Enable Large Receive Offload
Large receive offload (LRO) is a technique
for increasing the inbound throughput on high-bandwidth network
connections by decreasing CPU overhead. Without LRO, the firewall
drops packets larger than the configured maximum transmission unit
MTU, which is a maximum of 9216 bytes when the firewall is enabled
for jumbo frames. With LRO enabled, the firewall accepts packets
up to 64KB in size and the does not drop packets larger than the
configured MTU. Instead, it segments the larger packets into smaller
chunks of 9000 bytes. For example, if the VM1 sends a 64KB packet to
VM2 and the packet is divided into eight segments.
LRO is disabled by default
on new NSX deployments and upon upgrade. You can enable or disable LRO
and view the LRO status on through the CLI. Enabling LRO on the
VM-Series firewall automatically enables jumbo frames. Additionally,
LRO and TCP Segmentation Offload (TSO) must be enabled on VMXNET3
network adapter on the VM-Series firewall host machine.
- Verify that large receive offload and TCP segmentation
offload is enabled on the host.For information about LRO and TSO on the host machine, see the VMware vSphere documentation.
- Log in to vSphere and navigate to your host machine.
- Select
- Locate the following parameters and verify that their
value is set 1. A 1 indicates that the parameter is enabled on the
VMXNET3 adapter.
- For LRO—Net.Vmxnet3HwLRO
- For TSO—Net.UseHwTSO and Net.UseHwTSO6
- Enable LRO on the VM-Series firewall.
- Access the firewall CLI.
- Use the following command to enable LRO:
admin@PA-VM> set system setting lro enable - Reboot the firewall using the following command:
> request restart system - Verify the LRO is enabled with the following command:
admin@PA-VM> show system setting lro Device LRO mode: on Current device mtu size: 9192You can disable LRO using the command set system setting lro disable.