Hi Stefan,

This is in regards to your question: 
Question 9:
Section 3.2.4.27-3.2.4.29 seems to actions triggered when the client receives 
an RESP_ASYNC_NOTIFY, but there's no specification on how the individual 
witness registrations handle specific notification events. E.g. based on the 
different posibilities for RESOURCE_CHANGE.ResourceName Is a 
CLIENT_MOVE_NOTIFICATION a better choice when using a single InterfaceGroupName 
for all nodes?

I'm ready to file document change requests to explain the processing, but I 
don't fully understand your example question. Resource Change notifications are 
used when resources such as disks change status, while Client Move 
notifications are used when a node has gone down and the client needs to move 
to another node. 

They aren't interchangeable. Could you clarify your question? 

Best regards,
Jeff McCashland (He/him) | 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

-----Original Message-----
From: Tom Jebo <tomj...@microsoft.com> 
Sent: Tuesday, November 7, 2023 9:47 AM
To: metze <me...@samba.org>
Cc: cifs-protocol@lists.samba.org; Microsoft Support <supportm...@microsoft.com>
Subject: RE: [EXTERNAL] Trying to let a Windows client use MS-SWN against a 
samba cluster - TrackingID#2311070040009453 

[dochelp to bcc]
[support mail to cc]

Hi Stefan, 

Thanks for your request regarding MS-SWN (various questions). One of the Open 
Specifications team members will respond to assist you. In the meantime, we’ve 
created the following cases to track this request (I've added the first case to 
the subject so initially, please leave that case number in the subject when 
communicating with our team about this request.

Q1: 2311070040009453
Q2: 2311070040009696
Q3: 2311070040009793
Q4: 2311070040009927
Q5: 2311070040010003
Q6: 2311070040010094
Q7: 2311070040010182
Q8: 2311070040010257
Q9: 2311070040010334
Q10: 2311070040010406
Q11: 2311070040010486

Best regards,
Tom Jebo
Microsoft Open Specifications Support

-----Original Message-----
From: Stefan Metzmacher <me...@samba.org> 
Sent: Tuesday, November 7, 2023 6:30 AM
To: Interoperability Documentation Help <doch...@microsoft.com>
Cc: cifs-protocol@lists.samba.org
Subject: [EXTERNAL] Trying to let a Windows client use MS-SWN against a samba 
cluster

Hi DocHelp,

I'm currently implementing MS-SWN for samba in order to allow clients to move 
to a different network interface or cluster node if a specific interface or a 
complete cluster node gets offline.

In a Samba cluster we have multiple nodes, but just a single netname for all of 
them, so there's only a single computer with it's sAMAccountName in active 
directory. But each node can have multiple ip addresses, which may move around 
between nodes, but some can be node local.

Now my goal is to let a Windows client use the witness service in order to get 
notified about ip addresses going down, because the interface link or a whole 
node gets offline.

In order to archive that I need to understand the exact client behavior 
implemented in the Windows clients (also with possible differences of various 
Windows versions).

However this is hard from just reading the existing docs...

MS-SWN "3.2 Witness Client Details" doesn't contain any detail for the logical 
processing, e.g.

- 3.2.4.1 Application Requests Witness Register
   doesn't say that WITNESS_INTERFACE_INFO.InterfaceGroupName
   is that name used as part of the servicePrincipalName
   (after being prefixed by 'CIFS/') passed to the authentication
   layer (spnego, kerberos, ntlm), but I'm seeing this
   behavior from a Windows 2022 server as client.

   In older version (Windows 2012) I saw that the principal
   was requested by the method from MS-RPCE 2.2.1.3.4
   rpc_mgmt_inq_princ_name.

Question 1:
Can you please update this with a product behavior note reflecting the reality 
with all Windows versions.

- 3.2.4.2 Application Requests Witness Event Notification
   only says: ...
   The status and any received RESP_ASYNC_NOTIFY result obtained from
   the server in the previous step MUST be returned to the caller.

- 3.2.4.3 Application Requests Witness UnRegister
   Has the following notable section:
     ... or if the WitnessRegistration.WitnessNotifyRequest is TRUE,
     the client MUST stop processing and return an implementation-defined
     local error to the caller.

   So it seems with a pending AsyncNotify request the Unregister
   seems to be skipped.

With that I'd expect the core logic/behavior of a Windows client being 
specified in MS-SMB2, when I look there I found the following


3.2.5.2 Receiving an SMB2 NEGOTIATE Response

   ...

   If SMB2_GLOBAL_CAP_PERSISTENT_HANDLES is set in the Capabilities field of the
   SMB2 NEGOTIATE Response, the client SHOULD invoke the event as specified in
   [MS-SWN] section 3.2.4.1 by providing Connection.ServerName as Netname
   parameter.

Question 2:
I don't see this happening from a Windows Server 2022 acting as client.
Can you please update this with a product behavior note reflecting the reality 
with all Windows versions.


3.2.5.5 Receiving an SMB2 TREE_CONNECT Response

   ...

   - TreeConnect.IsCAShare MUST be set to TRUE, if the
     SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY bit is set in the Capabilities
     field of the response.

   ...

   If Connection.Dialect belongs to the SMB 3.x dialect family and the 
Capabilities
   field in the response includes SMB2_SHARE_CAP_CLUSTER bit, the client SHOULD
   invoke the event as specified in [MS-SWN] section 3.2.4.1 by providing
   Connection.ServerName as Netname parameter.

   ...

   If Connection.Dialect belongs to the SMB 3.x dialect family and the 
Capabilities
   field in the response includes the SMB2_SHARE_CAP_SCALEOUT bit, the client 
MUST
   set TreeConnect.IsScaleoutShare to TRUE.

   ...

   If Connection.Dialect is "3.0.2" or "3.1.1" and the Capabilities field in the
   response includes the SMB2_SHARE_CAP_ASYMMETRIC bit, the client MUST verify
   whether both of the following conditions are true:

     ...

     If the SMB2 TREE_CONNECT request is successful, the client SHOULD invoke 
the
     event as specified in [MS-SWN] section 3.2.4.1 by providing
     Connection.ServerName as the Netname parameter and TreeConnect.ShareName 
as the
     ShareName parameter, and by setting the IsShareNameNotificationRequired
     parameter to TRUE.

Question 3:
I don't see this happening from a Windows Server 2022 acting as client.
The only relevant flags in order to let the client try a witness connection are 
SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY together with SMB2_SHARE_CAP_CLUSTER.
Can you please update this with a product behavior note reflecting the reality 
with all Windows versions.


3.2.5.6 Receiving an SMB2 TREE_DISCONNECT Response

   ... If Connection.Dialect belongs to the SMB 3.x dialect family and if
   Session.TreeConnectTable is empty in all sessions in the 
Connection.SessionTable
   for which Connection.ServerName matches the server name, the client SHOULD
   invoke the event as specified in [MS-SWN] section 3.2.4.3.

Question 4:
I don't see this happening from a Windows Server 2022 acting as client.
The witness registration stays until a reboot.
There's also no new witness registration after a reconnect to a different ip, 
which means that the smb connection and witness connection may stay on the same 
server ip address, which means there's no benefit from it.
Can you please update this with a product behavior note reflecting the reality 
with all Windows versions.

3.2.7.1 Handling a Network Disconnect

   ...

   If Connection.Dialect belongs to the SMB 3.x dialect family and if
   Session.TreeConnectTable is empty in all sessions in the 
Connection.SessionTable
   for which Connection.ServerName matches the server name, the client SHOULD
   invoke the event as specified in [MS-SWN] section 3.2.4.3.

Question 5:
I don't see this happening from a Windows Server 2022 acting as client.
The witness registration stays until a reboot.
There's also no new witness registration after a reconnect to a different ip, 
which means that the smb connection and witness connection may stay on the same 
server ip address, which means there's no benefit from it.
Can you please update this with a product behavior note reflecting the reality 
with all Windows versions.


3.2.4.3.5 Application Requests Creating a File Opened for Durable Operation

   ...

   -  If TreeConnect.IsCAShare is TRUE, the client MUST set the
      SMB2_DHANDLE_FLAG_PERSISTENT bit in the Flags field. Otherwise, the 
client SHOULD
      perform one of the following:

        - Request a batch oplock by setting RequestedOplockLevel in the create 
request to
          SMB2_OPLOCK_LEVEL_BATCH.

        - Request a handle caching lease by including an 
SMB2_CREATE_REQUEST_LEASE or
          SMB2_CREATE_REQUEST_LEASE_V2 Create Context in the create request 
with a
          LeaseState that includes SMB2_LEASE_HANDLE_CACHING.

    ...

Question 6:
 From the documentation the above is the only reference that is impacted by 
SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY and it seems that it implicitly disables 
handle caching, is that really true?
And SMB2_DHANDLE_FLAG_PERSISTENT doesn't seem to be impacted by 
SMB2_GLOBAL_CAP_PERSISTENT_HANDLES, which is strange.
Can you please cross-check this?


3.2.4.27 Application Notifies Offline Status of a Server

   This optional interface is applicable only for the SMB 3.x dialect family. 
The
   application provides the following:

   - ServerName: The name of the server which became unavailable.

   For each Connection in the ConnectionTable where Connection.ServerName 
matches
   ServerName, the client MUST determine if any TreeConnect exists in the
   Session.TreeConnectTable with TreeConnect.IsScaleoutShare set to TRUE.

   If a tree connect entry is found, the client MUST do the following:

   - Disconnect the connection by performing the steps as specified in section 
3.2.7.1.

   - Invoke the event as specified in section 3.2.4.28 with ServerName set to 
the
     caller-supplied ServerName.

   If no tree connect entry is found, the client MUST disconnect the connection
   by performing the steps as specified in section 3.2.7.1.

Question 7:
The above section is the only place in the whole documentation that references 
SMB2_SHARE_CAP_SCALEOUT, is that really correct?
And it seems to be required in order trigger an immediate reconnect.
Can you please cross-check this?

3.2.4.28 Application Notifies Online Status of a Server

   This optional interface is applicable only for the SMB 3.x dialect family. 
The
   application provides the following:

   -  ServerName: The name of the server which became available.

   For each Open in the GlobalFileTable, where Open.Session.ChannelList is empty
   and the server name identified from Open.FileName matches ServerName, the 
client
   MUST re-establish the durable open as specified in section 3.2.4.4.


3.2.4.29 Application Requests Moving to a Server Instance

   This optional interface is applicable only for SMB 3.x dialect family. The
   application provides the following:

   -  ServerName: The name of the server.

   -  NewServerAddress: The IPv4 or IPv6 address of the server which the client
      is required to move to.

   For each Connection in the ConnectionTable where Connection.ServerName 
matches
   ServerName, the client MUST disconnect the connection by performing the 
steps as
   specified in section 3.2.7.1.

   For each Open in the GlobalFileTable, where Open.Session.ChannelList is empty
   and the server name identified from Open.FileName matches ServerName, the 
client
   MUST re-establish the durable open as specified in section 3.2.4.4, and by 
using
   NewServerAddress as the TransportIdentifier for the rules specified in 
section
   3.2.4.2.



Question 8:
The impact of SMB2_SHARE_CAP_CONTINUOUS_AVAILABILITY
without SMB2_GLOBAL_CAP_PERSISTENT_HANDLES is a very important part of this.

Question 9:
Section 3.2.4.27-3.2.4.29 seems to actions triggered when the client receives 
an RESP_ASYNC_NOTIFY, but there's no specification on how the individual 
witness registrations handle specific notification events. E.g. based on the 
different posibilities for RESOURCE_CHANGE.ResourceName Is a 
CLIENT_MOVE_NOTIFICATION a better choice when using a single InterfaceGroupName 
for all nodes?

Question 10:
MS-SWM 3.1.6.1 Server Application Notifies of an Interface Being Enabled or 
Disabled

   The calling application provides the interface group name, IPv4 and/or IPv6
   addresses, and state.

   ...

   Then for each entry in the WitnessRegistrationList where
   WitnessRegistration.NetworkName
   matches the application-provided interface group name ...

This seems to indicate that there's actually just a single InterfaceGroupName 
matching the single NetworkName.


Question 11:
I'm also wondering if ServerGlobalName is really a single name, as I can the 
client can use a dns or netbios name of the server!


Thanks!
metze

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