Using Jumbo frames with Private Networking

Description

How to use Jumbo frames with Private networking


Contents

Description

LeaseWeb Private Networking supports Jumbo frames with sizes up to 9k (9000 bytes). By default, a network interface's Maximum Transmission Unit (MTU) will be limited to 1500 byte frames. This article describes how to increase this limit on common operating systems.

Linux

Checking the current MTU

To check the current MTU of an interface, run the ip link show eth1 command, where eth1 is the interface that is connected to the LeaseWeb Private network:

me@myserver:~$ ip link show dev eth1
3: eth1: <BROADCAST,MULTICAST,SLAVE,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP mode DEFAULT group default qlen 1000
    link/ether 00:11:22:33:44:55 brd ff:ff:ff:ff:ff:ff

In this example, mtu 1500 indicates the current MTU of this interface is 1500 bytes.

Debian and Ubuntu

The network configuration is stored in /etc/networking/interfaces. Edit this file and add a line with: "mtu 9000".

auto eth1
iface eth1 inet dhcp
        mtu 9000

For the changes to take effect, cycle the interface using the command ifdown eth1; ifup eth1

CentOS

The network configuration is stored in /etc/sysconfig/network-script/ifcfg-eth1. Edit this file and add a line with "MTU=9000".

MTU=9000

For the changes to take effect, cycle the interface using the command ifdown eth1; ifup eth1

BSD

Checking the current MTU

To check the current MTU of an interface, run the ifconfig em1 command, where em1 is the interface that is connected to the LeaseWeb Private network:

em1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500
        options=c019b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,TSO4,VLAN_HWTSO,LINKSTATE>
        ether 11:22:33:44:55:66
        inet 0.0.0.0 netmask 0xff000000 broadcast 255.255.255.255
        nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL>
        media: Ethernet autoselect (1000baseT <full-duplex>)
        status: active

In this example, mtu 1500 indicates the current MTU of this interface is 1500 bytes.

Changing the MTU

The network configuration is stored in /etc/rc.conf or /etc/rc.conf.d/network. Edit this file and add "mtu 9000" to the "ifconfig_em1" line.

ifconfig_em1="DHCP mtu 9000"

For the changes to take effect, use the command ifconfig em1 mtu 9000

Windows

In Windows the MTU of a network interface can be changed from the "Advanced" tab of a network interface's properties:

Depending on the model, the property may be named "Jumbo Packet", "MTU", "Ethernet Frame size", or something similar.

VMware ESXi

Please refer to the documentation of VMware:



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