Tiny Deathstars of Foulness

When we transfer certain amounts of data in a packet we might cause that packet to fragment. The less fragmentations without requiring a collision or a re-send of a packet, the more efficient network traffic can be. The MTU defines the packet size. Different types of data or network links respond differently. To change the MTU on a Windows Server we’re going to use the netsh command. First, we’re going to use ping to ping a host on our network, using -f and then -l which allows us to define the MTU size. In this case we’re going to use 1500:

ping -f -l 1500

We should get an error:

Packet needs to be fragmented but DF set.

Now, let’s try

ping -f -l 1464

Now, let’s look at the interfaces along with what the current MTU is on each:

netsh interface ipv4 show interfaces

Then, let’s make the mtu 1464 persistently using the Idx number of the interface to change from the above command in quotes:

netsh interface ipv4 set subinterface "10" mtu=1464 store=persistent

September 17th, 2013

Posted In: Microsoft Exchange Server, Network Infrastructure, Windows Server

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