Network Working Group G. Camarillo
Request for Comments: 4457 G. Blanco
Category: Informational Ericsson
April 2006
Network Working Group G. Camarillo
Request for Comments: 4457 G. Blanco
Category: Informational Ericsson
April 2006
The Session Initiation Protocol (SIP) P-User-Database Private-Header (P-Header)
会话启动协议（SIP）P-用户-数据库专用头（P-头）
Status of This Memo
关于下段备忘
This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited.
本备忘录为互联网社区提供信息。它没有规定任何类型的互联网标准。本备忘录的分发不受限制。
Copyright Notice
版权公告
Copyright (C) The Internet Society (2006).
版权所有（C）互联网协会（2006年）。
Abstract
摘要
This document specifies the Session Initiation Protocol (SIP) P-User-Database Private-Header (P-header). This header field is used in the 3rd-Generation Partnership Project (3GPP) IMS (IP Multimedia Subsystem) to provide SIP registrars and SIP proxy servers with the address of the database that contains the user profile of the user that generated a particular request.
本文档指定了会话启动协议（SIP）P-User-Database专用头（P-Header）。该报头字段用于第三代合作伙伴关系项目（3GPP）IMS（IP多媒体子系统），以向SIP注册者和SIP代理服务器提供包含生成特定请求的用户的用户配置文件的数据库地址。
Table of Contents
目录
1. Introduction ....................................................2
2. Scenarios .......................................................2
2.1. User Registering to the IMS ................................2
2.2. Incoming Request for an Unregistered User ..................3
3. Requirements ....................................................4
4. P-User-Database Header Field Definition .........................4
5. Applicability ...................................................5
6. IANA Considerations .............................................5
7. Security Considerations .........................................5
8. Acknowledgements ................................................6
9. References ......................................................6
9.1. Normative References .......................................6
9.2. Informative References .....................................6
1. Introduction ....................................................2
2. Scenarios .......................................................2
2.1. User Registering to the IMS ................................2
2.2. Incoming Request for an Unregistered User ..................3
3. Requirements ....................................................4
4. P-User-Database Header Field Definition .........................4
5. Applicability ...................................................5
6. IANA Considerations .............................................5
7. Security Considerations .........................................5
8. Acknowledgements ................................................6
9. References ......................................................6
9.1. Normative References .......................................6
9.2. Informative References .....................................6
The 3rd-Generation Partnership Project (3GPP) IMS (IP Multimedia Subsystem) uses the Session Initiation Protocol (SIP) [2] as its main signalling protocol. (For more information on the IMS, a detailed description can be found in 3GPP TS 23.228 [5] and 3GPP TS 24.229 [6].) 3GPP has identified a set of requirements that can be met, according to the procedures in RFC 3427 [3], by defining a new SIP Private-Header (P-header).
第三代合作伙伴计划（3GPP）IMS（IP多媒体子系统）使用会话发起协议（SIP）[2]作为其主要信令协议。（有关IMS的更多信息，可在3GPP TS 23.228[5]和3GPP TS 24.229[6]中找到详细说明）。3GPP已确定了一组可以通过定义新的SIP专用头（P-Header）来满足的要求，根据RFC 3427[3]中的程序。
The remainder of this document is organized as follows. Section 2 describes the scenarios considered by 3GPP and Section 3 discusses the requirements derived from these scenarios. Section 4 defines the P-User-Database header field, which meets those requirements, and Section 5 discusses the applicability and scope of this new header field. Section 6 registers the P-User-Database header field with the IANA and Section 7 discusses the security properties of the environment where this header field is intended to be used.
本文件的其余部分组织如下。第2节描述了3GPP考虑的场景，第3节讨论了从这些场景派生的需求。第4节定义了满足这些要求的P-User-Database头字段，第5节讨论了这个新头字段的适用性和范围。第6节向IANA注册P-User-Database头字段，第7节讨论打算使用该头字段的环境的安全属性。
In the 3GPP IMS, there are two scenarios where a set of proxies handling a request need to consult the same user database. These scenarios consist of a user registering to the IMS network and an unregistered user receiving an incoming request that triggers a service (e.g., a voice mail service).
在3GPP IMS中，存在两种场景，其中处理请求的一组代理需要咨询同一用户数据库。这些场景包括注册到IMS网络的用户和接收到触发服务（例如语音邮件服务）的传入请求的未注册用户。
In the 3GPP IMS, SIP REGISTER requests generated by a User Agent (UA) traverse a set of SIP proxy servers before reaching the SIP registrar. A REGISTER request sent by a UA is routed to the outbound proxy of the UA, which is referred to as the P-CSCF (Proxy-Call/Session Control Function).
在3GPP IMS中，由用户代理（UA）生成的SIP注册请求在到达SIP注册器之前穿过一组SIP代理服务器。UA发送的注册请求被路由到UA的出站代理，该代理称为P-CSCF（代理呼叫/会话控制功能）。
The P-CSCF routes the REGISTER request to another proxy, which is referred to as the I-CSCF (Interrogating-CSCF) and is always located in the home domain of the user. The I-CSCF consults the user database of the domain, which is referred to as the Home Subscriber Server (HSS), in order to choose the registrar that will process the REGISTER request.
P-CSCF将注册请求路由到另一个代理，该代理被称为I-CSCF（询问CSCF），并且始终位于用户的主域中。I-CSCF咨询域的用户数据库（称为归属订户服务器（HSS）），以选择将处理注册请求的注册器。
With the information received from the HSS, the I-CSCF routes the REGISTER request to the appropriate registrar, which is referred to as the S-CSCF (Serving-CSCF). At this point, the S-CSCF needs to contact the same HSS that was previously contacted by the I-CSCF in order to fetch the user profile of the user that generated the REGISTER request.
根据从HSS接收到的信息，I-CSCF将注册请求路由到适当的注册机构，该注册机构称为S-CSCF（服务CSCF）。此时，S-CSCF需要联系I-CSCF先前联系的同一HSS，以便获取生成注册请求的用户的用户配置文件。
The interface between the I-CSCF and the HSS and between the S-CSCF and the HSS is called Cx interface and is based on Diameter [4].
I-CSCF和HSS之间以及S-CSCF和HSS之间的接口称为Cx接口，并基于直径[4]。
When there is a single HSS (i.e., user database) handling all the users in the domain, both the I-CSCF and the S-CSCF can be configured with its address so that they contact it when necessary. However, some domains have several HSSs, each of which handles a particular set of users. When dealing with a REGISTER request, the I-CSCF and the S-CSCF need to discover which is the HSS that contains the profile of the user that generated the REGISTER request.
当有一个HSS（即用户数据库）处理域中的所有用户时，i-CSCF和S-CSCF都可以配置其地址，以便它们在必要时联系它。但是，有些域有几个HSS，每个HSS处理一组特定的用户。在处理注册请求时，I-CSCF和S-CSCF需要发现哪个HSS包含生成注册请求的用户的配置文件。
In networks with more than one HSS, a Diameter redirect agent referred to as the Subscription Locator Function (SLF) is implemented. The interface between the I-CSCF and the SLF and between the S-CSCF and the SLF is called Dx interface and, like the CX interface, is based on Diameter. The SLF provides the I-CSCF and the S-CSCF with the address of the HSS that handles the user they are dealing with.
在具有多个HSS的网络中，实现了称为订阅定位器功能（SLF）的直径重定向代理。I-CSCF和SLF之间以及S-CSCF和SLF之间的接口称为Dx接口，与CX接口一样，基于直径。SLF向I-CSCF和S-CSCF提供处理他们正在处理的用户的HSS地址。
Therefore, in a network with more than one HSS, the SLF is consulted twice per REGISTER request, first by the I-CSCF, and later by the S-CSCF. If the I-CSCF could provide the S-CSCF with the address of the HSS handling the user that generated the REGISTER request, the S-CSCF could contact directly that HSS. That is, the S-CSCF would not need to contact the SLF in order to obtain the address of the HSS.
因此，在具有多个HSS的网络中，每个注册请求都会咨询SLF两次，首先由I-CSCF咨询，然后由S-CSCF咨询。如果I-CSCF可以向S-CSCF提供处理生成注册请求的用户的HSS的地址，则S-CSCF可以直接联系该HSS。也就是说，S-CSCF不需要联系SLF来获取HSS的地址。
In the 3GPP IMS, incoming requests for a user traverse an I-CSCF in the home domain of the user. This I-CSCF consults the HSS, using the Diameter-based Cx interface, in order to decide which S-CSCF should handle the request. After consulting the HSS, the I-CSCF forwards the request to a S-CSCF, which is also located in the home domain of the user.
在3GPP IMS中，用户的传入请求在用户的归属域中穿过I-CSCF。该I-CSCF使用基于直径的Cx接口咨询HSS，以决定哪个S-CSCF应处理该请求。在咨询HSS之后，I-CSCF将请求转发给S-CSCF，S-CSCF也位于用户的主域中。
If the user the request is addressed to is registered to the IMS network, the S-CSCF receiving the request knows which HSS handles the user. The S-CSCF stored this information when the user registered. However, if the user is not registered, the S-CSCF needs to consult the SLF (assuming more than one HSS in the network) in order to discover the HSS handling the user.
如果向其发送请求的用户已注册到IMS网络，则接收该请求的S-CSCF知道由哪个HSS处理该用户。当用户注册时，S-CSCF存储该信息。但是，如果用户未注册，则S-CSCF需要咨询SLF（假设网络中有多个HSS），以便发现处理该用户的HSS。
Therefore, like in the previous scenario, in a network with more than one HSS, the SLF is consulted twice per incoming request addresses to an unregistered user. First by the I-CSCF, and later by the S-CSCF. If the I-CSCF could provide the S-CSCF with the address of the HSS handling the user that generated the request, the S-CSCF could contact directly that HSS. That is, the S-CSCF would not need to contact the SLF in order to obtain the address of the HSS.
因此，与前面的场景一样，在具有多个HSS的网络中，对于未注册用户，每个传入的请求地址都会咨询SLF两次。首先是I-CSCF，然后是S-CSCF。如果I-CSCF可以向S-CSCF提供处理生成请求的用户的HSS的地址，则S-CSCF可以直接联系该HSS。也就是说，S-CSCF不需要联系SLF来获取HSS的地址。
This section lists the requirements derived from the previous scenarios:
本节列出了从前面的场景派生的需求：
1. It is necessary to optimize the registration process in the 3GPP IMS by reducing the time it takes for a UA to register to the IMS network.
1. 有必要通过减少UA注册到IMS网络所需的时间来优化3GPP IMS中的注册过程。
2. It is necessary to optimize the handling of incoming requests to unregistered users in the 3GPP IMS by reducing the time it takes for a domain to handle these requests.
2. 有必要通过减少域处理这些请求所需的时间来优化对3GPP IMS中未注册用户的传入请求的处理。
3. It is necessary to improve the scalability of SLFs in the 3GPP IMS by reducing the amount of traffic the SLF of a network needs to handle.
3. 有必要通过减少网络的SLF需要处理的通信量来提高3GPP IMS中SLF的可伸缩性。
This document defines the SIP P-User-Database P-header. This header field can be added to requests routed from an I-CSCF to an S-CSCF. The P-User-Database P-header contains the address of the HSS handling the user that generated the request.
本文档定义了SIP P-User-Database P-header。此标头字段可以添加到从I-CSCF路由到S-CSCF的请求中。P-User-Database P-header包含处理生成请求的用户的HSS的地址。
The augmented Backus-Naur Form (BNF) [1] syntax of the P-User-Database header field is the following:
P-User-Database头字段的扩充Backus Naur Form（BNF）[1]语法如下：
P-User-Database = "P-User-Database" HCOLON database *( SEMI generic-param ) database = LAQUOT DiameterURI RAQUOT
P-User-Database=“P-User-Database”HCOLON数据库*（半通用参数）数据库=LAQUOT DiameterURI RAQUOT
DiameterURI is defined in RFC 3588 [4]. HCOLON, LAQUOT, RAQUOT, and generic-param are defined in RFC 3261 [2].
在35RF88中定义了[DiameterURI]。RFC 3261[2]中定义了HCOLON、LAQUOT、RAQUOT和generic param。
The following is an example of a P-User-Database header field:
以下是P-User-Database标头字段的示例：
P-User-Database: <aaa://host.example.com;transport=tcp>
P-User-Database: <aaa://host.example.com;transport=tcp>
According to RFC 3427 [3], P-headers have a limited applicability. Specifications of P-headers such as this RFC need to clearly document the useful scope of the proposal, and explain its limitations and why it is not suitable for the general use of SIP on the Internet.
根据RFC 3427[3]，P型封头的适用性有限。该RFC等P-Header规范需要清楚地记录提案的有用范围，并解释其局限性以及为什么不适合在Internet上普遍使用SIP。
The P-User-Database header field is intended to be used in 3GPP IMS networks. This header field carries the address of a user database, which is referred to as HSS, between two proxies, which are referred to as I-CSCF and S-CSCF. The I-CSCF and the S-CSCF belong to the same administrative domain and share a common frame of reference to the user database. The I-CSCF inserts the P-User-Database header field into a SIP request and the S-CSCF removes it before routing the request further.
P-User-Database报头字段旨在用于3GPP IMS网络中。此标头字段携带两个代理（称为I-CSCF和S-CSCF）之间的用户数据库（称为HSS）的地址。I-CSCF和S-CSCF属于同一管理域，并共享用户数据库的公共参考框架。I-CSCF将P-User-Database报头字段插入到SIP请求中，S-CSCF在进一步路由请求之前将其删除。
When SIP is used on the Internet, there are typically no proxies querying a user database between the UA sending a REGISTER request and the registrar. Consequently, the P-User-Database header field does not seem useful in a general Internet environment.
当在因特网上使用SIP时，在发送注册请求的UA和注册器之间通常没有查询用户数据库的代理。因此，P-User-Database头字段在一般的Internet环境中似乎没有用处。
This document defines a new SIP header field: P-User-Database. This header field has been registered by the IANA in the SIP Parameters registry under the Header Fields subregistry.
本文档定义了一个新的SIP头字段：P-User-Database。IANA已在SIP参数注册表的header Fields子区下注册了此header field。
The P-User-Database defined in this document is to be used in an environment where elements are trusted and where attackers are not supposed to have access to the protocol messages between those elements. Traffic protection between network elements is sometimes achieved by using IP Security (IPsec) and sometimes by physically protecting the network. In any case, the environment where the P-User-Database header field will be used ensures the integrity and the confidentiality of the contents of this header field.
本文档中定义的P-User-Database将用于元素受信任且攻击者不应访问这些元素之间的协议消息的环境中。网元之间的流量保护有时通过使用IP安全（IPsec）实现，有时通过物理保护网络实现。在任何情况下，使用P-User-Database头字段的环境都可以确保该头字段内容的完整性和机密性。
There is a slight security risk if a P-User-Database header field is allowed to propagate out of the administrative domain where it was generated. No user-sensitive information would be revealed by such a breach, but this could result in disclosure of information about the topology of the operator network that goes beyond the level of disclosure explicit in SIP messages without this extension. Consequently, operators need to ensure that the P-User-Database header field is removed from requests before these are sent to another administrative domain.
如果允许P-User-Database头字段传播到生成它的管理域之外，则存在轻微的安全风险。此类违规不会泄露任何用户敏感信息，但这可能会导致有关运营商网络拓扑的信息泄露，超出没有此扩展的SIP消息中明确的泄露级别。因此，操作员需要确保在将请求发送到另一个管理域之前，从请求中删除P-User-Database头字段。
Nuria Esteban, Stephen Terrill, and Jeroen van Bemmel provided comments on this document. Dean Willis performed a thorough review of this document.
Nuria Esteban、Stephen Terrill和Jeroen van Bemmel对本文件发表了评论。迪安·威利斯对这份文件进行了彻底的审查。
[1] Crocker, D. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 4234, October 2005.
[1] Crocker，D.和P.Overell，“语法规范的扩充BNF:ABNF”，RFC 42342005年10月。
[2] 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.
[2] Rosenberg，J.，Schulzrinne，H.，Camarillo，G.，Johnston，A.，Peterson，J.，Sparks，R.，Handley，M.，和E.Schooler，“SIP：会话启动协议”，RFC 3261，2002年6月。
[3] Mankin, A., Bradner, S., Mahy, R., Willis, D., Ott, J., and B. Rosen, "Change Process for the Session Initiation Protocol (SIP)", BCP 67, RFC 3427, December 2002.
[3] Mankin，A.，Bradner，S.，Mahy，R.，Willis，D.，Ott，J.，和B.Rosen，“会话启动协议（SIP）的变更过程”，BCP 67，RFC 3427，2002年12月。
[4] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[4] Calhoun，P.，Loughney，J.，Guttman，E.，Zorn，G.，和J.Arkko，“直径基础协议”，RFC 3588，2003年9月。
[5] 3GPP, "IP Multimedia Subsystem (IMS); Stage 2", 3GPP TS 23.228 5.14.0, October 2005.
[5] 3GPP，“IP多媒体子系统（IMS）；第2阶段”，3GPP TS 23.228 5.14.012005年10月。
[6] 3GPP, "Internet Protocol (IP) multimedia call control protocol based on Session Initiation Protocol (SIP) and Session Description Protocol (SDP); Stage 3", 3GPP TS 24.229 5.14.0, October 2005.
[6] 3GPP，“基于会话发起协议（SIP）和会话描述协议（SDP）的互联网协议（IP）多媒体呼叫控制协议；第3阶段”，3GPP TS 24.229 5.14.0，2005年10月。
Authors' Addresses
作者地址
Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420 Finland
Gonzalo Camarillo Ericsson Hirsalantie 11 Jorvas 02420芬兰
EMail: Gonzalo.Camarillo@ericsson.com
EMail: Gonzalo.Camarillo@ericsson.com
German Blanco Ericsson Via de los Poblados 13 Madrid 28035 Spain
德国布兰科爱立信Via de los Poblados 13马德里28035西班牙
EMail: german.blanco@ericsson.com
EMail: german.blanco@ericsson.com
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