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During November 2008 Martin Kearn and Pete Reid worked on a session at the TechEd 2008 conference in Barcelona entitled "SharePoint Ports, Protocols and Proxies. An end-to-end overview of SharePoint inter-server communication" (OFC402). The slides from the TechEd presentation can be found here, these include more detail than is presented in this article.
The session talked in great detail about how the various servers in the SharePoint farm communicate with each other and this article is a summary of the key messages from that talk.
Why is this important to understand?
So the first question is "why do we care about farm communications"? .... There are three reasons why every SharePoint architect, consultant (insert SharePoint-related role here) should know about this stuff and they are as follows:
SharePoint Transport Protocols
All traffic within SharePoint occurs over one of three transport protocols, they are:
In addition to the above, SharePoint obviously has to communicate with other servers such as Active Directory, DNS etc which require other ports, they are as follows:
The term ‘Inter-Server' is used to describe traffic which occurs between servers inside the SharePoint farm. This includes the SQL server. The vast majority of traffic in this area is traffic to and from SQL server, which is why people always say that the SQL is the most important server in the SharePoint farm. This diagram describes the inter-server traffic. A large version of this image can be found here.
The term ‘Extra-Server' is used to describe traffic that occurs between the SharePoint farm and other servers. This would typically include AD, DNSD etc but you must also consider any external Indexing and BDC connections. This diagram describes the extra-server traffic, a larger version can be found here.
Client server communication refers to all traffic between the SharePoint farm and clients which may include Office, Browsers, and SharePoint Designer etc. All of this traffic occurs over HTTP and only ever interfaces with the Web Front End server. None of the other servers in the SharePoint farm handle client-server traffic. This diagram describes Client-Server communications, a larger version can be found here.
The actual communications that occur within SharePoint happen using a wide range of SharePoint-specific protocols. These protocols are documented in great detail here; additionally there are similar documents for Office protocols here.
The documents contained in the above links include a massive amount of detail on how specific operations within SharePoint occur. For example, if you want to know which servers, stored procedures and other protocols are involved when you interact with the recycle bin, check out ‘[MS-WSSCADM]: Windows SharePoint Services Content Database Administrative Communications Protocol Specification‘.
These documents are a great resource for really understanding the low-level details of what your SharePoint servers are doing.
One of the main type of Inter-Server communication is based around Search and Indexing. Interestingly, the communications channels used are primarily SMB which means that SMB must be allowed through firewalls if different servers are on different network segments.
Search & Index has 3 main types of activity, they are as follows:
In terms of troubleshooting, there are three tools that are invaluable in terms of understanding network communications, they are:
This is a list of useful resource related to this topic:
That is the end of the article, I hope you found it useful.
This article was published by
Martin Kearn Senior Consultant Microsoft Consulting Services UK Martin.Kearn@Microsoft.com
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