Connect to a 2nd instance of SQL server while UDP 1434 is blocked

I have two instances of SQL 2000 on one of our servers. I can connect to the
first instance that has the machine name and port 1434 from anywhere I want.
But when I try to connect to the second instance on the same machine with
then name of machinename\G3 from a server on a second network where UDP 1434
port is blocked by the firewall, the connection fail and the second instance
is not available. I followed this article on Microsoft knowledge base
http://support.microsoft.com/kb/265808/ where I created an alias for the G3
server on the client machine using the IP address and the assigned port
number, but that didn’t help and I still could not connect to the server.
I
basically followed those steps:
2. Configure the server alias on the client computer.
SQL Server 2000a. Start the Client Network Utility.
b. On the General tab, verify that TCP/IP appears in the list under Enabled
protocols by order.
c. Click the Alias tab, and then click Add.
d. Under Network libraries, select TCP/IP.
e. In the Server name text box, type the IP address of the server that is
running SQL Server 2005.
Note The IP address that you type here is the one that is configured to use
the TCP/IP port number.
f. Click to clear the Dynamically determine port check box, and then type
the port number of the instance of SQL Server 2005 in the Port number text
box.
g. Type a name in the Server alias text box, and then click OK.
I asked the IT department to unblock the UDP 1434 temporarily to see if I
can connect to the G3 server, and I was able to connect with no problem.
Unfortunately, they are required to block UDP 1434 so I have to deal with
that.
Does anybody have any idea that could help? Please let me know.
ThanksHi Danny
A named instance will use a dynamic port by default and UDP 1434 is used to
transmit the name of the instance name back to the client. You will need to
make the port fixed on the server and the corresponding port configured on
the client.
Check out http://support.microsoft.com/kb/287932.
John
"Danny Mansour" wrote:

> I have two instances of SQL 2000 on one of our servers. I can connect to t
he
> first instance that has the machine name and port 1434 from anywhere I wan
t.
> But when I try to connect to the second instance on the same machine with
> then name of machinename\G3 from a server on a second network where UDP 14
34
> port is blocked by the firewall, the connection fail and the second instan
ce
> is not available. I followed this article on Microsoft knowledge base
> http://support.microsoft.com/kb/265808/ where I created an alias for the G
3
> server on the client machine using the IP address and the assigned port
> number, but that didn’t help and I still could not connect to the server
. I
> basically followed those steps:
> 2. Configure the server alias on the client computer.
> SQL Server 2000a. Start the Client Network Utility.
> b. On the General tab, verify that TCP/IP appears in the list under Enabl
ed
> protocols by order.
> c. Click the Alias tab, and then click Add.
> d. Under Network libraries, select TCP/IP.
> e. In the Server name text box, type the IP address of the server that is
> running SQL Server 2005.
> Note The IP address that you type here is the one that is configured to us
e
> the TCP/IP port number.
> f. Click to clear the Dynamically determine port check box, and then type
> the port number of the instance of SQL Server 2005 in the Port number text
> box.
> g. Type a name in the Server alias text box, and then click OK.
>
> I asked the IT department to unblock the UDP 1434 temporarily to see if I
> can connect to the G3 server, and I was able to connect with no problem.
> Unfortunately, they are required to block UDP 1434 so I have to deal with
> that.
> Does anybody have any idea that could help? Please let me know.
> Thanks
>|||One way to avoid the dependency on UDP 1434 is to specify the port number
explicitly on the connection string. So assume that the server name is
ServerA, its IP address is A.B.C.D, and the instance listens on TCP port
1234, you connect to the instance as follows:
ServerA,1234
or
A.B.C.D,1234
When you connect to an instance using the ServerName\InstanceName
convention, the client needs to retrieve the port number first, and it talks
to UDP 1434 to get the port number.
Linchi
"Danny Mansour" wrote:

> I have two instances of SQL 2000 on one of our servers. I can connect to t
he
> first instance that has the machine name and port 1434 from anywhere I wan
t.
> But when I try to connect to the second instance on the same machine with
> then name of machinename\G3 from a server on a second network where UDP 14
34
> port is blocked by the firewall, the connection fail and the second instan
ce
> is not available. I followed this article on Microsoft knowledge base
> http://support.microsoft.com/kb/265808/ where I created an alias for the G
3
> server on the client machine using the IP address and the assigned port
> number, but that didn’t help and I still could not connect to the server
. I
> basically followed those steps:
> 2. Configure the server alias on the client computer.
> SQL Server 2000a. Start the Client Network Utility.
> b. On the General tab, verify that TCP/IP appears in the list under Enabl
ed
> protocols by order.
> c. Click the Alias tab, and then click Add.
> d. Under Network libraries, select TCP/IP.
> e. In the Server name text box, type the IP address of the server that is
> running SQL Server 2005.
> Note The IP address that you type here is the one that is configured to us
e
> the TCP/IP port number.
> f. Click to clear the Dynamically determine port check box, and then type
> the port number of the instance of SQL Server 2005 in the Port number text
> box.
> g. Type a name in the Server alias text box, and then click OK.
>
> I asked the IT department to unblock the UDP 1434 temporarily to see if I
> can connect to the G3 server, and I was able to connect with no problem.
> Unfortunately, they are required to block UDP 1434 so I have to deal with
> that.
> Does anybody have any idea that could help? Please let me know.
> Thanks
>