[cifs-protocol] [EXTERNAL] Endpoint mapper max_towers parameter behavior in Map call - TrackingID#2012220050006398

Jeff McCashland jeffm at microsoftsupport.com
Tue Dec 22 15:38:56 UTC 2020


[DocHelp to BCC, Tracking ID on Subject]

Hi Samuel,

Thank you for your question. We have created SR 2012220050006398 to track this issue. One of our engineers will respond soon. 

Best regards,
Jeff McCashland | Senior Escalation Engineer | Microsoft Protocol Open Specifications Team 
Phone: +1 (425) 703-8300 x38300 | Hours: 9am-5pm | Time zone: (UTC-08:00) Pacific Time (US and Canada)
Local country phone number found here: http://support.microsoft.com/globalenglish | Extension 1138300
We value your feedback.  My manager is Natesha Morrison (namorri), +1 (704) 430-4292

-----Original Message-----
From: Samuel Cabrero <scabrero at samba.org> 
Sent: Tuesday, December 22, 2020 5:01 AM
To: Interoperability Documentation Help <dochelp at microsoft.com>
Cc: cifs-protocol at lists.samba.org
Subject: [EXTERNAL] Endpoint mapper max_towers parameter behavior in Map call

Hi DocHelp,

I have found a strange behavior of the max_towers parameter in the EPM Map call when it is issued to an address assigned to a clustered file server role.

After booting the cluster, all EPM Map calls issued to the IP address assigned to the clustered file server role, asking for the witness endpoint, and having max_towers equal to 1 return 0x16C9A0D6 (There are no elements satisfying the specified search criteria, according to MS- RPCE). Once a call having max_towers greater than 1 is issued, subsequent requests having max_towers equal to 1 succeed.

Please check the attached capture for an example of this behavior. The IP address 192.168.103.200 is assigned to a clustered file server as you can see in the screenshot.

* Map requests having max_tower == 1 in frames 34, 37, 40, 43 and 46 does not return the tower.
* Map request having max_tower == 2 in frame 49 succeed.
* Map requests having max_tower == 1 in frames 53, 56, 59, 62 and 65 succeed.

I have not found any requirements for the max_towers parameter in MS- RPCE. Is there a minimum value for any particular case? Could you please explain this behavior?

--
Samuel


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