Archive for ‘Networking’

December 1st, 2009

Building a SharePoint 2007/2010 development environment – Part VI: Issues and Results

by Tristan Watkins

In the first five parts of this series I covered the project objectives and the system design, then turned my attention to the Hyper-V host image build, automated deployment and the guest virtual machine build. In this post I review some of the questions and issues we’ve encountered after a few months of working this way and some overall reflections on the approach. read more »

October 23rd, 2009

More on routine loss of external network connectivity on Hyper-V hosts (not guests)

by Tristan Watkins

Further to my post from a few months ago on the this topic (dating back to the RC build), I’ve seen this same problem a few more times on the RTM build of Windows Server 2008 R2. My suggested approach still fixes the problem and it doesn’t recur, but I’ve still not been able to pin down a cause and I can find no documentation on host machine MAC assignments anywhere. read more »

September 29th, 2009

Disabling IPv6 on Server Core and Hyper-V Server

by Tristan Watkins

Note: this original KB article from which this guidance was taken has now been removed. Please see the comments below for more information.

I recently posted about the Conflicting Microsoft guidance on IPv6. While you can remove IPv6 from a NIC on a full installation of Windows Server 2008 by un-ticking the IPv6 box in the NIC properties (satisfying the Hyper-V performance guidance), you may have noticed that there’s no obvious way to disable IPv6 in server core or Hyper-V Server. If you looked in to it in a bit more detail you may have noticed a registry “fix” for this. Personally I’m always a bit skeptical of registry fixes until I see Microsoft recommending them, but now Tonyso has posted a link to a Microsoft KB article that endorses this approach (when necessary):

To completely disable IPv6 on a Windows Server 2008-based computer yourself, follow these steps:

  1. Open Registry Editor.
  2. Locate the following registry subkey:
    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip6\Parameters
  3. In the details pane, click New, and then click DWORD (32-bit) Value.
  4. Type DisabledComponents, and then press ENTER.
  5. Double-click DisabledComponents, and then type 0xffffffff in Hexadecimal or 4294967295 in Decimal.Note The 0xffffffff value or the 4294967295 value disables all IPv6 components except for the IPv6 loopback interface.

A reboot is required before the change will take effect.

September 17th, 2009

Conflicting guidance on IPv6

by Tristan Watkins

I recently noticed that Cable Guy is saying “don’t disable IPv6“. While I broadly agree with the approach and the reasons he suggests not to, I’ve not yet seen any down-side to disabling it, and I know we aren’t using the IPv6 technologies that Cable Guy mentions. But why did I turn it off? SharePoint’s Hyper-V performance and capacity guidance suggests that performance is improved by disabling it.

Use IPv4 as the network protocol for Hyper-V guests. During the tests, better performance was observed when IPv4 was used exclusively. IPv6 was disabled on each network card for both the Hyper-V host and its guest VMs.”

In this case, I’m going with the SharePoint guys, especially when there’s a quantified test versus a theory, especially when it simplifies troubleshooting and not everyone is IPv6-fluent yet.

August 26th, 2009

Windows Deployment Services trumps Internet Connection Sharing

by Tristan Watkins

I imagine the responses to this post’s title will fall in to one of three categories:

  • What’s Windows Deployment Services?
  • What’s Internet Connection Sharing?
  • Why on earth would you use both in one machine?

To answer the last question I need to unveil a bit about the network approach that we’ve adopted for the Hyper-V on Windows Server 2008 R2 laptop build that I mentioned in my last post. read more »

August 25th, 2009

Routine loss of connectivity on a Hyper-V host’s external connection

by Tristan Watkins

We’ve recently been piloting a laptop developer build on Windows Server 2008 R2 Release Candidate (Build 7100) with the Hyper-V role. One of the first receipients of this build complained of connectivity problems in Office Communicator once every minute or two. For as-yet undiagnosed reasons we have lengthy sign-in times for Communicator, so this loss of connectivity rendered it completely unusable. This same problem was visible in Outlook, although less disruptive since we use Cached Exchange Mode. Both Exchange and the OCS server are hosted but we also noticed the problem with interrupted file transfers so it clearly wasn’t just an internet connectivity issue. It looked like something to do with the NIC, the cable or a network device.

The network trouble was accompanied by a series of System log event errors from MVSMP:

Port ‘SWITCHPORT-SM-F277C685-E5F8-490D-8CD1-913B854FABD2-0-1′ was prevented from using MAC address ’00-15-C5-7E-EB-39′ because it is pinned to port ‘SWITCHPORT-SM-F277C6′. read more »

August 24th, 2009

Hyper-V Manager over VPN may fail if the server is VMM-managed

by Tristan Watkins

About a year ago John Howard published guidance on how to get Hyper-V Manager to connect to Hyper-V servers over VPN. His network monitoring and suggestion to change the VPN connection IP settings so that the VPN adapter registers the machine’s new address in DHCP/DNS went a long way towards fixing the issue  for me – however, we recently uncovered a couple of caveats as detailed in the comments on his original post. read more »