Internet Engineering Task Force (IETF) D. Bryan
Request for Comments: 7890 Cogent Force, LLC
Category: Informational P. Matthews
ISSN: 2070-1721 Nokia
E. Shim
Samsung Electronics Co., Ltd.
D. Willis
Softarmor Systems
S. Dawkins
Huawei (USA)
June 2016
Internet Engineering Task Force (IETF) D. Bryan
Request for Comments: 7890 Cogent Force, LLC
Category: Informational P. Matthews
ISSN: 2070-1721 Nokia
E. Shim
Samsung Electronics Co., Ltd.
D. Willis
Softarmor Systems
S. Dawkins
Huawei (USA)
June 2016
Concepts and Terminology for Peer-to-Peer SIP (P2PSIP)
对等SIP（P2PSIP）的概念和术语
Abstract
摘要
This document defines concepts and terminology for using the Session Initiation Protocol in a peer-to-peer environment where the traditional proxy-registrar and message-routing functions are replaced by a distributed mechanism. These mechanisms may be implemented using a Distributed Hash Table or other distributed data mechanism with similar external properties. This document includes a high-level view of the functional relationships between the network elements defined herein, a conceptual model of operations, and an outline of the related problems addressed by the P2PSIP working group, the REsource LOcation And Discovery (RELOAD) protocol, and the SIP usage document defined by the working group.
本文档定义了在对等环境中使用会话启动协议的概念和术语，在对等环境中，传统的代理注册器和消息路由功能被分布式机制取代。这些机制可以使用分布式哈希表或具有类似外部属性的其他分布式数据机制来实现。本文件包括本文定义的网络元件之间的功能关系的高级视图、操作的概念模型、P2PSIP工作组解决的相关问题的概述、资源定位和发现（重新加载）协议以及工作组定义的SIP使用文件。
Status of This Memo
关于下段备忘
This document is not an Internet Standards Track specification; it is published for informational purposes.
本文件不是互联网标准跟踪规范；它是为了提供信息而发布的。
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Not all documents approved by the IESG are a candidate for any level of Internet Standard; see Section 2 of RFC 7841.
本文件是互联网工程任务组（IETF）的产品。它代表了IETF社区的共识。它已经接受了公众审查，并已被互联网工程指导小组（IESG）批准出版。并非IESG批准的所有文件都适用于任何级别的互联网标准；见RFC 7841第2节。
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at http://www.rfc-editor.org/info/rfc7890.
有关本文件当前状态、任何勘误表以及如何提供反馈的信息，请访问http://www.rfc-editor.org/info/rfc7890.
Copyright Notice
版权公告
Copyright (c) 2016 IETF Trust and the persons identified as the document authors. All rights reserved.
版权所有（c）2016 IETF信托基金和确定为文件作者的人员。版权所有。
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.
本文件受BCP 78和IETF信托有关IETF文件的法律规定的约束(http://trustee.ietf.org/license-info)自本文件出版之日起生效。请仔细阅读这些文件，因为它们描述了您对本文件的权利和限制。从本文件中提取的代码组件必须包括信托法律条款第4.e节中所述的简化BSD许可证文本，并提供简化BSD许可证中所述的无担保。
Table of Contents
目录
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. High-Level Description . . . . . . . . . . . . . . . . . . . 4
2.1. Services . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Clients . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Relationship between P2PSIP and RELOAD . . . . . . . . . 5
2.4. Relationship between P2PSIP and SIP . . . . . . . . . . . 5
2.5. Relationship between P2PSIP and Other AoR-Dereferencing
Approaches . . . . . . . . . . . . . . . . . . . . . . . 6
2.6. NAT Issues . . . . . . . . . . . . . . . . . . . . . . . 6
3. Reference Model . . . . . . . . . . . . . . . . . . . . . . . 6
4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. The Distributed Database Function . . . . . . . . . . . . 12
5.2. Using the Distributed Database Function . . . . . . . . . 13
5.3. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . 14
5.4. Locating and Joining an Overlay . . . . . . . . . . . . . 14
5.5. Clients and Connecting Unmodified SIP Devices . . . . . . 15
5.6. Architecture . . . . . . . . . . . . . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7. Informative References . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Background . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. High-Level Description . . . . . . . . . . . . . . . . . . . 4
2.1. Services . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Clients . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Relationship between P2PSIP and RELOAD . . . . . . . . . 5
2.4. Relationship between P2PSIP and SIP . . . . . . . . . . . 5
2.5. Relationship between P2PSIP and Other AoR-Dereferencing
Approaches . . . . . . . . . . . . . . . . . . . . . . . 6
2.6. NAT Issues . . . . . . . . . . . . . . . . . . . . . . . 6
3. Reference Model . . . . . . . . . . . . . . . . . . . . . . . 6
4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 8
5. Discussion . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. The Distributed Database Function . . . . . . . . . . . . 12
5.2. Using the Distributed Database Function . . . . . . . . . 13
5.3. NAT Traversal . . . . . . . . . . . . . . . . . . . . . . 14
5.4. Locating and Joining an Overlay . . . . . . . . . . . . . 14
5.5. Clients and Connecting Unmodified SIP Devices . . . . . . 15
5.6. Architecture . . . . . . . . . . . . . . . . . . . . . . 16
6. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7. Informative References . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
One of the fundamental problems in multimedia communication between Internet nodes is the rendezvous problem, or discovering the host at which a given user can be reached. In the Session Initiation Protocol (SIP) [RFC3261], this problem is expressed as the problem of mapping an Address of Record (AoR) for a user into one or more Contact URIs [RFC3986]. The AoR is a name for the user that is independent of the host or hosts where the user can be contacted, while a Contact URI indicates the host where the user can be contacted.
Internet节点之间多媒体通信的一个基本问题是会合问题，即发现可以到达给定用户的主机。在会话发起协议（SIP）[RFC3261]中，此问题表示为将用户的记录地址（AoR）映射到一个或多个联系人URI[RFC3986]的问题。AoR是独立于可以联系用户的主机的用户名称，而联系人URI表示可以联系用户的主机。
In the common SIP-using architectures that we refer to as "Conventional SIP" or "Client/Server SIP", there is a relatively fixed hierarchy of SIP routing proxies and SIP user agents. To deliver a SIP INVITE to the host or hosts at which the user can be contacted, a SIP UA follows the procedures specified in [RFC3263] to determine the IP address of a SIP proxy, and then sends the INVITE to that proxy. The proxy will then, in turn, deliver the SIP INVITE to the hosts where the user can be contacted.
在我们称之为“传统SIP”或“客户机/服务器SIP”的使用普通SIP的体系结构中，存在SIP路由代理和SIP用户代理的相对固定的层次结构。为了将SIP INVITE发送到可以联系用户的一个或多个主机，SIP UA遵循[RFC3263]中指定的过程来确定SIP代理的IP地址，然后将INVITE发送到该代理。然后，代理将依次将SIP INVITE发送到可以联系用户的主机。
This document gives a high-level description of an alternative solution to this problem. In this alternative solution, the relatively fixed hierarchy of Client/Server SIP is replaced by a peer-to-peer overlay network. In this peer-to-peer overlay network, the various mappings of AoRs to Contact URIs are not centralized at proxy/registrar nodes but are instead distributed amongst the peers in the overlay.
本文档对该问题的替代解决方案进行了详细描述。在此替代解决方案中，相对固定的客户机/服务器SIP层次结构被对等覆盖网络所取代。在该对等覆盖网络中，AOR到联系人URI的各种映射不是集中在代理/注册器节点上，而是分布在覆盖中的对等方之间。
The details of this alternative solution are specified by the RELOAD protocol [RFC6940], which defines a mechanism for distribution using a Distributed Hash Table (DHT) and specifies the wire protocol, security, and authentication mechanisms needed to convey this information. This DHT protocol was designed specifically with the purpose of enabling a distributed SIP registrar in mind. While designing the protocol, other applications were considered, and then design decisions were made that allow RELOAD to be used in other instances where a DHT is desirable, but only when such decisions did not add undue complexity to the RELOAD protocol. The RELOAD SIP document [P2PSIP] specifies how RELOAD is used with the SIP protocol to enable a distributed, server-less SIP solution.
此替代解决方案的详细信息由重新加载协议[RFC6940]指定，该协议定义了使用分布式哈希表（DHT）进行分发的机制，并指定了传输此信息所需的有线协议、安全性和身份验证机制。该DHT协议是专门为实现分布式SIP注册而设计的。在设计协议时，考虑了其他应用，然后做出了设计决策，允许在需要DHT的其他情况下使用重新加载，但前提是此类决策不会给重新加载协议增加不必要的复杂性。重新加载SIP文档[P2PSIP]指定如何将重新加载与SIP协议一起使用，以启用分布式、无服务器SIP解决方案。
A Peer-to-Peer SIP (P2PSIP) Overlay is a collection of nodes organized in a peer-to-peer fashion for the purpose of enabling real-time communication using the Session Initiation Protocol (SIP). Collectively, the nodes in the Overlay provide a distributed mechanism for mapping names to Overlay locations. This provides for the mapping of Addresses of Record (AoRs) to Contact URIs, thereby providing the "location server" function of [RFC3261]. An Overlay also provides a transport function by which SIP messages can be transported between any two nodes in the Overlay.
对等SIP（P2PSIP）覆盖是以对等方式组织的节点集合，目的是使用会话发起协议（SIP）实现实时通信。总体而言，覆盖中的节点提供了一种分布式机制，用于将名称映射到覆盖位置。这提供了记录地址（AOR）到联系URI的映射，从而提供了[RFC3261]的“位置服务器”功能。覆盖还提供传输功能，通过该功能，可以在覆盖中的任意两个节点之间传输SIP消息。
A P2PSIP Overlay consists of one or more nodes called "Peers". The nodes in the Overlay collectively run a distributed database algorithm. This distributed database algorithm allows data to be stored on nodes and retrieved in an efficient manner. It may also ensure that a copy of a data item is stored on more than one node, so that the loss of a node does not result in the loss of the data item to the Overlay.
P2PSIP覆盖由一个或多个称为“对等点”的节点组成。覆盖中的节点共同运行分布式数据库算法。这种分布式数据库算法允许数据存储在节点上，并以高效的方式进行检索。它还可以确保数据项的副本存储在多个节点上，以便节点的丢失不会导致覆盖数据项的丢失。
One use of this distributed database is to store the information required to provide the mapping between AoRs and Contact URIs for the distributed location function. This provides a location function within each Overlay that is an alternative to the location functions described in [RFC3263]. However, the model of [RFC3263] is used between Overlays.
该分布式数据库的一个用途是存储为分布式位置功能提供AOR和联系人URI之间映射所需的信息。这在每个覆盖中提供了一个位置函数，它是[RFC3263]中描述的位置函数的替代。但是，重叠之间使用[RFC3263]模型。
The nature of peer-to-peer computing is that each peer offers services to other peers to allow the overlay to collectively provide larger functions. In P2PSIP, Peers offer both distributed storage and distributed message-routing services, allowing these functions to be implemented across the Overlay. Additionally, the RELOAD protocol offers a simplistic discovery mechanism specific to the Traversal Using Relays around NAT (TURN) [RFC5766] protocol used for NAT traversal. Individual Peers may also offer other services as an enhancement to P2PSIP functionality (for example, to support voicemail) or to support other applications beyond SIP. To support these additional services, Peers may need to store additional information in the Overlay. [RFC7374] describes the mechanism used in P2PSIP for resource discovery.
点对点计算的本质是每个点向其他点提供服务，以允许覆盖层共同提供更大的功能。在P2PSIP中，对等点同时提供分布式存储和分布式消息路由服务，允许跨覆盖层实现这些功能。此外，重新加载协议提供了一种简单的发现机制，该机制特定于使用NAT（TURN）[RFC5766]协议（用于NAT遍历）周围的中继进行的遍历。个别对等方还可以提供其他服务作为P2PSIP功能的增强（例如，支持语音邮件）或支持SIP以外的其他应用程序。为了支持这些附加服务，对等方可能需要在覆盖中存储附加信息。[RFC7374]描述了P2PSIP中用于资源发现的机制。
An Overlay may or may not also include one or more nodes called "Clients". Clients are supported in the RELOAD protocol as peers that have not joined the Overlay, and therefore do not route messages
覆盖可能包括也可能不包括一个或多个称为“客户端”的节点。重新加载协议支持客户端作为未加入覆盖的对等方，因此不路由消息
or store information. Clients access the services of the RELOAD protocol by connecting to a Peer that performs operations on the behalf of the Client. Note that in RELOAD, there is no distinct client protocol. Instead, a Client connects using the same protocol, but never joins the Overlay as a Peer. For more information, see [RFC6940].
或者储存信息。客户端通过连接到代表客户端执行操作的对等方来访问重新加载协议的服务。请注意，在重新加载中，没有不同的客户端协议。相反，客户端使用相同的协议进行连接，但从不作为对等方加入覆盖。有关更多信息，请参阅[RFC6940]。
A special Peer may also be a member of the P2PSIP Overlay and may present the functionality of one or all of a SIP registrar, proxy, or redirect server to conventional SIP devices (i.e., unmodified SIP user agent (UA) or client). In this way, existing, unmodified SIP clients may connect to the P2PSIP network. Note that in the context of P2PSIP, the unmodified SIP client is also sometimes referred to as a "client". These unmodified SIP devices do not speak the RELOAD protocol, and this is a distinct concept from the notion of "Client" discussed in the previous paragraph.
特殊对等方也可以是P2PSIP覆盖的成员，并且可以向传统SIP设备（即，未修改的SIP用户代理（UA）或客户端）呈现一个或全部SIP注册器、代理或重定向服务器的功能。通过这种方式，现有的、未修改的SIP客户端可以连接到P2PSIP网络。注意，在P2PSIP的上下文中，未修改的SIP客户端有时也被称为“客户端”。这些未修改的SIP设备不使用重新加载协议，这是一个与上一段中讨论的“客户端”概念不同的概念。
The RELOAD protocol defined by the P2PSIP working group implements a DHT primarily for use by server-less, peer-to-peer SIP deployments. However, the RELOAD protocol could be used for other applications as well. As such, a "P2PSIP" deployment is generally assumed to be a use of RELOAD to implement distributed SIP, but it is possible that RELOAD is used as a mechanism to distribute other applications, completely unrelated to SIP.
P2PSIP工作组定义的重新加载协议实现了DHT，主要用于无服务器的对等SIP部署。但是，重新加载协议也可以用于其他应用程序。因此，“P2PSIP”部署通常被认为是使用重新加载来实现分布式SIP，但重新加载可能被用作分发其他应用程序的机制，与SIP完全无关。
Since P2PSIP is about peer-to-peer networks for real-time communication, it is expected that most Peers and Clients will be coupled with SIP entities (although RELOAD may be used for other applications than P2PSIP). For example, one Peer might be coupled with a SIP UA, another might be coupled with a SIP proxy, while a third might be coupled with a SIP-to-PSTN gateway. For such nodes, the Peer or Client portion of the node is logically distinct from the SIP entity portion. However, there is no hard requirement that every P2PSIP node (Peer or Client) be coupled to a SIP entity. As an example, additional Peers could be placed in the Overlay to provide additional storage or redundancy for the RELOAD Overlay, but might not have any direct SIP capabilities.
由于P2PSIP是用于实时通信的对等网络，因此预计大多数对等网络和客户端将与SIP实体耦合（尽管重新加载可用于P2PSIP以外的其他应用程序）。例如，一个对等方可以与SIP UA耦合，另一个对等方可以与SIP代理耦合，而第三个对等方可以与SIP到PSTN网关耦合。对于这样的节点，节点的对等方或客户端部分在逻辑上不同于SIP实体部分。然而，没有硬性要求每个P2PSIP节点（对等方或客户端）耦合到SIP实体。例如，可以在覆盖中放置额外的对等点，为重新加载覆盖提供额外的存储或冗余，但可能没有任何直接的SIP功能。
As noted above, the fundamental task of P2PSIP is to turn an AoR into a Contact. This task might be approached using zero configuration techniques such as multicast DNS (mDNS) and DNS Service Discovery (DNS-SD) [RFC6762] [RFC6763], Link-Local Multicast Name Resolution [RFC4795], and dynamic DNS [RFC2136].
如上所述，P2PSIP的基本任务是将AoR转变为联系人。可以使用零配置技术（如多播DNS（mDNS）和DNS服务发现（DNS-SD）[RFC6762][RFC6763]、链路本地多播名称解析[RFC4795]和动态DNS[RFC2136]来完成此任务。
These alternatives were discussed in the P2PSIP working group, and not pursued as a general solution for a number of reasons related to scalability, the ability to work in a disconnected state, partition recovery, and so on. However, there does seem to be some continuing interest in the possibility of using mDNS and DNS-SD for the bootstrapping of P2PSIP overlays.
这些替代方案在P2PSIP工作组中进行了讨论，但由于与可伸缩性、在断开连接状态下工作的能力、分区恢复等相关的许多原因，这些替代方案并没有作为一般解决方案进行研究。然而，对于使用MDN和DNS-SD引导P2PSIP覆盖的可能性，似乎有一些持续的兴趣。
Network Address Translators (NATs) are impediments to establishing and maintaining peer-to-peer networks, since NATs hinder direct communication between nodes. Some peer-to-peer network architectures avoid this problem by insisting that all nodes exist in the same address space. However, RELOAD provides capabilities that allow nodes to be located in multiple address spaces interconnected by NATs, to allow RELOAD messages to traverse NATs, and to assist in transmitting application-level messages (for example, SIP messages) across NATs.
网络地址转换器（NAT）是建立和维护对等网络的障碍，因为NAT阻碍节点之间的直接通信。一些对等网络架构通过坚持所有节点都存在于相同的地址空间中来避免这个问题。但是，重新加载提供的功能允许节点位于NAT互连的多个地址空间中，允许重新加载消息遍历NAT，并帮助跨NAT传输应用程序级消息（例如SIP消息）。
The following diagram shows a P2PSIP Overlay consisting of a number of Peers, one Client, and an ordinary SIP UA. It illustrates a typical P2PSIP Overlay but does not limit other compositions or variations; for example, Proxy Peer P might also talk to an ordinary SIP proxy as well. The figure is not intended to cover all possible architecture variations, but simply to show a deployment with many common P2PSIP elements.
下图显示了P2PSIP覆盖，该覆盖由多个对等方、一个客户端和一个普通SIP UA组成。它说明了典型的P2PSIP覆盖层，但不限制其他成分或变化；例如，代理对等点P也可能与普通SIP代理通信。该图并不是为了涵盖所有可能的架构变化，只是为了显示具有许多常见P2PSIP元素的部署。
--->PSTN
+------+ N +------+ +---------+ /
| | A | | | Gateway |-/
| UA |####T#####| UA |#####| Peer |########
| Peer | N | Peer | | G | # RELOAD
| E | A | F | +---------+ # P2PSIP
| | T | | # Protocol
+------+ N +------+ # |
# A # |
NATNATNATNAT # |
# # | \__/
NATNATNATNAT +-------+ v / \
# N | |#####/ UA \
+------+ A P2PSIP Overlay | Peer | /Client\
| | T | Q | |___C__|
| UA | N | |
| Peer | A +-------+
| D | T #
| | N #
+------+ A # RELOAD
# T # P2PSIP
# N +-------+ +-------+ # Protocol
# A | | | | #
#########T####| Proxy |########| Redir |#######
N | Peer | | Peer |
A | P | | R |
T +-------+ +-------+
| /
| SIP /
\__/ / /
/\ / ______________/ SIP
/ \/ /
/ UA \/
/______\
SIP UA A
--->PSTN
+------+ N +------+ +---------+ /
| | A | | | Gateway |-/
| UA |####T#####| UA |#####| Peer |########
| Peer | N | Peer | | G | # RELOAD
| E | A | F | +---------+ # P2PSIP
| | T | | # Protocol
+------+ N +------+ # |
# A # |
NATNATNATNAT # |
# # | \__/
NATNATNATNAT +-------+ v / \
# N | |#####/ UA \
+------+ A P2PSIP Overlay | Peer | /Client\
| | T | Q | |___C__|
| UA | N | |
| Peer | A +-------+
| D | T #
| | N #
+------+ A # RELOAD
# T # P2PSIP
# N +-------+ +-------+ # Protocol
# A | | | | #
#########T####| Proxy |########| Redir |#######
N | Peer | | Peer |
A | P | | R |
T +-------+ +-------+
| /
| SIP /
\__/ / /
/\ / ______________/ SIP
/ \/ /
/ UA \/
/______\
SIP UA A
Figure 1: P2PSIP Overlay Reference Model
图1:P2PSIP覆盖参考模型
Here, the large perimeter depicted by "#" represents a stylized view of the Overlay (the actual connections could be a mesh, a ring, or some other structure). Around the periphery of the Overlay rectangle, we have a number of Peers. Each Peer is labeled with its coupled SIP entity -- for example, "Proxy Peer P" means that Peer P is coupled with a SIP proxy. In some cases, a Peer or Client might be coupled with two or more SIP entities. In this diagram, we have a Public Switched Telephone Network (PSTN) gateway coupled with Peer "G", three Peers ("D", "E", and "F") that are each coupled with a UA, a Peer "P" that is coupled with a SIP proxy, an ordinary Peer "Q"
在这里，用“#”表示的大周长表示覆盖的样式化视图（实际连接可以是网格、环或其他结构）。在覆盖矩形的外围，我们有许多对等点。每个对等点都标有其耦合的SIP实体——例如，“代理对等点P”表示对等点P与SIP代理耦合。在某些情况下，对等方或客户端可能与两个或多个SIP实体耦合。在该图中，我们有一个公共交换电话网（PSTN）网关与对等方“G”耦合，三个对等方（“D”、“E”和“F”）各自与UA耦合，一个对等方“P”与SIP代理耦合，一个普通对等方“Q”
with no SIP capabilities, and one Peer "R" that is coupled with a SIP redirector. Note that because these are all Peers, each is responsible for storing Resource Records and transporting messages around the Overlay.
没有SIP功能，一个对等“R”与SIP重定向器耦合。请注意，因为这些都是对等的，所以每个都负责存储资源记录并在覆盖中传输消息。
To the left, two of the Peers ("D" and "E") are behind network address translators (NATs). These Peers are included in the P2PSIP Overlay, and thus participate in storing resource records and routing messages, despite being behind the NATs.
在左边，两个对等点（“D”和“E”）位于网络地址转换器（NAT）后面。这些对等点包含在P2PSIP覆盖中，因此参与存储资源记录和路由消息，尽管它们位于NAT后面。
On the right side, we have a Client "C", which uses the RELOAD Protocol to communicate with Proxy Peer "Q". The Client "C" uses RELOAD to obtain information from the Overlay, but has not inserted itself into the Overlay, and therefore does not participate in routing messages or storing information.
在右侧，我们有一个客户端“C”，它使用重新加载协议与代理对等方“Q”通信。客户端“C”使用重载从覆盖中获取信息，但尚未将自身插入覆盖中，因此不参与路由消息或存储信息。
Below the Overlay, we have a conventional SIP UA "A" that is not part of the Overlay, either directly as a Peer or indirectly as a Client. It does not speak the RELOAD P2PSIP protocol and is not participating in the Overlay as a Peer or a Client. Instead, it uses SIP to interact with the Overlay via an adapter Peer or Peers that communicate with the Overlay using RELOAD.
在覆盖层下面，我们有一个传统的SIP-UA“a”，它不是覆盖层的一部分，直接作为对等方或间接作为客户端。它不使用重新加载P2PSIP协议，也不作为对等方或客户端参与覆盖。相反，它使用SIP通过一个或多个适配器对等点与覆盖层交互，这些对等点使用重载与覆盖层通信。
Both the SIP proxy coupled with Peer "P" and the SIP redirector coupled with Peer "R" can serve as adapters between ordinary SIP devices and the Overlay. Each accepts standard SIP requests and resolves the next hop by using the P2PSIP protocol to interact with the routing knowledge of the Overlay, and then processes the SIP requests as appropriate (proxying or redirecting towards the next hop). Note that proxy operation is bidirectional -- the proxy may be forwarding a request from an ordinary SIP device to the Overlay, or from the P2PSIP Overlay to an ordinary SIP device.
与对等方“P”耦合的SIP代理和与对等方“R”耦合的SIP重定向器都可以用作普通SIP设备和覆盖之间的适配器。每个都接受标准SIP请求，并通过使用P2PSIP协议与覆盖的路由知识交互来解析下一跳，然后根据需要处理SIP请求（代理或重定向到下一跳）。注意，代理操作是双向的——代理可以将请求从普通SIP设备转发到覆盖，或者从P2PSIP覆盖转发到普通SIP设备。
The PSTN Gateway at Peer "G" provides a similar sort of adaptation to and from the PSTN.
对等点“G”处的PSTN网关提供了与PSTN之间类似的适配。
This section defines a number of concepts that are key to understanding the P2PSIP work.
本节定义了理解P2PSIP工作的关键概念。
Overlay Network: An overlay network is a computer network that is built on top of another network. Nodes in the overlay can be thought of as being connected by virtual or logical links, each of which corresponds to a path, perhaps through many physical links, in the underlying network. For example, many peer-to-peer
覆盖网络：覆盖网络是建立在另一个网络之上的计算机网络。覆盖中的节点可以被认为是通过虚拟或逻辑链路连接的，每个虚拟或逻辑链路对应于底层网络中的一条路径，可能通过许多物理链路。例如，许多对等网络
networks are overlay networks because they run on top of the Internet. Dial-up Internet is an overlay upon the telephone network.
网络是覆盖网络，因为它们运行在互联网之上。拨号上网是覆盖在电话网络上的。
P2P Network: A peer-to-peer (or P2P) computer network is a network that relies primarily on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers. P2P networks are typically used for connecting nodes via largely ad hoc connections. Such networks are useful for many purposes. Sharing content files containing audio, video, data, or anything in digital format is very common, and real-time data, such as telephony traffic, is also exchanged using P2P technology. A P2P Network may also be called a "P2P Overlay", a "P2P Overlay Network", or a "P2P Network Overlay", since its organization is not at the physical layer, but is instead "on top of" an existing Internet Protocol network.
P2P网络：点对点（或P2P）计算机网络主要依赖于网络参与者的计算能力和带宽，而不是集中在数量相对较少的服务器上。P2P网络通常用于通过主要的自组织连接来连接节点。这种网络有许多用途。共享包含音频、视频、数据或任何数字格式的内容文件非常常见，而且实时数据（如电话流量）也使用P2P技术进行交换。P2P网络也可以被称为“P2P覆盖”、“P2P覆盖网络”或“P2P网络覆盖”，因为其组织不在物理层，而是在现有因特网协议网络的“顶部”。
P2PSIP: A suite of communications protocols related to the Session Initiation Protocol (SIP) [RFC3261] that enable SIP to use peer-to-peer techniques for resolving the targets of SIP requests, providing SIP message transport, and providing other SIP-related functions. At present, these protocols include [RFC6940], [RFC7363], [RFC7374], [RFC7851] and [P2PSIP].
P2PSIP：与会话启动协议（SIP）[RFC3261]相关的一套通信协议，使SIP能够使用对等技术来解析SIP请求的目标，提供SIP消息传输，并提供其他与SIP相关的功能。目前，这些协议包括[RFC6940]、[RFC7363]、[RFC7374]、[RFC7851]和[P2PSIP]。
User: A human that interacts with the Overlay through SIP UAs located on Peers and Clients (and perhaps in other ways).
用户：通过位于对等方和客户机上的SIP UAs与覆盖交互的人（可能以其他方式）。
The following terms are defined here only within the scope of P2PSIP. These terms may have conflicting definitions in other bodies of literature. Some draft versions of this document prefixed each term with "P2PSIP" to clarify the term's scope. This prefixing has been eliminated from the text; however, the scoping still applies.
以下术语仅在P2PSIP范围内定义。这些术语在其他文献中可能有相互冲突的定义。本文件的一些草案版本在每个术语前加上“P2PSIP”以澄清术语的范围。此前缀已从文本中删除；然而，范围界定仍然适用。
Overlay Name: A human-friendly name that identifies a specific P2PSIP Overlay. This is in the format of (a portion of) a URI, but may or may not have a related record in the DNS.
覆盖名称：标识特定P2PSIP覆盖的人性化名称。这是URI（部分）的格式，但DNS中可能有也可能没有相关记录。
Peer: A node participating in a P2PSIP Overlay that provides storage and transport services to other nodes in that P2PSIP Overlay. Each Peer has a unique identifier, known as a Peer-ID, within the Overlay. Each Peer may be coupled to one or more SIP entities. Within the Overlay, the Peer is capable of performing several different operations, including: joining and leaving the Overlay, transporting SIP messages within the Overlay, storing information on behalf of the Overlay, putting information into the Overlay, and getting information from the Overlay.
对等：参与P2PSIP覆盖的节点，该覆盖向该P2PSIP覆盖中的其他节点提供存储和传输服务。每个对等体在覆盖中都有一个唯一的标识符，称为对等体ID。每个对等方可以耦合到一个或多个SIP实体。在覆盖内，对等方能够执行若干不同的操作，包括：加入和离开覆盖、在覆盖内传输SIP消息、代表覆盖存储信息、将信息放入覆盖以及从覆盖获取信息。
Node-ID: Information that uniquely identifies each Node within a given Overlay. This value is not human-friendly -- in a DHT approach, this is a numeric value in the hash space. These Node-IDs are completely independent of the identifier of any user of a user agent associated with a Peer.
节点ID：唯一标识给定覆盖内每个节点的信息。这个值对人不友好——在DHT方法中，它是散列空间中的一个数值。这些节点ID完全独立于与对等方关联的用户代理的任何用户的标识符。
Client: A node that participates in a P2PSIP Overlay but does not store information or forward messages. A Client can also be thought of as a peer that has not joined the Overlay. Clients can store and retrieve information from the Overlay.
客户端：参与P2PSIP覆盖但不存储信息或转发消息的节点。客户机也可以被视为未加入覆盖的对等机。客户端可以从覆盖中存储和检索信息。
User Name: A human-friendly name for a user. This name must be unique within the Overlay, but may be unique in a wider scope. User Names are formatted so that they can be used within a URI (likely a SIP URI), perhaps in combination with the Overlay Name.
用户名：用户的友好名称。此名称在覆盖中必须是唯一的，但在更大范围内可能是唯一的。用户名被格式化，以便可以在URI（可能是SIPURI）中使用，可能与覆盖名称结合使用。
Service: A capability contributed by a Peer to an Overlay or to the members of an Overlay. Not all Peers and Clients will offer the same set of services, and P2PSIP provides service discovery mechanisms to locate services.
服务：由对等方提供给覆盖层或覆盖层成员的功能。并非所有对等方和客户端都将提供相同的服务集，P2PSIP提供服务发现机制来定位服务。
Service Name: A unique, human-friendly name for a service.
服务名称：服务的唯一、人性化的名称。
Resource: Anything about which information can be stored in the Overlay. Both Users and Services are examples of Resources.
资源：任何可以存储在覆盖中的信息。用户和服务都是资源的例子。
Resource-ID: A non-human-friendly value that uniquely identifies a resource and that is used as a key for storing and retrieving data about the resource. One way to generate a Resource-ID is by applying a mapping function to some other unique name (e.g., User Name or Service Name) for the resource. The Resource-ID is used by the distributed database algorithm to determine the Peer or Peers that are responsible for storing data for the Overlay.
资源ID：一个非人性化的值，唯一标识资源，并用作存储和检索资源数据的键。生成资源ID的一种方法是将映射函数应用于资源的其他唯一名称（例如，用户名或服务名）。分布式数据库算法使用资源ID来确定负责存储覆盖数据的对等点。
Resource Record: A block of data, stored using the distributed database mechanism of the Overlay, that includes information relevant to a specific resource. We presume that there may be multiple types of resource records. Some may hold data about Users, and others may hold data about Services, and the working group may define other types. The types, usages, and formats of the records are a question for future study.
资源记录：使用覆盖的分布式数据库机制存储的数据块，包括与特定资源相关的信息。我们假定可能有多种类型的资源记录。有些可能保存关于用户的数据，有些可能保存关于服务的数据，工作组可能定义其他类型。记录的类型、用途和格式是未来研究的问题。
Responsible Peer The Peer that is responsible for storing the Resource Record for a Resource. In the literature, the term "Root Peer" is also used for this concept.
负责对等方负责存储资源记录的对等方。在文献中，“根节点”一词也用于此概念。
Peer Protocol: The protocol spoken between P2PSIP Overlay Peers to share information and organize the P2PSIP Overlay Network. In P2PSIP, this is implemented using the RELOAD protocol [RFC6940].
对等协议：P2PSIP覆盖对等方之间的协议，用于共享信息和组织P2PSIP覆盖网络。在P2PSIP中，这是使用重新加载协议[RFC6940]实现的。
Client Protocol: The protocol spoken between Clients and Peers. In P2PSIP and RELOAD, this is syntactically the same protocol as the Peer Protocol. The only difference is that Clients are not routing messages or routing information, and have not (or cannot) insert themselves into the Overlay.
客户端协议：客户端和对等方之间的协议。在P2PSIP和RELOAD中，这在语法上与对等协议相同。唯一的区别是客户端没有路由消息或路由信息，并且没有（或不能）将自己插入到覆盖中。
Peer Protocol Connection / P2PSIP Client Protocol Connection: The Transport Layer Security (TLS), Datagram Transport Layer Security (DTLS), TCP, UDP, or other transport-layer protocol connection over which the RELOAD Peer Protocol messages are transported.
对等协议连接/P2PSIP客户端协议连接：传输层安全性（TLS）、数据报传输层安全性（DTLS）、TCP、UDP或其他传输层协议连接，通过这些连接传输重新加载对等协议消息。
Neighbors: The set of P2PSIP Peers that a Peer or Client know of directly and can reach without further lookups.
邻居：对等方或客户端直接知道的P2PSIP对等方的集合，无需进一步查找即可访问。
Joining Peer: A node that is attempting to become a Peer in a particular Overlay.
加入对等节点：试图成为特定覆盖中的对等节点的节点。
Bootstrap Peer: A Peer in the Overlay that is the first point of contact for a Joining Peer. It selects the Peer that will serve as the Admitting Peer and helps the Joining Peer contact the Admitting Peer.
引导对等点：覆盖中的对等点，是加入对等点的第一个接触点。它选择将作为接纳对等方的对等方，并帮助加入对等方联系接纳对等方。
Admitting Peer: A Peer in the Overlay that helps the Joining Peer join the Overlay. The choice of the Admitting Peer may depend on the Joining Peer (e.g., depend on the Joining Peer's Peer-ID). For example, the Admitting Peer might be chosen as the Peer which is "closest" in the logical structure of the Overlay to the future position of the Joining Peer. The selection of the Admitting Peer is typically done by the Bootstrap Peer. It is allowable for the Bootstrap Peer to select itself as the Admitting Peer.
接纳对等方：覆盖层中帮助加入的对等方加入覆盖层的对等方。接纳对等方的选择可能取决于加入对等方（例如，取决于加入对等方的对等ID）。例如，可以选择接纳对等方作为覆盖逻辑结构中与加入对等方的未来位置“最近”的对等方。接纳对等方的选择通常由引导对等方完成。引导对等机可以选择自己作为接纳对等机。
Bootstrap Server: A network node used by Joining Peers to locate a Bootstrap Peer. A Bootstrap Server may act as a proxy for messages between the Joining Peer and the Bootstrap Peer. The Bootstrap Server itself is typically a stable host with a DNS name that is somehow communicated (for example, through configuration, specification on a web page, or using DHCP) to Peers that want to join the Overlay. A Bootstrap Server is NOT required to be a Peer or Client, though it may be if desired.
引导服务器：一个网络节点，用于连接对等点以定位引导对等点。引导服务器可以充当加入对等机和引导对等机之间消息的代理。引导服务器本身通常是一个稳定的主机，其DNS名称以某种方式（例如，通过配置、网页上的规范或使用DHCP）传递给希望加入覆盖的对等方。引导服务器不必是对等服务器或客户机，但如果需要，也可以是对等服务器或客户机。
Peer Admission: The act of admitting a node (the "Joining Peer") into an Overlay as a Peer. After the admission process is over, the Joining Peer is a fully functional Peer of the Overlay. During the admission process, the Joining Peer may need to present credentials to prove that it has sufficient authority to join the Overlay.
对等接纳：将节点（“加入对等方”）作为对等方接纳到覆盖中的行为。在接纳过程结束后，加入的对等方是覆盖的全功能对等方。在接纳过程中，加入的对等方可能需要出示凭证以证明其有足够的权限加入覆盖。
Resource Record Insertion: The act of inserting a P2PSIP Resource Record into the distributed database. Following insertion, the data will be stored at one or more Peers. The data can be retrieved or updated using the Resource-ID as a key.
资源记录插入：将P2PSIP资源记录插入分布式数据库的行为。插入后，数据将存储在一个或多个对等点上。可以使用资源ID作为密钥检索或更新数据。
A P2PSIP Overlay functions as a distributed database. The database serves as a way to store information about Resources. A piece of information, called a "Resource Record", can be stored by and retrieved from the database using a key associated with the Resource Record called its "Resource-ID". Each Resource must have a unique Resource-ID. In addition to uniquely identifying the Resource, the Resource-ID is also used by the distributed database algorithm to determine the Peer or Peers that store the Resource Record in the Overlay.
P2PSIP覆盖层用作分布式数据库。数据库是存储资源信息的一种方式。一段称为“资源记录”的信息可以由数据库存储，也可以使用与称为“资源ID”的资源记录相关联的键从数据库中检索。每个资源必须具有唯一的Resource-ID。除了唯一标识资源外，分布式数据库算法还使用资源ID来确定覆盖中存储资源记录的对等点。
Users are humans that can use the Overlay to do things like making and receiving calls. Information stored in the resource record associated with a user can include things like the full name of the user and the location of the UAs that the user is using (the user's SIP AoR). Full details of how this is implemented using RELOAD are provided in [P2PSIP].
用户是人类，可以使用覆盖来做一些事情，如拨打和接听电话。存储在与用户关联的资源记录中的信息可以包括诸如用户的全名和用户正在使用的UAs的位置（用户的SIP AoR）之类的内容。[P2PSIP]中提供了如何使用重新加载实现此功能的完整详细信息。
Before information about a user can be stored in the Overlay, a user needs a User Name. The User Name is a human-friendly identifier that uniquely identifies the user within the Overlay. In RELOAD, users are issued certificates, which in the case of centrally signed certificates, identify the User Name as well as a certain number of Resource-IDs where the user may store their information. For more information, see [RFC6940].
在覆盖中存储有关用户的信息之前，用户需要用户名。用户名是一个人性化的标识符，可在覆盖中唯一标识用户。在RELOAD中，向用户颁发证书，在集中签名证书的情况下，证书标识用户名以及用户可以存储其信息的一定数量的资源ID。有关更多信息，请参阅[RFC6940]。
The P2PSIP suite of protocols also standardizes information about how to locate services. Services represent actions that a Peer (and perhaps a Client) can do to benefit other Peers and Clients in the Overlay. Information that might be stored in the resource record associated with a service might include the Peers (and perhaps Clients) offering the service. Service discovery for P2PSIP is defined in [RFC7374].
P2PSIP协议套件还标准化了有关如何定位服务的信息。服务表示对等方（可能还有客户机）可以执行的操作，以使覆盖中的其他对等方和客户机受益。可能存储在与服务关联的资源记录中的信息可能包括提供服务的对等方（可能还有客户端）。[RFC7374]中定义了P2PSIP的服务发现。
Each service has a human-friendly Service Name that uniquely identifies the service. Like User Names, the Service Name is not a Resource-ID, rather the Resource-ID is derived from the service name using some function defined by the distributed database algorithm used by the Overlay.
每个服务都有一个人性化的服务名称，唯一地标识该服务。与用户名一样，服务名称不是资源ID，而是使用覆盖使用的分布式数据库算法定义的某个函数从服务名称派生的资源ID。
A class of algorithms known as Distributed Hash Tables (DHTs) are one way to implement the distributed database. The RELOAD protocol is extensible and allows many different DHTs to be implemented, but specifies a mandatory-to-implement DHT in the form of a modified Chord DHT. For more information, see [Chord].
一类称为分布式哈希表（DHT）的算法是实现分布式数据库的一种方法。RELOAD协议是可扩展的，允许实现许多不同的DHT，但指定了以修改的Chord DHT形式实现DHT的强制命令。有关详细信息，请参见[Chord]。
While there are a number of ways the distributed database described in the previous section can be used to establish multimedia sessions using SIP, the basic mechanism defined in the RELOAD protocol and SIP usage is summarized below. This is a very simplistic overview. For more detailed information, please see the RELOAD protocol [RFC6940].
虽然有许多方法可以使用上一节中描述的分布式数据库使用SIP建立多媒体会话，但下面总结了重新加载协议和SIP使用中定义的基本机制。这是一个非常简单的概述。有关更多详细信息，请参阅重新加载协议[RFC6940]。
Contact information for a user is stored in the resource record for that user. Assume that a user is using a device, here called "Peer A", that serves as the contact point for this user. The user adds contact information to this resource record, as authorized by the RELOAD certificate mechanism. The resource record itself is stored with Peer Z in the network, where Peer Z is chosen by the particular distributed database algorithm in use by the Overlay.
用户的联系信息存储在该用户的资源记录中。假设用户正在使用一个称为“对等a”的设备，该设备充当该用户的联络点。根据重新加载证书机制的授权，用户将联系人信息添加到此资源记录中。资源记录本身与对等点Z一起存储在网络中，其中对等点Z由覆盖使用的特定分布式数据库算法选择。
When the SIP entity coupled with Peer B has an INVITE message addressed to this user, it retrieves the resource record from Peer Z. It then extracts the contact information for the various Peers that are a contact point for the user, including Peer A, and uses the Overlay to establish a connection to Peer A, including any appropriate NAT traversal (the details of which are not shown).
当与对等方B耦合的SIP实体有一条发送给该用户的INVITE消息时，它从对等方Z检索资源记录。然后，它提取作为用户联系点的各个对等方（包括对等方a）的联系信息，并使用覆盖建立到对等方a的连接，包括任何适当的NAT遍历（未显示详细信息）。
Note that RELOAD is used only to establish the connection. Once the connection is established, messages between the Peers are sent using ordinary SIP.
请注意，重新加载仅用于建立连接。一旦建立了连接，对等方之间的消息将使用普通SIP发送。
This exchange is illustrated in the following figure. The notation "Store(U@A)" is used to show the distributed database operation of updating the resource record for user U with the contract A, and "Fetch(U)" illustrates the distributed database operation of retrieving the resource record for user U. Note that the messages between the Peers A, B, and Z may actually travel via intermediate Peers (not shown) as part of the distributed lookup process or so as to traverse intervening NATs.
下图说明了这种交换。符号“存储”(U@A)“用于显示使用契约A更新用户U的资源记录的分布式数据库操作，“Fetch（U）”说明了检索用户U的资源记录的分布式数据库操作。请注意，对等点A、B、B之间的消息，并且Z实际上可以作为分布式查找过程的一部分经由中间对等方（未示出）移动，或者以便遍历介入的nat。
Peer B Peer Z Peer A
| | |
| | Store(U@A)|
| |<------------------|
| |Store-Resp(OK) |
| |------------------>|
| | |
|Fetch(U) | |
|------------------->| |
| Fetch-Resp(U@A)| |
|<-------------------| |
| | |
(RELOAD IS USED TO ESTABLISH CONNECTION)
| | |
| SIP INVITE(To:U) | |
|--------------------------------------->|
| | |
Peer B Peer Z Peer A
| | |
| | Store(U@A)|
| |<------------------|
| |Store-Resp(OK) |
| |------------------>|
| | |
|Fetch(U) | |
|------------------->| |
| Fetch-Resp(U@A)| |
|<-------------------| |
| | |
(RELOAD IS USED TO ESTABLISH CONNECTION)
| | |
| SIP INVITE(To:U) | |
|--------------------------------------->|
| | |
Figure 2: SIP Exchange Using Distributed Database Function
图2：使用分布式数据库功能的SIP交换
NAT traversal in P2PSIP using RELOAD treats all Peers as equal and establishes a partial mesh of connections between them. Messages from one Peer to another are routed along the edges in the mesh of connections until they reach their destination. To make the routing efficient and to avoid the use of standard Internet routing protocols, the partial mesh is organized in a structured manner. If the structure is based on any one of a number of common DHT algorithms, then the maximum number of hops between any two Peers is log N, where N is the number of peers in the overlay. Existing connections, along with the Interactive Connectivity Establishment (ICE) NAT traversal techniques [RFC5245], are used to establish new connections between Peers, and also to allow the applications running on Peers to establish a connection to communicate with one another.
P2PSIP中使用RELOAD的NAT遍历将所有对等方视为相等，并在它们之间建立连接的部分网格。从一个对等点到另一个对等点的消息沿着连接网格中的边缘路由，直到到达目的地。为了提高路由效率并避免使用标准的Internet路由协议，以结构化的方式组织部分网格。如果该结构基于多个常见DHT算法中的任意一个，则任意两个对等点之间的最大跳数为logn，其中N是覆盖中的对等点数。现有连接以及交互式连接建立（ICE）NAT穿越技术[RFC5245]用于在对等点之间建立新连接，并且还允许在对等点上运行的应用程序建立连接以相互通信。
Before a Peer can attempt to join a P2PSIP Overlay, it must first obtain a Node-ID, configuration information, and optionally a set of credentials. The Node-ID is an identifier that uniquely identifies the Peer within the Overlay, while the credentials show that the Peer is allowed to join the Overlay.
对等方在尝试加入P2PSIP覆盖之前，必须首先获取节点ID、配置信息和一组凭据（可选）。节点ID是唯一标识覆盖内对等方的标识符，而凭据显示允许对等方加入覆盖。
The P2PSIP WG does not impose a particular mechanism for how the Peer-ID and the credentials are obtained, but the RELOAD protocol does specify the format for the configuration information and how this information may be obtained, along with credentials and a Node-ID, from an offline enrollment server.
P2PSIP WG没有对如何获取对等ID和凭据施加特定机制，但重新加载协议确实指定了配置信息的格式，以及如何从脱机注册服务器获取该信息以及凭据和节点ID。
Once the configuration information is obtained, RELOAD specifies a mechanism whereby a Peer may obtain a multicast-bootstrap address in the configuration file and broadcast to this address to attempt locating a Bootstrap Peer. Additionally, the Peer may store previous Peers it has seen and attempt using these as Bootstrap Peers, or it may obtain an address for a Bootstrap Peer by some other mechanism. For more information, see the RELOAD protocol.
一旦获得了配置信息，RELOAD指定了一种机制，通过该机制，对等方可以获得配置文件中的多播引导地址，并广播到此地址以尝试定位引导对等方。此外，对等方可以存储它所看到的先前对等方并尝试将其用作引导对等方，或者它可以通过某种其他机制获得引导对等方的地址。有关详细信息，请参见重新加载协议。
The job of the Bootstrap Peer is simple: refer the Joining Peer to a Peer (called the "Admitting Peer") that will help the Joining Peer join the network. The choice of the Admitting Peer will often depend on the Joining Peer -- for example, the Admitting Peer may be a Peer that will become a neighbor of the Joining Peer in the Overlay. It is possible that the Bootstrap Peer might also serve as the Admitting Peer.
引导对等机的工作很简单：将加入对等机交给一个将帮助加入对等机加入网络的对等机（称为“接纳对等机”）。接纳对等方的选择通常取决于加入对等方——例如，接纳对等方可能是将成为覆盖中加入对等方的邻居的对等方。引导对等机也可能充当接纳对等机。
The Admitting Peer will help the Joining Peer learn about other Peers in the Overlay and establish connections to them as appropriate. The Admitting Peer and/or the other Peers in the Overlay will also do whatever else is required to help the Joining Peer become a fully functional Peer. The details of how this is done will depend on the distributed database algorithm used by the Overlay.
接纳的对等方将帮助加入的对等方了解覆盖中的其他对等方，并在适当时建立与它们的连接。允许加入的对等方和/或覆盖中的其他对等方也将做任何其他需要的事情，以帮助加入的对等方成为功能齐全的对等方。如何做到这一点的细节将取决于覆盖所使用的分布式数据库算法。
At various stages in this process, the Joining Peer may be asked to present its credentials to show that it is authorized to join the Overlay. Similarly, the various Peers contacted may be asked to present their credentials so the Joining Peer can verify that it is really joining the Overlay it wants to.
在该过程的不同阶段，加入的对等方可能被要求出示其凭证，以表明其有权加入覆盖。类似地，可能会要求联系的各个对等方提供其凭据，以便加入的对等方可以验证它是否真的加入了它想要加入的覆盖。
As mentioned above, in RELOAD, from the perspective of the protocol, Clients are simply peers that do not store information, do not route messages, and have not inserted themselves into the Overlay. The same protocol is used for the actual message exchanged. Note that while the protocol is the same, the Client need not implement all the capabilities of a Peer. If, for example, it never routes messages, it will not need to be capable of processing such messages or understanding a DHT.
如上所述，在重新加载中，从协议的角度来看，客户端只是不存储信息、不路由消息并且没有将自己插入覆盖的对等方。实际交换的消息使用相同的协议。注意，虽然协议是相同的，但客户机不需要实现对等机的所有功能。例如，如果它从不路由消息，则不需要能够处理此类消息或理解DHT。
For SIP devices, another way to realize this functionality is for a Peer to behave as a proxy/registrar as specified in [RFC3261]. SIP devices then use standard SIP mechanisms to add, update, and remove registrations and to send SIP messages to Peers and other Clients. The authors here refer to these devices simply as a "SIP UA", not a "P2PSIP Client", to distinguish it from the concept described above.
对于SIP设备，实现此功能的另一种方法是对等方充当[RFC3261]中指定的代理/注册器。然后，SIP设备使用标准SIP机制添加、更新和删除注册，并向对等方和其他客户端发送SIP消息。本文作者将这些设备简单地称为“SIP UA”，而不是“P2PSIP客户端”，以区别于上述概念。
The architecture adopted by RELOAD to implement P2PSIP is shown below. An application (for example, SIP or another application using RELOAD) uses RELOAD to locate other Peers and (optionally) to establish connections to those Peers, potentially across NATs. Messages may still be exchanged directly between the Peers. The overall block diagram for the architecture is as follows:
RELOAD实现P2PSIP所采用的体系结构如下所示。应用程序（例如，SIP或使用重新加载的另一个应用程序）使用重新加载来定位其他对等方，并（可选地）建立到这些对等方的连接，可能跨越NAT。消息仍然可以在对等方之间直接交换。架构的总体框图如下所示：
__________________________
| |
| SIP, other apps... |
| ___________________|
| | RELOAD Layer |
|______|___________________|
| Transport Layer |
|__________________________|
__________________________
| |
| SIP, other apps... |
| ___________________|
| | RELOAD Layer |
|______|___________________|
| Transport Layer |
|__________________________|
Figure 3: Architecture for Implementing P2PSIP
图3：实现P2PSIP的体系结构
This specification is an overview of existing specifications and does not introduce any security considerations on its own. Please refer to the security considerations of the respective specifications, particularly the RELOAD protocol specification ([RFC6940]) for further details.
本规范是对现有规范的概述，不单独介绍任何安全注意事项。请参考各个规范的安全注意事项，特别是重新加载协议规范（[RFC6940]），以了解更多详细信息。
[Chord] Stoica, I., Morris, R., Liben-Nowell, D., Karger, D., Kaashoek, M., Dabek, F., and H. Balakrishnan, "Chord: A scalable peer-to-peer lookup protocol for internet applications", IEEE/ACM Transactions on Networking, Volume 11, Issue 1, pp. 17-32, DOI 10.1109/TNET.2002.808407, February 2003.
[Chord]Stoica，I.，Morris，R.，Liben Nowell，D.，Karger，D.，Kaashoek，M.，Dabek，F.，和H.Balakrishnan，“Chord：互联网应用的可扩展对等查找协议”，IEEE/ACM网络交易，第11卷，第1期，第17-32页，DOI 10.1109/TNET.2002.808407，2003年2月。
[P2PSIP] Jennings, C., Lowekamp, B., Rescorla, E., Baset, S., Schulzrinne, H., and T. Schmidt, "A SIP Usage for RELOAD", Work in Progress, draft-ietf-p2psip-sip-21, April 2016.
[P2PSIP]Jennings，C.，Lowekamp，B.，Rescorla，E.，Baset，S.，Schulzrinne，H.，和T.Schmidt，“重新加载的SIP使用”，在建工程，草案-ietf-P2PSIP-SIP-212016年4月。
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound, "Dynamic Updates in the Domain Name System (DNS UPDATE)", RFC 2136, DOI 10.17487/RFC2136, April 1997, <http://www.rfc-editor.org/info/rfc2136>.
[RFC2136]Vixie，P.，Ed.，Thomson，S.，Rekhter，Y.，和J.Bound，“域名系统中的动态更新（DNS更新）”，RFC 2136，DOI 10.17487/RFC2136，1997年4月<http://www.rfc-editor.org/info/rfc2136>.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, DOI 10.17487/RFC3261, June 2002, <http://www.rfc-editor.org/info/rfc3261>.
[RFC3261]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，DOI 10.17487/RFC3261，2002年6月<http://www.rfc-editor.org/info/rfc3261>.
[RFC3263] Rosenberg, J. and H. Schulzrinne, "Session Initiation Protocol (SIP): Locating SIP Servers", RFC 3263, DOI 10.17487/RFC3263, June 2002, <http://www.rfc-editor.org/info/rfc3263>.
[RFC3263]Rosenberg，J.和H.Schulzrinne，“会话启动协议（SIP）：定位SIP服务器”，RFC 3263，DOI 10.17487/RFC3263，2002年6月<http://www.rfc-editor.org/info/rfc3263>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, January 2005, <http://www.rfc-editor.org/info/rfc3986>.
[RFC3986]Berners Lee，T.，Fielding，R.，和L.Masinter，“统一资源标识符（URI）：通用语法”，STD 66，RFC 3986，DOI 10.17487/RFC3986，2005年1月<http://www.rfc-editor.org/info/rfc3986>.
[RFC4795] Aboba, B., Thaler, D., and L. Esibov, "Link-local Multicast Name Resolution (LLMNR)", RFC 4795, DOI 10.17487/RFC4795, January 2007, <http://www.rfc-editor.org/info/rfc4795>.
[RFC4795]Aboba，B.，Thaler，D.，和L.Esibov，“链路本地多播名称解析（LLMNR）”，RFC 4795，DOI 10.17487/RFC4795，2007年1月<http://www.rfc-editor.org/info/rfc4795>.
[RFC5245] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Protocol for Network Address Translator (NAT) Traversal for Offer/Answer Protocols", RFC 5245, DOI 10.17487/RFC5245, April 2010, <http://www.rfc-editor.org/info/rfc5245>.
[RFC5245]Rosenberg，J.，“交互式连接建立（ICE）：提供/应答协议的网络地址转换器（NAT）遍历协议”，RFC 5245，DOI 10.17487/RFC5245，2010年4月<http://www.rfc-editor.org/info/rfc5245>.
[RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using Relays around NAT (TURN): Relay Extensions to Session Traversal Utilities for NAT (STUN)", RFC 5766, DOI 10.17487/RFC5766, April 2010, <http://www.rfc-editor.org/info/rfc5766>.
[RFC5766]Mahy，R.，Matthews，P.，和J.Rosenberg，“使用NAT周围的中继进行遍历（TURN）：NAT（STUN）会话遍历实用程序的中继扩展”，RFC 5766，DOI 10.17487/RFC5766，2010年4月<http://www.rfc-editor.org/info/rfc5766>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, DOI 10.17487/RFC6762, February 2013, <http://www.rfc-editor.org/info/rfc6762>.
[RFC6762]Cheshire，S.和M.Krochmal，“多播DNS”，RFC 6762，DOI 10.17487/RFC6762，2013年2月<http://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013, <http://www.rfc-editor.org/info/rfc6763>.
[RFC6763]Cheshire，S.和M.Krocmal，“基于DNS的服务发现”，RFC 6763，DOI 10.17487/RFC6763，2013年2月<http://www.rfc-editor.org/info/rfc6763>.
[RFC6940] Jennings, C., Lowekamp, B., Ed., Rescorla, E., Baset, S., and H. Schulzrinne, "REsource LOcation And Discovery (RELOAD) Base Protocol", RFC 6940, DOI 10.17487/RFC6940, January 2014, <http://www.rfc-editor.org/info/rfc6940>.
[RFC6940]Jennings，C.，Lowekamp，B.，Ed.，Rescorla，E.，Baset，S.，和H.Schulzrinne，“资源定位和发现（重新加载）基础协议”，RFC 6940，DOI 10.17487/RFC6940，2014年1月<http://www.rfc-editor.org/info/rfc6940>.
[RFC7363] Maenpaa, J. and G. Camarillo, "Self-Tuning Distributed Hash Table (DHT) for REsource LOcation And Discovery (RELOAD)", RFC 7363, DOI 10.17487/RFC7363, September 2014, <http://www.rfc-editor.org/info/rfc7363>.
[RFC7363]Maenpaa，J.和G.Camarillo，“用于资源定位和发现（重新加载）的自调优分布式哈希表（DHT）”，RFC 7363，DOI 10.17487/RFC7363，2014年9月<http://www.rfc-editor.org/info/rfc7363>.
[RFC7374] Maenpaa, J. and G. Camarillo, "Service Discovery Usage for REsource LOcation And Discovery (RELOAD)", RFC 7374, DOI 10.17487/RFC7374, October 2014, <http://www.rfc-editor.org/info/rfc7374>.
[RFC7374]Maenpaa，J.和G.Camarillo，“资源定位和发现（重新加载）的服务发现使用”，RFC 7374，DOI 10.17487/RFC7374，2014年10月<http://www.rfc-editor.org/info/rfc7374>.
[RFC7851] Song, H., Jiang, X., Even, R., Bryan, D., and Y. Sun, "Peer-to-Peer (P2P) Overlay Diagnostics", RFC 7851, DOI 10.17487/RFC7851, May 2016, <http://www.rfc-editor.org/info/rfc7851>.
[RFC7851]Song，H.，Jiang，X.，Even，R.，Bryan，D.，和Y.Sun，“点对点（P2P）覆盖诊断”，RFC 7851，DOI 10.17487/RFC7851，2016年5月<http://www.rfc-editor.org/info/rfc7851>.
Authors' Addresses
作者地址
David A. Bryan Cogent Force, LLC Cedar Park, Texas United States
美国德克萨斯州雪松公园David A.Bryan Cogent Force有限责任公司
Email: dbryan@ethernot.org
Email: dbryan@ethernot.org
Philip Matthews Nokia 600 March Road Ottawa, Ontario K2K 2E6 Canada
加拿大安大略省渥太华三月路600号菲利普·马修斯诺基亚K2K 2E6
Phone: +1 613 784 3139
Email: philip_matthews@magma.ca
Phone: +1 613 784 3139
Email: philip_matthews@magma.ca
Eunsoo Shim Samsung Electronics Co., Ltd. San 14, Nongseo-dong, Giheung-gu Yongin-si, Gyeonggi-do 446-712 South Korea
韩国京畿道吉乡古永仁寺农色洞永顺三星电子有限公司San 14 446-712
Email: eunsooshim@gmail.com
Email: eunsooshim@gmail.com
Dean Willis Softarmor Systems 3100 Independence Pkwy #311-164 Plano, Texas 75075 United States
Dean Willis Softarmor Systems 3100 Independence Pkwy#311-164美国德克萨斯州普莱诺75075
Phone: +1 214 504 1987
Email: dean.willis@softarmor.com
Phone: +1 214 504 1987
Email: dean.willis@softarmor.com
Spencer Dawkins Huawei Technologies (USA)
斯宾塞·道金斯华为技术（美国）
Phone: +1 214 755 3870
Email: spencerdawkins.ietf@gmail.com
Phone: +1 214 755 3870
Email: spencerdawkins.ietf@gmail.com