Microsoft KB Archive/192496

= Slow Write Performance Using IBM DOS Lan Requester =

Article ID: 192496

Article Last Modified on 10/31/2006

-

APPLIES TO


 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 4.0 Standard Edition

-



This article was previously published under Q192496



SYMPTOMS
Write operations are a magnitude slower that read operations against a server running Windows NT when using IBM DOS LAN Requester.



MORE INFORMATION
In the Network Monitor trace below, the client uses a send window of 1. With this send window, the client does not send any more frames before the last frame has been acknowledged. When Windows NT receives this frame, it does not immediately acknowledge it to optimize the number of frames sent in return. If several frames arrive in a short period of time, they can be acknowledged in one reply. When the server has any data to send back to the client, the acknowledgement can be sent together (piggybacked) with the response.

To use these optimizations (also known as delayed acknowledgement), Windows NT NetBEUI waits for a maximum of 150 ms (T2), and then sends an acknowledgement.

This causes a round-trip delay of about 200 ms for each frame, seriously degrading throughput.

 303 17.903 SMB C write block raw, FID = 0x802, Write 0xfd8 of 0xabec at 0xabec 304 18.086 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x5E 305 18.089 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 306 18.286 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x5F 307 18.289 NETBIOS Data Only Last (0x16): LSN = 0x04, RSN = 0x3D, Length = 2028 308 18.292 NETBIOS Data Ack (0x14): LSN = 0x3D, RSN = 0x04 309 18.292 SMB    R write block raw 310 18.292 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x26 311 18.293 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x27 312 18.293 NETBIOS Data Ack (0x14): LSN = 0x04, RSN = 0x3D 313 18.486 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x61 314 18.490 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 315 18.687 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x62 316 18.691 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 317 18.887 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x63 318 18.890 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 319 19.087 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x64 320 19.090 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 321 19.287 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x65 322 19.291 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 323 19.489 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x66 324 19.492 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 325 19.688 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x67 326 19.691 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 327 19.888 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x68 328 19.891 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028 329 20.089 LLC    RR DSAP=0xF0 SSAP=0xF1 R N(R) = 0x69 330 20.092 NETBIOS Data First Middle (0x15): LSN = 0x04, RSN = 0x3D, Length = 2028



RESOLUTION
Use an updated client that uses a send window or sets the POLL bit in the LLC header for immediate acknowledgements or Change MaximumIncomingFrames in the registry to 1. However, this setting will degrade performance for all clients.

For additional information, please see the following article in the Microsoft Knowledge Base:

102998 REG: Network Services Entries, Part 4

For information regarding this product, please connect to IBM's main Web page:

http://www.software.ibm.com

The third party products discussed here are manufactured by a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

Additional query words: slow performance delayed nbf

Keywords: kbprb KB192496

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© Microsoft Corporation. All rights reserved.