Multiple RRAS Client Disconnects Cause Increased CPU Usage

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When you run the Routing and Remote Access Service on a system with clientswho continuously connect and disconnect over a period of several hours, younotice a systematic slowdown on the server with a corresponding increase inCPU usage.

The slowdown can be characterized by using Performance Monitor to view theProcessor object's % Processor Time counter, which indicates a maximumvalue of 100. Monitoring the Network Interface object's Bytes Sent andBytes Received counters will also show consistent spikes during a client'sconnection period.
During a client's connection, the router will allocate memory on the serverto perform a query against the interface table, allocating memory for thewhole table. It does so by looking at the count of interfaces and allocatesan amount equal to the number of connections multiplied by the number ofbytes used by the router's interface table. Clients who dial in are countedas an interface by the router and are added to the table. However, when aclient disconnects, the system does not decrement the connection count andsubsequent connections continue to add to the size of the table. Repeatedqueries on the increasingly large amount of memory allocated to the routerinterface table results in the perceptible slowdown of the server.
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack

Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.

Article ID: 193499 - Last Review: 10/10/2013 22:23:35 - Revision: 1.2

Microsoft Windows NT Server 4.0, Terminal Server Edition, Microsoft Windows NT Workstation 4.0 Developer Edition, Microsoft Windows NT Server 4.0 Standard Edition

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