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Oracle® VM Server for SPARC 3.6 Administration Guide

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Updated: September 2019
 
 

Configuring Jumbo Frames

The Oracle VM Server for SPARC virtual switch (vsw) and virtual network (vnet) devices can now support Ethernet frames with payload sizes larger than 1500 bytes. These drivers are therefore now able to increase network throughput.

You enable jumbo frames by specifying the maximum transmission unit (MTU) for the virtual switch device. In such cases, the virtual switch device and all virtual network devices that are bound to the virtual switch device use the specified MTU value.

If the required MTU value for the virtual network device should be less than that supported by the virtual switch, you can specify an MTU value directly on a virtual network device.


Note - Only on the Oracle Solaris 10 5/09 OS, the MTU of a physical device must be configured to match the MTU of the virtual switch. For information about configuring particular drivers, see the man page that corresponds to that driver in Section 7D of the Oracle Solaris reference manual. For example, to obtain information about the Oracle Solaris 10 nxge driver, see the nxge(7D) man page.

In rare circumstances, you might need to use the ldm add-vnet or ldm set-vnet command to specify an MTU value for a virtual network device that differs from the MTU value of the virtual switch. For example, you might change the virtual network device's MTU value if you configure VLANs over a virtual network device and the largest VLAN MTU is less than the MTU value on the virtual switch.

If you use the ldm set-vnet command to specify an mtu value on a virtual network device, future updates to the MTU value of the virtual switch device are not propagated to that virtual network device. To re-enable the virtual network device to obtain the MTU value from the virtual switch device, run the following command:

primary# ldm set-vnet mtu= vnet-name domain-name

On the control domain, the Logical Domains Manager updates the MTU values that are initiated by the ldm set-vsw and ldm set-vnet commands as delayed reconfiguration operations. To make MTU updates to domains other than the control domain, you must stop a domain prior to running the ldm set-vsw or ldm set-vnet command to modify the MTU value.

How to Configure Virtual Network and Virtual Switch Devices to Use Jumbo Frames

  1. Log in to the control domain.
  2. Become an administrator.

    For Oracle Solaris 11.4, see Chapter 1, About Using Rights to Control Users and Processes in Securing Users and Processes in Oracle Solaris 11.4.

  3. Determine the value of MTU that you want to use for the virtual network.

    You can specify an MTU value up to 16000 bytes. The specified MTU must match the MTU of the physical network device that is assigned to the virtual switch.

    Use the ldm list-netdev -l command to obtain the MTU value of the physical network device.

    primary# ldm list-netdev -l -o net0 primary
    
    DOMAIN
    primary
    
    NAME CLASS   MEDIA  STATE  SPEED OVER LOC
    ---- -----   -----  -----  ----- ---- ---
    net0 PHYS    ETHER  up     1G    igb0 /SYS/RIO/NET0
         [/pci@400/pci@1/pci@0/pci@2/network@0]
         MTU       : 1500 [60-9216]
         IPADDR    : 10.129.68.118/255.255.255.0
                   : fe80::210:e0ff:fe0e:e0c0/ffc0::
                   : 2606:b400:418:17b2:210:e0ff:fe0e:e0c0/ffff:ffff:ffff:ffff::
         MAC_ADDRS : 00:10:e0:0e:e0:c0
  4. Specify the MTU value of a virtual switch device or virtual network device.

    Do one of the following:

    • Enable jumbo frames on a new virtual switch device in the service domain by specifying its MTU as a value of the mtu property.

      primary# ldm add-vsw net-dev=device mtu=value vswitch-name ldom

      In addition to configuring the virtual switch, this command updates the MTU value of each virtual network device that will be bound to this virtual switch.

    • Enable jumbo frames on an existing virtual switch device in the service domain by specifying its MTU as a value of the mtu property.

      primary# ldm set-vsw net-dev=device mtu=value vswitch-name

      In addition to configuring the virtual switch, this command updates the MTU value of each virtual network device that will be bound to this virtual switch.

Example 51  Configuring Jumbo Frames on Virtual Switch and Virtual Network Devices

The following example shows how to add a new virtual switch device that uses an MTU value of 9000. This MTU value is propagated from the virtual switch device to all of the client virtual network devices.

First, the ldm add-vsw command creates the virtual switch device, ldg1-vsw0, with an MTU value of 9000. Note that the network device net0 is specified as a value of the net-dev property.

primary# ldm add-vsw net-dev=net0 mtu=9000 ldg1-vsw0 ldg1

Next, the ldm add-vnet command adds a client virtual network device to this virtual switch, ldg1-vsw0. Note that the MTU of the virtual network device is implicitly assigned from the virtual switch to which it is bound. As a result, the ldm add-vnet command does not require that you specify a value for the mtu property.

primary# ldm add-vnet vnet01 ldg1-vsw0 ldg1

    Depending on the version of the Oracle Solaris OS that is running, do the following:

  • Oracle Solaris 11 OS: Use the ipadm command to view the mtu property value of the primary interface.

    # ipadm show-ifprop -p mtu net0
    IFNAME PROPERTY PROTO PERM CURRENT PERSISTENT DEFAULT POSSIBLE
    net0   mtu      ipv4  rw   9000    -- 	      9000    68-9000

    The ipadm command creates the virtual network interface in the guest domain, ldg1. The ipadm show-ifprop command output shows that the value of the mtu property is 9000.

    ldg1# ipadm create-ip net0
    ldg1# ipadm create-addr -T static -a 192.168.1.101/24 net0/ipv4
    ldg1# ipadm show-ifprop -p mtu net0
    IFNAME PROPERTY PROTO PERM CURRENT PERSISTENT DEFAULT POSSIBLE
    net0   mtu      ipv4  rw   9000    --         9000    68-9000
  • Oracle Solaris 10 OS: The ifconfig command creates the virtual network interface in the guest domain, ldg1. The ifconfig vnet0 command output shows that the value of the mtu property is 9000.

    ldg1# ifconfig vnet0 plumb
    ldg1# ifconfig vnet0 192.168.1.101/24 up
    ldg1# ifconfig vnet0
    vnet0: flags=201000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4,CoS> mtu 9000 index 4
            inet 192.168.1.101 netmask ffffff00 broadcast 192.168.1.255
            ether 0:14:4f:f9:c4:13
Example 52  Changing the MTU Value of a Network Interface

The following example shows how to change the MTU value of the network interface to 4000.

Note that the MTU of an interface can only be changed to a value that is less than the MTU of the device that is assigned by the Logical Domains Manager. This method is useful when VLANs are configured and each VLAN interface requires a different MTU.

  • Oracle Solaris 11 OS: Use the ipadm command.

    primary# ipadm set-ifprop -p mtu=4000 net0
    primary# ipadm show-ifprop -p mtu net0
    IFNAME PROPERTY PROTO PERM CURRENT PERSISTENT DEFAULT POSSIBLE
    net0   mtu      ipv4  rw   4000    --         9000    68-9000
  • Oracle Solaris 10 OS: Use the ifconfig command.

    primary# ifconfig vnet0 mtu 4000
    primary# ifconfig vnet0
    vnet0: flags=1201000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4,CoS,FIXEDMTU>
    mtu 4000 index 4
            inet 192.168.1.101 netmask ffffff00 broadcast 192.168.1.255
            ether 0:14:4f:f9:c4:13