Improve Vista and Windows 7 networking

A lot of discussion is always heard when ‘we’ talking about our tweaks for networking.

We have found with several networks and not just our own that disabling LLMNR (Link-Local Multicast Name Resolution)  improves network speed.

Information on LLMNR –

Link-local Multicast Name Resolution (LLMNR) is a new protocol that provides an additional method to resolve the names of neighboring computers. LLMNR is especially useful for networks that do not have a Domain Name System (DNS) server. LLMNR uses a simple exchange of request and reply messages to resolve computer names to Internet Protocol version 6 (IPv6) or IP version 4 (IPv4) addresses…more

If you use LLMNR and have a local DNS server and have network discovery on, LLMNR can work.  If you want to check to see, A LLMNR data pack is sent via a dynamic UDP port. The destination port is UDP 5355.  Therefore you can see or should see these packets if you monitor your network with Wireshark, Packetyzer , Microsoft’s Monitor or other analyzers.

Many users are reporting resolution problems and LLMNR can be disabled.  Performance increases are seen in many networks especially with SQL servers.

However, you can disable LLMNR if you are having name resolution problems with computers by –

Modify Group Policy – Go to Search – Type GPEdit.msc – Enter – Navigate to the following and make sure Enabled is checked –

Computer Configuration\Administrative Templates\Network\DNS Client
\Turn off Multicast Name Resolution = Enabled


To further optimize your network and speeds, you can also experiment with trying these settings at an elevated prompt –

netsh int tcp set heuristics disabled
netsh int tcp set heuristics disabled
netsh int tcp set global rss=enabled
netsh int tcp set global chimney=enabled
netsh int tcp set global autotuninglevel=normal
(netsh interface tcp set global autotuninglevel=highlyrestricted ) This will set the autotuninglevel to “Allow the receive window to grow beyond its default value, but do so very conservatively” and my be a better option than the ‘normal setting.

netsh int tcp set global congestionprovider=ctcp
netsh int tcp set global ecncapability=disabled
netsh int tcp set global timestamps=disabled

To return to your default settings, go to a command prompt as an administrator and type –

netsh int tcp set heuristics default
netsh int tcp set global rss=default
netsh int tcp set global chimney=default
netsh int tcp set global autotuninglevel=normal
netsh int tcp set global congestionprovider=default
netsh int tcp set global ecncapability=default
netsh int tcp set global timestamps=default

So what is heuristics?  Windows Vista/7 has the ability to automatically change its own TCP Window auto-tuning behavior.

What is RSS?  The receive-side scaling setting enables parallelized processing of received packets on multiple processor.

What is Chimney?  TCP chimney offloading enables Microsoft Windows Vista or Windows 7 to offload all TCP processing for a connection to a network adapter.

What is autotuning?  Uses a fixed value for the tcp receive window. Limits it to 64KB (limited at 65535)


Don’t forget that tweaking your MTU settings can make a difference.

(The MTU (Maximum Transmission Unit) is the size of the largest datagram that can be sent over a network. If a datagram is larger than an MTU, the datagram must be fragmented into multiple smaller datagrams.)

So what do you set your MTU to?  Normally your MTU is set to 1500.   Every connection is different.  First log into your router if you have one and set it to 1492.  Retry the sites that are timing out.  If this did not work, you may need to set the MTU on your network card (in the operating system)

How to set the MTU in Vista and Windows 7 –

netsh interface ipv4 show subinterface

(to see the name of your network Interface – it is important to write down the MTU settings and network interface name at this time)

To set the MTU value to 1492, type the following command at a a command prompt (Note: You MUST substitute the name of your network connection  –

netsh interface ipv4 set subinterface “The Name of Your Connection” mtu=1492 store=persistent

Many users have reported an increase in download and internet speeds after adjusting their MTU to 1492.

So what are some sizes for MTU?

 Ethernet                   1500
 IEEE 802.3/802.2           1492
 PPPoE (WAN Miniport)       1480

This setting  may not be the optimal setting everyone.


Link Aggregation

There is truly an advantage to adding multiple NIC cards to a computer.   It won’t speed up a single internet connection but it can help with loss of signal, detecting access points, transferring information to and  from computers.

When adding a second NIC card to a computer, you can highlight both by holding down the CTRL key and clicking on them and then right clicking to bridge the connections so they act as one…this can allow you to bridge a wireless network to a wired network or to aggregate more than one wired card.


Of course making sure that bitorrents, and other network bandwidth hogs are not on your network will greatly increase the speed. Another tip to remember is that a quality network card also makes a huge difference.

Disabling LLMNR (Below)

Professional or Enterprise (Gpedit.msc)

Home Edition

Create a registry key as follows –

A few more tips….(Best tip – Step 6!)

Do you have a computer that responds slow on the network or hesitates?  Follow these steps and you will see a significant difference. (Because we have not shown how to disable advanced settings in your network card, simply go to your device manager and double click on your network card – disable TCP offload and any advanced settings such as proxy and other settings that may make the card hesitate)

  1. Remove any add-ins on your Browsers that you don’t need
  2. Remove Toolbars
  3. Adjust your MTU Settings
  4. Adjust your Network Speed
  5. Disable LLMNR
  6. Disable all advanced settings on your card
Advanced settings example

About TCAT Shelbyville IT Department

The Tennessee College of Applied Technology - is one of 46 institutions in the Tennessee Board of Regents System, the seventh largest system of higher education in the nation. This system comprises six universities, fourteen community colleges, and twenty-six Applied Technology Colleges.
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One Response to Improve Vista and Windows 7 networking

  1. Pingback: My 7 Links Challenge « TTC Shelbyville – Technical Blog

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