Set the MTU for your Amazon EC2 instances - Amazon Elastic Compute Cloud
Check the path MTU between two hostsCheck the MTU for your instanceSet the MTU for your instance

Set the MTU for your Amazon EC2 instances

The maximum transmission unit (MTU) of a network connection is the size, in bytes, of the largest permissible packet that can be passed over the connection. All Amazon EC2 instances support standard frames (1500 MTU) and all current generation instance types support jumbo frames (9001 MTU).

You can view the MTU for your Amazon EC2 instances, view the path MTU between your instance and another host, and configure your instances to use either standard or jumbo frames.

Check the path MTU between two hosts

You can check the path MTU between your EC2 instance and another host. You can specify a DNS name or an IP address as the destination. If the destination is another EC2 instance, verify that its security group allows inbound UDP traffic.

The procedure that you use depends on the operating system of the instance.

Run the tracepath command on your instance to check the path MTU between your EC2 instance and the specified destination. This command is part of the iputils package, which is available by default in many Linux distributions.

This example checks the path MTU between the EC2 instance and amazon.com.

[ec2-user ~]$ tracepath amazon.com

In this example output, the path MTU is 1500.

 1?: [LOCALHOST]     pmtu 9001
 1:  ip-172-31-16-1.us-west-1.compute.internal (172.31.16.1)   0.187ms pmtu 1500
 1:  no reply
 2:  no reply
 3:  no reply
 4:  100.64.16.241 (100.64.16.241)                          0.574ms
 5:  72.21.222.221 (72.21.222.221)                         84.447ms asymm 21
 6:  205.251.229.97 (205.251.229.97)                       79.970ms asymm 19
 7:  72.21.222.194 (72.21.222.194)                         96.546ms asymm 16
 8:  72.21.222.239 (72.21.222.239)                         79.244ms asymm 15
 9:  205.251.225.73 (205.251.225.73)                       91.867ms asymm 16
...
31:  no reply
     Too many hops: pmtu 1500
     Resume: pmtu 1500
To check path MTU using mturoute

  1. Download mturoute.exe to your EC2 instance from http://www.elifulkerson.com/projects/mturoute.php.

  2. Open a Command Prompt window and change to the directory where you downloaded mturoute.exe.

  3. Use the following command to check the path MTU between your EC2 instance and the specified destination. This example checks the path MTU between the EC2 instance and www.elifulkerson.com.

    .\mturoute.exe www.elifulkerson.com

    In this example output, the path MTU is 1500.

    * ICMP Fragmentation is not permitted. *
* Speed optimization is enabled. *
* Maximum payload is 10000 bytes. *
+ ICMP payload of 1472 bytes succeeded.
- ICMP payload of 1473 bytes is too big.
Path MTU: 1500 bytes.

Check the MTU for your instance

You can check the MTU value for your instance. Some instances are configured to use jumbo frames, and others are configured to use standard frame sizes.

The procedure that you use depends on the operating system of the instance.

To check the MTU setting on a Linux instance

Run the following ip command on your EC2 instance. If the primary network interface is not eth0, replace eth0 with your network interface.

[ec2-user ~]$ ip link show eth0

In this example output, mtu 9001 indicates that the instance uses jumbo frames.

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 9001 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 02:90:c0:b7:9e:d1 brd ff:ff:ff:ff:ff:ff

The procedure that you use depends on the driver on your instance.

ENA driver
Version 2.1.0 and later

To get the MTU value, use the following Get-NetAdapterAdvancedProperty command on your EC2 instance. Use the wildcard (asterisk) to get all Ethernet names. Check the output for the interface name *JumboPacket. A value of 9015 indicates that Jumbo frames are enabled. Jumbo frames are disabled by default.

Get-NetAdapterAdvancedProperty -Name "Ethernet*"
Version 1.5 and earlier

To get the MTU value, use the following Get-NetAdapterAdvancedProperty command on your EC2 instance. Check the output for the interface name MTU. A value of 9001 indicates that Jumbo frames are enabled. Jumbo frames are disabled by default.

Get-NetAdapterAdvancedProperty -Name "Ethernet"
Intel SRIOV 82599 driver

To get the MTU value, use the following Get-NetAdapterAdvancedProperty command on your EC2 instance. Check the entry for the interface name *JumboPacket. A value of 9014 indicates that Jumbo frames are enabled. (Note that the MTU size includes the header and the payload.) Jumbo frames are disabled by default.

Get-NetAdapterAdvancedProperty -Name "Ethernet"
AWS PV driver

To get the MTU value, use the following command on your EC2 instance. The name of the interface can vary. In the output, look for an entry with the name "Ethernet," "Ethernet 2," or "Local Area Connection". You'll need the interface name to enable or disable jumbo frames. A value of 9001 indicates that Jumbo frames are enabled.

netsh interface ipv4 show subinterface

Set the MTU for your instance

You might want to use jumbo frames for network traffic within your VPC and standard frames for internet traffic. Whatever your use case, we recommend that you verify that your instance behaves as expected.

The procedure that you use depends on the operating system of the instance.

To set the MTU value on a Linux instance

  1. Run the following ip command on your instance. It sets the desired MTU value to 1500, but you could use 9001 instead.

    [ec2-user ~]$ sudo ip link set dev eth0 mtu 1500

  2. (Optional) To persist your network MTU setting after a reboot, modify the following configuration files, based on your operating system type.

    • For Amazon Linux 2, add the following line to the /etc/sysconfig/network-scripts/ifcfg-eth0 file:

      MTU=1500

      Add the following line to the /etc/dhcp/dhclient.conf file:

      request subnet-mask, broadcast-address, time-offset, routers, domain-name, domain-search, domain-name-servers, host-name, nis-domain, nis-servers, ntp-servers;

    • For Amazon Linux AMI, add the following lines to your /etc/dhcp/dhclient-eth0.conf file.

      interface "eth0" {
supersede interface-mtu 1500;
}

    • For other Linux distributions, consult their specific documentation.

  3. (Optional) Reboot your instance and verify that the MTU setting is correct.

The procedure that you use depends on the driver on your instance.

ENA driver

You can change the MTU using Device Manager or the Set-NetAdapterAdvancedProperty command on your instance.

Version 2.1.0 and later

Use the following command to enable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "*JumboPacket" -RegistryValue 9015

Use the following command to disable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "*JumboPacket" -RegistryValue 1514
Version 1.5 and earlier

Use the following command to enable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "MTU" -RegistryValue 9001

Use the following command to disable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "MTU" -RegistryValue 1500
Intel SRIOV 82599 driver

You can change the MTU using Device Manager or the Set-NetAdapterAdvancedProperty command on your instance.

Use the following command to enable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "*JumboPacket" -RegistryValue 9014

Use the following command to disable jumbo frames.

Set-NetAdapterAdvancedProperty -Name "Ethernet" -RegistryKeyword "*JumboPacket" -RegistryValue 1514
AWS PV driver

You can change the MTU using the netsh command on your instance. You can't change the MTU using Device Manager.

Use the following command to enable jumbo frames.

netsh interface ipv4 set subinterface "Ethernet" mtu=9001

Use the following command to disable jumbo frames.

netsh interface ipv4 set subinterface "Ethernet" mtu=1500