HP Integrity Virtual Machines Release Notes
7.7 Do Not Turn on TSO on the VM Host and on HP-UX Guests
TCP Segmentation Offload (TSO) is turned off by default in HP-UX. HP recommends that you
leave it turned off on both the VM Host system and on HP-UX guests. This applies to both the
virtual network interface cards in the guest and any physical network interface cards in the VM
Host that are used by vswitches. When TSO is enabled, guest networks are interrupted.
To verify whether TSO is turned on, enter the following command:
# lanadmin -x vmtu n
Where n is theVM Host interface, as displayed by the hpvmnet command. For example, to verify
that TSO is on for lan0, enter the following command:
# lanadmin -x vmtu 0
Driver/Hardware supports TCP Segmentation Offload, Current VMTU = 32160
To turn TSO off on lan0, use the following command:
# lanadmin -X vmtu 0 0
Virtual MTU is set to 0
7.8 Do Not Configure VLAN Vswitches on HP-UX VLANs
Do not use the hpvmnet command to create a virtual switch that is associated with a VLAN port
on the VM Host (that is, a LAN created with lanadmin -V). This “nested VLAN” configuration
is not supported.
7.9 For VLANs Between VM Host and Guests, Turn Off CKO
Checksum offload (CKO) on the network interface used by the vswitch is turned off by default
during vswitch creation. When you use a VLAN vswitch for communication between guests
and the VM Host, turn off transmit checksum offload (CKO) on the network interface used by
the vswitch. On the VM Host, identify the PPA of the network interface for the vswitch using
the hpvmnet command. For example:
# hpvmnet
Name Number State Mode PPA MAC Address IP Address
======== ====== ======= ========= ====== ============== ===============
localnet 21 Up Shared N/A N/A
vmlan0 22 Up Shared lan0 0x00306ea72c0d 15.13.114.205
vmlan4 23 Up Shared lan4 0x00127942fce3 192.1.2.205
vmlan900 24 Up Shared lan900 0x00306e39815a 192.1.4.205
Check the status of the transmit CKO using the following command:
# lanadmin -x cko 4
Hardware TCP/UDP (IPv4) transmit checksum offload is currently enabled.
Hardware TCP/UDP (IPv4) receive checksum offload is currently disabled.
In this example, the VLANs are configured over the vswitch vmlan4. This vswitch is created on
PPA 4 on the VM Host. To turn off CKO on PPA 4, enter the following command on the VM
Host:
# lanadmin -X send_cko_off 4
Hardware TCP/UDP (IPv4) transmit checksum offload is currently disabled.
7.10 Restarting Vswitches
It is necessary to restart the vswitch when:
• You replace the physical network card associated with the vswitch.
• You change a VM Host IP address associated with the vswitch's network interface card.
• You change the network interface characteristics on the VM Host; for example, by using the
lanadmin command to change checksum offloading (CKO).
For information about how to restart vswitches, see the HP Integrity Virtual Machines Installation,
Configuration, and Administration manual.
44 Networking Information