以下各节介绍了各个组件。
交换服务器与交易所的过去和未来版本之间的通信发生在协议层。不允许跨层通信。该通信架构概括为“每个服务器都是岛”。该架构具有以下优点：
减少服务器间通信。
版本感知通信。
孤立的失败。
每个服务器内的集成设计。
交换服务器之间的协议层通信如下图所示。
Exchange使用邮箱服务器和边缘传输服务器。以下各节介绍了这些服务器角色。
邮箱服务器包含用于路由邮件的传输服务。有关更多信息，请参阅邮件流和传输管道
邮箱服务器包含处理，呈现和存储数据的邮箱数据库。有关详细信息，请参阅管理Exchange Server中的邮箱数据库。
邮箱服务器包含接受所有协议的客户端连接的客户端访问服务。这些前端服务负责路由或代理与邮箱服务器上相应后端服务的连接。客户端不直接连接到后端服务。有关详细信息，请参阅本主题后面的“ 客户端访问协议体系结构”部分。
在Exchange 2016中，邮箱服务器包含统一消息（UM）服务，这些服务为邮箱提供语音邮件和其他电话功能。
注意
Exchange 2019中不提供统一消息。
您可以使用Exchange管理中心（EAC）和Exchange命令行管理程序管理邮箱服务器。有关详细信息，请参阅Exchange Server和Exchange Server PowerShell中的Exchange管理中心（Exchange命令行管理程序）。
边缘传输服务器处理Exchange组织的所有外部邮件流。
边缘传输服务器通常安装在外围网络中，并订阅内部Exchange组织。当邮件进入和离开Exchange组织时，EdgeSync同步过程使边缘传输服务器可以使用收件人和其他配置信息。
邮件进入和离开Exchange组织时，边缘传输服务器会提供反垃圾邮件和邮件流规则。有关详细信息，请参阅Exchange Server中的反垃圾邮件防护
您可以使用Exchange命令行管理程序管理边缘传输服务器。有关详细信息，请参阅Exchange Server PowerShell（Exchange命令行管理程序）。
有关边缘传输服务器的详细信息，请参阅边缘传输服务器。
以下各节介绍了Exchange Server中的高可用性功能。
数据库可用性组（DAG）是Exchange Server中内置的高可用性和站点恢复框架的基本元素。DAG是一组邮箱服务器，它们托管一组数据库，并提供从数据库，网络和服务器故障中自动进行数据库级恢复。与Exchange 2013相比，Exchange 2016或更高版本中的DAG已得到改进。有关DAG的详细信息，请参阅数据库可用性组。
传输服务为传输中的所有邮件制作冗余副本。此功能称为卷影冗余。
传输服务为所有传递的消息制作冗余副本。此功能称为安全网。
在Exchange Server中，DAG表示传输高可用性边界。您可以通过跨多个Active Directory站点跨越DAG来实现站点恢复。
在Exchange Server中，传输高可用性不仅仅是消息冗余的最佳工作，因为冗余不依赖于发送邮件服务器的受支持功能。因此，您可以说Exchange Server通过在传递期间和之后保留多个邮件副本来尝试保证邮件冗余。
有关更多信息，请参阅传输高可用性。
Exchange邮箱服务器上的客户端访问服务负责接受所有形式的客户端连接。客户端访问（前端）服务将这些连接代理到目标邮箱服务器（本地服务器或保存用户邮箱的主动副本的远程邮箱服务器）上的后端服务。客户端不直接连接到后端服务。此通信如下图所示。
The protocol that's used by a client determines the protocol that's used to proxy the request to the backend services on the destination Mailbox server. For example, if the client connected using HTTP, the Mailbox server uses HTTP to proxy the request to the destination Mailbox server (secured via SSL using a self-signed certificate). If the client used IMAP or POP, then the protocol that's used is IMAP or POP.
In Exchange 2016, telephony requests are different than other client connections. Instead of proxying the request, the Mailbox server redirects the request to the Mailbox server that holds the active copy of the user's mailbox. Telephony devices are required to establish their SIP and RTP sessions directly with the Unified Messaging services on the destination Exchange 2016 Mailbox server.
Note
Unified Messaging is not available in Exchange 2019.
Server role consolidation: In Exchange 2013 or earlier, you could install the Client Access server role and the Mailbox server role on separate computers. In Exchange 2016 or later, the Client Access server role is automatically installed as part of the Mailbox server role, and the Client Access server role isn't available as a separate installation option. This change reflects the philosophy of Exchange server role co-location that's been a recommended best practice since Exchange 2010. A multi-role Exchange server architecture gives you the following tangible benefits:
All Exchange servers in your environment (with the likely exception of any Edge Transport servers) can be exactly the same: the same hardware, the same configuration, etc. This uniformity simplifies hardware purchasing, and also maintenance and management of the Exchange servers.
You'll likely need fewer physical Exchange servers. This results in lower ongoing maintenance costs, fewer Exchange server licenses, and reduced rack, floor space, and power requirements.
Scalability is improved, because you're distributing the workload across a greater number of physical machines. During a failure, the load on the remaining Exchange multi-role servers increases only incrementally, which ensures the other functions on the Exchange servers aren't adversely affected.
Resiliency is improved, because a multi-role Exchange server can survive a greater number of Client Access role (or service) failures and still provide service.
Search improvements: The local search instance is now able to read data from the local mailbox database copy. As a result, passive search instances no longer need to coordinate with their active counterparts to perform index updates, and bandwidth requirements between the active copy and a passive copy have been reduced by 40% compared to previous versions of Exchange. Also, search is now able to perform multiple asynchronous disk reads prior to a user completing a search term. This populates the cache with relevant information, and provides sub-second search query latency for online clients like Outlook on the web.
Office Online Server Preview for Outlook on the web document preview: In Exchange 2013 or earlier, Outlook Web App included WebReady Document Viewing for the built-in preview of Office and PDF documents. In Exchange 2016 or later, Outlook on the web uses Office Online Server Preview to provide rich preview and editing capabilities for documents. While this provides a consistent document experience with other products like SharePoint and Skype for Business, it does require you to deploy Office Online Server Preview in your on-premises environment if you don't already have it. For more information, see Install Office Online Server in an Exchange organization.
MAPI over HTTP是Outlook连接的默认设置：基于HTTP的MAPI是在Exchange 2013 Service Pack 1中引入的，并且提供了对传统Outlook Anywhere（RPC over HTTP）连接方法的改进。在Exchange 2016或更高版本中，默认情况下启用MAPI over HTTP，并提供其他控件，例如是否能够为每个用户启用或禁用基于HTTP的MAPI，以及是否将其通告给外部客户端。有关详细信息，请参阅Exchange Server中的MAPI通过HTTP。
联系客服
