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Configuring Load Balancing

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Each RPC Proxy machine that is to act as a Load Balancing Server (LBS) service must be configured as an LBS service with knowledge of the servers in the server farm. Optionally, the default resource can be set and the security of Proxy to LBS and LBS to LBS RPC calls can be set. These settings are configured by a set of Required Registry Keys and Optional Registry Keys as described below.

Required Registry Keys

Several registry keys and values are required to configure an LBS server. If any keys are missing or are entered in error, a Windows Event is logged. See the description of each key and value for information on the event logged.

To configure the server farm, a registry key must be created HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy called LBSConfiguration. Under the LBSConfiguration key, a key is created for each resource in the server farm. The key name is the string representation of the GUID for the resource. At least one resource key must exist, and this resource is identical to the UUID set by clients on the binding handle, RPC_BINDING_HANDLE, when they create the RPC/HTTP binding (For more information please see RpcBindingSetObject). Under each Resource UUID key, there must exist a DWORD value named ConfigurationType which describes the configuration used. There must also exist a REG_SZ of semicolon delimited server identifiers called ServerFarm. The servers identified in the ServerFarm key are the servers which are members of the load balancing server farm.

The following is a detailed breakdown of the required registry keys and values:

HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration

Registry Key. The LBSConfiguration key is the registry key that holds the LBS configuration. This includes the Resource UUIDs that are to be load balanced, the configuration type for each resource and the servers in the server farms which participate in load balancing. If this key is missing or invalid, LBS will not be considered to be configured and the LBS service will not run.

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HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

Registry Key. The Resource UUID key identifies the resource UUID to be load balanced. This resource UUID is the same as the UUID that clients set on the binding handle, RPC_BINDING_HANDLE. There must be at least one resource UUID to be load balanced, there may be multiple resource UUIDs. There can be only one server farm and all endpoints must be on all servers within the server farm. If this key cannot be parsed to a valid UUID, the event RPCPROXY_EVENTLOG_LB_INVALID_KEY (0xC0000006) will be logged to the Windows Event Log.

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HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\ConfigurationType

DWORD. The ConfigurationType DWORD is stored under the Resource UUID key. The only allowed value is 1. If this value is anything other than 1, the event RPCPROXY_EVENTLOG_LB_UNKNOWN_CFG_TYPE (0xC0000007) will be logged to the Windows Event Log.

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HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX\ServerFarm

REG_SZ. The ServerFarm registry value contains a semicolon delimitated list of server identifiers. The format for the server identifiers is:

"ServerID1,ServerPort1,LBSPort1,[LBSPort2, …LBSPortN];"

Multiple server identifiers should be listed in the ServerFarm registry key. They must be delimited by a semicolon. The fields which are part of the server identifier are described in the following table. If this field cannot be parsed correctly, the event RPCPROXY_EVENTLOG_LB_BAD_CONFIG_ENTRY (0xC0000008) will be logged to the Windows Event Log.

Identifier Field Requirement Description
ServerID Required A resolvable network name for the server. This can be a DNS name, a netbios name, or an IP address.
ServerPort Optional If specified, the port on which the server listens for RPC/HTTP connections. If not specified, the End point mapper on the server machine is used to find the server port.
LBSPort Optional If specified, the port the on which the server listens for LBS. To use this key, the LBS interfaces must be set to a static endpoint using a netsh RPC firewall command. See Load Balancing Best Practices for examples of the netsh command.

 

Optional Registry Keys

There are three optional registry values to configure an LBS server. The keys primarily control the level of security for calls to and from the LBS service, and also control the default resource UUID to be used. The following are optional values:

The following is a detailed breakdown of the required registry keys and values:

HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\NoSecurity

DWORD. When the NoSecurity DWORD is not present or set to 0, incoming non-secure calls to the LBS service are rejected. When present and not 0, incoming non-secure calls to the LBS service are not rejected. This key is read once on startup of the LBS service.

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HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\AssumeResourceUUID

DWORD. When the AssumeResourceUUID DWORD is not present no change in the LBS service occurs. When present, it must be set with a valid UUID. This UUID will be used as the resource UUID for all connections which do not specify a resource UUID. This is commonly used in cases where clients do not specify a Resource UUID when they create the RPC/HTTP binding, but an administrator wishes to load balance the RPC/HTTP traffic to a server farm. If this key cannot be parsed to a UUID, an internal RPC error is lodged, generating RPC_EXTENDED_ERROR_INFO if it is enabled.

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HKLM\Software\Microsoft\Rpc\RPCHTTPLBSServer\NoSecurity

DWORD. When the NoSecurity DWORD is not presented or set to 0, all outgoing calls made to LBS services will have security. If present and not set to 0, all outgoing calls made to LBS services will not have security. Ensure this setting matches the HKLM\SOFTWARE\Microsoft\Rpc\RpcProxy\LBSConfiguration\NoSecurity setting.