Beginning Microsoft SQL Server 2008 ... - S3 Tech Training

Chapter 2: Tools of the Trade
❑ SQL Server — The core database engine that works on data storage, queries, and system configuration
for SQL Server.
❑ SQL Server Browser — This supports advertising your server so those browsing your local
network can identify that your system has SQL Server installed.
Network Configuration
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A fair percentage of the time, any connectivity issues discovered are the result of client network configuration,
or how that configuration matches with that of the server.
SQL Server provides several of what are referred to as Net-Libraries (network libraries), or NetLibs. These
are dynamic-link libraries (DLLs) that SQL Server uses to communicate with certain network protocols.
NetLibs serve as something of an insulator between your client application and the network protocol, which
is essentially the language that one network card uses to talk to another, that is to be used. They serve
the same function at the server end, too. The NetLibs supplied with SQL Server 2008 include:
❑ Named Pipes
❑ TCP/IP (the default)
❑ Shared Memory
❑ VIA (a special virtual interface that your storage-hardware vendor may support)
VIA is a special network library that is made for use with some very special (and expensive) hardware. If
you’re running in a VIA environment, you’ll know about the special requirements associated with it. For
those of you that aren’t running in that environment, it suffices to say that VIA offers a very fast but expensive
solution to high-speed communication between servers. It would not usually be used for a normal client.
The same NetLib must be available on both the client and server computers so that they can communicate
with each other via the network protocol. Choosing a client NetLib that is not also supported on the
server will result in your connection attempt failing with a Specified SQL Server Not Found error.
Regardless of the data access method and kind of driver used (SQL Native Client, ODBC, OLE DB), it will
always be the driver that talks to the NetLib. The process works as shown in Figure 2-2. The steps in order are:
1. The client app talks to the driver (SQL Native Client, ODBC).
2. The driver calls the client NetLib.
3. This NetLib calls the appropriate network protocol and transmits the data to a server NetLib.
4. The server NetLib then passes the requests from the client to SQL Server.
In case you’re familiar with TCP/IP, the default port that the IP NetLib will listen on
is 1433. A port can be thought of as being like a channel on the radio — signals are
bouncing around on all sorts of different frequencies, but they only do you any good
if you’re listening on the right channel. Note that this is the default, so there is no
guarantee that the particular server you’re trying to connect to is listening to that particular
port — indeed, most security experts recommend changing it to something
nonstandard.