Hi all,

I have a load balanced Exchange 2013 CAS by using KEMP LB.

ActiveSync & Outlook Anywhere works fine, but users with MacBook connecting via EWS having an issue.

When I run testexchangeconnectivity, all of them pass except the below error.

Creating a temporary folder to perform synchronization tests.
	Failed to create temporary folder for performing tests.
	Additional Details   Exception details: Message: The request failed. The remote server returned an error: (501) Not Implemented. Type: Microsoft.Exchange.WebServices.Data.ServiceRequestException Stack trace:    at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)    at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.ValidateAndEmitRequest(IEwsHttpWebRequest& request)    at Microsoft.Exchange.WebServices.Data.ExchangeService.InternalFindFolders(IEnumerable`1 parentFolderIds, SearchFilter searchFilter, FolderView view, ServiceErrorHandling errorHandlingMode)    at Microsoft.Exchange.WebServices.Data.ExchangeService.FindFolders(FolderId parentFolderId, SearchFilter searchFilter, FolderView view)    at Microsoft.Exchange.WebServices.Data.Folder.FindFolders(SearchFilter searchFilter, FolderView view)    at Microsoft.Exchange.Tools.ExRca.Tests.GetOrCreateSyncFolderTest.PerformTestReally() Exception details: Message: The remote server returned an error: (501) Not Implemented. Type: System.Net.WebException Stack trace:    at System.Net.HttpWebRequest.GetResponse()    at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.Microsoft.Exchange.WebServices.Data.IEwsHttpWebRequest.GetResponse()    at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request) Elapsed Time: 7897 ms.

Is this a concern to rectify? Where should I start checking?

Thanks and Regards,

Low

Hi Low,

Thank you for your question.

This issue was occurred by KEMP LB.

When the LoadMaster operates at full Layer 7, requests sent to Client Access Servers (CAS) can have two additional headers inserted automatically. These are the X-Forwarded-For and Via headers which inform the server of the IP address of the client and the IP address of the service respectively. The via header is used by proxies to indicate to servers that there may be a hop in between. The presence of this header causes the CAS to set the 'Persistent-Auth' header to 'false'. Ordinarily this would be fine - it would simply require each request to be sent with credentials rather than once per connection. Occasionally this is a problem because the Mac Mail application does not always re-send the credentials.

To resolve this issue, you can create a rule in the LoadMaster to delete this header:

1. In the main menu of the LoadMaster Web User Interface (WUI), select Rules & Checking and Content Rules.
2.        Click Create New
3.        Enter a recognizable Rule Name, for example Remove_Via.
4.        Select Delete Header as the Rule Type.
5.        Enter Via as the Header Field to be Deleted.
6.        Click Create Rule.
7.        In the main menu, select Virtual Services and View/Modify Virtual Services.
8.        Click Modify on the relevant Virtual Service.
9.        Expand the Advance Properties section.
10.    Click Show Header Rules.
11.    Add the relevant rule as a request rules.

After the rule has been created and assigned to the Virtual Service, the via header will be deleted going forward.

If there are any questions regarding this issue, please be free to let me know. 

Best Regard,

Jim

Hi Jim,

Wow, I am amazed by your reply, looks like its a known issue when using KEMP LB on EWS huh?

Alright I will try to check with my KEMP support and discuss on this with them.

Thanks for advice!

Thanks and Regards,

Low