Enabling Jumbo Frames on Windows Server 2012 R2 using PowerShell and on Cisco 3560G using IOS commands.

Jumbo frames are Ethernet frames with a payload greater than the standard mtu of 1500. Increasing the mtu size on a 1 GB network usually improves network performance and efficiency.The following PowerShell cmdlets will help display and check current jumbo frame values and edit them.The maximum value of a Jumbo frame on an Ethernet adapter varies depending on the network adapter brand.

I have a Windows Server 2012R2 with four NICs in a team. After setting the Jumbo frame values at the individual NICs, they should be inherited by the NIC team adapter.The Advanced Properties of the NICs are displayed below:

Jumbo1

The Get-NetAdapterAdvancedProperty -Name nic2 cmdlet displays the current Jumbo frame value of NIC2 in the team:

Jumbo2

My attempt to set the Jumbo frame value on this NIC to 9014 failed, with the following error message “the value must be within the range 1500-9000” as indicated :

Jumbo3

Set the new value to 9000:

Get-NetAdapterAdvancedProperty -Name nic2 -RegistryKeyword "*jumbopacket" | Set-NetAdapterAdvancedProperty -RegistryValue 9000

The new value is shown in the following screen shot:

Jumbo4

I completed the same configuration on the remaining team NICs.To optimize performance on the network and take full advantage of this configuration, the next logical step in the process is to configure the corresponding Cisco switch port for Jumbo frames.

By default, the switch and it’s gigabit ports/interfaces are set to the standard 1500 mtu. As indicated in the following command :

L3Switch#sh system mtu

System MTU size is 1500 bytes
System Jumbo MTU size is 1500 bytes
Routing MTU size is 1500 bytes

This could also be verified by using the sh run command as shown below:

L3Switch#sh running-config
Building configuration...

Current configuration : 3666 bytes
!
version 12.2
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
service password-encryption
!
hostname L3Switch
!
boot-start-marker
boot-end-marker
!
enable secret 5 $1$w7It$7sxFdFRIbKR7zfDZeYJq2/
!
no aaa new-model
clock timezone CST -5
system mtu routing 1500

And the sh interfaces gigabitEthernet0/21 command for a specific interface:

L3Switch#sh interfaces gigabitEthernet0/21
GigabitEthernet0/21 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is 64d8.148e.8015 (bia 64d8.148e.8015)
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255

Configure Jumbo Frame values on the Cisco Gigabit switch globally:

L3Switch#config t
Enter configuration commands, one per line. End with CNTL/Z.
L3Switch(config)#system mtu jum
L3Switch(config)#system mtu jumbo ?
Jumbo MTU size in bytes
L3Switch(config)#system mtu jumbo 9000 ?

L3Switch(config)#system mtu jumbo 9000
Changes to the system jumbo MTU will not take effect until the next reload is done
L3Switch(config)#^Z
L3Switch#
*Mar 1 00:23:12.967: %SYS-5-CONFIG_I: Configured from console by console
L3Switch#reload

System configuration has been modified. Save? [yes/no]: y
Building configuration...
[OK]
Proceed with reload? [confirm]

After reload, verify Jumbo Frame settings have taken effect:

L3Switch#sh system mtu

System MTU size is 1500 bytes
System Jumbo MTU size is 9000 bytes
Routing MTU size is 1500 bytes

Verify the settings for a specific interface:

L3Switch#sh interfaces gigabitEthernet0/21
GigabitEthernet0/21 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet, address is 64d8.148e.8015 (bia 64d8.148e.8015)
MTU 9000 bytes, BW 10000 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255

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This entry was posted in Jumbo Frames, Network, Powershell 4.0 and tagged , , , . Bookmark the permalink.

2 Responses to Enabling Jumbo Frames on Windows Server 2012 R2 using PowerShell and on Cisco 3560G using IOS commands.

  1. Mike Lewis says:

    on average, percentage wise, how much of an increase in perf do you see from enabling jumbo frames?

  2. eldigital911 says:

    On average, approx what percentage of perf gain do you see by simply switching to jumbo frames?

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