Category Archives: Technical Articles

MTU Size for Comcast with Vocalocity VoIP Service

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While working with Comcast tech support on Internet issues at a client’s site we were told to change the MTU size on the WAN interface of the client’s firewall to 1492. Comcast engineer claimed this setting will provide for fewer VoIP voice-quality issues with Comcast Internet services.

I thought I’d pass the information along to those who may be experiencing voice-quality issues with Internet-hosted VoIP services and have Comcast as their Internet Service Provider.

Facts:
ISP: Comcast Business
Hosted VoIP Provider: Vocalocity / Vonage Business Solutions
Firewall: SonicWALL TZ200

———————

Cheers

Windows Server 2012 Domain Controller & RemoteApps, No More

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I recently migrated a client from Windows Server 2003 to 2012. Knowing what I know about Windows Server 2008 RDS and RemoteApps I thought I’d take the same approach. Microsoft has made many improvements to Remote Desktop Services in Windows 2012 but with that, I soon discovered, they dropped the ability to host RemoteApps in environments with single server running Active Directory Domain Services Role.

Basically, small business organizations with single server wanting to take advantage of Active Directory authentication and RemoteApps are out of luck.

Though, all is not lost. If you forgo RemoteApps you may install Remote Desktop Licensing and Remote Desktop Session Host roles on a Domain Controller, which will allow you to provide Remote Desktop Services in the environment, minus RemoteApps.

So if you find yourself in my situation check-out the following Microsoft KB article on how to deploy Windows Server 2012 RDS on servers running Active Directory Domain Services http://support.microsoft.com/kb/2833839

Cheers!

How to Forcibly Remove DHCP Failover Partner in Windows Server 2012

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Hello folks,

Ivailo here to talk about the new DHCP failover feature in Windows Server 2012. A real failover is finally possible. Split scopes are things of the past. Now it’s possible to configure DHCP partners in “Hot Standby” and “Load Balance” mode. Configuring DHCP failover is outside of the scope of this blog.

I would like to show you haw to forcibly remove a failed failover partner. I recently had to do this for a customer. The primary DHCP server was for some reason configured with invalid IP address (169.254.84.126) as a partner. That was not my install so I don’t have an explanation as to how this happened. In order to remove a partner in the DHCP manager the two servers have to be able to talk to each other. If one of the servers is unavailable the removal will fail. The following command can be used to force the removal of the partner:

Remove-DhcpServerv4Failover -ComputerName <server name> -Name <name of the failover partnership> -force

 

Ivailo Mitkov

How to configure an authoritative time server in Windows Server 2012

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Hello folks,

Ivailo here to talk about setting up an NTP on a PDCe. Remember this http://support.microsoft.com/kb/816042?wa=wsignin1.0? The MS tool on the page used to work like a charm. Unfortunately even though according to the “Applies to” it should work on Windows Server 2012 – it doesn’t. Of course one can follow the instructions how to configure NTP manually but I am doing this way too often for my customers so I decided to save few minutes the next time I need to configure NTP on a PDCe. This is why I created the following registry hack that can be applied simply by double clicking on it. Of course you can also apply the settings using the following command…

w32tm /config /syncfromflags:manual /manualpeerlist:”<Server1>,0x1 <Server2>,0x1 <Server3>,0x1″ /update /reliable:yes

…but it will only change the AnnounceFlags, Type, and the source and leave all intervals intact which is not a best practice.

Copy the text bellow including “Windows Registry Editor Version 5.00” and paste in your favorite text editor (notepad will work)! Change the time sources depending on the server physical location (in my case US). Append 0x1 to each server and separate multiple servers with space! Save the file (for example NTPConfiguration.reg)!

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Config]
“MaxNegPhaseCorrection”=dword:00000e10
“MaxPosPhaseCorrection”=dword:00000e10
“AnnounceFlags”=dword:00000005

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\Parameters]
“NtpServer”=”0.us.pool.ntp.org,0x1 1.us.pool.ntp.org,0x1 2.us.pool.ntp.org,0x1 3.us.pool.ntp.org,0x1”
“Type”=”NTP”

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpClient]
“SpecialPollInterval”=dword:00000384

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer]
“Enabled”=dword:00000001

 

Restart the time service:

net stop w32time && net start w32time

 

Ivailo Mitkov

VMware ESXi 5 VM reset stuck at 95%

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Hi folks,
Ivailo here to talk about a problem I had few days ago. While I was working on a customer’s server running a VM on ESXi 5.0, the VM froze so I had to forcibly reset it. When I did so, the reset task got stuck at 95%. I did some digging and found few threads talking about the same issue but they were all for ESXi 4. I had to do some additional research and modify the commands in order to make them work on ESXi 5. Bellow are the steps that resolved my problem:

  1. With vSphere Client, connect to the host or the VC server that controls the host.
  2. Click on the host and go to the Configuration tab.
  3. Click on Security Profile.
  4. Click on Properties in the Services table.
  5. Start ESXi Shell and SSH services.
  6. Open a SSH session to the host.
  7. Execute /sbin/services.sh restart. This will restart all agents. The vSphere Client or the vCenter server will lose connection to the host. Reconnect! The VM may show as (invalid).
  8. Find the PID of the process by typing ps|grep “<VMName>”. The second number before the name of the VM is the PID.
  9. Kill the process by typing kill -9 <PID>.
  10. Go to /vmfs/volumes/<DataStoreName>/<VMName>.
  11. Delete the swap file by typing rm –r <SwappFileName.vswp>
  12. In vSphere Client right click the VM and select Remove From Inventory.
  13. Browse the data store, open the VM folder, right click on the .vmx file and select Add to Inventory.
  14. Power On the VM.

Hope this helps.

Ivailo Mitkov