Q123337: HOWTO: How SNA Server Communicates with Other SNA Server Compute
Article: Q123337
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Operating System(s):
Keyword(s): kbnetwork kbsna211sp1 kbsna211sp2 kbsna300sp1 kbsna300sp2 kbsna300sp3 sna4 kbsna400sp1
Last Modified: 12-JUN-2001
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The information in this article applies to:
- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 2.11 SP1, 2.11 SP2, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1
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IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.
SUMMARY
=======
SNA Server uses broadcasts to propagate its Service Table updates to other SNA
server computers in the domain. This is necessary to keep all SNA Server
computers abreast of any configuration change that is made or any action that is
being taken in the SNA Server domain. SNA Server version 2.1 and later provides
choices that allow an administrator of an SNA Server network to optimize the way
this Service Table propagation occurs. This article should be read as a
supplement to the Server Broadcasts dialog box Help file that can be launched
from within the Server Broadcasts dialog box.
MORE INFORMATION
================
SNA Server 2.0
--------------
By default, SNA Server 2.0 sends broadcasts using the following method:
- WriteFile API call:
SNA Server uses a WriteFile API call to send broadcasts to other SNA Server
computers in the domain. It does this by submitting a WriteFile API call that is
sent in turn over all network protocols that the Workstation Service is bound
to. For instance, if the Workstation Service is bound to NetBEUI, TCP/IP, and
NWLink NetBIOS, SNA Server sends MailSlot broadcasts over all three of these
protocols. Sending MailSlot broadcasts over all transports is a function of the
WriteFile API call. This may cause unnecessary network traffic, however. In SNA
Server 2.0, there is no way to disable this other than to remove unnecessary
protocols from the Network applet in Control Panel.
- IPX Sockets if NWLink is installed:
If NWLink is installed, SNA Server 2.0 will send a mailslot broadcast over NWLink
NetBIOS as described above, using the WriteFile API AND over a well- known IPX
socket.
- TCP/IP MailSlots:
WARNING: Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee that
problems resulting from the incorrect use of Registry Editor can be solved. Use
Registry Editor at your own risk.
For information about how to edit the registry, view the "Changing Keys And
Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete
Information in the Registry" and "Edit Registry Data" Help topics in
Regedt32.exe. Note that you should back up the registry before you edit it.
If the SNA Server computers are divided by TCP/IP routers, then enable the
following registry parameter:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Snabase\Parameters\
: EnableIPMailSlots:REG_SZ:YES
With this value enabled, SNA Server will send MailSlot broadcasts to domain
controllers in the domain using only TCP/IP, even though other protocols may be
installed. If the SNA Server computers do not reside on a domain controller with
this option chosen, no SNA Server computer will [ASCII 147]listen[ASCII 148] for
these MailSlots.
- For Comm Server Support:
WARNING: Using Registry Editor incorrectly can cause serious problems that may
require you to reinstall your operating system. Microsoft cannot guarantee that
problems resulting from the incorrect use of Registry Editor can be solved. Use
Registry Editor at your own risk.
For information about how to edit the registry, view the "Changing Keys And
Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete
Information in the Registry" and "Edit Registry Data" Help topics in
Regedt32.exe. Note that you should back up the registry before you edit it.
By default, SNA Server 2.0 has turned on support for Comm Server Gateways,
sending specific MailSlot broadcasts that they can recognize. If there are no
Comm Server computers in the domain, add the following value to:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Snabase\Parameters\
: CommServerSupport:REG_SZ:NO
Setting this value to NO will reduce broadcast traffic by nearly one-half.
SNA Server 2.1, 2.11, 2.11SP1 and 2.11SP2
-----------------------------------------
SNA Server Admin enables the user to choose how two or more SNA Server computers
communicate with each other. Go to the Server Broadcasts dialog box under the
Options menu in SNA Server Admin. This dialog box includes the following
choices:
- Microsoft Networking
- Novell NetWare (IPX/SPX)
- Banyan Vines/IP
- Windows Sockets (TCP/IP)
- Router Server Broadcasts over IP routers
- SNA Server 2.0 servers in the same domain
- DCA/Microsoft Comm Server Client Support
- Microsoft Networking:
When you select the [ASCII 147]Microsoft Networking[ASCII 148] option only, SNA
Server versions 2.1, 2.11, 2.11 SP1 and 2.11 SP2 send MailSlot broadcasts using
the WriteFile API, just as SNA Server 2.0 does by default. SNA Server does this
by submitting a WriteFile API call that is sent in turn over all network
protocols that the Workstation Service is bound to. For instance, if the
Workstation Service is bound to NetBEUI, TCP/IP, and NWLink NetBIOS, SNA Server
sends MailSlot broadcasts over all three of these protocols. Sending MailSlot
broadcasts over all transports is a function of the WriteFile API call. This may
cause unnecessary network traffic, however.
- Native Transport Interface:
Unlike 2.0, SNA Server versions 2.1, 2.11, 2.11 SP1 and 2.11 SP2 have options
that enable the user to choose to send over selected native transports instead
of using the WriteFile API call. These other choices are:
- Novell NetWare (IPX/SPX)
- Banyan Vines/IP
- Windows Sockets (TCP/IP)
For example, if TCP/IP is installed on all SNA Server computers, then you want to
deselect [ASCII 147]Microsoft Networking[ASCII 148] and select [ASCII
147]Windows Sockets (TCP/IP)[ASCII 148]. This will reduce the number of MailSlot
broadcasts by sending over only one transport - TCP/IP in this case.
- Comm Server Support:
If there are no DCA/Microsoft Comm Server clients or servers, disable the
following Comm Server Support options: "SNA Server 2.0 servers in the same
domain" and "DCA/Microsoft Comm Server Client Support".
Clearing these values will reduce broadcast traffic by nearly one-half.
- TCP/IP MailSlots:
When SNA Server computers are separated by TCP/IP routers, select "Route Server
Broadcasts over IP routers" if there is an IP router separating SNA Server
computers. This is equivalent to setting EnableIPMailslots to YES under 2.0. As
in 2.0, SNA Server will send MailSlot broadcasts to domain controllers in the
domain over TCP/IP only, even though other protocols may be installed. For this
configuration, SNA Server computers must be installed on primary or backup
domain controllers. If the SNA Server computers do not reside on a domain
controller with this option chosen, no SNA Server computer will [ASCII
147]listen[ASCII 148] for these MailSlots. Note: This option can only be chosen
if [ASCII 147]Microsoft Networking[ASCII 148] is chosen.
SNA Server 3.0 and 4.0
----------------------
SNA Server Manager enables you to choose how two or more SNA Server computers
communicate with each other. Go to the Server Broadcasts tab under the
Properties page for the SNA Server Subdomain in SNA Server Manager. The Server
Broadcasts tab includes the following choices:
- Microsoft Networking (Named Pipes)
- IPX/SPX (Novell NetWare)
- TCP/IP
- Banyan Vines
- Microsoft Networking:
When you select only the "Microsoft Networking" option, SNA Server 3.0 and 4.0
sends MailSlot broadcasts using the WriteFile API, just as the previous versions
of SNA Server do by default. Version 3.0 and 4.0 does this by submitting a
WriteFile API call that is sent in turn over all network protocols that the
Workstation Service is bound to. For example, if the Workstation Service is
bound to NetBEUI, TCP/IP, and NWLink NetBIOS, SNA Server sends MailSlot
broadcasts over all three of these protocols. Sending MailSlot broadcasts over
all transports is a function of the WriteFile API call. This may cause
unnecessary network traffic, however.
- Native Transport Interface:
SNA Server 3.0 and 4.0 have options that enable you to choose to send over
selected native transports instead of using the WriteFile API call. These other
choices are:
- IPX/SPX (Novell NetWare)
- TCP/IP
- Banyan Vines
For example, if TCP/IP is installed on all SNA Server computers, then you want to
clear "Microsoft Networking" and select [ASCII 147]TCP/IP[ASCII 148]. This cuts
down on the number of MailSlot broadcasts by only sending over one transport -
TCP/IP in this case.
- TCP/IP MailSlots:
Unlike previous versions of SNA Server, SNA Server 3.0 and 4.0 does not have a
Route Server Broadcasts over IP routers" option. With SNA Server 3.0 and 4.0,
each SNA Server computer builds a list of other SNA Server computers in its
subdomain. The list of servers is built based on the current SNA Server
configuration file. During installation, the SNA Server 3.0 and 4.0 Setup
program tries to dynamically locate the primary SNA Server computer, based on a
UDP broadcast datagram. If this fails, the Setup program displays a prompt
asking for the primary SNA Server computer's name. Backup SNA Server computers
store in their registry the name of the primary SNA Server computer. Member SNA
Server computers store in their registry the names of all of the SNA Server
computers in their subdomain.
Due to this change, SNA Server 3.0 and 4.0 does not have to be installed on
Windows NT domain controllers even if the subdomain spans IP routers.
Additional query words: prodsna snafaq
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Keywords : kbnetwork kbsna211sp1 kbsna211sp2 kbsna300sp1 kbsna300sp2 kbsna300sp3 sna4 kbsna400sp1
Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210 kbSNAServ211SP1 kbSNAServ211SP2 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2
Version : WINDOWS:2.0,2.1,2.11,2.11 SP1,2.11 SP2,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Issue type : kbhowto
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