[cifs-protocol] Requesting clarification of CIFS client timeout behavior

Sebastian Canevari Sebastian.Canevari at microsoft.com
Wed Dec 1 07:54:13 MST 2010

Thanks for your question Jeff.

Someone from my team will follow up with you shortly.



Sebastian Canevari
Escalation Engineer, US-CSS DSC PROTOCOL TEAM
7100 N Hwy 161, Irving, TX - 75039
"Las Colinas - LC2"
Tel: +1 469 775 7849
e-mail: sebastc at microsoft.com

From: cifs-protocol-bounces at cifs.org [cifs-protocol-bounces at cifs.org] on behalf of Jeff Layton [jlayton at samba.org]
Sent: Tuesday, November 30, 2010 9:24 PM
To: Interoperability Documentation Help
Cc: pfif at tridgell.net; cifs-protocol at samba.org
Subject: [cifs-protocol] Requesting clarification of CIFS client timeout        behavior

I have a number of questions regarding Windows behavior with respect to
call timeouts. MS-CIFS says this in Appendix A:

    <186> Section Windows NT and Windows 98 CIFS clients
    periodically scan for any commands that have not completed. The
    default scanning period is 30 seconds. If there are outstanding
    commands that have exceeded the Client.SessionTimeoutValue, an
    SMB_COM_ECHO (section is sent to determine whether or not
    the connection has been lost. The client closes the connection only
    if there is no response to the echo request.

My questions are as follows:

1) If the server is responding to the echo requests, does the client
   still eventually return an error to the application or does it wait
   indefinitely for the response?

2) If it returns an error to the application, does the client send a
   SMB_COM_NT_CANCEL to cancel the outstanding request?

3) If it waits indefinitely, does it send more than one echo request?
   If so, how frequently are they sent?

4) Do more recent versions of Windows behave similarly?

Jeff Layton <jlayton at samba.org>
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cifs-protocol at cifs.org

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