFC 3764 [11], but MAY check for other enumservices.  The originating SSP MAY 
   consult a cache or alternate representation of the ENUM data rather than actual 
   DNS queries.  Also, the SSP may skip actual DNS queries if the originating SSP 
   is sure that the target address country code is not represented in e164.arpa.  
   If a sip: or sips: URI is chosen the SSP skips to Section 5.1.6.  

   If an im: or pres: URI is chosen for based on an "E2U+im" [8] or "E2U+pres" [9] 
   enumserver, the SSP follows the procedures for resolving these URIs to URIs for 
   specific protocols such a SIP or XMPP as described in the previous section.  

 
5.1.1.3. Infrastructure ENUM lookup  

   An originating SSP may check for a carrier-of-record in an Infrastructure ENUM 
   domain according to the procedures described in [12].  As in the previous step, 
   the SSP may consult a cache or alternate representation of the ENUM data in 
   lieu of actual DNS queries.  The SSP first checks for records for the "E2U+sip" 
   enumservice, then for the "E2U+pstn" enumservice as defined in [21].  If a 
   terminal record is found with a sip: or sips: URI, the SSP skips to Section 
   5.1.2.1. , otherwise the SSP continues processing according to the next 
   section. 

5.1.2. Location Routing Function (LRF) 

   The LRF of an Originating SSP analyzes target address and target domain 
   identified by the LUF, and discovers the next hop signaling function (SF) in a 
   peering relationship. The resource to determine the SF of the target domain 
   might be provided by a third-party as in the assisted-peering case. 

 
5.1.2.1. SIP DNS Resolution  

   Once a sip: or sips: in an external domain is identified as the target, the 
   originating SSP may apply local policy to decide whether forwarding requests to 
   the target domain is acceptable.  The originating SSP uses the procedures in 
   RFC 3263 [4] Section 4 to determine how to contact the receiving SSP.  To 
   summarize the RFC 3263 procedure: unless these are explicitly encoded in the 
   target URI, a transport is chosen using NAPTR records, a port is chosen using 
   SRV records, and an address is chosen using A or AAAA records. Note that these 
   are queries of records in the global DNS. 


 
 
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   When communicating with another SSP, entities compliant to this document should 
   select a TLS-protected transport for communication from the originating SSP to 
   the receiving SSP if available.   

 
5.1.2.2. Routing Table  

   If there are no End User ENUM records and the Originating SSP cannot discover 
   the carrier-of-record or if the Originating SSP cannot reach the carrier-of-
   record via SIP peering, the Originating SSP may deliver the call to the PSTN or 
   reject it.  Note that the originating SSP may forward the call to another SSP 
   for PSTN gateway termination by prior arrangement using the routing table.   

   If so, the originating SSP rewrites the Request-URI to address the gateway 
   resource in the target SSP's domain and MAY forward the request on to that SSP 
   using the procedures described in the remainder of these steps.  

5.1.2.3. SIP Redirect Server    

   A SIP Redirect Server using 3XX SIP Redirect is another option in resolving the 
   next-hop SF of the target domain. 

5.1.3. The Signaling Function (SF) 

   The purpose of signaling function is to perform routing of SIP messages as well 
   as optionally implement security and policies on SIP messages, and to assist in 
   discovery/exchange of parameters to be used by the Media Function (MF).  

   The signaling function performs the routing of SIP messages. The optional 
   termination and re-initiation of calls may be performed by the signaling path 
   Session Border Element (SBE).   

   Optionally, a SF may perform additional functions such as Session Admission 
   Control, SIP Denial of Service protection, SIP Topology Hiding, SIP header 
   normalization, and SIP security, privacy and encryption.  

   The SF of a SBE can also process SDP payloads for media information such as 
   media type, bandwidth, and type of codec; then, communicate this information to 
   the media function. Signaling function may optionally communicate with the 
   network to pass Layer 3 related policies [10]  

5.1.3.1. Establishing a Trusted Relationship 

   Depending on the security needs and trust relationships between SSPs, different 
   security mechanism can be used to establish SIP calls. These are discussed in 
   the following subsections. 

 
 
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5.1.3.1.1. TLS connection 

   Once a transport, port, and address are found, the originating SSP will open or 
   find a reusable TLS connection to the peer. The procedures to authenticate the 
   SSP's target domain is specified in [24]  

5.1.3.1.2. TLS 

   If the trust relationship was established through TLS, the originating SSP can 
   optionally verify and assert the senders identity using the SIP Identity 
   mechanism.  

   In addition, new requests should contain a valid Identity and Identity-Info 
   header as described in [12].  The Identity-Info header must present a domain 
   name that is represented in the certificate provided when establishing the TLS 
   connection over which the request is sent.  The originating SSP should include 
   an Identity header on in-dialog requests as well if the From header field value 
   matches an identity the originating SSP is willing to assert. 

5.1.3.1.3. IPSec  

   In certain deployments the use of IPSec between the signaling functions of the 
   originating and terminating domains can be used as a security mechanism instead 
   of TLS. 
    
5.1.3.1.4. Co-Location   

   In this scenario the SFs are co-located in a physically secure location and/or 
   are members of a segregated network. In this case messages between the 
   originating and terminating SSPs would be sent as clear text. 

5.1.3.2. Sending the SIP request 

   Once a trust relationship between the peers is established, the originating SSP 
   sends the request.   

 
5.2. Terminating SSP Procedures 

5.2.1. The Location Function (LF)  

5.2.1.1. Publish ENUM records  

   The receiving SSP should participate by publishing "E2U+sip" and "E2U+pstn" 
   records with sip: or sips: URIs wherever a public Infrastructure ENUM root is 
   available.  This assumes that the receiving SSP wants to peer by default. When 

 
 
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   the receiving SSP does not want to accept traffic from specific originating 
   SSPs, it may still reject requests on a call-by-call basis.  

5.2.1.2. Publish SIP DNS records  

   To receive SSP requests, the receiving SSP must insure that it   publishes 
   appropriate NAPTR, SRV, and address (A and/or AAAA) records in the LF relevant 
   to the SSP's SF.    

5.2.1.3. Subscribe Notify   

   Policies function may also be optionally implemented by dynamic subscribe, 
   notify, and exchange of policy information and feature information among SSPs 
   [21].   

5.2.2. Signaling Function (SF) 

5.2.2.1. TLS  

   When the receiving SSP receives a TLS client hello, it responds with its 
   certificate.  The Target SSP certificate should be valid and rooted in a well-
   known certificate authority. The procedures to authenticate the SSP's 
   originating domain are specified in [24].  

   The SF of the Target SSP verifies that the Identity header is valid, 
   corresponds to the message, corresponds to the Identity-Info header, and that 
   the domain in the From header corresponds to one of the domains in the TLS 
   client certificate. 

5.2.2.2. Receive SIP requests 

   Once a trust relationship is established, the Target SSP is prepared to receive 
   incoming SIP requests.  For new requests (dialog forming or not) the receiving 
   SSP verifies if the target (request-URI) is a domain that for which it is 
   responsible. For these requests, there should be no remaining Route header 
   field values. For in-dialog requests, the receiving SSP can verify that it 
   corresponds to the top-most Route header field value.  

   The receiving SSP may reject incoming requests due to local policy. When a 
   request is rejected because the originating SSP is not authorized to peer, the 
   receiving SSP should respond with a 403 response with the reason phrase 
   "Unsupported Peer". 





 
 
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5.3. Target SSP Procedures 

5.3.1. Signaling Function (SF) 

5.3.1.1. TLS  

   When the receiving SSP receives a TLS client hello, it responds with its 
   certificate.  The Target SSP's certificate should be valid and rooted in a 
   well-known certificate authority. The procedures to authenticate the SSP's 
   originating domain are specified in [24].  

   If the requests should contain a valid Identity and Identity-Info header as 
   described in [24] the target SF verifies that the Identity header is valid, 
   corresponds to the message, corresponds to the Identity-Info header, and that 
   the domain in the From header corresponds to one of the domains in the TLS 
   client certificate. 

5.3.1.2. Receive SIP requests 

   The procedures of the SF of the target SSP are the same as the ones described 
   in section 5.2.2.2 with the addition that it might establish a connection to 
   another target SSP, and in this case use the procedures recommended to an 
   originating SS (section 5.1). 

5.4. Media Function (MF)  

   The purpose of the MF is to perform media related functions such as media 
   transcoding and media security implementation between two SSPs.  

   An Example of this is to transform a voice payload from one codec (e.g., G.711) 
   to another (e.g., EvRC).  Additionally, the MF may perform media relaying, 
   media security, privacy, and encryption.  

5.5. Policy Considerations  

   In the context of the SPEERMINT working group when two SSPs peer, there MAY be 
   a desire to exchange peering policy information dynamically. There are 
   specifications in progress in the SIPPING working group to define policy 
   exchange between an UA and a domain [23] and providing profile data to SIP user 
   agents [24] These considerations borrow from both.  

   Following the terminology introduced in [12], this package uses the terms 
   Peering Session-Independent and Session-Specific policies in the following 
   context.  

     o Peering Session-Independent policies include Diffserv Marking, Policing, 
        Session Admission Control, and domain reachabilities, amongst others. The 
 
 
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        time period between Peering Session-Independent policy changes is much 
        greater than the time it takes to establish a call.   

     o Peering Session-Specific polices includes supported connection/call rate, 
        total number of connections/calls available, current utilization, amongst 
        others. Peering Session-specific policies can change within the time it 
        takes to establish a call.  

   These policies can be SSP dependent or independent, creating the following 
   peering policy definition:   

 
     o SSP Independent or Dependent                                       
        Session dependent                                         Session 
        independent   

6. Call Control and Media Control Deployment Options  

   The peering functions can be deployed along the following two dimensions 
   depending upon how the signaling and the media functions along with IP layer 
   are implemented:  

   Composed or Decomposed:  Addresses the question whether the media must flow 
   through the same physical and geographic elements as SIP dialogs and sessions.  

   Centralized or Distributed:  Addresses the question whether the logical and 
   physical interconnections are in one geographical location or distributed to 
   multiple physical locations on the SSP's network.  

   In a composed model, SF and MF functions are implemented in one peering logical 
   element.  
















 
 
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             Provider A                        Provider B 
             ----------   .               .   ---------- 
            /           \ .               .  /          \ 
           |            | .       _       . |            | 
           |       +----+ .     /   \_    . +----+       | 
           |       | SF |<-----/     \------| SF |       | 
           |       +-+--+ .   /Transit\   . |    |       | 
           |         | |  .  /   IP    \  . |    |       | 
           |       +-+--+ .  | Provider|  . |    |       | 
           |       | MF |<~~~| (Option)|~~~~| MF |       | 
           |       +----+ .   \        /  . +----+       | 
           |            | .    \ __ _ /   . |            | 
            \_________ /  .               .  \________ _/ 
             ----------                       ---------- 
    
   --- Signal (SIP) 
   ~~~ Bearer (RTP/IP) 
   ... Scope of peering 
                                     
                   Figure 3: Decomposed v. Collapsed Peering 
 
   The advantage of a collapsed peering architecture is that one-element solves 
   all peering issues. Disadvantage examples of this architecture are single point 
   of failure, bottleneck, and complex scalability.  

   In a decomposed model, SF and MF are implemented in separate peering logical 
   elements. SFs are implemented in a proxy and MFs are implemented in another 
   logical element.  The scaling of signaling versus scaling of media may differ 
   between applications.  Decomposing allows each to follow a separate migration 
   path.  

   This model allows the implementation of M:N model where one SF is associated 
   with multiple peering MF and one peering MF is associated with multiple SFs. 
   Generally, a vertical protocol associates the relationship between a SF and a 
   MF. This architecture reduces the potential of a single point of failure. It 
   allows separation of the policy decision point and the policy enforcement 
   point. An example of disadvantages is the scaling complexity because of the M:N 
   relationship and latency due to the vertical control messages between entities.   

 
7. Address space considerations  

 
   Peering must occur in a common IP address space, which is defined by the 
   federation, which may be entirely on the public Internet, or some private 
   address space. The origination or termination networks may or may not entirely 
 
 
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   be in the same address space.  If they are not, then a network address 
   translation (NAT) or similar may be needed before the signaling or media is 
   presented correctly to the federation. The only requirement is that all 
   associated entities across the peering interface are reachable.  

 
8. Security Considerations  

 
   In all cases, cryptographic-based security should be maintained as an optional 
   requirement between peering providers conditioned on the presence or absence of 
   underlying physical security of SSP connections, e.g. within the same secure 
   physical building.    

   In order to maintain a consistent approach, unique and specialized security 
   requirements common for the majority of peering relationships, should be 
   standardized within the IETF.  These standardized methods may enable 
   capabilities such as dynamic peering relationships across publicly maintained 
   interconnections.  

9. IANA Considerations  

   There are no IANA considerations at this time.  
 
10. Acknowledgments  

   The working group thanks Sohel Khan for his initial architecture  
   draft that helped to initiate work on this draft.  
 
   A significant portion of this draft is taken from [14] with  
   permission from the author R. Mahy. The other important contributor  
   is Otmar Lendl. Special thanks to Jim McEachern for detailed comments and 
feedback. 














 
 
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11. References 

11.1. Normative References 

   [1]   Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", 
         BCP 14, RFC 2119, March 1997.  

   [2]   Mealling, M. and R. Daniel, "The Naming Authority Pointer (NAPTR) DNS 
         Resource Record", RFC 2915, September 2000.  

   [3]   Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, 
         J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation 
         Protocol", RFC 3261, June 2002.  

   [4]   Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): 
         Locating SIP Servers", RFC 3263, June 2002.  

   [5]   Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., and T. 
         Wright, "Transport Layer Security (TLS) Extensions", RFC 4366, April 
         2006.  

   [6]   Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A 
         Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 
         2003.  

   [7]   Peterson, J., Liu, H., Yu, J., and B. Campbell, "Using E.164 numbers 
         with the Session Initiation Protocol (SIP)", RFC 3824, June 2004.  

   [8]   Peterson, J., "Address Resolution for Instant Messaging and 
         Presence",RFC 3861, August 2004.   

   [9]   Peterson, J., "Telephone Number Mapping (ENUM) Service Registration for 
         Presence Services", RFC 3953, January 2005.  

   [10]  ETSI TS 102 333: " Telecommunications and Internet converged Services 
         and Protocols for Advanced Networking (TISPAN); Gate control protocol".  

   [11]  Peterson, J., "enumservice registration for Session Initiation Protocol 
         (SIP) Addresses-of-Record", RFC 3764, April 2004.  

   [12]  Livingood, J. and R. Shockey, "IANA Registration for an          
         Enumservice Containing PSTN Signaling Information", RFC 4769, November 
         2006.  




 
 
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11.2. Informative References 

   [13]  Malas, D., "SPEERMINT Terminology", draft-ietf-speermint-terminology-16 
         (work in progress), February 2008.  

   [14]  Mule, J-F., "SPEERMINT Requirements for SIP-based VoIP Interconnection", 
         draft-ietf-speermint-requirements-04.txt, February 2008.  

   [15]  Mahy, R., "A Minimalist Approach to Direct Peering", draft-         
         mahy-speermint-direct-peering-02.txt, July 2007.  

   [16]  Penno, R., et al., "SPEERMINT Routing Architecture Message          
         Flows", draft-ietf-speermint-flows-02.txt", April 2007.  

   [17]  Houri, A., et al., "RTC Provisioning Requirements", draft-         
         houri-speermint-rtc-provisioning-reqs-00.txt, June, 2006.  

   [18]  Habler, M., et al., "A Federation based VOIP Peering         
         Architecture", draft-lendl-speermint-federations-03.txt, September 2006.  

   [19]  Mahy, R., "A Telephone Number Mapping (ENUM) Service          
         Registration for Instant Messaging (IM) Services", draft-ietf-         
         enum-im-service-03 (work in progress), March 2006.  

   [20]  Haberler, M. and R. Stastny, "Combined User and Carrier ENUM in the 
         e164.arpa tree", draft-haberler-carrier-enum-03 (work in progress), 
         March 2006.  

   [21]  Penno, R., Malas D., and Melampy, P., "A Session Initiation          
         Protocol (SIP) Event package for Peering", draft-penno-sipping-peering-
         package-00 (work in progress), September 2006.  

   [22]  Hollander, D., Bray, T., and A. Layman, "Namespaces in XML", W3C REC 
         REC-xml-names-19990114, January 1999.  

   [23]  Burger, E (Ed.), "A Mechanism for Content Indirection in          
         Session Initiation Protocol (SIP) Messages", RFC 4483, May 2006 

   [24]  Gurbani, V., Lawrence, S., and B. Laboratories, "Domain Certificates in 
         the Session Initiation Protocol (SIP)", draft-ietf-sip-domain-certs-00 
         (work in progress), November 2007. 






 
 
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Author's Addresses 

   Adam Uzelac  
   Global Crossing  
   Rochester, NY - USA  
   Email: adam.uzelac@globalcrossing.com  
    
   Reinaldo Penno 
   Juniper Networks  
   Sunnyvale, CA - USA  
   Email: rpenno@juniper.net  
    
   Mike Hammer  
   Cisco Systems  
   Herndon, VA - USA 
   Email: mhammer@cisco.com   
        
   Sohel Khan, Ph.D.  
   Comcast Cable Communications   
   USA 
   Email: sohel_khan@cable.comcast.com  
        
   Daryl Malas  
   CableLabs 
   Louisville, CO - USA 
   Email: d.malas@cablelabs.com  
       
    

    

















 
 
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