Write performance on IP-based NCP connection slower than using IPX-based connection from same workstation.

  • 10061307
  • NOVL43488
  • 24-Mar-2001
  • 09-Oct-2002

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Novell Client 2.71 for DOS/Windows

Novell Client 2.7 for DOS/Windows


Write performance on IP-based NCP connection slower than using IPX-based connection from same workstation.

Image upload using Norton Ghost (GHOST.EXE) from DOS-based IP boot disk slower than IPX-based connection or VLM-based boot disk.


The only complete workaround is to use an IPX-based connection with the Novell Client 2.71 for DOS/Windows. The Novell Client for DOS/Windows is not supported for logging into a NetWare server using an IP NCP connection ("pure IP") except to the extent necessary to allow successful over-the-wire installation of a NetWare server. Issues in any use of the DOS client making an IP NCP connection other than for NetWare server installation will be considered issues in an unsupported configuration.

Although performance differences between the IP performance and IPX performance will remain, the performance difference can potentially be reduced by turning off the delayed TCP ACK feature of the TCPIP.NLM on the NetWare server. This is accomplished by using SET TCP DELAYED ACKNOWLEDGEMENT = OFF on a NetWare 5.1 SP3 and later TCPIP.NLM, or SET TCP DELAYED ACK in pre-SP3 TCPIP.NLMs. See TID10068360, TCP DELAYED ACKNOWLEDGEMENT EXPLANATION and TID10061174, Server to Server TCP/IP communication is slow when using some third-party NetWare-based applications for additional information. Disabling the Nagle algorithm (SET TCP NAGLE ALGORITHM = OFF) in the server-side TCPIP.NLM has not been shown to provide additional benefit in the case of the DOS-mode client performing NCP writes.

What can be seen in the LAN trace is that as each 8KB-64KB NCP packet for the workstation's NCP write operations gets sent up to the NetWare server, after sending multiple full size TCP packets back-to-back the client delays for around 128ms-200ms before sending the last fragment which contains the remainder of the data. Increasing or reducing the size of the NCP packet doesn't change the behavior because the delay still occurs when the last fragment of the packet is ready to be sent. In an IPX connection the same delay doesn't occur at the end of the IPX packet burst, which is where most of the performance difference is realized.

In customer observations of using the Norton Ghost product on an IPX connection versus an IP connection both using the Novell Client 2.71 for DOS/Windows, the IP-based connection showed the same image download performance as IPX, but the image upload performance on IP was only around 20-30MB/minute whereas the same operation with an IPX-based server connection showed 100-120MB/minute performance. LAN traces showed the performance difference being attributed to the 128ms-200ms delays when the IP stack of the client workstation was transmitting the final TCP fragment of an NCP write. With the TCP DELAYED ACKNOWLEDGEMENT set to OFF, the throughput was closer to 60-80MB/minute but still half of the performance shown with IPX from the DOS-mode client.

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